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Issue 10 December 2020

Journal

Sustainable Design & Applied Research in Engineering and the Built Environment

The SDAR Journal is a scholarly journal in sustainable design and publishes peer-reviewed applied research papers SDAR Cover 2020.indd 1

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CIBSE Ireland Region …

… just a click away CIBSE Ireland’s interactive website gives a comprehensive overview of the Institution’s aims, objectives, officers and committee members, along with details of its extensive CPD programme and technical evenings. It also includes regular news updates, and reports on inter-association activity, industry awards, participation in Government consultation bodies, and other promotional activity on behalf of the building services industry.

CIBSE Ireland is the leading organisation for information, guidance and advice on all building services related matters. Membership brings many benefits, including access to the full suite of CIBSE publications available online via the knowledge portal. For more information on how to become a member, or to progress to a higher grade of membership, log on now.

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Contents 2 Editorial 3 Readers’ Guide 5 An overview of recent findings on the effect of light on circadian rhythms Ben Ransley, University College London, UK

15 Optimisation of air source heat pumps in residential retrofits Seamus Hoyne, Limerick Institute of Technology Padraic O’Reilly, Limerick Institute of Technology Michael O’Shea, Limerick Institute of Technology

25 Atria, roof-space solar collectors and windows for low-energy new and renovated office buildings: a review. Brian Norton, Dublin Energy Lab, TU Dublin; Tyndall Institute UCC; MAREI: The SFI Centre for Energy, Climate and Marine Steve N.G. Lo, Department of Agriculture & Civil Engineering, University of Bath

33 Experience of spaciousness and enclosure:

Welcome

SDAR Journal 2020 I would like to congratulate the SDAR Journal on reaching its 10th issue. It is published once a year and is an excellent collaboration between the Technological University of Dublin (TU Dublin) and CIBSE Ireland. I particularly like, and commend, the mix of established and new authors, and the positive encouragement for more authors from industry. The papers are insightful and help us all to move towards a better and more sustainable built environment. That is why the access figures for the SDAR Journal are impressive – to date papers have been downloaded 41,000 times from 2,560 institutions from 166 countries worldwide, and now average 7,000 downloads a year. These peer-reviewed papers tell us about innovative practices that are comprehensively evaluated and evidence-based. They include postoccupancy evaluations, and cutting-edge professional and industrial practices in architecture, building services engineering and construction. This particular edition has an excellent mix of subjects and authors, and will undoubtedly prove insightful and enlightening for all our readers.

distribution of light in spatial complexity Ulrika Wänström Lindh, Jönköping University, Jönköping, Sweden Monica Billger, Chalmers University of Technology, Gothenburg, Sweden Myriam Aries, Jönköping University, Jönköping, Sweden

47 Improving the sustainability of the built environment by upskilling SMEs in Building Information Modelling through the Horizon 2020 BIMcert Project Barry McAuley, School of Multidisciplinary Technologies, TU Dublin Avril Behan, School of Multidisciplinary Technologies, TU Dublin

Michael Curran, Chairman, CIBSE Ireland

Editor: Professor Kevin Kelly, TU Dublin and CIBSE Contact: kevin.t.kelly@tudublin.ie Deputy Editor: Dr Barry McAuley

Paul McCormack, Belfast Metropolitan College

Contact: barry.mcauley@tudublin.ie

Andrew Hamilton, Belfast Metropolitan College

Editorial Team: Barry McAuley, Keith Sutherland, Kevin Gaughan, Yvonne Desmond, Pat Lehane, Kevin Kelly.

Eduardo Rebelo, Belfast Metropolitan College Sheryl Lynch, Future Analytics Consulting Ltd

Reviewing Panel: Prof Peter Boyce; Roger Hitchin; Raymond Reilly; Dr Martin Barrett; Dr Keith Sunderland; Dr Barry McAuley; Dr James Duff; Dr Kit Cuttle; Prof Kevin Kelly. Upload papers and access articles online:http://arrow.dit.ie/sdar/ Published by: CIBSE Ireland and the College of Engineering & Built Environment, TU Dublin. Produced by: Pressline Ltd, Carraig Court, George’s Avenue, Blackrock, Co Dublin. Tel: 01 - 288 5001/2/3. email: pat@pressline.ie Printed by: W&G Baird ISSN 2009-549X © SDAR Journal 2020. Additional copies can be purchased for F50

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Editorial Board Professor Brian Norton TU Dublin Professor Andy Ford London South Bank University Professor Tim Dwyer University College London Dr Hywel Davies CIBSE Mona Holtköetter CIBSE Ireland Professor Gerald Farrell TU Dublin Professor John Mardaljevic Loughborough University Professor Michael Conlon TU Dublin Professor David Kennedy TU Dublin Professor Tony Day International Energy Research Centre – Cork Professor Kevin Kelly Emeritus Professor TU Dublin, CIBSE President-Elect

Editorial At a time when scientists in the journal Nature say that the rate of ice loss in Greenland is greater than has happened in over 12,000 years, Ireland is way behind the curve in reducing harmful emissions. In fact, our emissions per head for buildings is significantly higher than the EU average. While the Irish governance framework objective is to reduce emissions by at least 7% per annum over the next 10 years and reach carbon neutrality by 2050, it remains to be seen if the legislation is truly ground-breaking, as is claimed by government. However, responsibility also rests with building professionals to reduce our impact on the built environment. Given our new Covid world, a massively-changed economy and work practices, not to mention Brexit, the only constant ahead is change. That said, decarbonisation will offer opportunities for environmental entrepreneurs who can identify future trends and public demand. The built environment requires innovative responses and resilient buildings, with the public demanding safer, healthier indoor environments. Building retrofitting, renewables and energy storage all figure high in future opportunities. How we heat our buildings will change dramatically. Better insulated homes need less heat while greener generation in Ireland is progressing well. Ireland’s wind generation continues to increase and plans are advanced for solar power to provide renewable electricity for 230,000 homes by 2030 – 10% of Irish households. The use of heat pumps and lower temperature heat emitters in buildings will increase as our energy mix in the electrical supply system becomes more and more renewable based. Climate change has a parallel with Covid-19 in that it knows no borders. Ireland’s agricultural emissions are five times those of the EU but the question must be asked … who is the polluter? The farmer or the consumer? Irish people do not consume five times the food of our European neighbours. If Ireland is an environmentally-friendly farming environment, then emissions should surely be allocated to the consumer. Likewise with regard to data centres. If Ireland is a good location globally to locate data centres due to free cooling, then emissions should be allocated based on who data is stored for. Otherwise, we would be allocating CO2 emissions on a disproportionate scale to oil-producing countries and that is not what happens, nor should it. Finally, unlike larger countries such as the UK, Ireland does not have the economy of scale to respond with the same breadth and depth to the challenges of global warming. However, we still have an important position within the EU, and we also need to maintain international collaborations inside and outside the EU. This includes the UK post-Brexit. Where would our building industry be without the research, Codes and Guides published by CIBSE? This journal is a joint publication between TU Dublin and CIBSE Ireland, and is underpinned by CIBSE UK. That will continue after Brexit.

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Readers’ Guide Non-visual effect of lighting – Ben Ransley, a post-graduate research student in UCL, provides an excellent literature review of recent research findings in the nascent research area of the non-visual effects of lighting. Those responsible for lighting our buildings need to understand that neuroscientific research is informing us about how our circadian rhythms are influenced by the lighting in our buildings and outside. Ben compares two new metrics, EML and CS, which will be of particular interest to lighting designers. However, this paper will appeal to a much broader audience because of the wellness aspects that apply to all of us.

Superhomes and heat pumps – As the energy mix in Ireland shifts to a more renewable mix, the demand for heat pumps will increase. This will become a more prominent source of heating for our buildings. Here, Seamus Hoyne, Padraic O‘Reilly and Michael O‘Shea from Limerick Institute of Technology, explain how to ensure that these systems are reliable and effective in their installations. This impressive research project examines residential retrofits in Ireland. The paper highlights the areas where air source heat pump systems can underperform and how to deal with these by making recommendations on how to ensure systems operate to their full potential and so minimise CO2 reductions.

Realising low-energy buildings – Professor Brian Norton and Steve N.G. Lo explain how solar gains can help us achieve near zero energy buildings by optimising built form, internal layout, position, type and area of windows. Solar gains can displace heating and lighting energy in most non-domestic buildings. The authors show how such approaches have been adopted to successfully realise many low-energy buildings.

Light, spaciousness and enclosure – We are delighted to welcome our first paper from Sweden to the SDAR Journal. This is an interesting paper by Ulrika Wänström Lindh, Monica Billger and Myriam Aries based on a complex space study with insightful findings about light and its impact on feelings of spaciousness and enclosure. It is an explorative study that has generated several new hypotheses, one of them being that the experience of space is not equal to the boundaries of the physical built room. It also sets the context and pointers for future research and studies on the topic. BIM – To help the construction industry, which generates 33% CO2 emissions and 40% of global energy, to be more innovative in responding to the challenges of sustainability, a multidisciplinary team from TU Dublin and Belfast Metropolitan College show how BIM training can be implemented in the built environment. BIM integrates sustainability and renewable concepts. This paper targets the broader skills gap agenda.

How to get published in the SDAR Journal The SDAR Journal is intended as a platform for you, as working engineers and building professionals, to publish your innovative work. It is a free-to-publish journal that is listed in the Directory of Open Access Journals and it is thus free to download papers from it. The SDAR Journal is a joint publication between Technological University Dublin and CIBSE Ireland. We have generous support from CIBSE UK, our reviewers, editorial team and editorial board, all of whom contribute their time and input free. We are here to support you publish your insightful cutting-edge designs and post-occupancy evaluations of low energy design. Your interests are our interests, with the intention of moving engineers from ideologically-based green initiatives towards evidence-based sustainable built environment solutions. Authors will critically reflect on their own work. We want to publish your work if it will help contribute to a more sustainable world. We will also help and support you to do that.

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School of Electrical and Electronic Engineering The School of Electrical and Electronic Engineering, Technological University Dublin (SEEE), is the largest education provider in the electrical and electronic engineering space in Ireland in terms of programme diversity (apprentice to PhD), staff and student numbers. TU Dublin (City Campus), formerly DIT (Kevin Street), is based in Dublin city centre and will be at new facilities at Grangegorman by September 2020. The University is founded on a long educational heritage (since 1887) and it prides itself on providing practice-based and professionally-accredited programmes across a variety of full-time and part-time options. The School also focuses on applied research with a strong emphasis on producing useful and novel ideas to help Irish industry compete globally. SEEE research is recognised for its impact and quality, which in many cases is on a par with that of the very best groups internationally.

SEEE Programmes Level 9 (Masters) MSc in Energy Management

TU208 or TU215

ME in Sustainable Electrical Energy Systems

TU207 or TU705 TU203

MSc in Electronic and Communications Engineering

Level 8 (Hons) BE in Electrical and Electronic Engineering

TU821

BE in Computer and Communications Engineering

TU821

BSc in Electrical Services and Energy Management

TU802, TU820 or TU018

BSc in Networking Applications and Services

TU819

Level 7 BEngTech in Electrical Services Engineering Engineering BEng in Electrical and Communications

TU714

BEngTech in Electrical and Control Engineering

TU705

Level 7

TU706

BEngTech in Electrical Services Engineering BE BETech in Networking Technologies

TU716

For further information on the SEEE contact: School of Electrical and Electronic Engineering, Technological University Dublin, City Campus, Dublin 8 Tel: + 353 1 220-5952/5022/5950 Email: seee.admin@tudublin.ie

www.dit.ie/electricalelectronicengineering/ TU SEEE SDAR Advert 2020.indd 1

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Enhancing Thermal Mass Performance of Concrete

An overview of recent ÀQGLQJVRQWKH HIIHFWRIOLJKW RQFLUFDGLDQ UK\WKPV

Ben Ransley UNIVERSITY COLLEGE LONDON, UK ben.ransley.19@ucl.ac.uk

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Abstract Light, traditionally for vision, also has non-visual effects on human physiology. Recent developments in neuroscience have demonstrated that light reaching the retina entrains the human circadian system to the natural light and dark cycle. Studies have shown that exposure to bright light during the day, particularly in the morning, may be as important as avoiding light at night for the healthy functioning of this system. This paper provides a summary of the key experimental studies which have driven understanding of this nascent subject forward. These studies are largely neuroscientific in nature, but their implications relate directly to building services engineering as the emergence of “circadian lighting” is bringing with it new metrics and standards for the environmental design of buildings. Two such metrics, Equivalent Melanopic Lux (EML) and Circadian Stimulus (CS), are examined and compared. It is shown that while care must be taken when adopting incomplete knowledge into practice, it is already becoming clear that much of our current lit environment is inadequate when seen through the lens of non-visual light.

Keywords Circadian rhythms; non-visual light; daylight; ipRGCs; circadian stimulus; Equivalent Melanopic Lux. Acronyms CS: Circadian stimulus DLMO: Dim light melatonin onset EML: Equivalent Melanopic Lux ipRGC: Intrinsically photosensitive retinal ganglion cell LAN: Light at night LRC: Lighting Research Centre SCN: Suprachiasmatic nucleus 6

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An overview of recent findings on the effect of light on circadian rhythms

1. Introduction “Our biology and our society seem to be in serious opposition, and it is not clear which force will win. Although it is true that millions of years of natural selection have made us what we are, our problem is that we don’t really understand what that is.” (Foster & Wulff, 2005, p.413) That light, health and wellbeing are connected has been known intuitively long before the biological sciences began to discover why. Sunlight exposure at sanatoria situated high in the Swiss Alps was used for the treatment of tuberculosis in the late 19th century, and at the beginning of the 20th century physicians began using artificial light sources to replicate its effects (Wells, 2006). Before the use of antibiotics became widespread, light was considered a significant player in the treatment of disease, and hospitals were built away from dense city centres to avoid the lack of daylight and fresh air (Volf, 2020). Beginning in the 1980s, light began to be used as a treatment for depression (Rosenthal et al., 1984) and seasonal affective disorder gained popular recognition. However, knowledge of light’s relationship with health is shifting away from the treatment of acute cases of illness and towards a broader conception of everyday wellbeing. This is largely due to the discovery of new photoreceptors in the retina known as intrinsically photosensitive retinal ganglion cells (ipRGCs) (Berson et al., 2002), which are crucial in the synchronisation of human circadian rhythms. Circadian clocks are present in almost every cell in the body (Mohawk et al., 2012), and their proper synchronisation, or entrainment, has been linked to lower rates of cancer, obesity, substance addiction and neurodegenerative diseases such as Parkinson’s and Alzheimer’s (Roenneberg & Merrow, 2016). In industrialised societies where most people spend 90% of their time indoors (Klepeis et al., 2001), it is important that we understand what these non-image-forming effects of light are, and what quality and quantity of light stimulates them.

The paper discusses the types of research that have been conducted, what they are able to tell us, and what their limitations are. It will demonstrate that while many pieces of the puzzle have been put together, the full extent of our relationship with light and the natural environment is still very much incomplete.

2. Light, melatonin and circadian entrainment The connection between light and circadian entrainment had been suggested well before the discovery of the ipRGCs. Early research in the field of chronobiology had shown that in the absence of any lightdark cycles, a wide variety of organisms ceased to entrain their internal

In the early 1980s, seeking to investigate this effect in humans, Charles Czeisler and his team exposed two young men to a series of lighting conditions over the course of 66 days (Czeisler et al, 1981). At the time, other environmental time cues, or zeitgebers as they were known, were thought to be at least as powerful as the lightdark cycle in the entrainment of humans (Aschoff et al., 1971). These included factors such as knowledge of the time of day (eg. alarm clocks), social interaction and the timing of meals, rest and activities. However, Czeisler’s study showed that even with all these other cues removed, modulation of light by itself was able to properly entrain the subjects (Figure 1). While this finding was significant, and elevated the importance of light in human chronobiology, the study provided no explanation in physiological terms. In other words, light may simply have been acting as another psychological zeitgeber that influenced the subjects’ decision to go to bed. It was a contemporaneous study by Lewy et al. (1980) that first connected light exposure to acute human melatonin suppression. Melatonin is a hormone produced in the pineal gland at night-time by both diurnal and nocturnal animals and is hence often referred to as the “darkness hormone” (Arendt, 1998). Production of melatonin is regulated by the suprachiasmatic nucleus (SCN) in the brain, which is the master clock responsible for keeping circadian time. The SCN is in turn connected via the retinohypothalamic tract to the retina of the eye, a pathway which in many mammals is used for the transmission of light-dark signals for entrainment (or photoentrainment). TIME OF DAY (HOURS) 00 00 SCHEDULED REST-ACTIVITY

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This paper divides the literature into two main sections. The first covers work that has revealed the mechanisms in the eye and brain that connect light, melatonin production and circadian entrainment (Section 2). The second is focused more on the specific details of what kind of light is required to stimulate this system (Section 3). This includes the colour of light, the quantity needed, the effect of timing and the effect of spatial distribution in the field of view, and is related closely to resultant standards, metrics and practical recommendations.

clocks to 24-hour cycles of activity and would instead gradually shift their sleep-wake cycles continually forward or backward over time (Pittendrigh, 1960). This is akin to owning a slightly fast or slightly slow watch which needs adjusting every day – the longer one leaves it unchecked the more out of time, or phase shifted, it becomes. In the case of the biological clock, this adjusting is achieved by the rising and setting of the sun.

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Figure 1 – Triple plotted data showing the rest-activity cycle of one of Czeisler’s subjects. Sleep periods shown with black bars. Ethically questionable by today’s standards, the chart shows the subject spent 66 days living in an environment with no knowledge of time and limited social interaction. Between the unscheduled and scheduled conditions (labelled left), the only environmental factor changed was the cycle of light and dark. Triple plotting allows the phase shifting patterns to be more easily seen. Adapted from Czeisler et al. (1981).

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However, as already discussed, doubt surrounded the mechanism by which humans were being entrained, as previous studies had failed to detect melatonin suppression after light exposure. As a result it was proposed that while other mammals are entrained by light, humans have different, unique pathways derived from social cues, thereby elevating them above other species (Perlow et al., 1980). Lewy’s study, which employed higher light levels than previous studies, completely dispelled this theory. Blood melatonin concentration was measured after night-time exposure to illuminances of 500, 1500 and 2500 lux at the eye. The result was a clearly measurable suppression of the hormone, thereby drawing a direct connection between light exposure and melatonin suppression. Melatonin suppression is, however, only a proxy measure for circadian impact, and what the results did not show was evidence of actual sleep-wake phase shifting. Taken together though, the Lewy study and the Czeisler study (which did show phase shifting) provide evidence that the human SCN and the control of melatonin production is directly connected to light exposure. While this evidence was important, the real paradigm shift came as a result of a series of neuroscientific discoveries that connected specific cells in the retina to the SCN. Around the beginning of the 21st century, a third photoreceptor in the eye was uncovered in addition to the classical rods and cones. Despite the ethically questionable nature of such practices, research undertaken by genetically engineering rodless and coneless mice have been particularly important to this process (Foster & Hankins, 2002; Lucas et al., 1999). Lucas et al. showed that these mice could still photoentrain despite a complete lack of rods or cones, and that mice with their eyes fully removed could not, a result that pointed positively towards the existence of a novel non-rod, non-cone photoreceptor in the eye. However, doubts still remained due to a lack of anatomical evidence (Rea et al., 2002). A study published in 2002 began to provide this evidence (Berson et al., 2002), confirming the photosensitivity of the ipRGCs in the eye. By bathing a rat retina in chemicals that prevented any activity from the rods and cones, researchers in the Berson study could still detect electrical signals that projected to the SCN. In a second phase of the experiment in which the ipRGCs were entirely physically isolated from the retina, there was still a detectable signal in response to light, thereby demonstrating their intrinsicallyphotosensitive nature. By then exposing the cells to a series of narrow band light sources, the same study went on to determine that the ipRGCs respond most to light of around 484nm, towards the blue end of the light spectrum. This latter point indicated that melanopsin was the most likely candidate photopigment, one which had already been detected by others in frogs as well as the human retina (Provencio et al., 1998, 2000). This was confirmed in subsequent studies that involved the removal of the specific melanopsin-producing gene from rodents, with the result of desensitising the ipRGCs, thereby proving that melanopsin is the photopigment responsible for the ipRGC light response (Lucas et al., 2003; Panda et al., 2002). The ipRGCs and their connection to the SCN are not an entirely isolated system. Research has demonstrated that while the ipRGCs have an intrinsic response to light which they pass downstream to

the SCN, they also receive extrinsic upstream input from the rods and cones, a property common to other ganglion cells in the eye (Belenky et al., 2003; Dacey et al., 2005; Perez-Leon et al., 2006). Experiments in genetically-engineered mice have shown that this input can influence circadian functioning (Hattar et al., 2003). With the photosensitive element of the ipRGCs disabled, Hattar et al. showed that mice were still able to entrain to light-dark cycles, albeit to a lesser extent. When those ipRGCs were killed entirely, however, the entrainment ceased altogether (Güler et al., 2008). This shows that this newly-discovered rod and cone input to the circadian system operates solely through the ipRGC cells. As discussed in the next section, these findings may complicate the determination of spectral efficiency functions for circadian lighting, in that circadian stimulation cannot simply be equated with the intrinsic response of the ipRGCs. Similarly, the connection between the ipRGCs and the brain is not limited to the SCN and not limited to the function of circadian entrainment (Schmidt et al., 2011). There exist at least five sub-types of ipRGC found to be responsible for functions such as the regulation of pupil size (Lucas et al., 2003), contrast detection (Schmidt et al., 2014) and exacerbation of migraine intensity (Noseda et al., 2010). This further complicates the idea of circadian-specific lighting in that circadian effects cannot be manipulated by light independently of other brain functions.

3. Characteristics of circadian light 3.1 Spectral characteristics Light of any kind is distinct from radiant power in that it is defined according to the sensitivity of the human eye. To translate radiant power into light, it is necessary to apply a weighting system, or luminous efficiency function. Using such a function, wavelengths to which the eye has a greater sensitivity contribute more to the quantity of light than others, and vice versa. This weighting is usually done according to one of two models of the visual system: photopic or scotopic vision (though additional models exist). Photopic vision, and its associated efficiency function V(h , is based on relatively bright lighting conditions. Under these conditions the brain primarily uses the three cone photoreceptor types to see, and this is the conventional characterisation of light upon which the candela and lux metrics are based. In scotopic conditions, such as under moonlight, the brain primarily uses the rod photoreceptors to see. Rods have a different spectral sensitivity to the cones and so a different efficiency function is used V’(h , though scotopic units are relatively uncommon in practice. These two abilities of the eye – seeing in the day and seeing in the night – are now accompanied by a third, non-visual one: entraining the circadian clock. As such, a new efficiency function is needed. Two early landmark experiments (Brainard et al., 2001; Thapan et al., 2001) sought to solve this problem. Both studies exposed their subjects to multiple discreet narrow band light sources at multiple intensities at night via a full visual field device known as a Ganzfeld dome. They measured the resulting drop in melatonin in the blood for each wavelength and intensity. Despite there being differences between the two studies (in the Brainard study, subjects were

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An overview of recent findings on the effect of light on circadian rhythms

Melanopic lux and the EML metric is therefore a measure of the impact of light on human circadian rhythms in the absence of rods and cones. As a result, its spectral range (peak sensitivity: 480nm, Figure 2) differs from that of empirical melatonin suppression responses in normal humans as per Brainard (2001) and Thapan (2001) (peak sensitivity: ~460nm). This apparent mistuning was not by mistake. The authors of the 2014 Lucas paper published sensitivity functions for all five photoreceptors independently, without claiming the ability to predict precisely how they might interact with each other and what signal they might eventually send to the brain. They wrote “it is not yet possible to predict the non-image-forming impact of a given illuminant based on its intensity and spectral composition” (Lucas et al., 2014, p. 7).

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Figure 2 — Data from the Brainard et al. (2001) and Thapan et al. (2001) studies plotted together with efficiency functions for EML (labelled “Melanopic model”) and Gall and Bieske (2004). Also shown is an early function (labelled “Lens-adjusted 460nm ospin”) which was based on a hypothetical photopigment with peak sensivity at 460nm. The Brainard et al. study from 2008 plotted here measured only responses to light at 420nm. Adapted from Rea et al. (2012). Colourised by the author.

irradiated for 90 minutes as opposed to 30, and in the Thapan study the subjects had two control days before exposure whereas in the Brainard they had none), the resulting data from the two studies correlated well and the authors concluded with similar proposed ranges for peak melatonin suppression (446-477nm in Brainard et al. and 457-462nm in Thapan et al. – both blue as perceived by the photopic system). Gall and Bieske used the Brainard and Thapan melatonin suppression data to attempt to define a circadian metric (Gall & Bieske, 2004). They compiled the results from the two studies and interpolated an efficiency function for light-induced melatonin suppression using a best-fit methodology, with a resulting peak sensitivity at around 460nm (Figure 2). In the paper, Gall and Bieske go on to suggest the modification of existing light meters as approximate methods of measuring their new metric. The Gall and Bieske function would go on to be used in the German pre-standard DIN V 5031-100 (2009) (now withdrawn). However, this early effort to create a circadian efficiency function is limited in accuracy in that it does not account for a key feature of the Brainard and Thapan data – a distinctive spike in spectral sensitivity at around 500nm (Figure 2). 3.1.1 Equivalent Melanopic Lux (EML) Another notable circadian metric that has entered into building standards, but which nevertheless has its own limitations, is Equivalent Melanopic Lux (EML). EML is based on the spectral sensitivity function for melanopsin operating in isolation and does not take into account the upstream influence of the rods and cones (Lucas et al., 2014). The melanopic efficiency function was introduced by Al Enezi et al. (2011), who demonstrated that in mice lacking rods and cones, light tuned to the sensitivity range of melanopsin was most effective in altering their circadian rhythms. Adjustments were later made to account for variations between human and rodent pre-receptoral light filtration (Lucas et al., 2014).

Nevertheless, EML was adopted by the WELL Building Standard v1.0 in 2015 as a measure of circadian effectiveness (International WELL Building Institute, 2015). In the context of design and engineering, it could be argued that EML is “accurate enough” in that it would not lead to drastically inappropriate decisions. Light sources biased towards longer wavelengths will avoid circadian disruption at night and vice versa. For the purpose of a design guideline it may be sufficient. However, as a standard unit to measure circadian light it must be subject to greater scrutiny. 3.1.2 Circadian Stimulus (CS) Since 2005, researchers from the Lighting Research Centre (LRC) at Rensselaer Polytechnic Institute in New York have been developing their own metric dubbed Circadian Stimulus (CS) (Rea et al., 2005, 2010, 2012; Rea & Figueiro, 2018). What sets CS apart from EML is principally the modelling of rod and cone input to the ipRGCs, a mechanism which is complex partly because it involves subadditive brightness perception. In an additive model such as EML or the photopic luminous efficiency function V(h , light of different wavelengths delivered simultaneously to the eye simply add together in the perception of brightness. However, the opponent system of colour vision means that within one opponent channel (blue-yellow or red-green), light of one wavelength range can serve to cancel out its opponent wavelengths when delivered simultaneously, resulting in a sub-additive output from that channel as a whole. In the circadian system, research suggests the ipRGCs are reliant on input from the blue-yellow opponent channel (Dacey et al., 2005; Figueiro et al., 2004). The blue-yellow channel balances stimulation signals from the S (blue) cones against the combined M (green) and L (red) cones so that in the case of polychromatic light sources there is the possibility of spectral opponency. In the CS model, this means that the relative spectral power when all photoreceptors are considered can dip below zero for wavelengths of light towards the red and green area of the spectrum (Figure 3, next page). Rods are also implicated in that they control the sensitivity of the cones. The integration of rod and cone input in the CS model results in a closer fit to the Brainard and Thapan data than provided by other metrics (Rea et al., 2012). Rea et al. (2012) found a mean residual error for CS of 0.06 compared with 0.12 for the Gall and Bieske function, and 0.23 for EML when compared with the Brainard and Thapan data.

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3.2 Intensity and timing

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Figure 3 – Three spectral weighting functions used for calculation of Circadian Stimulus. B-y<0 (dashed line) applies to polychromatic light sources with a warm appearance, while b-y>0 (solid line) corresponds to a cool appearance. Under the cool lighting condition, the circadian response exhibits spectral opponency, causing luminous efficiency to dip below zero around 560nm. Also shown is the response to monochromatic illuminants (dotted line). This curve fits the Brainard and Thapan data closely as those experiments were carried out under monochromatic lighting conditions. 300 scotopic lux is the illuminance at the eye. Adapted from Rea et al. (2018).

3.1.3 EML versus CS Research into the interaction between ipRGCs and other photoreceptors is still incomplete (Spitschan et al., 2017), and very recent research has even shown that one subtype of ipRGC has an inhibitory, dampening effect on circadian phase shifting in mammals (Sonoda et al., 2020). The neurological pathways responsible for circadian entrainment are still in the process of being gradually unearthed, something which casts doubt on the validity of the CS model. In addition, the CS metric is more complex than others. In order to model the opponent colour channels in the retina, the CS algorithm requires the input of full spectral power distribution information and the selection of one of two efficiency functions, one for warm sources and one for cool sources. A more recent version has also indicated that illuminance levels further modify these functions (Rea & Figueiro, 2018). In contrast, EML could in theory be measured using a conventional photometer modified with a curve matching filter appropriate to the melanopic sensitivity function. Another potential problem with CS (as well as Gall and Bieske’s metric) is that it is based on nocturnal melatonin suppression and not circadian phase shifting. While these two things are very closely related, there is mounting evidence suggesting melatonin suppression and circadian phase shifting are not inseparable in their spectral or temporal response (Gooley et al., 2010; Najjar & Zeitzer, 2016; Rahman et al., 2018). CS is not perfect, and the state of neuroscience research is by definition never complete, but the metric has gained traction in lighting research (Chen et al., 2020; Leslie et al., 2012; van Creveld & Mansfield, 2020) and the question of whether it is suitable for implementation in lighting practice is still in discussion (Ashdown, 2019; Soler, 2019).

Aside from concerns for the spectral qualities of circadian effective light, the amount of light and the timing of that light have also been the subject of extensive research. Estimates have reduced over time. An early study showed that for a 60-minute exposure to light at night (LAN), minimum light levels for acute melatonin suppression were 350 lux at the eye (Mclntyre et al., 1989). Another study, using longer exposures of 120 minutes, found that levels of just 285 lux were sufficient (Aoki et al., 1998). However, these studies measured only acute melatonin suppression rather than any subsequent phase shifting effects. To determine the effect on phase shifting, it is necessary to expose subjects to LAN and then subsequently measure the shift in circadian phase. One way to do this is to measure the difference in dim light melatonin onset (DLMO) between a control night and the night immediately after the LAN intervention. Employing this methodology, one study found that LAN as low as 100 lux for 6.5 hours was capable of delaying DLMO as well as acutely suppressing melatonin (Zeitzer et al., 2000). More recently, research has suggested that a level of 30 lux for only 30 minutes (Figueiro et al., 2006) or 0.05 CS (Figueiro & Rea, 2013) is a safe working threshold for LAN. These levels are below those emitted to the retina by self-luminous displays like PCs, tablets and e-readers, and are not sufficiently mitigated by the use of apps that shift the spectral composition of those displays (Nagare et al., 2019). One study found that outdoor LAN in the business districts of Shanghai and Hong Kong was found to exceed the 0.05 CS threshold in 47% and 86% of tested viewpoints respectively (Chen et al., 2020). These low thresholds suggest that the effects of our urban environment could be at serious odds with circadian health. Two studies conducted at the University of Colorado provide compelling evidence for this by directly comparing the influence of electric and natural lighting environments on melatonin timing (Stothard et al., 2017; Wright et al., 2013). Participants in the studies spent one week of a two-week protocol in their normal urban environment and the second week on camping trips in the Rocky Mountains, with one study taking place in winter (Stothard et al., 2017) and one in summer (Wright et al., 2013). In the natural light condition participants experienced average daytime illuminances up to thirteen times that of the artificial condition, and LAN was restricted to a campfire. Melatonin onset and offset were measured before and after the week-long camping trip in lab conditions. Both the summer and winter studies showed that the natural light environment resulted in significantly earlier phase timing (Figure 4, next page). The studies had a particularly marked influence on subjects who habitually wake up and go to bed later (known as late chronotypes). These subjects experienced greater phase shifting effects as a result of exposure to natural light, such that their sleep-wake phase was closer to that of the other participants. This is significant in that late chronotypes are particularly likely to suffer from a problem known as “social jetlag” (Wittmann et al., 2006). Social jetlag occurs when people fail to adjust their circadian timing to the demands of society (usually work or school), a problem which is exacerbated when they sleep in during the weekends. This in turn leads to greater negative health outcomes such as daytime

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Seasonal Melatonin Rhythms A Electrical Lighting Melatonin Onset

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Figure 4 – 24-hour plot of melatonin phase during summer and winter relative to solar darkness. Subjects were exposed to one week of either normal natural and electrical lighting in an urban environment (A) or one week of natural lighting while camping (B). Timing of solar darkness is represented by the black bars. Closer correlation between melatonin on- and off-set and the solar cycle is shown in the natural condition. Note also that subjects adapted to the seasons, experiencing longer melatonin duration in the winter compared with the summer. Adapted from Stothard et al. (2017).

sleepiness, diabetes, mood disorders, substance addiction and obesity (Stothard et al., 2017). By promoting a later circadian cycle, modern artificial lighting environments may be a significant contributor to this problem. Similar to the negative influence of LAN, research has also shown the positive influence of bright light during the daytime for robust sleep cycles, something which is likely to have been a contributing factor in the Colorado experiments. One study measured the morning light levels experienced by a large subject group in an office environment (Figueiro et al., 2017). The aim of the study was to determine how exposure to relatively bright morning light affected sleep and mental health outcomes. Instead of using brief light interventions as in most LAN studies, the emphasis was on measuring existing light conditions via the use of a wearable light meter throughout the day. The results showed that subjects who experienced bright light in the mornings were less likely to report depression and experienced lower sleep onset latency and better self-reported sleep quality.

Bright light in the study was defined as light reaching the LRC’s recommended CS value of 0.3 or over (roughly equivalent to daylight of 180 lux or 200 EML measured vertically at the eye). This is still relatively dim when compared with an overcast day (approx. 1000 to 10,000 lux) and supports the application of the WELL standard’s higher recommendation of 240 EML from 9am to 1pm (though not necessarily the lower 150 EML option). However, one study using similar EML targets for artificial lighting found no significant effect on sleep and circadian phase outcomes (Ticleanu & Littlefair, 2020). More research in real world scenarios is needed to confirm the effects of applying daytime circadian light exposure recommendations. Prior exposure to bright light in the day may also have positive circadian effects by reducing subsequent sensitivity to LAN (Hébert et al., 2002; Kozaki et al., 2016). Early studies on people working in Antarctica found that during winter, when the sun does not rise for months and ambient light reaches a maximum of 500 lux, it took significantly less light to suppress melatonin at night when compared with a summer condition, in which ambient light was often at 100,000 lux during the day (Owen & Arendt, 2002). These effects have been shown in less extreme conditions, with studies taking place over the course of weeks (Hébert et al. 2002) and even a 24hour period (Kozaki et al., 2016). It has also been shown that blue-enriched light in the morning reduces the phase-delaying effects of LAN (Münch et al., 2017). This has implications for the validity of recommendations made regarding LAN in that sensitivity is dependent on individual prior light history. Broadly, the studies indicate that exposure to bright light during the day, particularly in the morning, is as important as avoiding LAN for circadian entrainment. 3.3 Other characteristics of circadian light As has been covered in this section, spectral composition, quantity and timing are all variables that need to be taken into account when discussing circadian light. However, more variables are emerging. The ipRGCs have been described by the LRC as “blue sky detectors” for their sensitivity to blue light (LRC, 2006), but this term may be accurate not only in terms of colour but also in terms of vertical distribution in the visual field. Glickman et al. (2003) found that by exposing only the upper retina, which is responsible for seeing below the horizon, to 200 lux at night, melatonin suppression was not significantly different from an entirely dark condition. The implication here is that circadian disruption will be significantly reduced if designers keep LAN to the lower half of the visual field. Interestingly, this resonates with lighting designer Richard Kelly’s assertion in the 1950s that light above eye level is “formal” while below eye level it is “informal or cozy” (Kelly, 1952, p.30). This echoes the polarity between high bright sky light in the day and low dim firelight in the evening, and it could be argued in this case that research is catching up with design intuition.

4. Conclusion There is a need in modern society to introduce light into otherwise dark environments. In industrialised countries, more and more people around the world have moved their lives indoors, into light that is orders of magnitude less than it is outdoors. Added to this, there is a

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SDAR Journal 2020

need to extend the solar day into the night, to accommodate working and social lives. The problem is that thus far, this light has been for one purpose: vision. As discussed in this paper, recent science is beginning to reveal that humans use light for purposes other than vision. Developments in neuroscience have been instrumental in understanding the circadian effects of light on the eye and brain, as have attempts to quantify the spectral and temporal response of the circadian system. We now know that light towards the blue end of the spectrum is most effective, and that bright light during the day should be combined with lower levels of light at night for robust circadian entrainment. While the research is far from conclusive, and metrics and standards are still up for debate, incorporating these principles into daily life would have a significant impact on health and wellbeing. However, in the time of the COVID-19 pandemic, “daily life” has changed dramatically for many people, as varying degrees of lockdown have become the “new normal”. As people spend less time in offices or commuting and more time at home, they may become less likely to go outside. In May 2020, the LRC surveyed around 600 people who worked from home during lockdown and found that subjects who described their indoor environment as bright or spent time outside during the morning experienced less anxiety, less daytime sleepiness and better sleep quality (LRC, 2020). This could mean that while people work from home, raising awareness of light exposure and encouraging light-seeking behaviour is an important factor in promoting resilience and health. Beyond lockdown, the potential for buildings to be considered either beneficial or detrimental to our health provides a greater incentive than ever for building owners, designers and engineers to be attentive to light and circadian rhythms.

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Acknowledgments I thank Dr Kevin Mansfield (University College London) for both his teaching on the Lighting Research Module and his comments on the manuscript; Dr Edward Barrett (University College London) for his support in the submission process; and also Mike Hankin (University of the Arts London) for many constructive discussions during the formative stages of writing this paper.

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LIMERICK INSTITUTE OF TECHNOLOGY padraic.oreilly@lit.ie

Michael O’Shea

LIMERICK INSTITUTE OF TECHNOLOGY michaelp.oshea@lit.ie

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Abstract Correctly applied air source heat pumps (ASHPs) are a proven technology that can reliably and effectively replace fossil fuel heating systems and achieve targeted heating-related CO2 reductions. However, poor-quality system design, installation or commissioning can lead to higher than expected running costs and poorly-performing heating systems, thus resulting in lower than expected CO2 savings. The retrofit ASHP systems studied in this research in residential retrofits in Ireland had significant engineering input at design stage, and comprehensive oversight during the installation and commissioning stages by the engineering team. Following analysis, most of the systems performed in line with, or exceeded, predictions but further opportunities for optimisation were identified. The research highlights the need for increased focus and resources to be applied by commissioning engineers to ensure that all ASHP installations are successful, a point that is especially critical in the context of the Irish Climate Action Plan targets of 500,000 retrofitted homes and the installation of 400,000 retrofit heat pumps by 2030 (Government of Ireland, 2019). This paper presents recommendations on how the ASHP installation process can deliver systems that operate to their full potential in terms of energy efficiency and CO2 reductions.

Keywords Air source heat pump, retrofit, compressor cycle, defrost, commissioning, handover. Abbreviations ASHP: Air source heat pumps; CO2:Carbon Dioxide; UFH: Underfloor heating; SH20: Superhome 2.0; LIT: Limerick Institute of Technology; TEA: Tipperary Energy Agency; KPIs: Key performance indicators; COP: Coefficient of Performance; SPF: Seasonal Performance Factor; CC: Compressor cycling; SH2.0_HS1: Superhomes 2.0 heating season 1; SH2.0_HS2: Superhomes 2.0 heating season 2; WCC: Weather compensation curve; Tout : Outside air temperature, °C; Tsf : Set flow temperature; Tf : Flow temperature; RH:Relative Humidity. 16

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1. Introduction

2. Background

Superhomes is an approach to the retrofitting of residential buildings that has been pioneered by the Tipperary Energy Agency CLG (TEA … www.tippenergy.ie). Superhomes has completed 311 retrofits since 2015 and the Limerick Institute of Technology (LIT) has collaborated with TEA to research various aspects of the deep retrofit process, including the Superhomes 2.0 (SH2.0) project(LIT, 2019) which had as its main focus the optimisation of ASHPs in deep retrofit.

SH2.0, funded by the International Energy Research Centre (LIT, 2019), ran from May 2017 to April 2019, collecting and analysing data from 20 ASHP systems designed and installed in domestic deep retrofit projects funded by the Sustainable Energy Authority of Ireland (SEAI). System design was advised by CIBSE guidelines (CIBSE, 2016) and IS EN standards (NSAI 2003, 2007, 2012). The design process involved carrying out room-by-room heat loss calculations to calculate an overall space-heating requirement and thereby select a heat pump with this heating capacity.

ASHPs are electrically powered renewable heating devices installed as heat generators in renewable heating systems. Heat pumps harness low temperature ambient energy from outside air, upgrading its temperature as it passes through the refrigeration process before transferring the upgraded heat into the water-based heating system in the dwelling. Space heat is provided through low-temperature emitters such as underfloor heating or correctly-sized radiators, and domestic hot water is produced in specially-designed storage cylinders. Typically, for every 3.5 units of heat energy supplied to the house, 2.5 units come from the ambient air and can be considered renewable energy. The remaining one unit of heat energy is obtained from the mechanical energy of the compressor added to the flow of energy through the heat pump. No fossil fuels are burnt on site and if homeowners purchase their power from a renewable supplier, they can consider their heating system to have zero CO2 operating emissions. Aside from the potential to reduce CO2 emissions, lower running costs are another attraction for homeowners considering installing a heat pump … the annual running cost of an ASHP would typically be 53% that of an oil boiler, 40% of natural gas or 31% of an LPG boiler (SEAI, 2109). This benefit must, however, be balanced by the extra capital cost involved with a heat pump installation where a period of 5-7 years may be required for the annual savings to overtake the extra capital spend over and above that of a boiler installation. Heat pumps have been installed commercially in Irish homes since around 2000. The design, installation and commissioning processes are more sophisticated that those traditionally employed for oil and gas-fired boilers due to the need for the overall system to operate at lower temperatures. Traditional fossil fuel boiler systems operate at flow temperatures in the region of 75°C and buildings built prior to 2005 typically have higher heat losses due to poorer insulation standards, when compared to 2020 standards. For these buildings, fossil fuel boilers were generally sized with a heat output significantly more than the peak heat load of the house, thus enabling relatively quick heat-up times. For heat pumps, equipment capacity should be much closer to peak space heating load, with design decisions to be made about whether to use back-up heaters to cater for peak demand (NSAI, 2007). This means that the sizing of domestic heating systems using heat pumps is a much more precise exercise than previously employed for fossil fuel boilers. Heat pumps represented new technology for most homeowners in the SH2.0 project and, while it was evident that most did not engage with the system controls, preferring instead to depend on the installer to set the system up and not to make any adjustments themselves, all of the homeowners in the study group provided very positive feedback from their experience with the systems.

The nature of the space heating emission systems varied across the 20 houses – 12 were heated exclusively by radiators, in which case existing radiators were replaced by new radiators sized to cater for the peak heating load with flow temperatures of 48°C; eight houses had underfloor heating in the living areas of the house, with three of these being newly-installed during the retrofit process; while five reused existing underfloor heating (UFH) systems. Of the eight houses with UFH systems, five had radiators while three had UFH in sleeping areas. Table 1 presents an overview of the 20 systems. Space heating control was managed by time schedules and room temperature thermostats. Houses with radiators in both living and sleeping zones had one master thermostat for each zone. This was set to achieve comfort levels during specific time slots, outside of which the units controlled to an adjustable set-back temperature. Superhome Total floor BER Reference area (m2) SH001 SH005 SH006

167 229 191

A3 A2 B1

SH009 SH014 SH016 SH018

214 203 296 133

A3 A3 A2 B1

SH020

303

A3

SH031 SH067 SH073

143 175 245

A3 A3 B2

SH076 SH086 SH103 SH123 SH127 SH139 SH149 SH202 SH212

231 201 196 215 168 227 227 148 129

B1 A3 A3 A3 A3 A3 A3 B1 B3

Heat Emitter Zone 1

Heat Emitter Zone 2

ASHP Capacity (kW)

Radiators Radiators UFH and Radiators UFH UFH Radiators Radiators and Aga UF and Radiators Radiators UFH UFH + 1 Radiator Radiators Radiators Radiators Radiators Radiators Radiators Radiators UFH UFH

Radiators Radiators Radiators

8.5 11.2 8.5

Radiators UFH Radiators Radiators

11.2 11.2 11.2 7.5

Radiators

16

Radiators Radiators Radiators

8.5 8.5 11.2

Radiators Radiators Radiators Radiators Radiators Radiators Radiators Radiators Radiators

8.5 8.5 8.5 8.5 8.5 11.2 8.5 8.5 8.5

Table 1: Overview of SH2.0 test sites.

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3. Heat pump performance research methodology

The dataset for SH2.0_HS1 was assessed to determine the scale of CC occurring across the systems. Measures to optimise CC were identified and applied and further analysis conducted on SH2.0_HS2 data to determine the relevant impacts. ASHP COP increases as the difference between the outside air temperature and flow temperature reduces. Thus, ASHP space heat-ing systems are classified as low temperature systems and typically use underfloor heating or radiators as room heat emitters. When working with heat pumps, underfloor heating systems are designed to deliver peak heat loads with flow temperatures in the range 30-35°C, while radiator systems are typically designed for peak flow temperatures in the range 45°C/55°C. The ASHPs in the study all had the option of being controlled using weather compensation curves (WCC), where the target flow temperature is automatically adjusted in response to changing outside temperature. Following SH2.0_HS1, amendments were made to WCC across dwellngs to determine the impact on AHSP performance, in particular on CC and COP. A case study is presented of one of these field trials.

The purpose of SH2.0 was to research optimisation of real-world residential energy retrofit installations that included ASHPs. To this end, LIT was furnished with data and access to the installations for the purposes of carrying out tests over a two-year period. Opportunities such as this to assess the energy performance of systems in realworld buildings are limited as evidenced by the lack of performance data on ASHPs when reviewing the literature. SH2.0 ASHP data was available at a minute-by-minute scale, thus allowing for detailed analysis of performance factors. Data was collected in three ways – remote login to the manufacturer’s platform, site visits to collect data on SD cards, and downloads provided from the manufacturers. Quality assurance measures were employed to ensure data quality was to the highest levels. These data sources enabled macro assessment of the performance of each ASHP in terms of Key Performance Indicators (KPIs) such as Coefficient of Performance (COP), average flow temperature and compressor cycles, as well as detailed analysis of operating events on a minuteby-minute basis. In some cases, KPIs were taken directly from the monitored data while specific algorithms were developed for the quantification of other metrics, e.g. compressor cycles (CC). Data was collected over two heating seasons (Oct 2017 to April 2018 and September 2018 to April 2019).

3.2 Defrosting and the impact of heat pump sizing At low outside temperatures (Tout) and high relative humidity (RH), ice starts to build up on the surfaces of the evaporator during AHSP operation. Eventually, this ice causes a reduction in heat transfer from the outside air to the refrigerant. The ASHP controller will detect this occurrence and initiate a de-frost cycle whereby the refrigeration system is reversed so that hot gas enters the evaporator, thus causing the ice to melt. The process typically lasts three to four minutes and involves energy consumption by the compressor as well as a temporary interruption of the ASHP’s heat delivery to the house. The main considerations for the operation of the ASHP system resulting from the defrost process are: 1. The energy required to complete the process with no resultant heat to the house; 2. The effect of reducing output on COP as the ice builds up; 3. Defrost interruptions preventing the unit from achieving target flow temperatures and the related impact of heat pump sizing.

The initial phases of the research concentrated on data quality and dataset development for each dwelling/ASHP to enable ASHP performance to be compared to benchmarks from literature and to other systems in the study. Datasets were developed for the first heating season (SH2.0_HS1, Oct’17-Apr’18) and, based on the analysis of these datasets, areas for more detailed investigation were identified. Optimisation measures were devised and implemented for the next heating season (SH2.0_HS2). Table 2 presents a sample dataset. The areas chosen for further investigation were: 1. Compressor cycling (CC) and flow temperature control; 2. Defrosting and the impact of heat pump sizing.

Predicted annual performance could be overstated if points 1 and 2 are not taken into consideration. The impact of point 3 could lead to difficulties achieving target room temperatures during periods where defrosting is prevalent, especially where the heat pump is marginally undersized for the house space heating load. The systems in this survey did not employ electrical back-up heaters when operating in space heating mode. ASHP data was assessed to determine the frequency, scale and energy consumption associated with de-frost cycles and optimisation measured identified.

3.1 Compressor cycling and flow temperature control EN15450 states: “In order to minimise cycling, it shall be assured that the heating capacity delivered by the heat pump is completely transferred to the heating system” and recommends a target maximum of three compressor starts per hour. High CC leads to: • Reduction in COP and thus an increase in running costs; • Burning out of electrical components; • Reduction in the lifespan of the compressor.

Superhomes 2.0 Datasets Site

Month

SH005 SH005 SH005 SH005 SH005 SH005 SH005 SH005

Oct-17 Nov-17 Dec-17 Jan-18 Feb-18 Mar-18 Apr-18 May-18

Average Birr Degree Outdoor T in Days Heating

141 261 313 311 339 342 212 132

Avg. Tf in Heating

10.9 7.0 5.9 5.5 3.8 4.2 7.8 7.7

35 36 36 36 37 39 35 34

ǀŐ͘ȴdŝŶ Avg. Heating Heating Output (kW)

3.8 4.2 3.9 3.6 3.9 3.4 3.4 3.5

4.9 5.5 5.1 5.0 5.7 4.8 4.7 5.0

Heating Hours

Z1 SP Events

232 322 488 530 466 504 322 61

2 10 47 30 34 19 8 0

4

Z2 SP Events

Total Cycles 1, 2

Max Cycles 3 /hr

Z1+Z2 %

Z1 %

Z2 %

All Modes Consumed WH

Heating Consumed Wh

1 21 43 48 40 15 16 1

166 165 476 374 172 118 163 28

4 4 5 6 4 3 3 2

33% 47% 75% 64% 57% 32% 45% 53%

34% 29% 11% 28% 38% 67% 52% 46%

33% 24% 14% 8% 5% 1% 3% 2%

391,062 728,833 872,898 940,543 952,863 975,689 483,071 80,482

266,438 481,348 722,966 779,860 830,957 836,346 406,776 78,770

Heating Heating Hot Water Total CoP Consumed Wh CoP CoP (All modes) / DD / m2

4.3 3.7 3.5 3.4 3.2 2.9 3.7 3.9

2.9 2.2 2.5 2.6 2.3 2.3 2.6 2.4

3.8 3.2 3.3 3.2 3.1 2.8 3.5 3.9

8 8 10 11 11 11 8 3

Unique Defrost events

9 67 130 143 164 181 50 9

Table 2: Sample of SH2.0 dataset.

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the compressor switched on and off. Compressor switching is also evident from the fluctuations in consumed electrical energy.

Total CC for 4 month period Oct-17 to Jan -18 14000

11730

12000

Cycles

10000 8000 6000

3439

4000 2000

412

0

SH073

SH139

SH127

SH103

SH086

SH202

SH076

Avg

SH212

SH123

SH018

SH001

SH014

SH005

SH016

SH149

SH067

SH009

SH031

SH006

Figure 1: Compressor cycles.

4. Results and analysis 4.1 Compressor cycling Figure 1 shows the total number of cycles for the four-month period of October 2017 to January 2018 for 19 of the 20 Superhomes. Applying the target of three starts per hour from EN14540 for nine hours of active heating per day yields a target of 3,240 CC for the fourmonth period. The average for the 19 houses shown above in Figure 1 was higher than this at 3,439 with seven houses exhibiting CC higher than this, significantly so in some cases. On-site investigation of SH202 and SH073 found that the underfloor heating controls in these houses could create situations where the heat pump was required to provide heat to a small portion of the dwelling, thereby creating a mismatch between ASHP output and the heat emission capability of the system. The other above-average houses (SH076, SH086, SH103, SH127, SH139) had radiators in living and sleeping zones. For these systems, the focus of investigation was the impact of flow temperature on the effective operation of the heating system as a whole. The operating patterns of the dwellings with high CC were reviewed by assessing ASHP performance under varying conditions. Figure 2 presents AHSP performance for SH139 where the outside temperature ranged from 9-13°C. The target switch-off room temperature for Zone 1 was 21.5°C, but over the 11 hours depicted on the graph, this target was never reached, despite the system being active for the entire period. This indicates that the set-flow (Tsf) temperature of the ASHP, and thus the heating system temperature, was too low for the conditions on that day. Tsf varied from 30-35°C in response to changes in outside temperature – actual flow temperature tracked set-flow temperature very closely, oscillating a few degrees above and below the target as

Critically, examples such as this, where flow temperature was not high enough for the radiator system to heat the rooms to the set room temperature, were found in all radiator systems with high CC. WCCs were found to be set to deliver 48°C when outside temperature (Tout) was -3°C and 28°C/32°C when Tout was +15°C. This second setting was found to be too low for radiator systems, resulting in an insufficient temperature difference between the radiator and room temperatures, and leading to insufficient radiator heat output. In such scenarios, even when modulated to minimum output, the ASHP produced more heat than the radiators could emit and so, to avoid overshooting its target temperature, it was forced to switch off, switching back on again when the flow temperature had dropped below a re-start threshold. The problem was compounded by the fact that the situation could continue indefinitely as the ASHP would not switch off until the room target temperature was reached. This led to unnecessary energy consumption. Homeowners provided anecdotal evidence to support this finding. During milder weather, they found that the heating system did not work as well as it did during colder weather, which is explained by the higher flow temperatures as Tout approaches -3°C. 4.2 Flow temperature control experiment Figure 3 and Figure 4 (next page) show the results of tests carried out on SH086 to investigate the effect of adjusting the WCC on CC and COP. They present two 14-day periods where the Heating Degree Days (HDD) were very similar (approx. 155). For the range of Tout the graphs compare nominal heat pump output to the average actual heat output, nominal COP to actual COP, and the WCC target flow temperature to the actual average flow temperature. The graphs present two WCC settings where there was an increase in target Tflow at Tout = 15°C from 28°C (Figure 3) to 45°C (Figure 4). In Figure 3 with the lower WCC, CC is significant, and the average output of the heat pump ranges from 5.5kW down to 1kW, with fall-off in heat output for Tout > 6°C. According to the manufacturer’s datasheet, the minimum output possible for Tout between 6°C and 12°C for the flow temperature range presented is 3.68kW. The fact that average heat output is lower than this minimum in this region of the graph indicates extensive non-steady state compressor operation. In Figure 4 with a higher WCC, CC is almost eliminated, and the actual average ASHP output is in keeping with the manufacturer’s data indicating significant steady-state operation. This is further borne out

70

Temperature (°C)

35

60

30

50

21.5

25

40

20

30

15

20

19.5

10

10

5

0

0

13:00

-10

14:00

15:00

Z1 Room temp.

16:00

17:00

Z1 Switch oī Temp.

18:00

19:00

Set ŇŽw temp.

20:00 Flow temp.

21:00

22:00

23:00

Energy Consumed (Wh/min)

SH139_23Jan18_11 hrs of space heaƟng with Z1 target temp. of 20.5°C 40

Consumed electrical energy(Wh)

Figure 2: Space heating, flow temperature too low.

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10.0

Nominal Capacity

Actual average Capacity

Actual CoP

Target TŇow

Actual Average TŇow

Nominal COP

60

9.0

50

8.0 41.6

7.0 6.0

5.0

5.0

3.8

4.0 3.0

2.0 1.0

3.0

2.8

2.6

2.3

2.4

2.5

2.0

2.0

2.0

2.0

2.0

2.2

-3

-2

-1

0

1

2

2.2

40

38.0

2.2

3.2

5.4 4.0

3.7

4.2

4.4

4.9

4.6

30 20

3.5 2.2

2.5

2.5

2.7

2.7

2.7

2.3

6

7

8

9

10

Flow Temperature

CoP and Capacity (kW) and Cycles per Heating hour

SH086 at -3/48 to +15/28 from 1st to 14th Jan 2018 with 158 heaƟng degree days CC/hh

3.0 10

0.0

0

3 4 5 Outdoor Temperature

11

Figure 3: SH086 trial with low WCC setting for Tout = +15.

10.0

CC/hh

Nominal Capacity

Actual average Capacity

Actual CoP

Target TŇow

Actual Average TŇow

Nominal COP

60

9.0 50

47.5

8.0

46.7

7.0

40

6.0 5.0

30

4.0 3.0

2.1

2.2

2.0

2.2

2.3

2.3

2.4

2.6

2.7

2.4

2.5

2.5

2.5

2.5

2.6

1.0

2.8 2.8

2.9 2.9

3.1 2.9

3.0

3.2

3.4

3.4

3.1

3.2

3.3

20 10

0.5

0.5

0.4

3.2

Flow Temperature

CoP and Capacity (kW) and Cycles per Heating hour

SH086 at -3/50 to +15/45 from 16th to 29th Jan 2019 with 154 heaƟng degree days

0

0.0 -3

-2

-1

0

1

2

3 4 5 Outdoor Temperature

6

7

8

9

10

11

Figure 4: SH086 trial with high WCC setting for Tout = +15.

by the fact that the actual COP tracks the predicted COP very closely.

4.3 Defrost cycles

Where the heat pumps are directly coupled to radiator systems, higher target flow temperature allows the heat pump to operate for longer before having to switch off. The benefits arising from this are a more predictable COP, lower CC and the fact that the higher flow temperature will lead to a more responsive radiator system that is better able to satisfy room temperature target. In order to balance these benefits against the need for maximising COP, it is perhaps not necessary to increase the lower end of the WCC as far as 45°C. Correct radiator sizing and zoning to match radiator output to minimum ASHP output should enable systems to work efficiently with minimum flow temperature of 35°C for Tout = 15°C.

To assess the impact of the defrost cycle, ASHP data was analysed to determine the control process and activities of the ASHP components. Once the defrost cycle is initiated, the heat pump continues to operate in heating mode for approximately 90 seconds, after which time the fan switches off and the compressor continues to run at a low speed. Some seconds later, the reversing valve operates, thereby diverting hot gas to the evaporator. This process continues for approximately two minutes, after which the defrost signal disappears and the compressor switches off, signifying the end of the defrost period. Table 3 (next page) presents the data for a defrost event for SH006 from the 8th November 2018 when Tout was 3°C. The controller flags

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Minute

Consumed electrical energy (Wh)

Delivered heat (Wh)

Cop

1

51

144

2.82

0

2

53

123

2.32

0

3

54

125

2.31

0

4

54

120

2.22

0

5

54

112

2.07

2

6

16

48

3.00

2

7

8

0

0.00

2

8

9

0

0.00

2

4.3.1 Energy penalty due to ice build-up

Defrost

9

5

0

0.00

2

10

1

0

0.00

0

11

7

0

0.00

0

12

35

88

2.51

0

13

42

83

1.98

0

14

44

92

2.09

0

15

44

111

2.52

0

16

51

121

2.37

0

17

52

127

2.44

0

18

52

128

2.46

0

Figure 5 presents an example of the effect of evaporator ice build-up on the ASHP’s heat output and consequently on COP for SH006. At minute one, the AHSP commences operating in heating mode having come out of a defrost cycle. The Evaporator is free of ice and so the operation from minutes 1 to 14 can be regarded as normal operation, where the ASHP goes through a start-up period, modulation and then a gradual increase in heat output to the point where output begins to level off. From minutes 14 to 31, due to ice build-up, heat output and thus COP gradually reduce while the electrical consumption remains steady at approximately 52Wh/minute. During this period, the COP falls from 3.52 to 2.82. Between minutes 31 and 33, the fall in output is severe with the COP dropping from 2.82 to 2.22. At this point, heat output drops to zero signifying the beginning of a defrost event. In this example, the total heat produced was 3,279Wh with an electrical input of 1,116Wh, a COP for the event of 2.94. Had there been no drop off in heat output, the total heat produced would have been 4,559, giving a COP of 4.08. The “lost” energy output from the ASHP was calculated to be 313Wh. Applying this methodology to all the defrost events experienced by SH006 in SH2.0_HS1 indicated a total of 426kWh which was lost. This equates to 8.7% of the total energy consumed by the AHSP for that period. This loss in performance is in addition to the energy consumed during the defrost process. 4.3.2 Effect of defrost operations on ability to maintain house temperature

Table 3: Sample defrost event.

Figure 6 (next page) presents a 12-hour period of heat pump operation where Tout falls from 1˚C to -3˚C, thereby increasing the house’s heat load. The graph of consumed energy shows that the heat pump was in operation for the full duration of the period, the only breaks in electrical consumption arising from periodic defrost events. Energy consumption rose from around 65Wh/min to in excess of 100 Wh/ min for the period up to 2:00am due to a domestic hot water (DHW) event. As the night progressed and Tout fell to -3˚C, the level of

the defrost event in minute 5 but it is not until minute 7 that it can be said that the unit stops delivering heat to the house. Between minutes 7 and 11, a total of 30Wh of electrical energy was consumed without any related heat output. From minute 12 onwards, heat is again delivered to the house. During SH2.0_HS1, SH006 experienced 1,362 defrost events consuming approximately 41kWh or 1% of total energy consumed for that period.

SH006 Defrost 08-Nov-17 ambient 3 deg C

3.91

180

4.0

3.52

160

3.5

140

3.0

3.06

2.5

2.82

100 2.0

2.22

80

CoP

Energy (Wh)

120

1.5

60

1.0

40

0.5

20 0

0.0 1

2

3

4

5

6

7

8

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

Event Minutes Consumed energy (Wh)

Delivered energy (Wh)

stable

starts falling

Įƌst defrost

CoP

Figure 5: ASHP performance with ice build-up.

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SH014 7th/8th Jan 2018

Consumed & Deliverd Energy (Wh)

200

183

177

180

169

5.0

163

154

160

146

145

140

3.0

140 120

1.0

0

100

-1

80

66

-1.0

60 40

-3.0

Outdoor ambient and CoP/min

7.0

220

20 0

20:00

-5.0

21:00

22:00

23:00

00:00

01:00

Consumed electrical energy(Wh)

02:00

03:00

Delivered heat energy(Wh)

CoP per min

04:00

05:00

06:00

07:00

Outdoor ambient temp.

Figure 6: Heat pump sizing and defrost events. SH014 7th/8th Jan 2018 60

60 55

Degrees C)

50

46.5

45

42

41.5

40

35

40

38.5

37.5

30 25 20

20:00

21:00

22:00

23:00

00:00

01:00

02:00

SetŇow temp.

03:00

04:00

05:00

06:00

07:00

Flow temp.

Figure 7: Not achieving flow temperature target.

Category

SH014

SH127

DEAP W/K

515

345

House Load (kW) at -3°C Tout, Tint = 20°C

11.85

7.94

Heat Pump capacity (kW) at -3°C Tout (Tf = 50°C)

11.03

8.22

Spare capacity (kW)

-0.82

0.28

Spare capacity %

-6.9%

3.5%

Zone 1: Minutes below internal target temperature

47,381

77

Zone 2: Minutes below internal target temperature

34,387

2,675

Table 4: Comparison of heat pump sizing.

energy consumption increased slightly while the heat output of the unit reduced, in line with a drop in Tout. For the five cycles before 1:00am, each time the system re-started after a defrost event, heat output reached a peak before falling quickly to around 140 Wh/min with the peak achieved during consecutive cycles reducing from 185 to 155Wh/min. Later in the night when Tout was between -1˚C and -3˚C, the peak outputs achieved in each cycle were lower, but output degradation was also evident. Overall, the relatively consistent electrical consumption, together with reducing heat output, produced a reducing profile for COP. Figure 7 shows the effect of the reduction in heat output on the ability of the heat pump to achieve its target flow temperature for the same period of operation as described in Figure 6. Each time Tf drops from high to low represents a defrost event. Excluding the DHW spike in the middle of the graph, actual flow temperature is constantly below Tsf. The increase in Tsf after midnight is caused by a reduction in Tout with a resulting increase in the differential between

Tsf and Tflow. In this case, the ASHP was slightly undersized for the peak house load (see Table 4) and consequently the house internal temperatures were found to fall gradually during the night instead of being maintained at the living area target of 21˚C and sleeping area target of 18˚C. Undersized heat pumps will need to defrost frequently in low ambient temperatures, reducing the system’s ability to reach and maintain set point (IHPA, 2018). 4.3.3 ASHP sizing example Table 4 provides details of two of the SH2.0 systems in terms of maximum ASHP capacity, predicted maximum instantaneous house load as calculated by the Dwelling Energy Assessment Procedure (DEAP) tool, and the amount of time while in heating mode that the internal temperature was below target for each zone. The information presented includes all minutes during the heating season from October 2017 through to April 2018 when the ASHP was operating in space heating mode. The analysis demonstrated that the system, with a small % of spare capacity (SH127) i.e. slightly oversized, has significantly lower periods when the zone temperatures are below target when compared to the system which is slightly undersized (SH014).

5. Discussion and conclusions The primary aim of the Superhomes 2.0 project was to collate data from 20 ASHPs in domestic retrofits and to measure their performance in terms of several key performance indicators. The data showed that while all systems performed well within expected performance and efficiency ranges, some opportunities for optimisation were identified. All of the heat pumps in this study were of the variable capacity type (inverter) where the unit has the ability to adapt its heat output to match the house load. However, when the heat load available to the

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Optimisation of air source heat pumps in residential retrofits

heat pump is less than its minimum capacity, the heat pump will cycle on and off between the minimum output and zero output leading to compressor cycling (CC). This was identified as having a negative effect on COP and on the life expectancy of the equipment. The presence of cycling reduces the percentage of heat pump operating time spent in steady-state conditions which are the conditions that exist during heat pump output and COP tests in accredited laboratories. These steady-state COPs are used by national bodies when predicting national targets for energy consumption and CO2 reductions achieved by ASHPs, so it is critical that all parties involved in the ASHP value chain are aware of the importance of avoiding CC. In addition to ensuring a good match between heat pump and emission system outputs, optimal performance is achieved when interruptions to flow through the heat pump condenser, and thus CC, are minimised. This allows the ASHP to operate as closely as possible to the outputs and efficiencies in manufacturer’s performance charts. Interruptions can be mechanical such as the reduction in available heat load due to room-by-room zone valves in underfloor heating systems. This is also relevant to radiator systems using either thermostatic radiator valves or manifolds with electric actuators. These issues often originate from the practice of applying system designs that are appropriate for boilers but not appropriate for heat pumps. Buffer vessels are a solution to this problem in that they provide the heat pump with sufficient load to guarantee minimum run times that will allow for a maximum of three starts per hour. Where designers choose not to fit buffer tanks, system zoning and zone controls should ensure that the minimum emission load available to the heat pump is closely matched to its minimum heat output. Interruptions to steady-state operation can also be caused by a reduction in available heat emission and run-time due to flow temperature being too low due to inappropriate WCC setting, particularly with radiators. Systems were found to operate for long periods of time heating the water in the system to around 30°C before switching off, turning back on when the temperature dropped by about 5°C and a time delay had elapsed. Water circulating through the radiator system at this temperature was not hot enough to cause sufficient heat transfer into a zone which was already at 20°C and for which the target temperature was 21°C. Situations like this were found to exist for in excess of 12 hours at a time. End users had the impression that this was acceptable because of the idea that the system is “always on” but in fact SH2.0 analysis has shown that these situations use more energy at a lower COP than the same system working at higher flow temperature which doesn’t cycle, and heats the zone up to target temperature quicker before switching off. Due to the enhanced building fabric resulting from the deep retrofit process, the zone temperature can be maintained for a significant period before the compressor is called back to action. For AHSPs, ice build-up on the evaporator was shown to be a significant issue and further work is required to determine if the energy penalty highlighted in this paper is accurately captured in current national heat pump performance tools. Sizing of heat pumps needs to take account of the defrost process as it was shown that systems that are marginally undersized can struggle to maintain house temperatures when defrosting is occurring on a regular basis.

A combination of thorough commissioning, including at least one post-commissioning follow-up visit by the installer, greater homeowner engagement and ongoing annual inspections is required to ensure that each system is fully adapted to the requirements of the building and the residents that it serves.

6. Future work LIT is currently conducting additional research in relation to heat pumps to further inform the market and increase capacity. This research includes: • SEAI RD&D funded project FactHP is monitoring 40 domestic heat pump (air and ground source, new-build and retrofit) systems and will compare the combined annual Seasonal Performance Factor (SPF) for heating and hot water with that predicted by DEAP to determine if an in-use factor is required. This research is due for completion at the end of 20201; • Funded under the H2020 programme the HP4ALL project will develop tools and resources to increase skills across the heat pump supply chain2. Coordinated by LIT, this project commenced in September 2020 and will have a 30-month duration. As the quantity and range of heat pumps which are installed within the residential sector increases, additional research and analysis is also required across the following areas: • Impacts of heat pumps on the electrical grid; • Integration of heat pumps with electric vehicle (EV), renewable generation systems i.e. PV and battery storage; • Customer/homeowner knowledge and behaviour.

References 1. https://lit.ie/Research-Development/Development/Energy/FactHP-In-Use-Factorsfor-Heat-Pumps-and-other-ene 2. https://cordis.europa.eu/project/id/891775 CIBSE (2016) Environmental Design – CIBSE Guide A. CIBSE, London, UK Government of Ireland (2019) Climate Action Plan 2019 to tackle climate breakdown, Dublin, Ireland LIT (2019) https://lit.ie/Research-Development/Development/Energy/Superhomes2-0-Optimisation-of-Air-Source-Heat-Pum NSAI (2003) Heating systems in buildings – Method for calculation of the design heat load, I.S. EN 12831, NSAI, Dublin, Ireland NSAI (2007) Heating systems in buildings – Design of heat pump heating systems, I.S. EN 15450, NSAI, Dublin, Ireland NSAI (2012) Heating systems in buildings – Design for water-based heating systems, I.S. EN 12828, NSAI, Dublin, Ireland O’Reilly, P., O’Shea, M., Hoyne, S., Hunter, G. (2019) Superhomes 2.0 – Best Practice Guide for ASHP Retrofit. Superhomes 2.0 project report, Limerick Institute of Technology, Limerick, Ireland. Sustainable Energy Authority of Ireland (2019) Domestic Fuel Cost Comparison, Dublin, Ireland

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Enhancing Thermal Mass Performance of Concrete

Atria, roof-space solar collectors and windows for low-energy new and UHQRYDWHGRIÃ&#x20AC;FHEXLOGLQJV a review

Prof. Brian Norton DUBLIN ENERGY LAB, TU DUBLIN TYNDALL NATIONAL INSTITUTE, UCC MAREI: THE SFI CENTRE FOR ENERGY, CLIMATE AND MARINE brian.norton@ierc.ie

Steve N.G. Lo

DEPARTMENT OF ARCHITECTURE & CIVIL ENGINEERING, UNIVERSITY OF BATH s.n.g.lo@bath.ac.uk

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Abstract As part of achieving near zero energy ofďŹ ce buildings, solar gains can be optimised by built form, internal layout and the position, type and area of windows. Those solar gains can then displace heating and lighting energy in most nondomestic buildings without overt engineered solar energy harnessing features. Such approaches have been adopted to successfully realise many low-energy buildings. This review discusses key parameters and the particular challenges in the design of atria, windows and roof-space solar air heaters to reduce energy and carbon emissions associated with heating and lighting in newly-built and renovated non-domestic buildings.

Keywords Atria, roof-space collectors, solar energy, building renovation. 26

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Atria, roof-space solar collectors and windows for low-energy new and renovated office buildings: a review

1. Introduction Passive solar gains can assist in displacing heating and lighting energy in most buildings without overt engineered solar features. As part of achieving near zero energy office buildings, solar heat, daylight and solar induced ventilation can be optimised by built form, internal layout and the position, type and area of glazed features. Windows provide solar heat gains and daylight directly to a space. For atria and roof-space collectors, solar heat collection can be readily de-coupled from adjacent spaces by simply conveying solar heated air when required by using fans actuated by appropriate sensors and controls. Bringing daylight into office buildings can also usually, even with overcast skies, provide sufficient illumination for the majority of activities during most of many days. However, appropriate daylighting strategies depend on climate, the latitudinal sunpath, and the building’s function, form and site. It has thus been a critical part of building design. However, with the advent of electric lighting, air-conditioning, lifts and escalators, office buildings became larger and taller but also often floor plans became deeper allowing limited penetration of daylight. In office buildings, providing adequate daylight has many important health, comfort, amenity and economic benefits (Knoop et al, 2019). The only proviso is that conditions leading to glare or excessive solar gain are avoided. Properly supporting the stimulus that maintains daylight-driven circadian rhythms requires a complex combination of light intensity, duration and timing of exposure to daylight, the amount of particular wavelengths in the received daylight spectrum, and that daylight’s spatial distribution (Münch et al, 2020). To be successful, energy efficient design has to be reconciled harmoniously with a building’s specific physical constraints and functional requirements. Energy-efficient design itself has to address three functional requirements, namely: • reduce the energy required for heating, ventilating and/or lighting and thus the greenhouse gas emissions and running costs of the building; • incur low embodied energy and greenhouse gas emissions in the materials and processes of construction or renovation; • provide a comfortable, pleasant and aesthetically-pleasing internal environment, possibly with supplemental usable space.

comparison with one facing externally. Daylighting of the adjacent spaces may thus be increased (To and Chan, 2006); •

when in inclement weather an atrium is sufficiently warmer than the ambient environment, it constitutes useable space (Danielski et al, 2016)

In addition, during periods when the temperature of the atrium is similar to ambient, ventilative air flows from the heated building into the atrium, and then outside reduces heating loads indirectly. The temperature in the atrium will be elevated both directly and due to the ingress of warm air from the heated building. This can also lead to periods of overheating of an atrium (Lu et al, 2019). Atria may be categorised as those: •

separated from the main body of the building via a glazed lightweight partition allowing air flow. These cannot be thermally de-coupled readily from adjacent spaces. Heat gain to the building is either by natural ventilation, ventilation preheating, direct radiative gain, conduction and by a reduction of heat lost via adjacent facades. where the glazed area of the separating partition is small and the contribution of direct radiative gain is reduced compared with an integral direct system. The fabric of the partition is less leaky to air flow and solar ventilation pre-heating air-flow is often conveyed mechanically. The feature is more isolatable from the main body of the building. forming glazed streets where the glazed area is small. When forming linking areas between existing and new buildings, the separating partition is of external wall construction and remains insulated as such.

Examples of atria are shown in Figures 1 to 3. Figure 1 illustrates the use of structural slats to provide shading from direct solar gains in an atrium gallery space. Figure 2 illustrates the use of partially transparent photo- voltaic glazing in an atrium (James et al, 2009) to diminish solar gain, while converting some of the incepted solar energy into electricity. Figure 3 shows an atrium space illuminating a green wall in an emblematic building that forms part of an environmentallysustainable university campus (Walker and Mendler, 2017).

In doing so, energy efficient design can also introduce additional constraints on orientation, pattern of fenestration, built form and internal layout, for example where an atria forms a glazed courtyard

2. Atria An atrium may reduce the energy consumption of a building (Moosavi et al, 2014) by: •

conduction of heat through walls from the warm atrium to adjacent spaces;

the natural or forced recirculation of heated air between the atrium and the heated building;

pre-heating a net flow of ventilation air from the outside ambient environment into the heated building via the atrium;

the warmer-than-ambient environment of an atrium increases the thermally-optimum area for a window facing into it in

Figure 1: Atrium in the Corning Gass Museum, Corning, NewYork, USA.

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northern European climates, low airflow rates ensue for the small temperature differences typically encountered in spring and autumn; energy transport is consequentially often minimal. In summer, such action needs to be prevented in order to avoid overheating. When air entering the building via an atrium forms the major constituent of the air required for ventilation, then solar gains provide some reduction of a ventilation heat load (Moosavi at al, 2014). In addition, as buildings generally become better insulated, so the proportion of energy that is used to heat the essential requirements for ventilation air increase. In a shallow-plan building, infiltration may distribute solar heat from atria effectively. However, to efficiently distribute pre-heated ventilation air from an atrium in most buildings requires fans and purpose-built ducts.

Figure 2: Atrium with a semi-transparent photovoltaic glazed roof at the Fraunhofer Institute for Solat Energy Systems, Freiburg, Germany.

Well-designed atria can reduce building energy usage in both cold and warm climates by supplying daylight and natural ventilation to interiors. However, improper design of atria may lead to increasing energy consumption or occurring visual and thermal discomfort (Hossein et al, 2020). Squat-form buildings with atria that have square or round floor plans can provide daylight to more of the spaces adjacent to the atrium (Li et al, 2019).

3. Windows Direct solar gain presents particular challenges of glare (Hamedani et al, 2020); overheating (Camacho-Montano et al, 2020); occupant discomfort due to internal radiant temperature assymetry (La Ferla et al, 2020); and damage to fabrics and finishes from exposure to the ultra-violet band of the solar spectrum (Mohelníková et al, 2018). These challenges require that care be given to the pattern of fenestration (Barea et al, 2017), as well as the specification and control of window systems (Inouea and Ichinoseb, 2016), to give adequate daylighting with varying insolation being within the remit of the overall initial building design. Many low heat loss window options are now available using coatings and multiple panes, some with an intervening vacuum (Ghosh and Norton, 2018) or incorporating a ventilated air gap (Michaux et al, 2019). Window systems can also include blinds (Katsifaraki et al, 2017) and prismatic glazing (Tian et al, 2019) systems that deflect daylight deeper into an adjacent interior space,thereby displacing electric lighting. Figure 3: Atrium providing daylight to a green wall at Chatham University, Eden Hall Campus, Richland Township, Pennsylvania, USA.

The thermal effectiveness of thermal storage located in atria is reduced due to the high conductance to ambient (Hussain and Oosthuizen, 2012). However, where sparsely-furnished and uncarpeted finishes are acceptable, “thermal mass” can be provided readily. Such interior design also emphasises the periodically-habitable transition between the ambient and internal environments. However, if this remains an unheated area, care is required as to the activities that can be undertaken therein, particularly in relation to comfort conditions, daylighting and noise. Natural circulation of air between an atrium and adjacent spaces occurs when airflow is induced by the temperature difference between the warm conservatory and the cooler adjacent space. In

Close to the window

Distant from the window

Figure 4: Interior projection of daylight by a prismatic glazing at TU Darmstadt, Darmstadt, Germany.

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Atria, roof-space solar collectors and windows for low-energy new and renovated office buildings: a review

All these interventions may, at particular times, provide uneven penetrations of daylight. For example, as can be seen in Figure 4, a prismatic glazing system can provide good-quality lighting in the main body of a space but close to the window projects exterior reflected colours (in this case particularly the red of an outside parked vehicle). For efficient overall operation a heating system must respond readily, both to provide heating when solar gains to particular zones cease, and also to stop doing so when solar gains resume. Thermal mass is essential to ameliorate the immediate effects of direct solar gain through windows to provide stable internal temperatures. The level of thermal mass required can usually be met by either conventional masonry or timber-framed construction (Reilly and Kinnane, 2017). Moveable window insulation may also be incorporated to reduce heat losses from glazing. An example is sliding translucent shutters that may be used to alter the level of daylight entering the building and the amount of heat leaving via the glazing (Sun et al, 2017).

4. Roof-space collectors Roof-space solar-energy collectors employ passive solar collection combined with active distribution. A roof-space solar-energy collector is essentially a pithed-roof which is partially or fully glazed on its southerly aspect. Solar heated air from the roof-space collector is conveyed by an automatically-controlled fan via a duct, either directly into the building or as a pre-heated supply to either a warm-air space-heating system or to heat storage (Charvat et al, 2001). The roof-space collector is replenished with air, either from within the building or from outside the outside ambient environment.

As it can be designed for more optimal heat collection design to thus attain higher air temperatures, a roof-space collector can provide more efficient and effective pre-heating of ventilation air. Neither are possible within an atrium as internal conditions in an atrium must satisfy occupant comfort requirements.

5. Atria and roof-space collectors in energy efficient building renovation Holistic low-energy buildings use sustainable materials for construction as well as incurring low energy use in their operation. The use of materials with low embodied energy and carbon is thus essential in new construction. However, new buildings constitute only a small proportion of a building stock so, to make an impact on overall energy use and greenhouse gas emissions, it is important to prioritise the energy-efficient renovation, and if necessary repurposing, of existing buildings. Offices account for nearly a quarter of the total floor area of nonresidential buildings in the European Union (Economidou et al, 2011). In proportion to floor area, office buildings have higher energy use intensity than houses and 60% of them were built before 1980 (Stegnar and Cerovšek, 2019). Therefore, the potential for their renovation to achieve energy saving and carbon emissions reductions is greater than for other building types. Figure 6 shows a classification of energy renovation strategies for office buildings (Kwon, 2020).

When the air from the roof-space solar energy collector is at a lower temperature than the set level of the room thermostat, the air stream emerging from the roof-space collector forms a pre-heated supply to the auxilliary heating system (Lo and Norton, 1996). Warmth is stored, to some extent, within the structural elements of the roofspace collector. Ventilation is employed to prevent overheating in high summer. Examples of roof space collectors are shown in Figure 5. Figure 6: Classification of building envelope renovation strategies (Kwon, 2020).

In reality, energy renovation of a particular office building may combine, to varying extents, elements of each of the strategies shown in Figure 6. The retrofitting of an atrium between existing buildings, as illustrated in Figure 7 (next page), is a frequently-implemented, predominantly “climate skin” strategy that enables a building to continue to meet all functional requirements. It obviates the need to make significant changes in behaviour or work patterns, while additional tempered spaces with low overall energy consumption are provided for amenity, circulation and meeting.

Figure 5: Roof-space solar collector diagram showing (clockwise from bottom left) operation of a domestic system; interior view of glazed loft space; exterior view of a domestic system, aerial view of a group of domestic systems; staggered row of domestic systems; system on a school building (Norton, and Waterfield, 1990); aerial view of system on a school building.

A roof-space collector can have a low initial capital cost as its physical construction may not differ greatly from that of a conventional pitched roof (Norton and Waterfield, 1990). In addition, a reduction in additional cost may arise from the employment of fans and controls that would already be present in an air-heating system. Being roof-located, there are often fewer constraints to a roofspace collector being less frequently overshadowed (Lobaccaro et

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Acknowledgments This research was supported by (i) Science Foundation Ireland (SFI) through the MaREI centre for Energy, Climate and Marine Grant Number 12/RC/2302_P2 and (ii) Department of Communication, Climate Action and the Environment, Government of Ireland.

References Anon. (2020) Bond Bryan creates Engineering Heartspace at the University of Sheffield, Architecture Magazine, 5th February.

Figure 7: An atrium retrofitted between existing buildings at Sheffield University, UK. (Anon, 2020).

al, 2016). In contrast, harnessing solar energy features on façades in high-density urban locations may often be rendered ineffective by overshading, particularly at lower sun angles, by neighbouring buildings (Chatzipoulka et al, 2016). Mitigating risks of cost escalation associated with uncertainly as to the extent of improvements required to achieve specific energy performance goals is critical to the successful introduction of an atrium or roof-space collector as part of a building renovation. To reduce such risks, laser scanning can be used to gather geometric data of an existing building for Building Information Modelling (Sanhuudo et al, 2020). This can be integrated with infrared thermography to precisely locate and quantify building defects (Macher et al, 2020; Shariq and Hughes, 2020). Future energy use in buildings may be highly affected by changes in climate. For example, in southern Spain it has been estimated that global warming will increase the average percentage of indoor thermal discomfort hours during the summer by more than 35% (Escandon et al, 2019). Therefore, energy renovations need to be assessed both from a cost-optimal energy perspective and for their resilience to global warming (Ascione et al, 2017). Extreme future weather data has been synthesised for this purpose (Pernigotto et al, 2920). The controllability of heat removal from atria and roof-space collectors provides inherent adaptability to climate change as well as weather and occupancy variations.

6. Conclusion The performance flexibility arising from an ability to be thermally decoupled from other spaces renders atria and roof-space collectors particularly suited for consideration as part of energy-efficient renovation of office buildings. The additional usable space provided has meant atria have indeed formed part of many climate-skin renovation strategies. Roof-space collectors have not found similar levels of adoption because they do not extend a building’s habitable space. However, roof-space collectors merit more frequent attention as part of low-energy renovation. With careful design, significant energy saving benefits can be provided at a cost similar to traditional roof construction while incurring low embodied energy.

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School of Multidisciplinary Technologies College of Engineering & Built Environment The School of Multidisciplinary Technologies provides modules and programmes, at undergraduate and postgraduate levels, which link engineering and built environment disciplines for the design and operation of healthy, low-energy buildings and infrastructure for a modern sustainable world. These full-time and part-time programmes are founded on a research base and promote multidisciplinary themes across the Technological University Dublin, and with external partners. Themes include building information modelling and management (BIM), digital construction, construction analytics, engineering analytics, lean construction, educational research, sustainability, and energy. Undergraduate Programmes Bachelor of Engineering (Hons) Engineering (Gen. Entry)

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Enhancing Thermal Mass Performance of Concrete

Experience of Spaciousness and Enclosure: Distribution of Light in Spatial Complexity

Asst. Prof. Ulrika Wänström Lindh, JÖNKÖPING UNIVERSITY, JÖNKÖPING, SWEDEN Ulrika.Wanstrom-Lindh@ju.se

Prof. Monica Billger, CHALMERS UNIVERSITY OF TECHNOLOGY, GOTHENBURG, SWEDEN monica.billger@chalmers.se

Prof. Myriam Aries, JÖNKÖPING UNIVERSITY, JÖNKÖPING, SWEDEN myriam.aries@ju.se

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SDAR Journal 2020

Abstract This study explores how distribution of light impacts perceived space. The purpose of this study was to gain a rich and deep understanding of the relationships that exist between distribution of light and spatial experience. In this research, spatial complexity is studied through a qualitative approach with a combined methods strategy. Twenty one participants answered a questionnaire and drew sketches, followed by in-depth interviews, in a real-life auditorium with five light scenarios. The scenarios varied in light distribution, light level and light colour. All findings were triangulated in the final analysis. Surprisingly, a dark room appeared as more spacious when the spatial boundaries become unclearly defined. Simultaneously, findings indicate that bright walls can, in contrast to what most previous research suggests, contribute to a decreased spaciousness, if they become prominent enough. The results indicate a relationship between perception of increased width, caused by wall lighting, and reduced height, caused by indirect ceiling light. The experience of room size and spatial enclosure in relation to light distribution did not follow physical room boundaries. Furthermore, interview answers indicate that there can be a relationship between lighting and social interaction.

Keywords Lighting design, light distribution, spaciousness, enclosure, spatial experience, perception, spatial complexity, qualitative research. 34

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1. Introduction Light distribution with emphasis on vertical surfaces and spatial boundaries is of great importance to one’s feeling of security and comfort in a room. For example, cramped spaces can increase anxiety (Bokharaei & Nasar, 2016; Okken, van Rompay, & Ad, 2013; Stamps, 2013, 2015). There is a need for knowledge about spaciousness and enclosure. Lighting research, with a long tradition originating in physics, has worked almost exclusively with quantitative methods, focusing on visibility and visual comfort (Peter R. Boyce, 2004; Calvillo Cortés & Falcón Morales, 2016; Kelly, 2017). This means that lighting primarily has been studied through measurements of the physical environment and by mathematically analysed inquiries. This research has frequently been conducted in isolated laboratory contexts, while few studies have been conducted in authentic, complex spaces. Kronqvist claimed that quantitative methods alone cannot “explain complex interactions between human perceptions, well-being, visual comfort and performance” (Kronqvist, 2012, p. 5). Qualitative research can supplement previous experimental research by offering, as evidence, interviews that provide rich and detailed understanding of how participants think about lit spaces. Just like research methods diverge, the lighting field is clearly separated between science and art (Peter R. Boyce, 2017; Dugar, 2018). In fact, very little lighting research has been conducted from the perspectives of lighting designer and architect. Light distribution in complex rooms, which is hard to study in laboratories, is largely ignored by researchers (Peter R. Boyce, 2014). Prozman and Houser, as well as Boyce, claim there is a need for complex studies on the relationship between three-dimensional rooms and peoples’ impressions (Peter R. Boyce, 2004; Brent Prozman & Houser, 2005). It seems that the number of complex spatial studies is increasing, but there are still few based on user experiences collected using a qualitative approach.

2. Theoretical framework More than a century ago, it was found that brightness influences distance judgements (Ashley, 1898). About 60 years later, it was concluded that dark opposite sidewalls visually contract a space’s width, while bright opposite sidewalls increase the perceived width (Acking & Küller, 1966). Several more recent studies support that a bright ceiling increases the perceived height and gives a spacious impression (Houser, Tiller, Bernecker, & Mistrick, 2002; Oberfeld, Hecht, & Gamer, 2010). Furthermore, Houser et al. found that walls and ceiling importantly contributed to the perceived brightness (Houser et al, 2002). Matusiak has shown a clear relation between more light and a spacious impression. Matusiak and colleagues also found that when borders between surfaces in spaces were defined by a strong luminance contrast, observers were better able to assess the actual size of a space (Matusiak, 2004, 2006; Matusiak & Sudbø, 2008). Veitch’s and Tiller’s experiment showed that walls with a non-uniform illumination were perceived as brighter than if they were uniformly illuminated (Veitch & Tiller, 1995).

Flynn, Spencer, Martyniuk and Hendrick studied the distribution of light in relation to spatial experience in a complex study when they compared uniform lighting to lighting rich in contrasts and peripheral (wall-oriented) lighting to overhead (ceiling-oriented) lighting (Flynn, 1977; Flynn, Spencer, Martyniuk, & Hendrick, 1973, p. 89). Walloriented light and a low-intensity table lamp of varying contrasts contributed to a spacious impression preferable for a pleasant character. The research group of Flynn et al has been followed by other researchers who drew similar conclusions, when they studied different lighting scenarios in office rooms, with varying degrees of uniform illumination and different directions and distributions. Manav and Yener found, for example, that cove lighting (indirect light from a ceiling ledge) was associated with spaciousness (Manav & Yener, 1999). In the study of Durak et al a diffuse indirect wall lighting was preferred to increase spaciousness, and Prozman and Houser found that the spacious impression was increased with a higher light level on the walls (500 lux) compared to a lower level (320 lux) (Brent Prozman & Houser, 2005; Durak, Camgöz Olguntürk, Yener, Güvenç, & Gürçinar, 2007). It has also been shown that when all other factors are constant, people prefer a ceiling height higher than the standard height (Baird, Cassidy, & Kurr, 1978). Spatial perception is complex – perceived longer dimensions/larger room surfaces do not necessarily mean the same as a general increased spaciousness (von Castell, Oberfeld, & Hecht, 2014). One aspect – height, width, or depth – can affect the experience of space more than the others. In particular, the length/depth of the room is important (Bokharaei & Nasar, 2016). Gärling found that people judge depth and size differently and that they may mix up open spaces with large spaces (Gärling, 1969a, 1969b). Furnishings also affect experiences of spaciousness (von Castell et al., 2014). Unfurnished rooms feel larger than furnished, but smaller than halffurnished rooms (Bokharaei & Nasar, 2016). Spatial perception is highly contextually related. In complex authentic settings there are many factors that work together in a figure-ground relationship (Wagemans et al., 2012). The task of a lighting designer can be described as choosing between what is to be reinforced by light and what can remain in the background. A room’s shape can be transformed by shadows. A shadow may either follow the original shape and reinforce it (co-shading) or give a flatter impression (countershading) (Häggström, 2009, 2010; Tantcheva & Häggström, 2011). If a round shape is illuminated obliquely from above, it looks convex, but if the light is shining obliquely from beneath, it looks hollow (concave) (Gregory, 1998). Spatial enclosures comprise both the spatial boundaries and the experience of being surrounded inside a spatial unit and feeling its extension (Wänström Lindh, 2012). There is actually a specific area of the brain, the Parahippocampal cortex, that corresponds to spatial enclosure, but not to single objects (Epstein & Kanwisher, 1998). Enclosure is sometimes seen as an antonym to spaciousness (Stamps, 2009). But a closed room and a small room are not always related, and a spacious room does not have to be open. According to Bader, depth in built environments can be defined through the concepts of envelopment, overlap and enclosure (Peri Bader, 2015).

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According to Hesselgren, the experience of enclosure can be enhanced with a raised light level (from 0 up to 100 lux). Yet, when the room becomes too bright, the enclosure effect decreases (Hesselgren, 1969, pp. 364-365). The scale of a space has no influence on the perception of enclosure or spaciousness (Hayward & Franklin, 1974). Madsen, who investigated spatial enclosing areas of daylight as spaces within a space, introduced the term light zones to describe these spatial units made up of light within the space (Madsen, 2004, p. 1; 2006, p. 71). Additionally, Søndergaard has developed a method of capturing the embodied experience of sensing light when moving through a light zone — one person moves within the zone, another interviews this person and takes notes, while a third person observes her/him and takes photos (Søndergaard, 2011, 2012). Their work strengthens the approach of this article to describe spatial enclosedness in lit rooms. The purpose of this study is to explore relationships between the distribution of light, illuminated walls and atmosphere experience connected to enclosure and spaciousness. Of special interest is the relationship between the experienced “light zone” and the built room (Madsen, 2006). To this end, the effect of different light scenarios on the participants’ perception of, and experience with, the room’s shape and size was investigated. Three hypotheses were defined for this study: • Because illuminated walls were assumed to define a space and to contribute to a spacious impression, it was hypothesised that a room with lighting emphasis – bright light on the walls – would be perceived as open, high, wide, airy and spacious, while a room with weak wall lighting would be perceived as distinctly enclosing and smaller;

The interviews revealed how and why the participants answered the questions as they did. Where the questionnaire was limited, the interviews offered richness. The visual representations, that is the drawings, made the discussion about abstract spatial concepts more concrete and easier for the participant to understand, and it also made it easier for the researcher to understand the participants’ thoughts. 3.1 Experimental site and lighting scenarios A real-life room with existing lighting was used for the study. The University of Gothenburg has a main building that was built in 1907. The auditorium, “Sal 10”, has 100 seats and an interior characterised by warm beige walls, a white ceiling with stucco work, oak panels and heavy dark red velvet curtains. The room is 18m x 7m and 4.6m high. The auditorium’s lighting system was designed in 1998 by an experienced lighting designer and features five different preprogrammed lighting scenarios. Normally, several large windows allow daylight inside, but the room was darkened by thick curtains during the study (see Figures 1 and Figure 2). The light scenarios represented similarities as well as contrasting designs, including different distributions of light (indirect and direct light, wall-light, spotlights as well as centred light and separated light). Different luminaries and light sources, and various colours of light and light levels, further contributed to a rich, complex, experimental situation. At the time of this study, incandescent light was still used in this historic building. The specially-designed luminaires are inspired by the lighting character this building had 100 years ago.

• A room without wall lighting will most likely be perceived as distancing and not clearly delimited, but a room with bright walls would be more regarded as more spacious than a darker room; • Furthermore, wall lighting was assumed to create well-defined spatial boundaries and to enhance an angular impression of the room.

3. Methods A pre-study based on visual estimation (Arnkil, Fridell Anter, Klarén, & Matusiak, 2011; Fridell Anter & Klarén, 2017; Liljefors, 2005; Liljefors & Ejhed, 1990; Matusiak, Fridell Anter, Arnkil, & Klarén, 2011), and phenomenological observations (Depraz, Varela, & Vermersch, 2003; Ihde, 2000/1986), was undertaken in an auditorium to develop the initial assumptions for this study. A focus group consisting of the researcher and ten students within design education answered questions and discussed them in this setting. The final questionnaire was developed from these observations and discussions. In the main study, the research questions were studied through the questionnaire, the in-depth interviews and the sketching moment. The combination of three methods allows mitigation of weaknesses in each. For example, the questionnaire, which allowed for participants to give a loose description of each scenario, provided a structure so that the interviews would have more focus. The questionnaire facilitated comparisons between participants, scenarios and themes.

Figure 1 – Inventory sketch of the auditorium (by the author).

Figure 2 – The auditorium in daylight.

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Figure 3 – Photos of each light scenario (left to right): the Lecture, Picture Showing, Auditory, Display and Mood scenarios.

Figure 4 – Principal sketches of the author’s experience of the distribution of light in each scenario (Note: not to scale).

When the existing lighting was designed in 1998 by a reputable Swedish lighting designer, clear incandescent light was used to create a festive and warm atmosphere. While other light sources gave the main light, the incandescent light added to the spatial impression with sparkling, glowing accents. The retrofit LED light sources were at the time of the study not enough developed to give a fully corresponding lighting quality. Nowadays, the incandescent bulbs are replaced. Luckily, the lighting equipment did not change during the empiric collection of this study. The general lighting was provided by the combination of 14 recessed downlights of 50W low-voltage halogen lamps; warmhite compact fluorescent lights inside the ceiling crown for up/ down light respectively; clear incandescent 25W bulbs around the ceiling crown; 27 bulbs at the curved lighting brass track; and three at each of the ten wall luminaires. The wall luminaires mainly emitted raking light from the sides out to the wall, but the 300 incandescent bulbs also directed direct light into the room. Six spotlights with low-voltage halogen lamps were directed from this track toward the podium. There were five light scenarios (see Figure 3 and Figure 4): • The Lecture Scenario is bright but has less ceiling emphasis and greater focus on the podium. The uplight in the ceiling crown is off, while the crown’s other light sources are dimmed to approximately 75% (visually estimated, including vertical surfaces). Additionally, the spotlights and the overhead projector are switched on and directed toward the podium;

• The Picture Showing Scenario is the darkest of these scenarios, as it uses no incandescent lights and no wall lights. Only the recessed downlights are glowing weakly. The overhead projector is the main light source. The light in this scenario is not sufficient for notetaking. • The Auditory Scenario is the most uniform and brightest of these illuminations. With regard to the visual estimation of brightness, including vertical surfaces, this scenario appears to be the brightest, with all luminaries fully lit. The Auditory Scenario feels much brighter than what the measurements indicate; • The Display Scenario has a total light level that is downregulated to 75-50% of the Auditory Scenario. The overhead projector is lit, but there are no extra spotlights. • The Mood Scenario is similar to the Display Scenario, but it is much darker and uses neither the overhead projector nor the spotlights. The light in this scenario is too dark for notetaking. As a conscious choice by the lighting designer, the room was illuminated with lower horizontal illuminance levels than the levels recommended by international and European lighting standardisation committees (see Table 1). Instead, greater emphasis was placed on the vertical surfaces through the wall luminaires. The designer’s intent was to emphasise the podium, which benefits the audience, and to create a beautiful and well-defined room surrounding the podium. Despite the low average level of light, there was enough light for

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Table 1 – Estimated dimming percentages per light source type and scenarios as well as horizontal illuminance values measured the auditorium

Scenarios

Lecture Picture S. Auditory Display

Mood

Ceiling light Wall lamps Brass track Crown up Crown down Spotlight Overhead light Average illuminance É_avg Median illuminance É_med Maximum illuminance É_max Minimum illuminance É_min Uniformity Uo

75% <25% 100% 50% 75% Off 100% 50% 75% Off 100% 50% Off Off 100% 25% 75% Off 100% 25% On Off Off Off On On Off On 62 lux 29 lux 44 lux 50 lux

25% 25% 25% 25% 25% Off Off 12 lux

33 lux 12 lux 39 lux 28 lux 6 lux 252 lux 141 lux 83 lux 165 lux 26 lux 21 lux 5 lux 29 lux 19 lux 4 lux 0,6

0,42

0,73

0,68

0,67

The estimation of light level dimming is based on visual observation, with the auditorium light being at the 100% level.

taking notes for a short time, as the designer reported in a followup interview. 3.2 Procedure In total, 21 participants filled out a questionnaire and then provided a spontaneous written description of the room for each scenario. Subsequently, they were interviewed by the principal investigator, and the experiment ended with a sketching session. The duration of the experiment and interviews, both held in the room, was between 90120 hours. Only one participant was in the room at a time, together with the researcher. Every participant had some degree of higher education, 13 were designers and nine were not, 14 were women and seven men, with an age span between 25-65 years and an average of 44 years. The light scenarios were arranged in four sets of presentation orders, each observed by one group of interviewees. The participants were initially seated at two different places in the room – half of the participants sat in the centre of the room in an audience row (position A); the other half sat in a windowsill on one short side of the room (position B), see Figure 5. The researcher began by explaining the purpose of the study, namely, to study the relationship between light scenarios and spatial perception. Each session started with an adaption time using the first scenario with curtains drawn to block out daylight. The participants silently filled in the questionnaire for one scenario before the light shifted to that of the next scenario. Questionnaire The participants filled in a questionnaire with answer possibilities on a seven-step rating scale. The Swedish words they used to assess the room were divided into two categories: (1) spatial shape (high, low, wide, narrow, deep, shallow, round, square, large and small), and (2) spatiality (delimited, open, enclosed/embraced, excluding, airy, confined alienating and close). The study participants were also asked to select adjectives describing the atmosphere out of 45. Of these,

the most frequently-used words were subdued, calm, warm, public, legible, soft, embracing, welcoming, inviting and diffuse. The selection of words was based on Küllers’ SDE-method (Küller, 1972, 1975), but some words were changed to better fit the purpose of this study. Only two categories from the SDE seemed relevant to the scope of this study – enclosedness and complexity. The categories pleasantness, social status, originality, affection, unity and potency were not relevant to the study, with its focus being on descriptions rather than preferences. Words from the enclosedness category such as masculine, fragile, powerful and feminine seemed relevant neither to the room nor to the scope of the study. Also, other words not included in the SDE were needed to grasp the spatial atmosphere, for example, embracing, enclosing, inclusive, excluding and inviting. It was decided to not use the SDE’s factor analysis for the questionnaire answers, since the focus of this study is more on revealing personal interpretations behind the concepts, rather than on quantifying them. Following this, the questionnaires were primarily used qualitatively, as manuscripts for the interviews. Interview After all the light scenarios were shown and assessed, the interview phase began. The participant and researcher moved to the podium to see the room from another angle. During the conversation, which lasted 1 to 2.5 hours, each scenario was shown again as they were being discussed. The individual questionnaire answers were used to compile the script for the interviews. With this script the interviews had a medium level of standardisation and were semi-structured, the focus on follow-up questions to their written answers (Alvesson, 2011). The interview complemented the questionnaire with such questions as, “Can you describe why you think this room looks higher now?”; “What differences do you experience regarding this and the previous scenario?”; “What is it that makes it high?”; “Is there another word that would describe it better?” One scenario at a time was discussed in the interviews, and the illumination was changed so that the scenario that was the topic of discussion and the one being viewed were the same. Reflective notes were taken by the researcher throughout the session (Kelly, 2017). The participants could speak rather freely, but the interviewer helped them maintain a focus on the participant at hand and asked follow-up questions. The open-ended interview style followed Kvale’s interview method (Kvale, 1996). During the interview the participants were also given the task of drawing the spatial boundaries and directions of the experienced rooms (Branzell, 1976, 1995; Lynch, 1960). Sketching session During the sketching session at the end of the interview, the participants were encouraged to walk around the space. The sketching task required that the participants draw the limits of the experienced light zone as well as the limits of the experienced physical space (see Figure 5). This was inspired by the methodology of Branzell (Branzell, 1995). These drawings were used to guide discussion during the interview session. 3.3 Analysing empirics The interview process resulted in 27 hours of recorded material. The interviews, lasting from 54-108 minutes, were transcribed into

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Figure 5 – This participant is sitting at position B in the windowsill in the Lecture Scenario. Position A is in a chair in the centre of row 3. To the right, a floor plan with assessment positions A and B and interview position C.

written text. The longest interview was transcribed into 11,380 words. After transcribing the interviews, the selection of quotations was made by searching first for statements that related to the research questions and that explained the questionnaire answers. In the material, 357 quotations were found to be characteristic and specific enough to be selected for the following analysis. Next, the selection was organised into themes. Statements that occur with several participants were chosen. Finally, the most frequent, expressive, and the best explanatory quotations were selected for this article. When several participants spontaneously explained their experiences in a similar manner, this strengthened the results, despite their being just a few participants who did so. Similarly, if some participants expressed an opinion (e.g., that the room is large) and others expressed an idea with the same meaning but in a sort of reverse manner (e.g., in this case, that the room is not small), the hypothesis is strengthened. A reflective log was kept during the entire procedure to also reveal

the researcher’s own questioning and interpretation of the interviews. The selection of the most interesting concept was based also on word clouds from the frequent atmosphere encircled words, generated through NVivo (Zamawe, 2015). The questionnaire’s scale answers were mainly used as the basis of a script for the interviews. The drawings were analysed in two ways. First, they were used as visual comparison material when reading the interview and questionnaire material. Later, they were analysed using a sorting and mapping process. All drawings were sorted by scenario in order to compare whether the room directions were drawn similarly. Additionally, they were sorted by whether the experienced light spaces followed the built room boundaries, whether these were extended or were smaller, and in which way. Comparisons were made both for each participant separately and for each group of participants. The room experiences were also analysed in relation to the different presentation orders.

Figure 6 – Sketches by participant No: 2 (Note that they are not to scale).

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An important component of the study consists of the triangulations and pattern-matching between the multiple cases and their units of analysis (Stake, 2006; Yin, 2003). Therefore, the results of the questionnaire, interview and drawings were combined. Looking at the example in Figure 6, the middle sketch was made during the Auditory Light Scenario. The image shows that the experienced light space stretches above the ceiling. This scenario was regarded as high. This finding was compared with the questionnaire and the interview answers that said that the Auditory Scenario was high.

4. Results 4.1 Spaciousness and perceived dimensions The auditorium is by itself built rather high, with its 4.6m up to the inner vault. Even so, the lighting changed the impression of height, some scenarios were experienced as higher than others. The Auditory Scenario was assessed by most participants as high (20 people). It was followed by the Display Scenario (17) and the Mood Scenario (16), while the other two scenarios fell close behind (15 for both). This was mirrored in the interviews. Most of the interviewees (20 people) considered the room in the Auditory Scenario as having the highest wall luminance and the highest degree of indirect light up into the ceiling, as the most open, and also the airiest scenario. Different reasons for a raised impression were given, including a light emphasis on the furniture – just chairs and a podium – uplighting in the ceiling and the movement of the gaze, attracted by the brightness of the ceiling. This high impression seemed clearly affected by the spotlights being switched on or off. According to some interviewees (Nos: 11 and 17), the room seemed low and heavy without spotlights. One interviewee (No: 3) was clearly affected by the bright ceiling in the Auditory Scenario: “Maybe this was the reason that I wrote uplifting. It is almost hard to focus at eye height, because it is so obvious that the gaze is attracted upwards”. Another interviewee (No: 2) adds more information: “If I just direct my gaze in front of me, it falls on the white surface, and then it is like everything above disappears, and I then regard it (the room) as low. But, if I raise my gaze a bit higher, it (the room) becomes high again. So, it depends on which position I had on my eyes if I assessed it as high or low”. No scenario was considered especially deep. Yet, most scenarios were assessed as more deep than shallow. The Mood Scenario, which had a low light level with a separated and rather uniform distribution of light, was the one assessed as the deepest. Surprisingly, the scenario with most wall emphasis in relation to other rooms’ surfaces was assessed as the least deep one (the Display Scenario) – 76% assessed it as shallow, and 67% answered that it was not deep at all. Some interviewees (Nos: 6 and 14) explained that a raised impression made the room seem narrower. The Display Scenario was primarily regarded as low and wide. It had less indirect light up into the ceiling and more wall-light emphasis. Two interviewees (Nos: 9 and 15) stated that unclear spatial boundaries gave an appearance of openness. One of them (No:15) said this about the Mood Scenario: “The light from the wall luminaires were like openings in the wall”. In the Picture Showing Scenario,

an interviewee (No: 9) described how the light zone shrank as the darkness made the space more difficult to define. In that case, the dark room could be perceived as being larger and infinite. Several interviewees said the darkest scenarios, the Mood Scenario (Nos: 14, 18 and 11), shrunk and that the Picture Showing Scenario felt delimited and close (No: 19): “In a way, you do not see over there anymore since there is no light there that shows the position of the walls. Actually, the room feels smaller”. According to one interviewee (No: 11), the inwardly directed “energy” in the Mood Scenario, created by the prominent ceiling crown and dimmed wall lighting, contributed to an impression of smallness. Two interviewees (Nos: 5, 11) assessed the Mood Scenario as narrow, since focus was concentrated inwards and upwards towards the ceiling crown. One interviewee (No: 7) reported that there was a relationship between the clarity created in the brighter scenarios with the spotlight, and a larger and spacious impression. 4.2 Shape – angularity and roundness The darkest scenario, the Picture Showing Scenario, with a dominant directed and cold metal halide light from the overhead projector towards the podium, constituted the greatest change in observed room shape. The room in this light was clearly judged to be angular, while the room in all other scenarios was judged as being more round than angular. Four participants (Nos: 1, 4, 7 and 12) explained in the interviews that the angular impression was primarily caused by the strong spotlights, a sharp contrasting light that emphasised the room’s angularity. Some interviewees (Nos: 1 and 16) described this sharp spotlight as a flat light. However, several of the interviewees addressed the angularity or roundness among the scenarios differently and used quite different explanations to support their observations. One (No: 10) said the Auditory Scenario, which lacked a strong focus from the spotlights or overhead projector, emphasised the roundness of the chair rows, while three others (Nos: 11, 12 and 21) described the same scenario as more angular due to the whole illuminated room where the baywindow area was seen as flatter in this light. One interviewee (No: 12) described how the wall-emphasised light in the Display Scenario widened the room and simultaneously made it rounder and softer. Contrastingly, another interviewee (No: 13), who saw the Display Scenario with the lit overhead projector, described how the wall lighting made the room rounder, since his focus on the sides was reduced, but also that the contrasting weak wall lighting diminished the room. More interviewees (Nos: 1, 3 and 8) described the Mood Scenario as round because the corners were less visible. The strong contrast with the overall subdued light compared to the brighter ceiling crown created an inner central focus, with a round spread light that also emphasised the circular-shaped ceiling ornament. One participant (No: 9) described how the separated, dotted light all over the space drew attention to other shapes in this room that was made to appear very angular due to the light scenario. Still, there was one participant (No: 12) who considered the Mood Scenario to be angular because of the prominent wall light.

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Five interviewees (Nos: 9, 10, 13, 15 and 16) spontaneously reported that they had seen a vaulted ceiling, a round shape above the ceiling crown. One of the interviewees (No: 16) was so certain of her observation that she did not really believe that the only edges that were rounded were those closest to the joints of the ceiling and walls. The interviewees made these observations in both the Auditory, the Display and the Mood Scenarios. 4.3 The experienced spatial boundaries One of the tasks of the participants was to draw the limits of the light zone, as well as the limits of the experienced space. Most of them simultaneously also talked about how they interpreted these spaces. Hence, the following sections are based on both the drawings and the interviews. One interviewee (No: 9) explained how the light zone she drew in the Lecture Scenario expanded out in the corners. Another interviewee (No: 11) described how the light zone in the Lecture Scenario became more important than the physical built space. He explained further that he experienced two different light zones, in conflict with each other, one brighter in the centre and with a duller zone around it.

Scenario, with a soft, warm glowing and separated, distributed light emanating both from the ceiling and the walls. 4.3.2 Light zones as including or excluding Community is experienced rather similarly within the Display and Lecture Scenarios, with the effect of the spotlights as excluding conversation and encouraging one-way communication being the same. The room was said to be anonymous, and the light was thought to create a feeling of being safe as a part of a crowd, a mass of people in full control of the space. This could simultaneously be regarded as an excluded light for those who might enter the room. Seven interviewees said this light directed attention towards the lecturer. However, they thought it could only be useful for one-way communication, such as in a public panel. In this lighting, the lecturer is not able to see much of the audience due to the glare from the spotlights.

In the Picture Showing Scenario, the physical room was experienced as disappearing by several interviewees (nos. 12, 15, 18). Others (Nos: 1, 4, 5, 12, 13, 14 and 17) judged this room as having the least spatiality. The light did not reach the walls and the space appeared to shrink, according to one interviewee (No: 13). In the sketches, the light zone and the physical room seemed to coincide most within the Auditory Scenario, where the light filled the space.

The difference between being in the light zone or outside of it becomes more obvious in the Mood Scenario. Six interviewees (Nos: 10, 11, 17, 18, 20 and 21), who initially sat on the edge of the room, described the light as excluding, that they did not belong or even exist within the space. This feeling was, according to some interviewees (Nos: 17 and 21), related to the more diffuse wall lighting. Contrastingly, the fully illuminated Auditory Scenario was described by five interviewees (Nos: 5, 6, 8, 9 and 21) as contributing to a democratic atmosphere, where everybody holds the potential to contribute. A community is created that includes both the audience and people on the stage.

In the Display Scenario, several interviewees (Nos: 1, 7, 11 and 17) reported that they were more conscious of the room’s surfaces, walls, ceiling and floor. Two persons (Nos: 1 and 4) said this was t he most spatial room. The light zone was as wide as the room but lower in height.

Two interviewees (Nos: 20 and 21) commented that they were alone with the interviewer in a space made for a large audience and that this had significant impact on the experience of the space. One of them (No: 20) said that the lack of other people in the space was especially strong in the Lecture and Mood Scenarios.

According to three interviewees (Nos: 7, 15 and 20), the light zone in the Mood Scenario did not reach the walls and the edges were experienced as diffuse. Yet, others (nos. 6 and 16) described a feeling that they were in the whole physical space. One interviewee (No: 9) described that this diffuse limitation impacted the feeling that the space continued outside the building. The corners were less emphasised in this scenario. Some (Nos: 11 and 21) experienced this light zone as being located above eye height, around the ceiling crown. Even if the participants were asked about delimitation referring to spatial boundaries, 12 interviewees (Nos: 5, 6, 7, 9, 10, 11, 13, 14, 17, 18, 20 and 21) also answered as if the question dealt with how the space limited them personally. 4.3.1 Spatial enclosedness In the interviews, the bright Lecture Scenario, with the overhead projector and with spotlights directed towards the podium, was not mentioned as enclosing (embracing) – no interviewee mentioned this scenario in relation to enclosedness. Yet, they (Nos: 6, 11, 12 and 17) talked about this scenario as closed, limited and delimited. Also, the Display Scenario, with its great wall emphasis, was not mentioned in relation to the enclosing concept. This contrasts with the three other scenarios that were all regarded to some extent as enclosed (Picture – Nos: 8 and 14; Auditory – Nos: 13 and 15; Mood – Nos: 5, 8 and 9). Yet, enclosing was most associated with the dark Mood

5. Discussion Most of the existing research on this topic generally addresses brightness as a factor that increases perceived size and spaciousness (Acking & Küller, 1966; Flynn, 1977; Houser et al., 2002; Matusiak, 2004). In this study it was found, through both the questionnaire and interviews, that darkness can increase the experience of spaciousness. This was shown when the darkness makes the spatial boundaries less defined, and it becomes unclear where the room ends. According to Matusiak, distinct borders between room surfaces are needed to perceive a room’s accurate size (Matusiak, 2004). A possible explanation to the opposite – that brightness can also decrease size – is when brighter light makes walls more prominent. This might be related to the figure-ground relationship, as the walls are perceived as being closer in relation to the other surfaces (Wagemans et al., 2012). In Hesselgren’s study, the light seemed to reach a level when it made the walls too bright for an enclosed experience (Hesselgren, 1969, pp. 364-365). A similar threshold might also be relevant for a spacious experience. The Lecture and the Display Scenarios were assessed as the widest ones. They had more wall light emphasis. But the interviews provide evidence of rather different explanations for both rooms. With respect to the Display Scenario, an interviewee (No: 12) referred to

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the wall luminaires showing how big the room really was, as the light emphasised the spatial boundaries. Regarding the Lecture Scenario, an interviewee described it as wide because it felt open at the sides (No:. 9).

Another cause for the vaulted impression can be that the boundaries between walls and ceiling are not clearly visible, and the surfaces seem to merge into each other. A brighter centred spot created by the ceiling crown may have increased the raised effect even more.

On the other hand, the darkest scenarios in the auditorium were described as smaller by some interviewees (Nos: 11, 14, 18 and 19) since it was hard to detect the walls, while another interviewee (No: 9) experienced the room as being larger in the darkness, since it could continue into infinity. This relates to another study by the author, in which illuminated tree trunks created spatial boundaries in a park (Wänström Lindh, 2011, 2012, 2013). Interviewees, in both studies, either said the lit semi-open boundaries made the space smaller or larger, but they gave the same cause for their experience. The ones who said it became larger explained: “Now with the lit spatial boundaries, I can really see how big it is”; while the other ones said: “Now with the lit spatial boundaries, I can really see where it ends, so I think it is small”.

5.1 Methodological discussion On one hand, comparing the answers between the in-depth interviews and the questionnaire clearly shows the limitations of the quantitative questionnaire method – people interpret concepts and spaces very differently according to their pre-understanding and, moreover, people answer questionnaires in unique ways. On the other hand, the questionnaire was very helpful as support for the interviews and for providing a structure for analysing qualitative data that was collected for the study. The relatively small number of participants decreases the validity of the study from a quantitative research perspective.

The interviewees said that bright areas on the sides of the room attracted their gaze, giving a wider impression of the space. This connects to a previous study, in which side wall lightness increased perceived width (Acking & Küller, 1966). Brighter lit areas on the auditory ceiling that attracted the gaze gave the impression of a higher ceiling, which also follows from earlier studies (Houser et al., 2002; Oberfeld et al., 2010). However, another study by Oberfeld & Hecht, (2011) found no relationship between perceived height and width size. Still, in the auditorium, a wider impression created by wall lighting might have contributed to reducing the high impression created by indirect ceiling light. This is in line with the findings of Oberfeld and Hecht (2011) concerning the additive effect between ceiling and wall lightness. Shadows can both reinforce a shape, by following it, or flatten and transform it (Häggström, 2009, 2010; Tantcheva & Häggström, 2011). In the auditorium, visible walls and clear spatial boundaries either emphasised angularity or roundness, depending on the level of light and the shadow contrasts in the transitions between room surfaces. Yet, a sharp light also contributed to an angular impression, according to the interviewees. The character of the overhead projector light, with its clear contrasts and distinct borders between light and shadow, together with an angular light image falling on room surfaces, influenced the room’s shape as a whole. In addition to the pattern, light that falls on spatial surfaces constitutes patterns. Luminaire openings also form patterns. In the auditorium, the bent luminaire track and the wall luminaire placements both contributed to creating a round impression of the room, especially in the brighter scenarios. In the darker scenarios, the light was seen as being more separated from the fixtures. In some scenarios, the indirect light directed upwards from the crown in the ceiling created, according to five interviewees (in spontaneous narratives), an experience of being in a high space with a vaulted inner ceiling. Hypothetically, when an overly-bright light is directed towards the ceiling it may appear to be approaching and can be perceived as slightly more convex, rather than concave (Gregory, 1998). This can be the effect of the brightness contrasts surrounding the ceiling.

However, the participants’ experiences are collected in various ways and in greater depth, which strengthens the study in terms of adequacy. Kelly argues adequacy replaces reliability in qualitative research (2017). This study shall primarily be regarded as a qualitative study that provides examples of how people can experience spaces, and creates pieces for a larger puzzle by generating hypotheses for further and more controlled studies. It is important to mention that these findings are context-dependent and not directly applicable to illuminated rooms in general. There are many factors that relate to each other in every spatial context, and the aim of this study was to reveal a small number of them to enhance our understanding of this variety. Some words in the questionnaire were especially tricky because the participants interpreted them quite differently, as shown in the interviews. In the questionnaire, the Swedish word “avgränsad” was used. This concept corresponds best to the English word delimited. Delimitation and limitation generated interpretations related either to a distinctly defined light zone, to drawn curtains or to feeling excluding from the activity within a light zone. Several concepts in this study were shown to contain a similar ambiguity. Previous research shows that this problem is not unique to this study. People sometimes confuse or conflate open spaces and large spaces (Gärling, 1969a, 1969b). Even researchers may refer to essential concepts differently, with some speaking of spaciousness while referring to the floor/ground area (Stamps, 2009) and others referring to volume. Bokharei and Nasar present contradictory results in previous research with the concepts used for representing spaciousness either as narrow-wide or as large-small (Bokharaei & Nasar, 2016). In this study, large can imply either the height or the width of the space, or both. Here, angularity was interpreted either as a sharp contrasting light or as distinct spatial boundaries. It seemed clear that some participants changed their attitudes between scenarios, not only with respect to the concepts – for example, their interpretation of “limitation/delimitation” – but also in the way they answered the semantic scales. In the first scenario, several of the observers judged the physical space by its furniture, materials and colours, while for each scenario that followed, they progressively placed more emphasis on the light zone. As one of the

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interviewees (No: 4) articulated: “After a while you became blind to the room”. This connects to what Boyce refers to in the studies by Flynn et al. and Hawkes et al, that even if participants in one study are asked to assess the room in terms of different lighting, but in another to assess the lighting of the room, the results between them were consistent (Peter Robert Boyce, 1981). Another interviewee (No: 20) described how the light zone received more emphasis so that eventually she saw the light zone as the space. Since the scenario order shifted for the participants, this difference was at least balanced to some extent in the questionnaire conclusion. There was a clear difference between the scenarios — in the darker scenarios, it was easier to assess the light separately from the physical room. Additionally, there was a general transformation of the discourse from starting out as a discussion of the lighting scenarios as scenarios and rooms to a discussion of the scenarios only as different rooms. Because the room had an unusual shape, short and wide from back wall to front wall (and the podium), participants judging the room from two different directions sometimes addressed the depth and the width in contrast to each other.

6. Conclusion This explorative qualitative study has generated several new hypotheses. These are built on relationships which need to be further studied in different contexts, to secure their validity. Most findings follow previous research. Simultaneously, contradictory participant experiences are also found. The context, including spatial complexity together with the participants’ pre-understanding, generate several possible explanations. This study supports previous research in that uplight, together with wall lighting, reinforces height and openness (the Auditory Scenario). Additionally, a moderate wall lighting and less ceiling light, was associated with a wide and a low impression (the Display Scenario). Surprisingly, darkness was associated with an impression of spaciousness (the Picture Showing Scenario). According to most previous research, brightness was predicted to give an enlargement effect. Furthermore, a scenario with prominent lit walls in relation to other dimmed room surfaces (the Display Scenario) was assessed as shallow and small. Another unexpected finding is that the room with most wall lighting emphasis was shown to be the least enclosing (the Lecture Scenario). As indicated by several participants, the movement of the gaze when attracted to brightness may be possible to relate to size impressions. If so, this can be important for future studies’ methodological approaches. Interesting quotations concerned how the light zones within the room may affect social interactions. The experience of democracy and participation changed with the light scenarios. This study can be summarised with the conclusion that the experience of a space is not equal to the boundaries of the physical built room. Spatial empathy, supported by research, is needed to encircle possible interpretations. This knowledge will support lighting design which intends to visually enlarge and diminish rooms. By this, the feeling of being safe can increase, since the feeling of being safe can be associated with enclosedness and spaciousness.

Based on the main hypotheses developed here we suggest for future studies: • To further study the effect of brightness and darkness on perception of spatial size and distance, to surfaces and objects in complex environments; • To study peoples’ experiences of room size with different light scenarios in various contexts; • To study the gaze movement attracted by light in relation to spatial size impression; • To study peoples’ interaction in relation to light zones. Acknowledgments Thanks to Karin Fridell Anter for great advice. This study was primarily done at Gothenburg University, School of Design and Crafts, Gothenburg, Sweden. The article was finished at School of Engineering. Jönköping University, Department of Construction Engineering and Lighting Science.

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Enhancing Thermal Mass Performance of Concrete

Improving the sustainability of the built environment by upskilling SMEs in Building Information Modelling through the Horizon 2020 BIMcert Project

Dr Barry McAuley SCHOOL OF MULTIDISCIPLINARY TECHNOLOGIES, TU DUBLIN barry.mcauley@tudublin.ie

Dr Avril Behan SCHOOL OF MULTIDISCIPLINARY TECHNOLOGIES, TU DUBLIN avril.behan@tudublin.ie

Paul McCormack BELFAST METROPOLITAN COLLEGE PaulMcCormack@belfastmet.ac.uk

Andrew Hamilton BELFAST METROPOLITAN COLLEGE AndrewHamilton@belfastmet.ac.uk

Eduardo Rebelo BELFAST METROPOLITAN COLLEGE ERebelo@belfastmet.ac.uk

Dr Sheryl Lynch FUTURE ANALYTICS CONSULTING LTD sheryl.lynch@futureanalytics.ie

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Abstract The construction industry consumes up to 50% of mineral resources excavated from nature, generates about 33% of CO2 present in the atmosphere, and is responsible for 40% of total global energy through construction and operation of buildings. There is a realisation that SME’s perceived lack of innovation is causing a genuine concern in the AEC industry as they do not have the skills or tools required to help address these concerns. To assist in overcoming these barriers, a number of funding initiatives have been put in place through Horizon 2020 with a focus on BIM, due to it having the potential to rapidly produce energy outputs that enable design teams to analyse and compare the most costeffective energy-efficient options. One of these initiatives, the BIMcert project, aims to educate all areas of the supply chain in the use of BIM, to achieve better energy efficiency during the design, construction and ongoing maintenance of an asset. The goal is to develop more efficient and suitable training programme materials that integrate sustainability and renewable concepts with practical application by integration with technology. This paper explores the final phase of testing and the launch of the platform. It discusses how the developed training material assists in improving sustainability in the built environment by training its practitioners in an efficient and greener manner of design and construct through the BIM process. The paper also defines recommendations to target the broader skills gap agenda.

Keywords Building information modelling, sustainability, education, Horizon 2020. 48

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Improving the sustainability of the built environment by upskilling SMEs in Building Information Modelling through the Horizon2020 BIMcert Project

1. Introduction The construction industry is dominated by SMEs, with estimates considering that these organisations account for around 97% of all construction businesses throughout the EU (Gledson and Phonix, 2017). Given that the construction sector is responsible for one-third of global carbon emissions, one-third of global resource consumption, and 40% of global waste generated, it is imperative that SMEs play a pivotal role in decreasing these alarming figures (Balasubramanian and Shukla. 2017). Sustainability in practice is becoming increasingly more important for SMEs as they contribute to the green agenda and demonstrate positive engagement in order to win constructionrelated contracts or meet customers’ criteria. Whereas larger organisations have time, staff and financial resources readily available, SMEs don’t have such resources and therefore sustainability measures are perceived as costly and time-consuming (Goddard et al., 2016). Moreover, SMEs are perceived to lack innovation, which is causing a genuine concern for the industry despite the potential to improve existing processes and technologies, thus leading to significant practical and commercial benefits (Gledson and Phonix, 2017). Innovations in relation to the digital transformation of construction are now seen as critical change agents for the industry that can offer effective environmental solutions in targeting the rapidly-changing climate and global energy crisis (Farmer, 2016 and Chen, 2018). SMEs have the potential to benefit from digital construction more than large firms because of their stature. Smaller-sized projects with a short duration can result in higher implementation rates. Their speed in decision-making permits SMEs to develop and deliver practical technical innovations (Saka and Chan, 2020 and Hardie and Newell, 2011). Such innovations include Building Information Modelling (BIM), which can be described as a collaborative process in which all parties involved in a project use three-dimensional design applications where information is shared between stakeholders and managed throughout an asset’s lifecycle. BIM is now seen as the centre of the AEC industry’s digital transformation agenda (World Economic Forum, 2018). More importantly, in the context of sustainability, BIM can be used to model buildings and sequentially perform multiple analyses, enabling energy performance predictions that compare design alternatives, thus allowing for an improved final decision (Sanhudoa et al. 2018). While energy simulations are used to evaluate the energy performance of building operations, emerging BIM technology is expected to facilitate building lifecycle performance simulation with predefined and enriched building information (Li et al., 2020). For BIM to be successfully adapted within an SME, they will need to address several barriers to entry, such as access to finance, cultural change, inadequate levels of communication and information exchange, adopting technology, resources, construction project coordination, and bureaucracy (Carroll and McAuley, 2017). This is difficult, as construction projects frequently suffer from many problems such as low product quality and working efficiency, budget overruns, and substantial construction waste (Avelar et al., 2019). Vidalakis et al. (2020) warn that SMEs’ knowledge in existing BIM support systems is particularly low, with monetary-related issues

identified as the main barrier. Further to these, non-financial factors such as peer education, industry initiatives and effective leadership were highlighted as the most useful in facilitating further adoption. Consequently, and to reach EU energy-related targets, a number of funding initiatives have been initiated through EU interventions, including FP7 framework programmes and Horizon 2020, with a focus on BIM to contribute to energy savings to enable design teams to determine cost-effective and energy-efficient options. One such initiative is the BIMcert project. This allocates resources on a platform, with a methodology to educate the supply chain in BIM adoption.

2. Energy BIMcert background Horizon 2020 is an initiative by the EU Research and Innovation programme where F80 billion of funding was made available from 2014 to 2020. As part of this programme, the initial funding focused on supporting innovation through research by demonstrating energydriven technologies and solutions. The BIMcert consortium, which comprises of industry and academia, is deemed expert in providing BIM solutions, skills, training and education to the AEC sector. This consortium is supported by a Technical Advisory Board comprising of stakeholders and external experts. The consortium put forward a proposal to develop a method, materials and micro accreditation for upskilling the AEC industry supply chain to adopt BIM techniques and technologies to address energy efficiency demands. The aim of BIMcert is to develop efficient and pertinent training programme materials that integrate concepts of sustainability with practical application and technology, based on real-life industry needs and limitations. The BIMcert consortium consists of members from Northern Ireland (Belfast Metropolitan College and Construction Industry Training Board (CITB NI)); Republic of Ireland (Technological University (TU) Dublin and Future Analytics Consulting); Portugal (CERIS/Instituto Superior Técnico); Macedonia (Institute for Research in Environment, Civil Engineering, and Energy (IECE)); and Croatia (Energy Institute Hrvoje Pozar (EIHP)). The primary objectives of the consortium were: 1. Improve the sustainability of the built environment by training its workforce in more efficient and greener ways of designing and constructing through to use of BIM processes, better materials, products and energy sources; 2. Engage with the entire construction sector supply chain via BIM to develop more extensive European links and to encourage a system of peer support across states of varying maturity concerning to delivery of more energy-efficient new-builds and renovated buildings; 3. Encourage greater workforce mobility, continuous upskilling and to better employability for all levels of employee in the construction sector; 4. Create clear pathways of the development for individuals and SMEs to upskill from any starting point of knowledge to any required level of individual to collaborative expertise in support of sustainable energy-efficient construction; 5. Develop a pan-European framework for recognition and accreditation of BIMcert’s micro-accredited learning modules that will

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combine to build towards fully standardised skills recognition linking within existing national and European initiatives and frameworks of accredited courses and awards. The consortium established a series of work packages which were conducted in five stages: •

Stage 1 – State-of-the-Art: An open approach to gather stateof-the-art information through direct engagement with project stakeholders across Europe to ensure that the skills gaps identified by SMEs about the implementation of BIM technologies and methods in support of improved energy efficiency in the construction sector are correct;

Stage 2 – Development: Development of the BIMcert platform which enables users to access the BIMcert curriculum, support stake-holders’ communication and collaboration, provide information about the project, and share BIMcert outputs in the longer-term;

Stage 3 – Testing: The rigorous evaluation of the curriculum, the learning materials and the proposed platform. A total of three phases of testing were conducted;

Stage 4 – Accreditation: Accreditation of the proposed BIMcert training units and courses; Stage 5 – Exploitation and dissemination: The exploitation and dissemination of the project through a broad-ranging outreach campaign.

These work stages ran in parallel and were critical to each other’s success. Research papers by McAuley et al. (2019a&b) focused on testing at Phases 1 and 2, and will be discussed in the next section to provide context on how and what pilot materials were created. The remaining part of the paper focuses on the final test phase and the launch of the platform.

3. Consortium jurisdictional overview The maturity of BIM adoption across partners’ jurisdictions varied significantly. CITB NI conducted a survey in the five countries which yielded 548 responses. To validate the findings, five workshops with stakeholders took place between 2nd - 6th June 2018. These were applied to gather supplemental data to cross-reference with the survey results. The workshops were open to the industry, and representatives of the advisory partners were encouraged to attend. The results found that all respondents recognised that BIM training is required at all levels within their respective practice. The survey findings indicate that 57% of respondents have received no formal BIM training, although 61% use an element of BIM. The main challenges identified from the survey and reiterated at the workshops were identified as (a) the lack of BIM skills (46%), and (b) the lack of client awareness of the value of BIM (43%). Based on the workshop consultations, BIMcert coordinators noticed a discrepancy between industry knowledge and enthusiasm for adopting BIM. The results indicated that Government encouragement for BIM adoption, particularly within the UK and the Republic of Ireland, was a strong motivating factor. A lack of Government endorsement within Macedonia, and to a lesser extent Croatia, resulted in their AEC industry facing similar concerns to the aforementioned.

The lack of BIM maturity across Europe, and especially some of the partners’ jurisdictions, informed the consortium that for potential users to understand how BIM is used for energy-related purposes they would need a fundamental understanding of the core principles, as well as knowledge of how to access information for review purposes. Furthermore, these findings influenced the consortium in its selection of training courses for practice development. 3.1 Development and testing of material phase 1 and 2 A state-of-the-art literature review of the current global status of BIM regarding education and applicable pedagogical methodologies to deliver these courses was performed in parallel. The survey and workshop findings were aligned with the results from the state-ofthe-art literature review, where it was found that the most suitable pedagogical approach would involve a scaffolded learning environment guided by a series of instructor-led live lectures. This could be complemented through problem-based learning, design for disassembly, and guided self-learning, which would create an active learning environment. Different teaching approaches included narrative videos and live lectures, with a focus on engaging students in self-guided study through problem-based learning before they advance. The initial findings for the proposed training courses and methodologies were tested through a series of reality check workshops as part of Phase 2. The inherent outcomes from the workshops resulted in the established final training descriptors, including learning outcomes, syllabi, methodologies and delivery details. The consortium members decided that the optimum path was to divide the development of the curriculum into three strides. Figure 1 identifies the initial units and courses that best reflect the needs of the industry. The learner initially accesses the BIMcert portal and will be presented with one of two options. If the learner selects Option A, they must take the BIM Ready training unit plus online assessment. If the learner has prior knowledge of BIM, they can choose Option B, which will enable them to take the online assessment without enrolling in the training unit. Successful completion of the assessment, in either case, grants access to Stride 2. It was agreed to divide Stride 2 into three sections. Within Stride 2A, learners can select many stand-alone units that will introduce them to BIM principles, digital skills and modelling techniques. Stride 2B represents units aimed at those more experienced BIM users who wish to advance their knowledge in BIM, e.g., interoperability, collaboration processes, etc. While learning outcomes have been developed for these training units, it was not feasible for the BIMcert consortium to develop these any further during the Horizon 2020 project. Stride 2C offers learners the choice of one or more courses, each consisting of a series of units. Each unit within a course represents a specific learning outcome (LO). This LO/unit will be offered as an individual micro-size training option to ensure the BIMcert can attract learners who require specific areas of knowledge but do not have the time to complete a standard unit (Stride 2A and 2B) containing a series of LOs. After completion of all units associated with the course, the learner will receive a higher award. Learners can take advanced units once they complete the relevant Stride 2C course units, i.e.,

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Improving the sustainability of the built environment by upskilling SMEs in Building Information Modelling through the Horizon2020 BIMcert Project

Advanced BIM & Energy Efficiency. As with Stride 2B, it is not the intention of the consortium to develop all courses in this stride. Stride 3 is a more discipline-focused stride representing current specialisations of BIM usage, tools and concepts. The range of units can be expanded or adjusted in the next stage of the BIMcert project in response to market needs. Phase 2 testing comprised a total of five trial workshops, which were held across the partner jurisdictions (Republic of Ireland, United Kingdom, Croatia, Macedonia and Portugal). These workshops were hosted on partner city bases and online. A variety of material from a selection of LOs from the BIM Ready (Stride 1), BIM Fundamentals (Stride 2A), BIM Principles (Stride 2A), Digital Skills (Stride 2A) and Introduction to Low Energy Building Construction Course (Stride 2C) was developed for testing. The BIMcert consortium selected these learning units as they have the potential to promptly impact a significant number of practitioners across Europe. In addition, the material could be delivered by instructor-led live lectures, which would allow the lecturer/trainer to engage with the participants. The intention was to develop learning material that could be used for guided self-learning and gain insight into how potential users would interact with this material. The workshops targeted both novice and groups of practitioners au-fait with BIM, including designers, architects, engineers, contractors, policymakers and professional institutes. The over-arching purpose of the workshops was to establish if the pilot material was adequate to meet the AEC industry’s needs. A total of 140 attendees across the five cities participated in testing the pilot material. It was agreed to host this pilot material on the BIMcert webpage (https://energyBIMcert.eu), where attendees completed an evaluation form to provide feedback on the training material. The workshops took place from January to April 2019 in the five key stakeholder jurisdictions and were led by Future Analytics Consulting (FAC). While the delivered material was generally wellreceived, some pertinent comments were recorded from each workshop. The key findings from the workshop in Macedonia indicated that there should be a correlation with relevant national standards for construction and energy efficiency which could be a basis for BIM adoption. The training materials presented were found appropriate and legible. However, dividing the material into smaller learning units was suggested. A number of attendees recommended enriching the learning content with more information on BIM in the context of energy efficiency by presenting a prototype case study. In Croatia, the attendees requested more information on real case studies, BIM objects, libraries, a focus on how to extract data from BIM models, and more interaction and time with the lecturers. In Ireland, where BIM is more mature, key comments included the need for more practical application on materials. Other suggestions included reducing the learning scope and content to attract bluecollar workers and skilled tradespeople. In Portugal, there was a request for material that focused on standards related to the organisation and digitisation of information for buildings and civil engineering works, including ISO 19650, case studies, and with more information on certification pathways, as well

Learner accesses the BIMCert portal • Stride 1: option A: Learner takes BIM Ready plus online assessment; successful entry grants access to Stride 2. • Stride 1: option B: Learner directly takes online assessment; successful entry automatically grants access to Stride 2. FInal unit of BIM Ready assists the learner in the selection of the next module. Appropriate to their needs/roles. • Stride 2A: Learner selects a standalone unit aimed at BIM novices. • Stride 2B: option B: Learner selects a stand-alone unit aimed at those professionals with a deeper BIM knowledge. • Stride 2C: option B: Learner selects a course (c) which contains a number of units. Successful completion of relevant modules will give learners access to advanced modules. • Stride 3: Specialist modules to be developed. Figure 1 – BIMcert Learning Pathway.

as the use of interactive tools such as Kahoot or other interactive mediums via the BIMcert platform. Furthermore, the UK workshop found that material should be more practical in terms of how BIM will improve the workflow, reduce text on slides, and explore how BIMcert could be used for continuous professional development (CPD) points.

4. Development and testing of material – Phase 3 Based on the workshop findings, each partner refined their material. An agreement was reached that the LOs would be established as individual training modules which would be linked to an overall training plan, i.e., a Complete Unit. In addition, applying shared LOs across a number of training units provides further incentives for the users whereby they can select a single LO instead of being constrained to complete a whole training unit. This methodology was agreed based on the functionality of the platform. 4.1 Training material developmentT One of the key requests from the pilot workshops was for material to be “bite-size and shorter learning sections”. To achieve this, an agreement was reached to break the LOs into the bite-size offerings, as outlined in Table 1. To deliver the bite-size training while satisfying the workshop findings, narrative videos with guided self-learning elements were created for all submodules. Other learning methodologies included creating sub-pages on the platform which contained educational information. Each sub-page included blended multi-media resources such as researched materials, videos and links to education sources. The “book function” on the platform also enabled the creation of multi-page resources in a book-

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like format which generated an automatic table of contents for ease of navigation. Other modules contained structured coursebooks, complementary tutorial videos to create a building energy model, and presentations to demonstrate how BIM is applied for calculation and optimisation of energy consumption. 4.2 BIMCert platform The BIMcert platform was designed to be user friendly, with a clean and modern interface that can be used on mobile devices to engage with the entire supply chain. while enabling participants to achieve the appropriate qualification level. In addition, the platform is based on a well-known and tested framework (Moodle) which allows consistency, flexibility, and adaptability to different user needs. Prior to uploading the material onto the training platform, the

BIMcert team agreed on a standard template for each module, which is linked to a training plan whereby the user can see the relevant modules. All modules were presented by an image and a brief description with a “learn more” link, as illustrated in Figure 2. If the user selects the “learn more” option, this opens a more detailed understanding of the module and contains a rationale for this module’s importance and what the learner will gain. It also provides information on what training plan the module is linked to and what modules should be taken before this one. The time to complete the modules is also detailed in this section, i.e., a combination of the length of the lesson as well as the expected guided self-learning hours required. The user will then have the option to enrol in this module, as illustrated in Figure 3 for the BIM Dimensions module. Once the user is validated to the module, they

Module

Description

Training Plan

What are BIM (Maturity) Levels?

This module provides an understanding of BIM maturity levels and how they impact professional workflows.

BIM Principles

BIM Terms and Definitions

This module explains and provides an understanding of the essential BIM terms and definitions, allowing learners to start navigating the BIM jargon.

BIM Principles

BIM and Digitalisation BenefitsOverview

This module provides an overview of the benefits of BIM and digitisation to the AEC industry.

BIM Principles

BIM Dimension

On completion of this module, learners will be able to explain key terms and definitions within BIM, specifically BIM Dimensions.

BIM Principles

Intro to BIM tools for Low Energy Building Construction

This module enables the learner to develop a fundamental understanding of how BIM can be used as a digital enabling tool/ to help the AEC industry and professionals to reduce energy losses.

BIM to achieve Low Energy Buildings – Introduction

Energy system thinking key principles

The module provides an understanding of sustainable and energyefficient design, construction, and operation principles of buildings and how they are applied in construction practices.

BIM to achieve Low Energy Buildings – Introduction

What is BIM and digital construction?

This module provides the learner with an understanding of the context and essentials of BIM and its role as an enabler for energy efficiency and a tool to address climate change.

BIM Principles

Intro to BIM Implementation – Impacts in project delivery

On completion of this module, learners will be able to explain the impact of BIM Maturity Level 2 requirements for project delivery.

BIM Principles

Digital Skills – Accessing information through the cloud

This module explains how to use cloud-based platforms to access and exchange information.

Digital Skills

Digital Skills – Accessing information through Portable devices

This module explains how to use portable devices to access and exchange information.

Digital Skills

Digital Skills & Collaboration I – and File Structure

This module provides a focus on ICT file management. As well as an understanding of the technological requirements for BIM implementation, especially in relation to Common Data Environments.

BIM Principles and Digital Skills

Digital Skills and Collaboration II – CDE Access BIM Models

This module explains how to use cloud-based storage and portable devices to access and exchange information. This module combines the Digital Skills – Accessing information through the cloud and Digital Skills – Accessing information Portable devices modules into one large module.

BIM Principles and Digital Skills

Digital Skills and Collaboration III – review BIM models

This module provides an understanding of how to use digital design review tools to access and evaluate a BIM model.

Digital Skills

Table 1 – Module details and associated training plan.

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Figure 2 – BIMcert Interface: All modules were represented by an image and a brief description with a “learn more” link.

are presented with a number of sections to complete the module with an explanation of the key LOs, access to material, external links, and self-assessment review. Each of the modules concludes with an assessment to ascertain if the user meets the intended LOs. The assessments are selected on the recommendations from the pilot workshops, including international best practice. It is essential to have a different range of assessments to meet the needs of different user types. The assessments include multiple-choice quizzes, tests built into the tutorial videos, guided self-learning assessments, and interactive illustrated puzzle games (Figure 4). The variety of assessments available ensures that the enduser is tested and engaged throughout the use of the BIMcert platform. 4.3 Phase 3 testing and results To increase accessibility and participation for practitioners and academia, it was agreed among the partners that the subsequent workshops at Phase 3 would be hosted online, where trainees could also access the BIMcert platform easily. The flexibility of the delivery approach enables trial participants to engage with the platform by registering to enrol for modules via laptops or mobile devices anytime, anywhere. The webinars permit participants a first-hand experience to use the training platform whereby they can access the BIMcert training materials in the form of modules and training plans. The rationale for choosing a webinar is to reach out to a diversified audience and encourage greater engagement from different jurisdictions through virtual connectivity. Users were provided with the opportunity to seek clarifications on content, assessments and learning materials with BIMcert experts over a “virtual face-to-face”. Furthermore, it was decided to have “Practitioner Pop-Ups” for skilled tradespeople interested in understanding the BIM process. This resulted in a three-point approach where engagements were conducted separately for “trainers”, “trainees” and “skilled tradespeople”.

Level 0

Level 1

Figure 3 – Module Breakdown: BIM dimensions image.

The goal of the BIMCert project was to improve the sustainability of the built environment by training its workforce in more efficient and greener means of designing and constructing through the use of BIM processes. The final test proved that this had been achieved, whereas practitioners were provided with tools to support their learning paths through a micro-modules approach. The material assisted in upskilling the AEC industry supply chain by offering just-in-time training through a wide selection of training options to suit their needs. These micro-modules afford SMEs an opportunity to demonstrate to clients that they have fundamental capabilities to work in a digitally-focused environment with sustainability in mind. The outcome of Phase 3 indicates that the developed material permits users to advance through learnings at their own pace, thus satisfying their individual ambitions and learning curves. This creates a clear path for practitioners and SME professionals. Figure 5 illustrates the key outcomes from the BIMCert project, capped by the achievement of engaging with over 5000 practitioners throughout the supply chain.

Level 2

BIM 2D & 3D CAD 2D CAD

Level 3

iBIM

Figure 4 – Illustrated game puzzle, self-assessment.

Figure 5 – BIMCert results and outcomes.

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5. Potential impact for the UK and Ireland While the consortium members of Croatia and Macedonia have a much-needed resource for their respective AEC sectors due to low BIM maturity, the other three members (Portugal, Ireland and UK) have an upskilling tool that further helps drive digital construction uptake within SMEs and education providers. With regard to Ireland, the current COVID-19 crisis has seen organisations accelerate their digital agendas, thus enabling them to realise the relevant benefits that digital tools offer. Ireland already has a wide range of training solutions from HEIs and software providers, as well as industry roadmaps (National BIM Council Roadmap to Digital Transition 2017 – 2021), CPD events, an internationallyrecognised conference (CitA BIM Gathering), certification routes, e.g., NSAI ISO 19650 accreditation, as well as templates and guidance documents i.e., the Royal Institute of the Architects of Ireland BIM Pack and Construction Industry Federation Guides. These are all complemented by a broad selection of government reports that endorse BIM (McAuley et al., 2020). However, there is still no mandate in place, which leaves a critical lack of funding to provide guidance and training resources for SMEs. The BIMcert platform offers a potential vehicle to meet the training needs of underfunded SMEs.

comparable skills which are recognised across boundaries. As outlined by Sutherland (2019), the Head of Sector, EASME European Commission:“We don’t all need to know absolutely everything, but we need to pick up the elements of knowledge that are relevant and can be used to facilitate BIM upskilling”. The key ideology is to facilitate BIM upskilling within the broader agenda of digital skills to enable the imminent transition, which is essential to the industry’s decarbonisation and to achieve positive climate action.

6. Conclusion Facilitating BIM upskilling is recognised as an instrument to contribute to the European Green Deal by ensuring that the project life-cycle and costing analysis have a sustainable growth agenda for the future by using digital technologies. By association, promoting transferable skills via BIMcert is imperative in the AEC industry to instil digital transformation and for safeguarding a sustainable future for Europe. BIMcert has delivered flexible, iterative digital upskilling training to the entire construction supply chain by focusing on SMEs. This platform has offered an entry point for SMEs to begin their BIM journey, which can ultimately lead to increased productivity and guarantee better compliance with deadlines and energy targets, thus reducing cost and waste.

The UK has invested heavily in digital construction with the Centre for Digital Built Britain, which is funded as part of the HM Government’s recommendations in the 2017 Autumn Budget by up to £5.4 million. This enabled it to launch initiatives such as “Delivering a Digital Built Britain”, a request for feasibility studies, research projects, or experimental development projects ranging in value from £50,000 to £250,000. Other initiatives included an £18 million funding released by the UK Research and Innovation Department in 2019 to transform the construction industry through digital technology.

Further to this, this platform is accessible to participants globally for vocational education and remote blended learning access, which is critical during the current COVID-19 pandemic. The initiative has instigated change in standards and regulations in partner countries across Europe, especially those with low digitalisation maturity levels. The consortium’s pan-European approach has provided international recognition to the BIMcert brand, which has helped its adoption within international jurisdictions. It also has the potential to influence and support policies and mandates and, by utilising real-world prototypes, to achieve better employability for all levels of employees in a greener, more sustainable construction sector.

Regarding BIMcert, it holds the greatest potential within Northern Ireland, as BIM resources, especially for SMEs, are still a key gap. The BIMcert platform has been aligned to the Open College Network (OCN) Northern Ireland, a recognised UK awarding organisation based in Northern Ireland. This has enabled the successful upskilling of a selection of SMEs in Northern Ireland who have gained awards from both BIMcert and OCN NI.

The next iteration of BIMcert will be as part of the BIM Energy Performance Alliance (BIM–EPA) which will gather and link BIM modules, tools and materials from previous Horizon 2020 projects. This will enable the further development of a resource and skills recognition pathway that all stakeholders can utilise, deliver and stimulate.

As part of the findings from the final round of testing, the BIMcert team released a set of recommendations to assist with targeting the broader skills gap agenda. These recommendations included: • Incentivise energy efficiency, e.g., including energy criteria as part of pre-qualification in tenders; • Standardise BIM curriculum, i.e., introduce a Pan-European BIM Passport and guidelines for CPD vocational mobility; • Mandate BIM locally, i.e., localise via National Action plans and legislate for State buy-in / public procurement accordingly; • Utilise platforms such as BIMcert, which offer bite-size micro accreditations. A key enabler to facilitate BIM upskilling is to promote training curriculums. National skills agendas set locally should also include

Acknowledgments Barry Neilson and Gayle Beckett (CITB Northern Ireland ), Dr.António Aguiar Costa (Universidade Lisboa,) Paulo Carreira (iNESC-ID Lisboa), Dijana Likar and Dr.Angelina Taneva-Veshoska (Institute for Research in Environment, Civil Engineering, and Energy), Prof. William Hynes and Mallika Singh (FAC) and Toni Borkovic (Energy Institute Hrvoje Poza).

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References Avelar, W., Meirino, M. and Tortorella, G. (2019) The practical relationship between continuous flow and lean construction in SMEs, The TQM Journal, Vol. 32 No. 2, pp. 362-380 Balasubramanian, S., & Shukla, V. (2017). Green supply chain management: an empirical investigation on the construction sector. Supply Chain Management: An International Journal, 22(1), 58-81. Carroll, P. and McAuley, B. (2017) Establishing the key pillars of innovation required to execute a successful BIM strategy within a Construction SME in Ireland, Proceedings of the 3rd CitA BIM Gathering, Dublin, 23rd - 24th November, 2017, pp 84-91

Sanhudoa, L., Ramosb, N., Martinsa, J.P., Almeidab, R., Barreirab, M., Simõesb, L. and Cardosob, V. (2018) Building information modelling for energy retrofitting – A review Renewable and Sustainable Energy Reviews, Iss 89, 249–260. World Economic Forum, (2018), An Action Plan to Accelerate Building Information Modeling (BIM) Adoption, Shaping the Future of Construction, World Economic Forum Vidalkis, C., Abanda, F.H and Oti, A.H (2020) BIM adoption and implementation: focusing on SMEs, Construction Innovation, Vol. 20, No. 1, pp. 128-147

Chen, S.Y. (2018) A green building information modelling approach: building energy performance analysis and design optimization, MATEC Web of Conferences, Vol 169, EDP Sciences. European Commission ( 2020) The European Green Deal Investment Plan and Just Transition Mechanism explained, available at< https://ec.europa.eu/commission/ presscorner/detail/en/qanda_20_24/> accessed ( 09/20/2020). Farmer, M. (2016) The Farmer Review of the UK Construction Labour Model: Modernise or Die, Construction Leadership Council Gledson, B. and Phoenix, C. (2017) Exploring organisational attributes affecting the innovativeness of UK SMEs. Construction Innovation: Information, Process, Management, Vol 17, No 2, pp. 224-243 Goddard, J., Glass, J., Dainty, A. and Nicholson, I. (2016) Implementing sustainability in small and medium-sized construction firms: The role of absorptive capacity.Engineering, Construction and Architectural Management,, Iss 23, pp 407–427. Hardie, M. and Newell, G. (2011), Factors influencing technical innovation in construction SMEs: an Australian perspective, Engineering, Construction and Architectural Management, Vol. 18 No. 6, pp. 618-636. Li, H.X., Ma, Z., Liu, H., Wang, J., Al-Hussein, M. and Mills, A. (2020), “Exploring and verifying BIM-based energy simulation for building operations”, Engineering, Construction and Architectural Management, Vol. McAuley, B., West, R. and Hore, A. (2020) The Irish Construction industry’s State of readiness for a BIM mandate in 2020, Proceedings of the Civil Engineering Research in Ireland 2020 Conference, Cork, 27th - 28th August 2020, pp 740-745. McAuley, B., Behan, A., McCormack, P., Hamilton, A., Rebelo, E., Neilson, B., Beckett, G., Costa, A.A., Carreira, P., Likar, D., Taneva-Veshoska,A., Lynch, S., Hynes, W. and Borkovic, T., (2019), Improving the sustainability of the built environment by training its workforce in more efficient and greener ways of designing and constructing through the Horizon2020 Energy BIMcert project, Proc of the 4th CitA BIM Gathering, Galway, 63-70 McAuley, B., Behan, A., McCormack, P., Hamilton, A., Rebelo, E.,Neilson, B., Beckett, G., Costa, A.A., Carreira, P., Likar, D., Taneva-Veshoska,A., Lynch, S., Hynes, W. and Borkovic, T., 2019, Delivering energy savings for the supply chain through Building Information Modelling as a result of the Horizon2020 Energy BIMcert project, Proc of International SEEDS Conference 2019: Growing Sustainability –- Natural Capital and Society in the Built Environment, Leeds, pp 11 Saka, A.B. and Chan, D.W.M (2020) Profound barriers to building information modelling (BIM) adoption in construction small and medium-sized enterprises (SMEs) An interpretive structural modelling approach, Construction Innovation, Vol. 20, No. 2, pp. 261-284

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24/11/2020 09:10


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24/11/2020 09:10

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