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Issue 2 Jan/Feb 2017




perfectly pitched

BS EN 14351-1:2006+A1:2010

visionaryroof rooflights pitchglaze window 01379 658300



Editor’s Comment


Industry news


New Projects



Daylighting: the human factor Paul Bennett draws on research presented by the BRE and NARM, outlining the benefits of daylight.


Patent Glazing It’s not all stations & canopies... Richard Burgess explains

NARM Daylight Diary


Updates from the UK’s influential trade association for rooflight manufacturers

John Godley explains the importance of transmission values for rooflights


Daylighting icons The Crystal Palace

Too much of a good thing?


Defining non-fragility for rooflights Chris Pearce explains how today’s classification of non-fragility for rooflights was established.




Daylighting & the Passivhaus Standard

What’s trending on social media?

A look at ‘the world’s leading fabric first appraoch to low energy buildings’


More about DAYLIGHTING Magazine Forthcoming features and information for advertisers & contributors

DAYLIGHTING is published by: Bennett & Partners Pure Offices Lake View House Tournament Fields Warwick CV34 6RG United Kingdom TEL: +44 (0)1295 770833 EDITOR Paul Bennett Tel: 01295 770833 Mobile: 07900 895110 AD SALES Miki Bennett adsales@bennettand Tel: 01295 770833 DESIGN/PRODUCTION Jemma Pentney jemma@bennettand Tel: 01295 770833 WEBSITE CIRCULATION Daylighting is available by email, free of charge to subscribers. Our database currently numbers over 6,000 UK architects, specifiers, contractors, consultants and roofing professionals. Full details are available on our website.


Glazing innovation James Gresswell explains the advantages of Georgian Wired Polycarbonate


Perspective: through a glass darkly Professor John Mardaljevic takes a historical perspective and explains how realising a ‘well-tempered’ daylit building remains more of an art than a science.

All rights reserved. No part of this publication may be reproduced or transmitted without the consent of the publisher. While every effort is made to ensure the accuracy of content, the publisher does not accept liability for errors. The views expressed by contributors are not necessarily those of the editor or publisher. This publication contains editorial photographs which may have been supplied and paid for by suppliers. Full terms and conditions can be found on our website.

Front Cover: Lamilux PR60 Glass Roof System

Jan/Feb 2017


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Hello...again! We’re excited to be back with the second issue of DAYLIGHTING Magazine, following a great response to our pilot issue at the end of last year. A big ‘Thank you’ goes to our brilliant contributors; our advertisers who took a risk on a totally new and untried publication; and above all to our readers – many of whom have taken the time to respond and offer their support and suggestions for the magazine. Aside from the obvious lower production and delivery costs, a key attraction of running this as an online publication, is the sustainability angle: a topic that’s at the core of our agenda. Be reassured that almost no trees are harmed or highways polluted to get this copy to you! And there’s been another big benefit that in all honesty, I hadn’t bargained for. That of instant feedback. Through the miracle of digital publishing, we can see which of our pages are

gaining the most readers. This means we can be totally ‘customer’ focused and responsive, right from the start. So, those of you who enjoyed Professor John Mardaljevic’s fascinating article on daylighting in heritage buildings (one of last issue’s most-read features) will be glad to know he’s back in this issue, with another great article. This looks at how daylighting design has influenced architecture over the years. 2017 is going to be an interesting year for the construction industry, with new technology, evolving standards and legislation plus the potential for escalation in the climate debate as the new US administration gets its feet under the table.

Paul Bennett

Whatever we’ve got coming, if it relates to daylighting in the built environment, I’ll be on the case, to keep you informed and up-to-date. I hope you’ll enjoy this issue and will keep coming back for more!

Issue 1 is still available to read on-line at We love the digital magazine format for lots of reasons (as outlined above) and here’s another to add to the list... Previous issues will be available on-line indefinitely. So you can refer back to old issues whenever you like. It’s also on our ‘to-do’ list to set up a features index, so if you can’t remember in which issue you read that fascinating feature about XYZ, you’ll be able to find it in a moment.

Jan/Feb 2017



Name change for Daylight & Ventilation Solutions: now Lamilux U.K. Limited Daylight and Ventilation Solutions Limited (DVS), the East Anglia based roof lighting & ventilation specialist, has changed its name to Lamilux U.K. Limited. As sole UK reseller and installer for the highly regarded Germanmade Lamilux product range, DVS has established a close and successful working relationship with the manufacturer, Lamilux Heinrich Strunz Holding GmbH & CO. KG. In January of this year, Lamilux acquired a majority shareholding in DVS and the decision was taken to rename the company to reflect its new ownership status and to build on the success of the Lamilux brand here in the UK. Managing Director of Lamilux U.K., Daniel Boughton, said “This is a very exciting development for both the company and the wider UK marketplace – bringing investment from a major European manufacturer enabling us to improve our service and broaden the scope of our offering”. The Lamilux group of companies has an annual turnover in excess of almost €230 million and is planning rapid expansion in the United Kingdom. A

relatively buoyant UK construction sector and increased interest in sustainable daylighting and ventilation technologies offers a good fit for the Lamilux product range, which includes glass roof systems and skylights as well as polycarbonate rooflights and domes. The company was the first serving the UK market to offer daylighting & ventilation products certified to meet the Passivhaus standard. Daniel Boughton summed up: “Over the coming weeks, you will notice our name change on emails, bank details and company documents. However, our legal status and office address will remain the same. The company’s business remains fundamentally unaffected by this change and all contracts with existing customers, our suppliers and employees will remain unaltered, with corresponding obligations and rights assumed under the new name. Going forward, we look forward to building on the high quality service that DVS has offered to clients to date – and we ask all our stakeholders for their continued support – for Lamilux U.K. Limited”.

Daniel Boughton (left) and colleagues at Lamilux HQ in Bavaria, Germany

Filon Fixsafe Roadshows announced for 2017 Fixsafe, Filon’s patented replacement rooflight and roof sheet system is the answer to the HSE’s recommendations in their latest publication titled ‘Fragile Roofs - Safe Working Practices’. Filon presents Fixsafe Roadshows around the UK to spread the word about Fixsafe – and first confirmed 2017 dates for these poular events are listed here. • PLYMOUTH, 31st March 2017


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• IPSWICH, 28th September 2017 • COVENTRY, 1st & 2nd November 2017 The Fixsafe system allows the safe replacement of rooflights or roof sheets from inside the building and completely removes the need for accessing the fragile roofs associated with old asbestos cement sheets found on industrial buildings across the country.


JET-Group acquires Xtralite As of 14th of December 2016, the JET Group of Hüllhorst, Germany, which is active throughout Europe, acquired 100 percent of the shares in Xtralite Rooflights Ltd. The company is based in Northumberland and employs about 90 people. Xtralite is one of the largest manufacturers in the field of customized rooflights as well as structural glazing solutions in the United Kingdom. The company was founded in 1993 and has been in private hands up to now. The company founder Bob Tweedy and board members will continue to play an active part in the company. “We are very enthusiastic about the technical competence and strong brand reputation of Xtralite,” emphasizes Eric Pans, CEO of the JET Group.” Bob Tweedy adds “Such a

Partnership ensures a bright future for all at Xtralite and allows us to tap into the vast resource JET Group has to offer.” Xtralite’s portfolio is complementary to the products and services from JET Cox Ltd., a company of the JET Group, located in Wednesbury. Both companies will operate independently from each other and continue to serve their market segments. The JET Group, with its headquarters in Hüllhorst, Eastern Westphalia, Germany, is a leading European supplier of daylight solutions, ventilation products and smoke and heat exhaust ventilation (SHEV) systems. Its main products include, in particular, light domes and continuous rooflights.

Roofglaze joins Achilles Building Confidence Community Roofglaze has become an officiallyaudited member of the Achilles BuildingConfidence community. Achilles is a leading provider of supplier risk management services, and the Achilles BuildingConfidence community is an effective means of connecting buyers and suppliers in the UK Construction sector. It allows buyers to minimise their risk and also streamline the procurement process, while suppliers have a unique opportunity to connect with the major players in their industry. Suppliers who subscribe to Achilles Building Confidence, such as Roofglaze, will undergo a rigorous audit to assess their capability, competence and compliance with the current protocol.

Achilles reviews the supplier’s financial, health and safety, environmental and quality standards, identifying any potential areas for business improvement and risk reduction. What this means in practice, is that Main Contractors can be confident when dealing with Roofglaze safe in the knowledge that we have passed the Achilles supplier audit, which minimises the level of risk to them. Robert Culley, Sales Director at Roofglaze, said: “Roofglaze as a business has grown significantly over the last few years, and by obtaining the Achilles Certification and passing this audit first time, it is another important step for us towards opening up new strategic opportunities and partnerships with some of the UK’s leading Main Contractors.”

Jan/Feb 2017


NEW PROJECTS Wolfreton School, Kingston upon Hull At this large secondary school serving the East Riding of Yorkshire, an array of VELUX Modular Skylights were designed and installed by Roofglaze.

Architect: Ryder Architecture Main Contractor: BAM Construction Ltd (North East).

University of Sheffield Advanced Manufacturing Research Centre Some 1,800m2 of Rodeca’s 40mm PC 2540-4 wall translucent polycarbonate panel has been used as rainscreen and internal skin on a new apprentice training centre for young engineers at the Advanced Manufacturing Research Centre (AMRC) at The University of Sheffield. Architect: Bond Bryan Architects Contractor: Willmott Dixon


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O U R S TA N D A R D I S S O M U C H M O R E T H A N S TA N D A R D A L L R O O F L I G H T S W I T H L A M I N AT E D I N N E R PA N E S A S S TA N D A R D Sunsquare Limited offer a range of Rooflights including solutions for fixed units, hinged opening with electrical opening mechanism, rooftop access and walk-on Rooflights. For more information telephone 01284 848 790, email or visit The first and only Rooflight manufacturers to be BSI verified and awarded a Kitemark.

NEW PROJECTS Steel Processing (Midlands) Limited At this site, Filon triple skin site assembled GRP rooflights were installed as part of a factory extension programme. These provide a U value of 1.7Wm2/K – contributing to lower overall energy costs for the building and providing the required levels of diffused daylight suitable for a manufacturing environment. Contractor: Hallford Refurbishments

County Hall, Matlock, Derbyshire This Grade II listed building required a sympathetic roof restoration. Xtralite was commissioned to provide a series of rooflights including a bespoke 18 metre glazed rooflight system that was subject to strict planning requirements to ensure the heritage of the building was preserved. Client: Derbyshire County Council

Jan/Feb 2017



Daylighting: the human factor Paul Bennett draws on research published by the BRE and NARM, to highlight compelling evidence of the benefits of daylight in the built environment. Sunlight plays a vital role in human health – and while in recent years there has been publicity about skin conditions which can be caused by over-exposure to damaging UV rays, the World Health Organisation states that in fact a markedly larger global disease burden results from inadequate exposure to daylight. Exposure to sunlight enhances mood and energy through the release of endorphins. In fact, daylight is critical to mental wellbeing - as evidenced by the growing understanding of the condition known as SAD - Seasonal Affective Disorder, caused by inadequate exposure to daylight. Daylight is also recognised as contributing to healing processes and fighting infection. The beneficial effects of the sun and sunlight to human health and wellbeing have been recognised for thousands of years. Ancient civilisations developed architectural and cultural traditions exploiting and celebrating daylight. During the middle ages or what have become known as the dark ages, this wisdom lost some momentum. However, in the renaissance period which followed, daylighting became an aspirational feature in stately homes and public buildings as the beneficial effects were again highly valued. By the mid-19th century the medicinal and healing properties of light started being appreciated again and


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understood by healthcare pioneers, such as Florence Nightingale. In the 1920s a new architectural language exploiting the virtues of daylight was championed by architects such as Le Corbusier.

Florence Nightingale was among 19th Century medical practitioners who were aware of the medicinal properties of daylight

Rapid developments in building technology and medicine in the following years caused something of a backward step for daylighting design. The advent of air-conditioning and the introduction in the 1930’s of fluorescent lighting enabled architects to design deep buildings, without the need to exploit daylight. This trend was

DAYLIGHTING & HEALTH exacerbated by improved public health and in new treatments for TB, coupled with the introduction of antibiotics. As a result, the emphasis shifted away from the healing properties of the sun. Many buildings constructed over the past 70 years which rely on artificial light, have a negative impact on human health, productivity and wellbeing. In extreme cases the buildings are responsible for debilitating health problems associated with Sick Building Syndrome (SBS). The issues associated with SBS and/ or daylight deprivation, coupled with a renewed interest in the use of daylight in the design of low-energy, sustainable buildings is leading many architects and engineers to consider new ways of exploiting the benefits of daylight without the negative impacts associated with solar over-heating. However, there are concerns that current health implications associated with excessive solar exposure, could inhibit the reemergence of a renewed interest in solar architecture. The BRE Group states that: “It is critically important that the positive benefits of daylight do not become confused with the negative impacts associated with excessive solar radiation, not least because modern glazing can reduce the transmission UVs.” Daylight in healthcare environments In healthcare environments, the benefits of high levels of daylight are particularly significant. Following are just a few of the remarkable facts revealed by recent research studies, as published by BRE – the Building Research establishment.

“It is critically important that the positive benefits of daylight do not become confused with the negative impacts associated with excessive solar radiation, not least because modern glazing can reduce the transmission UVs.” BRE Group: Daylight Benefits in Healthcare Buildings

Jan/Feb 2017


22% The value of daylight less pain medication

used in daylit hospitals

What improves wellbeing in every sector? Daylight.

People do better in daylit spaces. They use up to 22% less pain medication in hospitals and recover 41% faster*. They achieve up to 25% better school test scores**. They take fewer sick days, are happier and more productive. Whitesales are the UK’s daylighting experts. Our rooflight designs maximise any building’s environmental performance, energy usage and with increased natural light they also improve occupier wellbeing. The right rooflights – like our most popular products, Em-Glaze and Em-Dome – control solar gain, air quality and increase daylight along with all the benefits that brings you.


faster recovery in well lit hospitals

* BRE, Daylight benefits in healthcare buildings ** Heschong Mahone Group, Daylighting in Schools

Engage the experts in rooflight design. Call us on 01483 271371 or email for your free site survey and condition report.

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DAYLIGHTING & HEALTH Access to daylight enables patients to be discharged from hospital sooner than patients without daylight access A study by Choi et al*. published in 2012, found that; ‘A significant relationship appears to exist between indoor daylight environments and a patient’s average length of stay (ALOS) in a hospital. 25% of the comparison sets showed that, in the brighter orientations, as in rooms located in the SE area, the ALOS by patients was shorter than that in the NW area by 16%-41%. Furthermore, no dataset showed a shorter patient ALOS in the NW area than in the SE.’ In 2006 a comprehensive review of the impact of light on outcomes in healthcare settings by Anjali Joseph* found that; ‘A retrospective study of myocardial infarction patients in a cardiac intensive-care unit treated in either sunny rooms or dull rooms found that female patients stayed a shorter time in sunny rooms (2.3 days in sunny rooms, 3.3 days in dull rooms). Mortality in both sexes was consistently higher in dull rooms (39/335 dull, 21/293 sunny).

can result in side-effects and for this reason any strategy which reduces the requirement for pain-relief medication is desirable. A study published in the Journal of Psychosomatic Medicine* in 1995 concluded; ‘Consecutive patients undergoing elective spinal surgery who were assigned postoperatively to rooms on either the bright or dim side of the hospital unit. The patients staying on the bright side received 46% more natural sunlight and required 22% less opioid equivalent analgesic medications during their hospitalization. The patients staying on the bright side also experienced a 21% reduction in analgesic medication cost compared with patients on the dim side.’ At least 11 strong studies suggest that bright light is effective in reducing depression among patients with bipolar disorder or seasonal affective disorder (SAD)

Access to daylight and windows with a view improves post-operative recovery rates

One of the studies carried out by Benedetti and colleague* found that bipolar depressed inpatients in eastfacing rooms (exposed to bright light in the morning) stayed an average of 3.67 days less in the hospital compared with similar patients who stayed in west-facing rooms.

A review of the effects of natural light on building occupants undertaken by Edwards and Torcellini* states;

Exposure to bright morning light has been shown to reduce agitation among elderly patients with dementia

‘Improving the mental well-being of patients improves their recovery rates. Recent studies show that daylit postsurgical facilities improve this mental well-being.

Sloane and colleagues* found that residents in facilities with low light levels displayed higher agitation levels.

There is a clear link between daylight/ sunlight and a reduced requirement for pain relief medication in hospitals The use of analgesic medication

Exposure to bright morning light has been shown to reduce agitation among elderly patients with dementia. When elderly patients with dementia were exposed to 2,500 lux for 2 hours in the morning for two 10-day periods,

Jan/Feb 2017


DAYLIGHTING & HEALTH their agitation reduced. Patients were significantly more agitated on nontreatment days. Experiments undertaken in the USA and the UK between 1941 and 1944 demonstrated the extraordinary and remarkable effectiveness of daylight in killing the bacteria streptococci The blue light in skylight was found to be particularly potent. The trials also examined the bactericidal effects of artificial light, which was found to have little value as a disinfecting agent. Even diffuse daylight passing through two layers of glass from a north window was found to be highly effective in killing haemolytic streptococci within 13 days, with the same strain surviving in the dark, at room temperature, for 195 days. Hobday, who has researched this issue extensively, reports that no significant further work on this issue has been undertaken since the mid1940’s. This is surprising given the current concerns regarding methicillinresistant staphylococcus aureus MRSA and other other highly infectious bacteria prevalent in many hospitals, which are becoming increasingly resistant to treatment with commonly prescribed antibiotics. It is interesting to reflect that if daylight has such a dramatic and potent impact on killing streptococci, it’s surprising that its potential for reducing super-bug infections in hospitals, has not been fully investigated. Sunlight and/or daylight may also have an important role to play in the prevention and treatment of heart disease.

‘Sunlight may prevent heart attacks in a similar manner to antidepressants by alleviating depressive symptoms …….. Regardless of the exact mechanisms involved the fact that being in a sunlit ward may have health benefits is a significant finding, which has profound implications not the least of which is the patients’ survival from lifethreatening conditions’. Acknowledgements * This article draws on research referenced by the Building Research Establishment and published on References in the article can be accessed here.

In his book The Light Revolution, Health, Architecture and the Sun, Hobday speculates that;


Jan/Feb 2017

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PATENT GLAZING – it’s not all stations and canopies Richard Burgess, Sales Director of Lonsdale Patent Glazing & Rooflights discusses where patent glazing systems fit in to today’s market. It became apparent to me a few years ago that architects and contractors regarded patent glazing as an old fashioned product only suitable for train station roofs, canopies or draughty warehouses where insulation values were not important. Modern PG has come a long way from the days of lead wing bars and greased asbestos cord and now offer without doubt the most cost-effective sloped glazing solution.

Robust systems are available to suit today’s requirements for non-fragility and in some cases even bomb-blast mitigation. Thermally broken systems can incorporate insulating glass units including triple glazing and most of the major manufacturers now offer air-tight systems. Traditionally, PG bars were installed at 24” pane widths as a hundred years ago, wired glass was the only option

Jan/Feb 2017


PATENT GLAZING for safe overhead glazing and it was manufactured in 48” wide sheets which meant minimal waste when cut in half. Similarly, 24” or 610mm is just the right size to fit under a human arm meaning it is easy to carry and handle on site. This ‘industry standard’ is still the optimum in terms of performance and cost of installation, but all the time, architects are demanding wider and wider panes of glass. New ‘hybrid’ systems are common and represent a half-way house both in terms of performance and cost between traditional 2-edge support PG and more sophisticated 4-edge support sloped curtain walling. These enable the installation of glass both, single or double glazing up to typically 1000mm wide. Wider panes require stronger glass and it is not uncommon to see insulating glass units featuring 10mm toughened outer panes with 11.5mm laminated inner panes. The ‘default’ glass specifications for 2-edge support PG are typically 6.4mm, 6.8mm or 8.8mm laminated annealed glass for unheated spacers or these can be used as the inner pane on insulating glass units with a 6mm toughened outer pane. In order to keep costs to a minimum, many domestic projects where the height above ground does not exceed 5m above floor level, insulating glass units featuring two toughened pieces of 4mm glass are commonly used as born witness by the plethora of ‘conservatory glass’ specialists offering this combination, but care must be taken to ensure the relatively harmless small glass dice, toughened glass shatters into when broken, will not pose a risk. An example is a swimming pool roof, where it might be near on impossible to fish out all the bits in the event of breakage that might be a hazard to swimmers. Thermal efficiency can be enhanced by low-emissivity coatings and solar


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control finishes and the choice of glass types is bigger than ever before. Many manufacturers are offering ever increasingly efficient thermal glass, ‘smart glass’ that reacts to sunlight to reduce solar gain or glare and even polycarbonate being laminated between two sheets of glass to provide extra security against intruders even if armed with a sledge-hammer! It really is a case of ‘watch this space’. ‘Self-cleaning’ is a bit of a misnomer in roof glazing as once it is out of the vertical, it is less efficient as the water does not carry off dirt and debris as efficiently. At Lonsdale, we prefer the term ‘low maintenance’ as a truer reflection of how this type of glass will perform on the slope. Today’s designers can confidently consider patent glazing systems not just for its traditional industrial and commercial use, but also to create light, airy spaces in the most prestigious of buildings or high end homes.

www. http://lonsdalemetal.


daylight diary The hard work continues into 2017 for the movers & shakers in rooflighting... NARM is an active trade association representing UK rooflight suppliers and associated businesses. We are dedicated to the application of best practice in the provision of natural light in built environments. Founded in 1998, NARM today comprises most of the UK’s leading rooflight businesses. Our membership covers all types of rooflighting products, from polycarbonate domes and barrel vaults, to GRP factory rooflights and structural glass skylights and atria. The Association engenders co-operation between member companies, in order to develop and maintain standards and codes of practice – and to provide an authoritative information portal for rooflight specifiers. Membership of NARM is conditional on compliance with the appropriate UK Building Regulations and Quality standards, so specifiers can be reassured rooflights from a NARM member company will be of a high quality and will comply with appropriate regulations for energy efficiency, non-fragility, fire performance and security where appropriate. Our influential Technical Committee plays an active role in advising Government on future Building Regulations. So what is NARM working on right now? • We’re working together with the NFRC (National Federation of Roofing



Contractors) to provide installation guidance and support for best rooflighting practice among roofing contractors. • NARM is a member of Eurolux - the body representing the interests of European rooflight manufacturers. A NARM representative has attended recent meetings to ensure the UK’s voice is heard in relation to standards and compliance. • Our Technical Committee has just published new guidance on glass specification for rooflights, which is available on our website at http:// specific-guide/ – soon to be followed by a document outlining the new Approved Document Part Q: Security in Dwellings – and how this affects rooflight specification. • Our marketing committee met in early January to discuss new initiatives for promoting the benefits of daylighting to specifiers and contractors in the UK. Download NARM Technical Documents at NARM has also published a RIBA approved on-line CPD Seminar entitled An introduction to daylighting with rooflights. BOOK NOW. Become a NARM member: become-a-narm-member/

Jan/Feb 2017


DAYLIGHTING ICONS The biggest: the best: the most awe-inspiring; the most outrageous; the most influential... In this regular feature we will be indulging ourselves and our readers with images of daylighting projects throughout the years, that simply deserve a double page feature...

The Crystal Palace, Hyde Park, London 1851 This was arguably the UK’s (and maybe the world’s) first landmark building to make glazed roofs and facades its defining feature. Designed by Joseph Paxton, the building was commissioned to house the Great Exhibition of 1851. It was 1,851 feet (564 m) long, with an interior height of 128 feet (39 m). The invention of the cast plate glass method in 1848 made possible the production of large sheets of cheap but strong glass, and its use in the Crystal Palace created a structure with the greatest area of glass ever seen in a building. It astonished visitors with its clear walls and ceilings that did not require interior lights. After the exhibition, in 1854 it was dismantled and relocated to a site in South London. A nearby residential area was re-named Crystal Palace after the famous landmark. Sadly, the building itself was destroyed by fire in 1936


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Too Much of a Good Thing? John Godley, Technical Manager for Hambleside Danelaw explains the importance of manufacturers providing relevant, specific and independent transmission values for rooflights.

The provision of natural daylight within the built environment can deliver genuine, positive benefits to the finished construction; benefits that can enhance the financial and environmental performance of the building in service, benefits that can improve the internal environment and make it a better, more pleasant place to be. Benefits that can make a real, measurable contribution to the Government’s original target of project carbon neutrality for nondomestic buildings by 2019. While considering the daylighting plan of any building, particularly relatively lightweight buildings such as those with metal clad envelopes, designers need to remain aware of the potential for overheating caused by excessive solar gain where there is no adequate ventilation strategy, or where there are significant heat gains due to internal processes. The design of the building and provision of rooflights has to balance several factors, in particular the perceived conflict between providing daylight and the associated energy savings together with the risk of overheating. For any building, there is an optimum target percentage of rooflights which will deliver the optimum level of natural daylight into the building, making the optimum saving in energy usage and costs. Beyond that point, solar gain can add to the energy consumption


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if powered cooling systems become necessary. In high internal volume industrial buildings, the most appropriate, but uncontrolled action, to counter overheating in the building will often be to increase the ventilation by opening doors. The ‘g-value’ is a measure of the total

solar heat energy that passes through a window or rooflight, most of which is directly transmitted through the material or construction in the visible light spectrum. Total solar heat gain includes directly transmitted solar heat and absorbed solar radiation, which is then re-radiated and conducted into the space. For this reason, the solar heat transmission correlates closely with light transmission. If properly considered at the design stage and well managed during the building’s service life, in a relatively temperate climate such as the UK, passive solar gain usually provides a benefit for

“Designers need to remain aware of the potential for overheating caused by excessive solar gain where there is no adequate ventilation strategy”

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most of the year, with the overheating effects only being a consideration for the hottest few weeks of the summer months.

“Evenly distributed rooflights up to 20% of the roof area can be used without significant solar overheating.” A study by De Montfort University concluded that the optimum rooflight area for minimum energy consumption is generally in the region of 15% to 18% of the buildings floor area, for a large single storey industrial type building. If wall-lights are being considered, then the figure can be increased to 20%. A National Association of Rooflight Manufacturers (NARM) study commissioned with Oxford Brookes University concluded that evenly distributed rooflights up to 20% of the roof area can be used without significant solar overheating. Section 12: Lighting of HM Government’s Non-Domestic Building Services Guide 2013 edition states that for a space below rooflights to be classed as ‘daylit’, the rooflight area should be at least 10% of the floor area with light transmittance at least 70%. If the transmittance is below 70% then the rooflight area should be increased proportionately. Notwithstanding this, Criterion 3 in Building Regulations Approved Document L2A requires the effects of heat gains in summer to be limited to reduce the need for air-conditioning, or the energy consumption of any airconditioning system that is installed. For buildings defined in the National Calculation Methodology database as ‘top lit’, those whose zone height is

less than 6m, a total of 10% rooflight area with a framing factor of 25% and a g-value of 68% is recommended. For buildings whose zone height is greater than 6m, the rooflight area increases to 20% with a framing factor of 15% and a g-value of 46% to go some way into taking account the effects of stratification, or the effect of internal temperatures being cooler at lower level occupied spaces.

“It is recommended that the designer uses the data provided from the manufacturer, obtained through responsible independent physical testing.” These recommended rooflight areas are calculated making certain assumptions on a limited range of light, thermal and solar transmission values for rooflights, whereas the designer has the freedom to specify a wider variation of product to meet the specific needs of the building. It is therefore recommended that the designer uses the data provided from the manufacturer, obtained through responsible independent physical testing. In the absence of any specific BS or EN standard governing the measurement of solar energy transmission through ‘plastic’ type rooflights, there is a clear need to ensure that the information provided on this issue by rooflight manufacturers, is relevant and specific. Hambleside Danelaw use full solar spectrum transmission data from physical testing by The National Physical Laboratory calculated in accordance with BS EN 410 for all rooflight assembly data produced.

For more specific technical requirements, please email sales@ hambleside-danelaw. or call 01327 701920


Jan/Feb 2017


Defining non-fragility for rooflights: a first step to greater roof safety Chris Pearce of Filon Products Ltd and founder member of ACR – the Advisory Committee for Roof Safety, explains how today’s classification of non-fragility for rooflights was established. I started my working life in 1965 working for Turners Asbestos Cement – manufacturer of the everyday roofing and cladding Bigsix corrugated sheet fitted to industrial, commercial and agricultural buildings in the days when asbestos was deemed to be safe. Therein lies the irony. The sheets were sold as ‘Fragile Roof’ sheets with the guideline: “Do not walk on the roof”. Maybe it was tongue in cheek that if you walked on these sheets fitted on a roof, you would have no need to be concerned that you could die from asbestosis in 35 years time !

had very little strength and with UV degradation, they readily led to roof failure, even without being walked on. These rooflights were later superseded by GRP (glass reinforced polyester ) and polycarbonate rooflights. Right through to the 1990s, roof sheeting was generally considered as ‘fragile’. Even metal sheeting was subject to corrosion and

( It is of note, that 50 years later there are still vast areas of asbestos cement roofing throughout the UK doing a wonderful job of keeping the buildings dry, but now the safety issues focus on the dangers of the asbestos instead of a focus on the fact that the sheets are now very very fragile - be aware death in 35 years or 35 seconds ! ) Back in 1965 it was accepted that roofs could be built to be fragile. Thus when corrugated rooflights were offered to the market to match and substitute the asbestos cement sheets, there was no perception that the rooflights should be non-fragile. In this period corrugated rooflights were made from Acrylic or PVC. They

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could be deemed to be fragile. It was not until the late 1990s with increasing incidences of accidents caused by falls through fragile materials, that the HSE decided that roof sheeting should be manufactured and fitted to be “non fragile”.

the understanding of the test.

At this time, as Managing Director of GRP rooflight manufacturer, Filon Products, I was aware of this situation and recognised that GRP would be a suitable material for ‘non-fragile’ rooflights. The challenge was simply to define what was fragile and non-fragile. At the HSE offices in Bootle, Liverpool, I met up with Technical Inspector Mr A (Hash) Maitra to discuss how we could define fragility and devise a test procedure that could be repeated by all manufacturers of roof sheeting materials to determine that their products were non-fragile when fitted to the roof to their design specification. We called together roof sheeting manufacturers and roofing trade associations, agreed the test procedure, carried out hundreds of drop tests to simulate a human being falling on to the frame assembly and determined what was deemed to be ‘non fragile’ We called ourselves the ‘ACR’ - Advisory Committee for Roofsafety. Our first publication was ACR (M) 001: 1999 Test for Non Fragility of Profiled Sheeted Roofing Assemblies - better known as The Red Book The Red Book is now accepted by the HSE, designers and the roofing industry as an acceptable test process for manufacturers to determine that their products have been manufactured to be non fragile when fitted to the roof structure in accordance with their stated fixing specification. Since the first publication of the Red Book in 1999, there have been a number of modifications to improve the detail and


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In 2015 the 5th Edition was published to include for the testing of sheet glass designed to be non-fragile. It should be noted that the rooflight products offered for testing have all been installed to the manufacturer’s specification – and that all components used to fix the rooflights to the structure are part of the non-fragile test. Using components that are not to the rooflight manufacturer’s recommendations may cause the structure to be fragile, so the fixing contractor is key to ensuring that the right components are used and fitted correctly and in the correct quantity and quality. The rooflight industry has made major changes to specification improvements since the year 2000 including-non fragility and compliance with Building Regulations. We’ve come a long way since the simple fragile rooflights of the 1960s...

In 2015/16 there were 43 fatal accidents on building sites. Of these 9 ( 20%) were falls from height. Of these 7 were repair and maintenance sites and 2 were new build. The ACR remains committed to supporting the HSE in reducing these figures.

The red Book and other ACR Publications can be download from the ACR web site free of charge: 1) Recommended Practice for work on profiled sheeted roofs 2) Guidance Note for Safe Working on Fragile Roofs or roofs with fragile elements 3) Recommended best practice for use of Safety Nets for roof work. 4) Guidance Note for competence and general fitness requirements to work on roofs 5) Practical methods of providing edge protection for working on roofs 6) Recommended practice for use of horizontal safety systems in roof work.

Innovative upgrade & refurbishment solutions for profiled fibre cement or metal roofs & cladding

Replacing rooflights or roof sheets? Fragile roofs put lives at risk and you could be liable. NO NEED TO ACCESS FRAGILE ROOFS

Insist your contractor uses Filon Fixsafe.


Figures published by the Health & Safety Executive show that falls through fragile roof materials caused over one quarter of fatal accidents in the construction industry. Fixsafe addresses the problem and is playing a major role in reducing this statistic. Fixsafe allows sheets to be replaced from below, eliminating the need to access fragile roofs and thereby greatly increasing site safety. By removing the requirement for costly safety netting, roof staging or external scaffolding, on-site time is reduced and access equipment costs are minimised. Replacing rooflights from below is an HSE recommended method and complies with Regulation 9 of the Work At Height Regulations 2005. Protect your roofers and yourself by insisting on Fixsafe. We also offer: • Insulated rooflights for energy-saving upgrades and refurbishment • Lightweight over-roofing for cost-effective roof refurb with minimal disruption.

For details, please call us on 01543 687300 or visit

Filon Fixsafe allows replacement rooflights or roof sheets to be installed from below, avoiding the need to access fragile roofs

Filon Products Ltd, Unit 3 Ring Road, Zone 2, Burntwood Business Park, Burntwood, Staffs WS7 3JQ


Daylighting and the Passivhaus Standard Paul Bennett explores the Passivhaus standard and gives an overview of the roles and requirements of vertical glazing and rooflights in Passivhaus buildings. The Passivhaus standard is defined by the BRE as ‘The world’s leading fabric first approach to low energy buildings’. Passivhaus* or ‘Passive House’ is the fastest growing energy performance standard in the world with 30,000 buildings completed to date with the majority of those since the turn of the century. The growth in adoption of the Passivhaus standard lies in the simplicity of its approach; create a building that has an excellent thermal performance, to the point where a traditional heating/cooling system is no longer considered essential. The Passivhaus standard can be applied not only to residential dwellings but also to commercial, industrial and public buildings. It is sometimes confused with more generic approaches to passive solar architecture, with which it shares some common principles. Where the Passivhaus standard differs from more generic concepts is in its ability to reduce the permitted space heating demand and primary energy consumption. It can therefore be considered both as a robust energy performance specification and a holistic low energy design concept, in which daylighting design can play a crucial role. To achieve the required levels of comfort and low life-cycle costs, the thermal quality of the components


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used in Passivhaus buildings must meet stringent requirements. The Passivhaus Institute (PHI) is an independent research institute which has played a decisive role in the development of the Passivhaus concept. The Passivhaus Standard is the only globally recognised energy standard for buildings which stands for tangible and verifiable efficiency values. The PHI has established component certification in order to define quality standards, facilitate the availability of highly efficient products and to provide specifiers and building owners with reliable characteristic values for input into energy balancing tools. Verifying Passivhaus suitability Passivhaus suitability is verified using the heat transfer coefficients (U-value) of the components and the temperature factor at the coldest point of the component. The U-values and the thermal bridge loss coefficients (y-values) are determined based on DIN EN ISO 10077, EN 673 and DIN EN 12631 standards. Passivhaus suitability is verified for the specified dimensions of the products to be certified and varies according to climate zone. Vertical window glazing and frames The entire window, ie: glazing and frame, should have a U-value of 0.80W/(m²K) or less (this value may have to be more stringent in more

PASSIVHAUS extreme climates, whereas milder climates may manage to meet the criteria with higher U-values) and the installed window should have a total U-value of no more than 0.85 W/(m²K). It is therefore essential to use wellinsulated window frames with multiple lip packing. Glazing should have a high total solar transmittance (g-value) of at least 50% making a net heat gain possible during the winter (although lower g-values may be appropriate for extremely warm, sunny climates). The windows themselves must be airtight and the spacers in the glass seal edge must be thermally separated. Windows should be installed in a thermal bridge free manner in the insulation layer.

milder climates may manage to meet the criteria with higher U-values). The installed rooflight should have a total U-value of no more than 0.85 W/m²K.

Window orientation and shading

For further details, refer to the Passivhaus Institute document here, which can be downloaded free of charge: certification_criteria_transparent_ components_en.pdf

Appropriate window orientation and shading are essential for Passivhaus buildings. To capture as much of the sun’s energy as possible when it is needed most, the largest window surfaces should face the equator if at all possible. When designing the windows, it is important to reduce the amount of window framing to a minimum so as to minimise unwanted heat losses (or gains). To prevent overheating, windows facing East and West should be equipped with shades. Especially in warmer climates, shades are also recommended for windows facing the equator. In order to ensure adequate cross ventilation on warmer days, every outward facing room must have windows that can be opened. Rooflights & glazed roofs For rooflights in temperate climates, the Passivhaus institute’s required maximum component U-value is 0.85 W/m²K. (As with vertical windows, this value may have to be more stringent in more extreme climates, whereas

Glazing should have a high total solar transmittance (g-value) of at least 50% making a net heat gain possible during the winter (although lower g-values may be appropriate for warm, sunny climates). It should be noted that the numeric values contained in this article are for general infomation only. Projectspecific factors may result in variance from these figures. Useful references

The Passive House Planning Package (PHPP) is a cost-saving energy balance tool for highly energy efficient buildings. It has been validated on the basis of measured projects, provides precise results and can be used reliably by all. All products certified by the PHI are accordingly listed in the Passive House Component Database and made accessible to the international public. Inte-grated tools and information offer a high added value for building owners, designers and manufacturers.

* The Passivhaus concept was pioneered in German-speaking countries, hence the name. Here in the UK the term ‘Passive House’ is also applicable.

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PASSIVHAUS – advertorial

Pioneering passivhaus rooflighting in the UK Daniel Boughton, Managing Director of Lamilux U.K. (formerly Daylight & Ventilation Solutions Ltd) explains the role that his company is playing in UK Passivhaus projects.

The Passivhaus standard is well established in Germany, where it was originally conceived, but here in the UK, we’re a little way behind on Passivhaus projects. However, that’s changing and we are proud to be playing a part in the UK’s Passivhaus revolution, with our Passivhaus certified rooflights and PR60 Energysave glass roof system. We recently designed, supplied and installed two Passivhaus certified glass roofs for the University of Leicester’s Centre for Medicine: the largest nonresidential Passivhaus building in the UK. This project is among many recent UK Passivhaus daylighting projects we’ve completed, including: Burry Port Primary School - the first Welsh Passivhaus school; Wilkinson Primary School in Wolverhampton, winner of the ‘large project’ category in the 2015 Passivhaus Awards, plus other schools, colleges, public buildings and private homes. Our Passivhaus certified rooflights and glazed roof system were developed in Germany by our parent company Lamilux Heinrich Strunz Holding GmbH & CO. KG. They have been successfully installed in countless buildings of all descriptions in Germany and right


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across Northern Europe. Lamilux Passivhaus Glass Roof PR60 Energysave features • Passivhaus certified: phA Advanced Component • Ucwi value for the complete skylight of <= 0.82 W/m²K • Warm edge triple layer glazing with SuperSpacer, as standard • Mullion/transom roof glazing system for designs of any shape, inclination and size • Framework supplied to your choice of any RAL colour • Wide range of options and accessories • Optional integrated vent for natural and/or BS EN 12101-2 certified smoke ventilation

The Lamilux range includes Passivhaus certified flat roof skylights as well as the well established PR60 Energysave glass roof system.

For further infomation, visit:

Passivhaus Certified rooflights

Passivhaus Glass Roof, University of Leicester Centre for Medicine

Lamilux U.K. Ltd (formerly Daylight & Ventilation Solutions Ltd) is the UK’s first supplier of Passivhaus certified rooflights • UK expertise, plus Europe’s finest rooflights • From modular rooflights to glass roofs • BIM ready solutions • Complete design to installation service • NEW CPD Seminar ‘Specifying glass roofs and skylights’

Lamilux U.K. Limited (formerly Daylight & Ventilation Solutions Ltd. or call us on 01284 749051


Daylighting & ventilation from concept to installation


With an experienced in-house design and specification department, plus our own teams of installers around the country, we are able to provide outstanding engineered daylighting and ventilation solutions for virtually any kind of project: new build or refurbishment. Our ‘concept to installation’ approach allows continuity and close quality control over every stage of every project, to deliver excellence – every time. Call us today to discuss how we can help to bring your next project to life.

T 01506 448140 F 01506 448141 E


Lareine Engineering Monovision rooflight gains Passivhaus Suitability Lareine Engineering has developed a new variant of its well-known Monovision flat glass rooflight, to meet Passivhaus requirements. The new rooflight incorporates a raft of modifications compared to the standard unit, including changes to the upstand, insulation and other aspects of the design. The resulting product has been tested at the Building Research Establishment (BRE) and has achieved a pass in all aspects of the Passivhaus requirement. Director Tom Bates, said: “Energy

efficiency has always been central to our product strategy and we are delighted to be among the first rooflight companies in the UK to achieve a Passivhaus Suitable Component pass. Monovision rooflights are part of a wide range of daylighting and ventilation products from the company, which is planning further Passivhaus suitable products over the coming years.

Half day Passivhaus Training Sessions The Green Register and WARM are pleased to be working together to provide four halfday technical sessions on the Passivhaus principles in 3 locations: London, Bristol and Manchester, between March & June 2017. Although their full Passivhaus training is a fantastic way to gain an in depth understanding of all aspects of Passivhaus design, some construction professionals may not have the time or resources to be able to attend the typical Passivhaus two week course. These afternoon sessions offer insight into all the main principles i.e. what makes a good low energy, comfortable building based on the Passivhaus standard. The training is ideal for architects and other design professionals as the focus in these courses is on design principles.

• Building Services for Passivhaus • Putting Passivhaus into Practice Each of these will be run by experts in the field who are actually successfully designing/ building Passivhaus in UK. Amongst others, Bill Butcher, Alan Clarke, Sally Godber, Nick Grant, Eric Parks, Marine Sanchez, Mark Siddall; and Passivhaus Certifiers Will South, Mike Roe and Peter Warm. Assisted by Passivhaus Designers Tom Dollard and Lucy Pedler. For dates and booking details, visit:

Delegates at a recent event, pinning up details of their own building projects for discussion with the aim of putting passivhaus principles into practice with their own work.

The sessions: • Fundamentals of Passivhaus • Construction for Passivhaus

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The modern alternative to Georgian Wired Glass James Gresswell of TBS Polycarbonates explains the advantages of Georgian Wire Polycarbonate over traditional Georgian Wire Cast Glass. It’s now 2017 and that means another year has gone by, but what have the advances been in the daylighting industry? Many products in the technology world have transformed dramatically with products such as VR glasses becoming a commodity and many people are asking ‘Alexa’ to turn on their lights or change the channel on TV. Clever stuff! There have been many changes, and one of these is a safe product, Georgian Wire Polycarbonate that has been introduced as an alternative to Georgian Wire Cast Glass. For decades GWG has been labelled as safety glass due to the areas of application it was used but in reality it is not safe at all, especially when it comes to human impact. • The 0.5mm steel mesh that is laminated into the product during manufacture actually acts as flaw lines, creating weaknesses in the glass. • If the glass is penetrated, the wires hold small particles of glass that can severely lacerate skin and flesh which is made worse when the object is retracted • The product is heavy and therefore creates a safety issue when handling. • Once the glass is cut to size it leaves sharp edges and exposed wires. • Unfit for use in interior design where edges are exposed All these issues have been well known in the industry and if you search the


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web there are numerous videos and images showing some of the fatal accidents there have been in sports complexes and schools, even resulting in some of the casualties having to have amputations. As well as vertical glazing applications, there are currently thousands of tonnes traditional GWG in roofing – and a lot of it needs renovating. One of the large industries where this product has been used is the rail sector, and there are many stations especially in London that still have this material as the roofing sheet. The purpose of the glass in this application was for safety in the fact that if the glass got damaged, the wire mesh holds onto most of the fragments of glass lessening the chance of injury for objects below and hopefully keeping the pane of glass in place. Georgian Wire Polycarbonate is the perfect replacement in any of these applications. Feedback from installers has shown these positives;

ARE YOU LOOKING FOR A GLASS ALTERNATIVE? LOOK NO FURTHER WITH PLASIAX™ WIRE Being half the weight of glass and virtually unbreakable Plasiax™ Wire is a product that is far easier and safer to work with, yet retaining the Georgian Wire image with the innovative grid etched into the sheet surface. The 6mm thickness of the polycarbonate and optional clear or obscure finish creates a straight replacement to most Georgian Wire Glass glazing.

SPECIALLY DESIGNED FOR: Roof glazing / Balustrade panels / Safety glazing / Heritage glazing / Canopy & walkway glazing / Door vision panels / Partitions / North light glazing Windows / Roof lights

• The material can be cut/adjusted to size on site with the most common tools such as jigsaw, drill or rail saw • Getting the sheets onto the roof is far easier as they are lighter (less than half the weight of glass) and virtually unbreakable which also saves a lot on access equipment • Sheets don’t have any dangerous razor sharp edges • Once the sheets are up the difference is indistinguishable in looks – perfect for heritage applications Another area of application for this product is interior and retail design. The retro look complements many modern themes and it’s safe to be used in applications such as a high street shops, where people may come near or into contact with these products. For further information, visit


Twinfix Georgian Wired Polycarbonate Non-Fragile Rooflights Twinfix is a family run business. As experienced innovators they offer a range of well-engineered glazing products, many of which are fitted on the roofs of Rail Stations and Depots. The Multi-Link-Panelinstalled installed an aluminiumThe Multi-Link-Panel byisStory Contracting framed, modular rooflight system, designed with a at Stirling Station in Scotland is an aluminium-framed, unique method that results in incredibly modularfixing rooflight system, designed with a unique quick fixing method thattimes. results in incredibly quick installation times. installation In to drive driveefficiencies efficiencies within their work in rail In order order to within their work in rail Twinfix haveutilised utilisedup-to-date up-to-date printing to aid Twinfix have 3D3D printing to aid product innovation employing thisthis product innovationand anddevelopment, development, employing new technology to view a 3D model of a revised new technology to view a 3D model of a revised MultiMulti-Link bar design for use in future applications. Link bar design for use in future railrail applications. For ease thethe Multi-Link-Panel is available For easeofofspecification specification Multi-Link-Panel is as a BIM object for download in IFC and Revit formats available as a BIM object for download in IFC and Revit from thefrom Twinfix formats thewebsite. Twinfix website. The Twinfix collaboration with Story Contracting This application is a great example of Twinfix on Georgian Stirling Station is a great example of Twinfix Georgian wired effect polycarbonate in their Multi-Link Nonwired effect polycarbonate in their Multi-Link Non-Fragile Fragile panel. The polycarbonate glazing looks the panel. The polycarbonate glazing looks the same as the same as the traditional Georgian wired glass but will traditional Georgian wired glass but will not break. not break.

The benefits of this system are: • Safe in use: All Multi-Link-Panels pass the ACR[M]001:2014 drop test, in accordance with HSE recommendations, with a ‘B’ designation. • The Twinfix Georgian wired grade solid polycarbonate is particularly popular as it mimics Georgian wired glass. • Polycarbonate absorbs vibrations without cracking, crazing or breaking. • The aluminium framework can be powder coated to a RAL colour to suit your project. • The light weight of the finished product results in less stress to the fabric of original buildings. • Sleek in-line access hatches (developed at the request of Network Rail) offer unobtrusive and safe access through the glazing for maintenance purposes. • Factory manufactured rooflight panels means no costly mistakes on site.

For more information contact us on:

Tel: 01925 811311


GLAZED CANOPIES Lewes Station, Sussex As part of a recent major refurbishment project at this station, Twinfix replaced 1,178 panels of roof and vertical glazing with their Multi-Link system using their Georgian Wired Polycarbonate glazing. This solution provides a look that is in keeping with the style and character of the station, whilst bringing significant benefits in terms of lightness, ease of installation, non-fragility and sustainability. Main Contractor: BAM Nuttall Ltd. Falmouth College, Cornwall This walkway is a freestanding structure designed and installed by Plastics in Construction for Falmouth College – a thriving sixth form of 200 students and part of Falmouth School, which converted to Academy status in 2011. The brief required a single central row of supporting posts and stipulated that it must be capable of withstanding severe coastal weather conditions, without looking ‘industrial’. www. plasticsinconstruction.

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THROUGH A GLASS DARKLY Over centuries, our use of glazing in construction has grown exponentially. Today, realising a ‘well-tempered’ daylit building remains more of an art than a science. An essay by Professor John Mardaljevic, Professor of Building Daylight Modelling School of Civil & Building Engineering, Loughborough University It was with the invention of glass that the story of daylighting design for buildings truly begins. Many cultures devoted considerable resources to sacred architecture and it is in these buildings that we see the earliest examples of designing for daylight, both to provide general illumination and to achieve elaborate effects through the controlled ingress and manipulation of light from the sky and the sun. The first recorded use of glass for windows is by the Romans, in around 100 AD. Although the largest panes that could be manufactured were fairly small, the use of vertical and horizontal dividers – mullions and transoms – increased the area that could be glazed.

building densities increased. This often resulted in the ground level rooms having the largest windows, with the window area gradually decreasing for the floors higher up. In the UK, this arrangement is generally referred to as the Georgian window pattern, although its use extended well beyond the Georgian era.

In the early 17th century glass windows became common in homes in the most developed parts of Europe. Then, with the advent of improved production techniques in the following century, the cost of glass became less of a limiting factor in its use, though its relative cost compared to other building components was still fairly high.

For example, on sun-exposed facades there would be small windows set in deep reveals to provide selfshading (passive control), or perhaps larger windows with moveable shutters (active control). In less hot and sunny climates, window apertures would tend to be larger and solar control less of an issue – though there would be other concerns such as heat loss. Thus, all buildings contained, to varying degrees, features in their design that were climate-adapted, and which, over time, became an intrinsic part of that locale’s vernacular architecture.

Notwithstanding the high cost of glass, the real cost of artificial light (as a proportion of the overall household expenditure) was several thousand times what it is today per lumen of light. Varying the window area according to the size and function of the space and degree of external obstruction became commonplace as


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Prior to the 1900s, buildings generally incorporated features that evolved from the need to temper the internal conditions in response to the prevailing climate for that locale. In hot climates with plenty of sunshine, buildings would be designed to include elements of solar control either by passive and/or active means.

‘All buildings contained, to varying degrees, features in their design that were climate-adapted, and which, over time, became an intrinsic part of that locale’s vernacular architecture’

However, the latter half of the 20th century witnessed a globalisation in architectural form. The confluence of


‘Many of the earliest examples of designing for daylight can be seen in sacred buildings’

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a number of economic, technological and aesthetic factors working together served to establish the highly glazed office tower as the preeminent urban building concept. The highly glazed office tower became the most conspicuous symbol of industrial progress, and hence an inspiration for architects and designers worldwide – regardless of their local climatic conditions. This was driven by the desire to reduce capital and running costs through higher occupant densities in deeper-plan spaces, and enabled by the development of curtain wall technology and the invention of the float glass technique, which allowed the manufacture of large sections of high-quality glazing at relatively low prices. Added to this were the refinement and widespread adoption of fluorescent lighting and high-capacity air handling and air conditioning systems that eliminated the necessity for ventilation or cooling by natural means. Modernist architecture became preoccupied with vaguely defined notions of ‘light’ and ‘transparency’ in the built form – the realisation of which was invariably highly glazed buildings. Designers typically rationalised the use of large glazing areas in terms of their daylight provision, but often it was more likely the pursuit of style. Aside, perhaps, from the possibility of a view to the outside, the daylighting benefit to the majority of occupants in a deep-plan space was not great. Furthermore, the daylighting potential of highly glazed buildings was often not realised because the manually operated shades/blinds needed to control direct sun were typically left closed long after the external condition had changed. This is the case in fairly temperate climates such as the UK and northern Europe, but the situation is worse still in sunnier locales. While internal shades provide occupants with immediate protection from direct


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sun, they generally have only a limited overall heat rejection effect. Thus, solar radiation, once it has passed through glazing, will inject heat energy to the space which may need to be removed by active cooling if it causes overheating. With the decline of climate-adapted design, the emphasis is now on developing and proving facade technologies that will allow highly glazed structures of the future to avoid many of the overheating/ glare problems that are commonplace in many post-1950s buildings. In contrast to using standard shade materials deployed either manually or automatically, a glazing with a transmissivity that varies continuously between clear and dark extremes would offer a much greater degree of control over the luminous environment – and preserve the view to the outside. Indeed, the dynamic control of daylight has been termed the ‘Holy Grail of the fenestration industry’. The majority of design guidelines worldwide currently recommend daylight provision in terms of daylight factor. The DF at a point in a space is the ratio of internal illuminance to unobstructed horizontal illuminance under standard CIE overcast sky conditions (a particularly extreme overcast sky type). The DF is usually expressed as a percentage, so there is no consideration of absolute illumination values. For a given building design, the predicted DF is insensitive to either the building orientation (due to the symmetry of the overcast sky) or the building location (since it is simply a ratio). Because the sun is not considered, any design strategies dependent on solar angle, solar intensity, orredirection of sunlight can have no influence on the daylight factor value. In my opinion, this is a major omission since the potential for direct sun to enter and illuminate a space is a key consideration in architecture, albeit one that has been

PERSPECTIVE traditionally evaluated qualitatively. Since the year 2000, the role that daylight evaluation plays in the design process has acquired a new impetus as the need to demonstrate compliance with various performance indicators’ becomes ever more pressing. The websites of both the UK rating system BREEAM and the US LEED system chart the growth in the building projects that have been certified using the respective schemes. These and similar rating systems are actively promoted by government departments and lobby groups. As a consequence, building designers are resorting more and more to prediction methods (invariably simulation) as a means of demonstrating compliance with the various schemes. This, one might reasonably hope, would lead to noticeable improvements in the practice of design evaluation, which in turn should improve the likelihood of realising a well-daylit building. However, in my view, basing design evaluation on the daylight factor has not been proven to result in better daylit buildings. While the message regarding the importance of ‘good daylighting’ appeared to be getting across, it was not being implemented effectively. Statements such as this in school design guidelines were fairly typical:

Varying the window area according to the size and function of the space and degree of external obstruction became commonplace as building densities increased. This often resulted in the window area gradually decreasing for the floors higher up. In the UK, this arrangement is generally referred to as the Georgian window pattern.

‘Maximising the use of daylight in order to improve student performance... is an absolute imperative.’ Or, in a similar vein: ‘An ADF [average daylight factor] of three per cent is better than an ADF of two per cent. Yes, it really is as simple as that.’ Taking these recommendations at face value, it might appear that a botanical greenhouse would be the ideal classroom. A half-century or more of (often uncritical) application of the daylight factor method had led to a ‘more is better’ mindset. And what of

the impact of this on school designs? It has now become something of an annual summer ritual to have the news media reporting on children fainting in new, overheating schools: ‘The large amount of glass used is contributing to the problem of many classrooms becoming “unbearably hot”, officials said.’ In 2013 the UK Education Funding Agency made climate-based daylight modelling (CBDM, see p51) a mandatory requirement for the evaluation of designs submitted for the UK’s Priority Schools Building Programme. School designs submitted to the PSBP must achieve certain ‘target’ criteria for the useful daylight illuminance metric. This is believed to be the first major upgrade to mandatory daylight requirements since the introduction of the daylight factor more than half a century ago. In the US, a climate-based daylight metric approved by IESNA, the Illuminating Engineering Society of North America, has appeared in the latest version of LEED. It would appear that the EFA’s bold decision to make climate based daylight modelling a mandatory requirement was, in part, to encourage designers to consider the effect of sunlight as an integral part of the daylight evaluation — something that I believe is not possible with the daylight factor. The application of CBDM and climate-based metrics is still evolving. Real world illuminance data on the daylighting performance of occupied spaces is needed to help validate and refine applied CBDM and the metrics derived from it. Both the theoretical basis and the practical application of daylighting in buildings are in the middle of a fundamental reappraisal. The emergence of findings that relate daylight exposure to positive outcomes in terms of productivity, health and wellbeing have led to a renewed focus on daylighting in buildings. Throughout

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the developed world, governments and regulatory bodies are encouraging the adoption of design guides and recommendations in the hope that reduced energy consumption in buildings can be achieved, in part, through effective daylighting design. A large number of advanced glazing systems and materials for enhancing the daylight in buildings have appeared on the market in the past decade, and there are new formulations in the early stages of development. Market penetration of innovative daylighting systems has, until now, proven to be difficult because the standard measure of performance (in other words, the daylight factor) gives no indication of how much natural light and how often. Data on the magnitude and occurrence of absolute measures of natural illumination – precisely how much and how often – are vital to reliably assess both the performanceeffectiveness and the cost-effectiveness of daylighting systems. I believe the wider adoption of climate-based daylight metrics would greatly assist in the evaluation of these daylighting systems and the marketing of those shown to be effective. These theoretical and technological advances have the potential to radically improve our

perception of what constitutes good daylighting in buildings, both in terms of basic design parameters and the use of novel glazing materials thus paving the way for daylighting guidelines and codes that lead to the reliable and robust production of truly healthy, lowenergy buildings. But in the meantime, the realisation of a ‘well-tempered’ daylit building in which the fixed (static) architectural form provides both good daylighting and effective solar protection, remains more of an art than a science.

Reichstag, Berlin, by Foster and Partners, 1992-99. A ‘light sculptor’ at the core reflects horizon light

John Mardaljevich is professor of building daylight modelling at Loughborough University. He has pioneered the development and application of climate-based daylight modelling. This article was first published in Lighting Magazine, 2016 It should also be noted that John’s article on daylighting in heritage buildings in our November/December 2016 issue, was first published in the CIBSE - Society of Light and Lighting SLL newsletter, 2016 For more information about Climate Based Daylight Modelling, visit: doku.php?id=cibse-dg

Jan/Feb 2017


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Inspiring Architecture All great architecture starts with a simple idea. Then comes the inspiration to turn it into built reality. At Wrightstyle we work with architects around the world, bringing to life even the most challenging ideas. We aren’t just one of the world’s most innovative suppliers of complete and guaranteed steel and glass systems. We’re also world leaders in reinventing what glass and steel facade systems can do. From large-span or fire-resistant glazing to curtain walling able to withstand a lorry bomb, we are at the forefront of our technologies, pushing the boundaries of what glass and steel are capable of achieving. Our interior and exterior systems can be found worldwide, and we have a portfolio of examples to illuminate and surprise. Our systems don’t simply protect buildings against the full range of threats. The inherent strength of steel and our opticallybrilliant glasses allow architects to think in new ways. So if you’ve got a design idea, talk to us. We’ll help provide the inspiration to make it happen.

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Jan/Feb 2017

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27/06/2013 17:15


Twitterings Follow us for regular updates between issues... in the meantime, more highlights...

Jan/Feb 2017



Stay up to date with DAYLIGHTING Magazine! Coming up in 2017 – we will be running features on just about every daylighting-related topic you can think of – and some you may not have... We’ll also be offering a wider range of opportunities for advertisers, including low cost product and project feature advertorials, a product finder and an email delivery service, allowing clients access to our email contacts database.

2017 Editorial Programme REGULAR FEATURES: Industry News & Comment, Technical Focus, Daylight & Energy Saving, Daylighting Standards

SEPTEMBER / OCTOBER • Daylight for Dramatic Effect • Daylighting in the Retail Sector • Refurbishment • Modular Rooflights • Daylight Harvesting NOVEMBER / DECEMBER

MARCH / APRIL • Vertical glazing • Daylighting in Education • Translucent GRP • Calculating Rooflight Areas • Daylight & Ventilation • Suntubes

• Daylight & Renewable Energy • Daylighting in Factories & Warehouses • Lighting Controls • Translucent Cladding • Roof Windows

MAY / JUNE • Tensile Membrane Structures • Glass Rooflights • Daylighting in the Workplace • BIM • Climate-based Daylight Modelling

Media Information Pack

JULY / AUGUST • Domestic Daylighting • Controlling Heat & Glare • Daylight in Agriculture & Horticulture • Architectural Glass

Our Media Information Pack gives details of circulation, advertising rates, 2017 features and editorial policy. Copies can be downloaded at: www. Note: Our suntubes feature is now scheduled for the March/April issue.


DAYLIGHTING is published by: Bennett & Partners Pure Offices Lake View House Tournament Fields Warwick CV34 6RG United Kingdom TEL: +44 (0)1295 770833 EDITOR Paul Bennett Tel: 01295 770833 Mobile: 07900 895110 AD SALES Miki Bennett adsales@bennettand Tel: 01295 770833 DESIGN/PRODUCTION Jemma Pentney jemma@bennettand Tel: 01295 770833 WEBSITE CIRCULATION Daylighting is available by email, free of charge to subscribers. Our database currently numbers over 6,000 UK architects, specifiers, contractors, consultants and roofing professionals. Full details are available on our website.

All rights reserved. No part of this publication may be reproduced or transmitted without the consent of the publisher. While every effort is made to ensure the accuracy of content, the publisher does not accept liability for errors. The views expressed by contributors are not necessarily those of the editor or publisher. This publication contains editorial photographs which may have been supplied and paid for by suppliers. Full terms and conditions can be found on our website.


Jan/Feb 2017

n D io ts K O W CP uct fligh BO O IBA rod oo N R nt r e n i it h lin A w n- r: g O ina htin m lig Se a y d to

NARM represents suppliers of glass, polycarbonate and GRP rooflight systems for daylighting applications across every sector.

Specifying rooflights? Look for the logo that means peace-of-mind NARM, the National Association of Rooflight Manufacturers, is the influential trade association representing the UKâ&#x20AC;&#x2122;s rooflight industry. We are closely involved in developing and implementing legislation affecting UK rooflighting. Choosing rooflights from a NARM member company is the simple and certain way to ensure adherence to standards and legislation. You can also gain access to a wealth of free and objective specification information on our website.

DAYLIGHTING Magazine issue 2 January/February 2017  

The bi-monthly magazine for architectural specifiers and technicians, building contractors and anyone interested in the provision of natural...

DAYLIGHTING Magazine issue 2 January/February 2017  

The bi-monthly magazine for architectural specifiers and technicians, building contractors and anyone interested in the provision of natural...