Passive House Plus (Sustainable building) issue 37 UK

INSULATION | AIRTIGHTNESS | BUILDING SCIENCE | VENTILATION | GREEN MATERIALS

S U S TA I N A B L E B U I L D I N G

BOXING CLEVER Stirling timber passive

house redefines the box

PLAYING ALL THE ANGLES

Sheltered housing

Post occupancy evaluation of a deep retrofit

Net zero carbon 33,000 fabric first homes planned

Shooting the moon

Why we must build back better and greener

Issue 37 £5.95 UK EDITION

Clever London infill triangulates tricky site

SAME HOUSE, DIFFERENT HOME.

PA S S I V E H O U S E +

Publishers

Temple Media Ltd PO Box 9688, Blackrock, Co. Dublin, Ireland t +353 (0)1 210 7513 | t +353 (0)1 210 7512 e info@passivehouseplus.ie www.passivehouseplus.co.uk

Editor

Jeff Colley jeff@passivehouseplus.ie

Deputy Editor

Lenny Antonelli lenny@passivehouseplus.ie

Reporter

John Hearne john@passivehouseplus.ie

Reporter

Kate de Selincourt kate@passivehouseplus.ie

Reporter

John Cradden cradden@passivehouseplus.ie

Reader Response / IT

Dudley Colley dudley@passivehouseplus.ie

Accounts

Oisin Hart oisin@passivehouseplus.ie

Art Director

Lauren Colley lauren@passivehouseplus.ie

Design

Aoife O’Hara aoife@evekudesign.com | evekudesign.com

Contributors

Toby Cambray Greengauge Building Energy Consultants Mhairi Grant Paper Igloo Marc O’Riain doctor of architecture Peter Rickaby energy & sustainability consultant Duncan Smith Renfrewshire County Council David W Smith journalist Jason Walsh journalist

EDITOR’S LETTER

editor’s letter W

hen we decided a decade ago to shift the focus of our former magazine, ‘Construct Ireland (for a sustainable future)’, to focus on passive house, the shift was cautioned against by a couple of dissenting voices from the green building world.

We had reached the conclusion, having published a sustainable building magazine since 2003, that not all approaches to notionally sustainable building were equal.

We developed a strong sense that some of the conventions of green design that have abounded since the 1970s – and which were still being espoused by authority figures – were unproven or problematic, particularly where it relates to natural ventilation or passive solar design.

I’m thinking of the architect who designed a stack ventilated office building, and who, when we asked him about reports from the facilities manager that office workers were complaining about stuffy conditions, railed and hit back, as far as I can recall: “It’s a sustainable building,” he said, “it’s not meant to be comfortable.”

I’m also minded of another green architect I admire who asked us to write about another nascent sustainable building standard, posited as an alternative to passive house.

When I replied and asked for a calculation methodology, airtightness test requirements, ventilation requirements and the likes I was told my response was very “left brain”, and that this was part of the problem. It was as if I was focussing too much on the numbers, and missing something more important.

The fact is that we are facing a confluence of environmental crises, with the climate emergency at the epicentre. We know this because of an extraordinary scientific effort to measure and record evidence and hypothesise as to what it means, and to dare to attempt to predict the consequences of our actions

ISSUE 37 on such a fiendishly complex area as climate.

I believe it’s incumbent upon us to apply the same kind of rigorous, science-based approach to ensuring our buildings help us to reduce and react to the environmental crises we face. It will be hard, and it will be messy at times. But there is no alternative.

When you stray from the relative comfort of empirical evidence – where it’s often possible to reach clear conclusions that stand up to scrutiny – things get messier. Take building life cycle assessment for instance.

If we’re considering the carbon emitted to produce a building up to the point of practical completion, it’s becoming possible to reach firm answers within pretty tight tolerances, especially as more and more manufacturers start publishing Environmental Product Declarations on their products.

It’s after that stage that things start to get messier. How long will the building last? How many times will the heating system need to be replaced within that time frame? How much will energy have decarbonised during the building’s lifespan? And what environmental damage or benefit will arise from the building’s components at their end of life?

The truth, of course, is that there are many uncertainties here, and that the values we calculate – for instance in the form of cradle-to-grave embodied carbon figures – won’t always be right. But that is not an argument against number crunching. It’s an argument for better number crunching. We must focus our efforts, and learn more about how to close the gaps that create uncertainties, at least where failing to do so may risk undermining our ambitions, or giving us no ability to appraise whether our efforts have produced exemplars for others to aspire to, or benchmarks to improve upon.

Regards, The editor

Print

GPS Colour Graphics www.gpscolour.co.uk | +44 (0) 28 9070 2020

Cover

Ostro passive house Photo by David Barbour Publisher’s circulation statement: Passive House Plus (UK edition) has a print run of 9,000 copies, posted to architects, clients, contractors & engineers. This includes the members of the Passivhaus Trust, the AECB & the Green Register of Construction Professionals, as well as thousands of key specifiers involved in current & forthcoming sustainable building projects.

Disclaimer: The opinions expressed in Passive House Plus are those of the authors and do not necessarily reflect the views of the publishers.

ABC Certified Average Net Circulation of 8,971 for the period 01/07/18 to 30/06/19

About Passive House Plus is an official partner magazine of The Association for Environment Conscious Building, The International Passive House Assocation and The Passivhaus Trust.

ph+ | editor’s letter | 3

CONTENTS

PA S S I V E H O U S E +

CONTENTS COVER STORY

06

20

32

06

INTERNATIONAL This issue features the University of Chicago’s Warren Woods ecological field station, which was the first passive certified building of its type in North America.

12

NEWS Over thirty thousand zero carbon homes planned across the UK, green groups are critical of the government’s latest budget, and the AECB launches a new standard for retrofit.

15

COMMENT Dr Marc O’Riain looks back at two American prototypes for the passive house standard that embraced heat pump technology as well as principles of superinsulation and airtightness; Dr Peter Rickaby writes on the concept of building back better and greener; and Duncan Smith suggests that Enerphit could be the key to decarbonising existing homes.

6 | passivehouseplus.co.uk | issue 37

PA S S I V E H O U S E +

42

20

52

CONTENTS

60

CASE STUDIES Boxing clever Striking Stirlingshire passive house is a true labour of love

This all-wood passive-certified home in the village of Kippen was built directly by its architect owners, who not only achieved the passive house standard but did so with an ecological approach that sought to use building materials ultra-efficiently and make it easy to deconstruct and recycle the building at the end of its life.

32

Playing all the angles Fabric-first London infill uses smart design on a tricky site

Angle House in north London is a wonderful example of sustainable urban housing: modest in scale and built on a run-down site in the heart of north London, it boasts a passive approach to energy efficiency and some beautiful design touches.

42

Senior college Deep retrofit transforms Wexford sheltered housing

The extensive energy and ventilation upgrade of 12 rundown bungalows at College View sheltered housing scheme in Wexford town not only transformed the lives and comfort of residents, but an extensive period of post-occupancy study has yielded important lessons for future projects.

INSIGHT Runaway train Ireland’s deep retrofit upskilling drive gathers steam

Following its commitment to retrofit one quarter of dwellings in the country by 2030, the Irish government has now announced the establishment of four new centres of excellence for retrofit training, building on the training approach developed to help the industry meet the NZEB standard for new buildings. Workers from state-owned company Bord na Móna are among the first to undergo training as the company transitions out of peat extraction.

Spectacular vernacular Galway home fuses modern, local-rooted design with low energy excellence

A new passive house on Galway Bay beautifully blends vernacular design with touches of Arts & Crafts while still appearing thoroughly contemporary, but under its neat exterior is the thinking of an architectural practice striving to reduce the environmental impact of its buildings, inspired by the Architects Declare pledge.

52

60

64

MARKETPLACE Keep up with the latest developments from some of the leading companies in sustainable building, including new product innovations, project updates and more.

70

Measuring humidity, the old school way

A chance purchase on eBay leads buildings physics expert Toby Cambray to admire the aesthetics and mechanics of old scientific instruments.

ph+ ph+ | contents | contents | 7 | 7

INTERNATIONAL PASSI V E & E CO B U I L DS F R OM A R OU ND T HE WO RLD

IN BRIEF Building: 198 m2 scientific field station Location: Warren Woods, Michigan Building method: Structural insulated panels Standard: Passive house classic certified

6

I N T E R N AT I O N A L

U N I T E D S TAT E S

Photos by Trent Bell Photography

WARREN WOODS ECOLOGICAL FIELD STATION

S

et on the edge of a state park with over 300 acres of old growth forest, the University of Chicago’s Warren Woods ecological field station was the first passivecertified building of its type in North America.

Finished in 2014, the field station was the vision of Joy M Bergelson, professor of ecology and evolution at the university, and chair of the same department.

Bergelson says that after the university bought the site — about ninety minutes’ drive from its main city campus — in 2010, it invited various architectural firms to present their own vision for a field station.

Warren Woods State Park is one of the most ecologically important sites in the state of Michigan. “We wanted the field station to be ecologically conscious,” says Bergelson, who had spent time in Germany and was aware of the passive house standard.

It was Maine-based architectural practice and passive house designers Go Logic (now operating as Opal Architecture) whose concept impressed the most. The firm is well known for delivering sympathetic, elegant buildings in sensitive rural locations.

“We were really taken by Go Logic,” Bergelson says. “We liked their vision.”

A fabric-first, low maintenance approach like passive house seemed a perfect fit for a building in a remote location with boom-bust occupancy patterns, and which would face extremes of winter cold.

But the project posed technical challenges far beyond those of a typical passive house: in particular, large quantities of heat generated by laboratory equipment, such as freezers operating down to -80 C, as well as heat-generating plant-growth chambers and centrifuges. Occupancy patterns would also be a challenge; left empty much of the time, the building would occasionally find itself filled with large groups of students and staff.

To deal with the challenge posed by internal heat gains, Go Logic located the laboratory space at the cooler north-west corner of the building, with a deep overhang shading its west-facing windows from the evening sun.

The building’s heat pumps can also capture heat from the lab and use it to heat the other internal spaces and provide hot water. Large groups can pose a challenge to indoor air quality, though the heat recovery ventilation system will automatically boost ventilation if it detects a rise in CO2. Lab manager Tim Morton says he will often manually boost ventilation in advance of groups arriving, though doors and windows may have to be opened too if groups of thirty or more show up.

This is not to say that the indoor air quality in the lab would decline any more than in a typical building – rather that the lab is run by staff who can monitor indoor air quality and adjust ventilation strategies as needed, which

may not even be possible with other similar buildings.

Built from EPS-insulated structural insulated panels, and with a cellulose-insulated roof, the spare detailing and industrial finishes lend themselves to easy maintenance, while the cedar cladding sits perfectly in the field station’s forest clearing.

Extensive glazing along the south-facing wall, meanwhile, collects passive solar heat during the winter months, while moveable, perforated-metal screens prevent overheating during Michigan’s hot and humid summers.

Staff and students have been coming out to the field station for six years now to study the nearby stands of old growth beech and sugar maple, of hickory and oak. “The field station has exceeded our expectations, it’s beautiful,” says Bergelson.

One of the biggest tests for the building came during the polar vortex that swept across the midwestern United States in January 2019, sending local temperatures down to -40 C. “There was a big group discussion going on here about how it would hold up during the polar vortex,” says Tim Morton. “I went out there to check on it, and the sun was so low, it was coming in through these large south-facing windows, warming up the concrete, and I didn’t even have to turn the heat on.”

ph+ | united states international | 7

8

Space-saving monobloc heat pump for outdoor installation: Vitocal 100-A – For new build and modernisation.

Maximum efficiency with minimum energy consumption.

Coefficient of Performance to EN 14511 up to 4.9 Energy efficiency class: A+++ Maximum flow temperature: to 60 °C at –8 °C outside temperature Installer does not require a refrigerant certificate Corrosion-resistant gold-plated heat exchanger

+ + + + +

viessmann.co.uk/vitocal

Viessmann Limited Hortonwood 30, Telford, TF1 7YP | Tel: 01952 6750000

U N I T E D S TAT E S

I N T E R N AT I O N A L

WANT TO KNOW MORE? The digital version of this magazine includes access to exclusive galleries of architectural drawings.

The digital magazine is available to subscribers on www.passive.ie

10 | passivehouseplus.co.uk | issue 37

CavityTherm

®

For more information contact our Technical Team

T 0371 222 1055 www.xtratherm.com

Meeting Future Homes, NZEB, 2030 Climate Challenge, today.

CavityTherm wall insulation delivers not only passive U-Values but also the detailing to combat thermal bridging heat loss.

A continuous wall insulation system delivering ultimate thermal performance with the added assurance of inbuilt protection from wind driven rain.

Accessories: Accessories:

Integral Rain Barrier

It’s not just about U-Values Preformed Corner Panels

Service Void Panels

Jointing Strip

Hockey Stick Insulation

Cavity Tray Channel

NEWS

PA S S I V E H O U S E +

NEWS

LETI: 33,000 NET ZERO CARBON HOMES PLANNED

P

lans for over 33,000 net zero carbon new homes are underway across the UK, Passive House Plus can reveal.

Data collated by the London Energy Transformation Initiative (LETI) indicates that 33,000 homes at master planning level are set to be designed to meet key performance indicators for scalable net zero, as defined by LETI – meaning they are highly energy efficient, such that they are using their fair share of the UK’s predicted renewable energy supply. LETI told Passive House Plus a further estimated 2,500 homes currently at stage two to four (post

planning but pre construction) are also set to meet the key performance indicators.

The LETI net zero carbon definition includes a total energy use intensity figure for energy consumed at the meter. The figure varies based on building type, ranging from 35 kWh/m2/ yr of gross internal area for dwellings, to 55 and 65 kWh/m2/yr for commercial offices and schools, respectively. LETI describe this as the maximum energy budget for the building, to enable a decarbonised grid to meet the remaining demand. The net zero carbon target also includes a space heating demand of 15 kWh/m2/yr. “It’s essentially building to the passive house standard with a heat pump,” said LETI’s Clara Bagenal George, adding that LETI’s targets were for in use energy, rather than just for calculated energy use.

LETI’s rise has been little short of meteoric.

While this may seem a remarkable phenomenon given the organisation’s voluntary, decentralised nature, Bagenal George cites these very characteristics as being essential to its success. “It wouldn’t have worked if it was a top down approach,” she said. “Our collaborative approach has fostered much more of a sense of ownership of the targets across the network.”

The group was set up to work collaboratively to put together evidence-based recommenda-

tions for two pieces of policy – the new London Environment Strategy and the rewrite of the London Plan. In the absence of clear, credible statutory targets for net zero carbon buildings, LETI decided to set its own, preparing a one page definition of net zero carbon in December 2019, and the LETI Climate Emergency Design Guide in January 2020. “We thought we needed to define good,” said Bagenal George. “We’ve been astounded by the response. I think it shows the collaborative approach works, rather than just a centralised approach.” LETI subsequently played a key role in mobilising engagement in the consultation process for the Future Homes standard.

Bagenal George said LETI began the process of collating numbers on projects so that other built environment professionals can point to the explosion of construction projects being designed to LETI’s net zero carbon targets. • (above) A rendering of a 600 unit net zero carbon passive house development planned for York City Council’s housing delivery programme. Designed

by Mikhail Riches, who won the Stirling Prize for the Goldsmith Street passive certified social housing scheme in Norwich, the new scheme also features air source heat pumps and PV arrays, and may be an early example of the kinds of schemes built in accordance with the LETI’s net zero carbon performance indicators.

Poorly ventilated retrofits can double radon retrofit risk, study finds R

esidential retrofits must ensure ventilation is carefully considered in order to avoid an increase in radon gas levels, researchers at NUI Galway in Ireland have found.

A team from the university’s school of physics conducted one of the first studies of its kind to quantify the impact of improved energy efficiency and airtightness on radon – a radioactive, odourless, colourless and tasteless gas that is a leading cause of lung cancer.

The modelling showed that if appropriate ventilation measures were not considered during the retrofitting process, there is a potential for radon levels to more than double.

However, the study also showed that when appropriate ventilation measures were implemented, radon concentrations could be reduced below initial levels. This finding is consistent with other evidence indicating that certain approaches may in fact reduce radon risks. As previously reported in Passive House Plus, a

12 | passivehouseplus.co.uk | issue 37

2020 monitoring study led by Barry McCarron found significantly lower radon levels in passive houses – which combine mechanical ventilation with heat recovery and advanced airtightness levels – than in neighbouring properties.

The new study was carried out by Dr James McGrath and led by Dr Miriam Byrne as part of research funded by Ireland’s Environmental Protection Agency. It has been published in the international journal Building and Environment.

“The research findings highlight that radon, and indoor air quality overall, needs to be given due consideration as a key element of any proposed retrofitting works,” James McGrath said.

Radon is responsible for about four per cent of lung cancer deaths in the UK each year. The study, ‘Factors influencing radon concentration during energy retrofitting in domestic buildings: A computational evaluation’, is available online at tinyurl.com/ NUIGradon. •

PA S S I V E H O U S E +

Green groups critical of latest budget

NEWS

AECB launches new retrofit standard T

L

eading environmental and green building charities have criticised the government’s lack of ambition on retrofit, upskilling and a green economic recovery in its latest budget.

“With just eight months until the UK hosts COP26 in Glasgow, this was a missed chance for global green leadership,” Harriet Lamb, chief executive of Ashden, the UK-based climate charity, said in response to the budget, which was announced by chancellor Rishi Sunak on 3 March.

“Where was the plan to retrofit our cold, old homes – or our public buildings such as schools where young people are crying out for climate action? There was not a squeak about the Green Homes Grant which has struggled because we do not have the people trained in the right skills and government is not offering long term certainty to companies.

“We have 96,000 gas engineers but just 750 accredited heat pump engineers and only 500 retrofit coordinators; and only 5 out of 200 FE colleges offer dedicated courses in renewable energy. This was the moment to score the twin goals of creating jobs and laying the foundations of the green economy – and the chancellor missed it.”

The UK Green Building Council (UKGBC) echoed these sentiments, especially regarding the uncertainly over the Green Homes scheme. “We are still none the wiser about the fate of the Green Homes Grant scheme, which just a few short months ago the Chancellor told us would support over 100,000 jobs in green construction up and down the country,” said chief executive Julie Hirigoyen.

“UKGBC, together with many others in our industry, have strongly advocated that the £1.4bn of unspent funding be rolled over to 2021/22, but today’s budget leaves both industry and householders still in the dark.

“Beyond the opportunities for green investment offered by the Infrastructure Bank and new green gilt and retail savings product, this budget appears to ignore the huge part that greening our buildings can play in delivering our post-Covid economic recovery. Tackling carbon emissions from buildings – particularly the existing housing stock – is not easy, but we cannot afford to duck the challenge any longer.

“The chancellor’s ‘investment-led’ green recovery should not ignore the voice of the industry calling for a national retrofit strategy to unlock vital green jobs across the whole country.” • (above) Chancellor of the Exchequer Rishi Sunak holding up the red box on budget day.

Photo by Harriet Pavey/No 10 Downing Street.

he Association for Environment Conscious Building has announced the launch of the new AECB Retrofit Standard, which like its AECB Building Standard, is based on the passive house standard and designed to promote a whole-house, fabric first approach.

The standard requires buildings to demonstrate a space heating demand of less than 50 kWh/m2/yr — though up to 100 kWh/m2/yr may be allowed with a special exemption — and a maximum airtightness of 2 air changes per hour (at 50 Pa).

“The AECB Retrofit Standard encourages the construction industry to decarbonise,” said AECB CEO Andy Simmonds. “We must prioritise the retrofitting of existing buildings at scale to meet 2050 environmental targets, as outlined in the Paris Agreement.”

“Individual self-builders and larger-scale developers can positively contribute to a low-carbon future by adopting the AECB Retrofit Standard when improving their buildings.”

While based on modelling in the Passive House Planning Package (PHPP), the AECB Retrofit Standard allows for self-certification. Projects can be self-certified through the client engaging an architect, engineer or other experienced consultant, or a suitably experienced contractor. For certification, evidence must be uploaded to the AECB Low Energy Buildings Database.

Writing about the launch of the standard at enhabit. uk.com, Dr Sarah Price, head of building physics at Enhabit and new technical author of the British Standards Institution's PAS 2035 retrofit standard, said that while the Passive House Institute’s Enerphit standard is a brilliant aspiration, “it can often be can often be unattainable and maybe too stringent for most homes in the UK”. (Enerphit requires a maximum space heating demand of 25 kWh/m2/yr).

She continued: “The AECB Retrofit Standard offers a pragmatic approach to the energy demand targets, which are still potentially lower than current UK new building regulations. The main difference that sets the AECB standard apart is that it recognises that every home is unique, and focusses on managing retrofit risks to avoid unintended consequences.

“The AECB Retrofit Standard also includes management of risks around moisture, flood, radon and fire, as well as requiring an excellent retrofit survey that ensures the building is fit for retrofit in the first place.”

Compliance with the AECB Retrofit Standard requires the building has been modelled in PHPP, construction quality has been verified and the supporting data has been publicly declared. Delivering the AECB Retrofit Standard also relies upon minimising thermal bridges using a PHPP verification sheet and following MVHR and airtightness testing protocols.

Meanwhile, the AECB’s popular and fully online AECB CarbonLite Retrofit training course is being complimented by a new retrofit co-ordinator training course. This will allow students to gain a level five diploma in retrofit coordination and risk management. For more see www.aecb.net. •

ph+ | news | 13

NEWS

PA S S I V E H O U S E +

Denmark sets out phased embodied carbon targets for buildings Timetable for phasing in and tightening of CO2e requirements New buildings over 1000 m2

New buildings under 1000 m2

Voluntary CO2e grade

Requirement for LCA calculation 2023

CO2e limit corresponding to 8 kg CO2e/ m2/yr

CO2e limit corresponding to 12 kg CO2e/m2/yr

By end of 2023

The parties to the agreement will meet with a view to determining the limit value from 2025, so that this can be determined from the latest knowledge and data.

2025

CO2e requirements limit value determined on the basis of the most recent knowledge and data.

With a requirement of e.g. 10.5 kg CO2e/m2/yr, approx. 1/3 of new construction should perform better climatically than currently.

By end of 2025

Parties to the agreement will meet to set a limit from 2027, so that this can be determined from the latest knowledge and data.

2027

CO2e requirements limit value determined on the basis of the most recent knowledge and data. With a requirement of e.g. 9 kg CO2e/m2/yr, approx. 3/4 of new construction should perform better climatically than currently.

End of 2027

Parties to meet to set a limit value from 2029

2029

CO2e requirements limit value determined on the basis of the most recent knowledge and data.

With a requirement of e.g. 7.5 kg CO2e/m2/yr, approx. 9/10 of new construction should perform better climatically than currently.

D

enmark is set to introduce embodied carbon targets into the country’s building regulations, a policy which has been backed with cross-parliamentary support.

The National Strategy for Sustainable Construction constitutes the government's action plan for the construction sector, and builds on a number of policy agreements, concluded since the current Danish government formed in 2019, to reduce construction emissions and help achieve the country’s 70 per cent reduction target by 2030.

The policy sets out a staged phasing in and tightening of embodied CO2 targets for buildings, including separate requirements initially for larger and smaller buildings.

Buildings below 1,000 m2 will initially only be required to calculate the life cycle assessment (LCA), while buildings over 1,000 m2 will also be required to meet embodied CO2 equivalent (CO2e) limits, which includes CO2 and other greenhouse gases converted into equivalent values of global warming potential.

The policy will also include more ambitious voluntary targets, building on the test

14 | passivehouseplus.co.uk | issue 37

CO2e limit corresponding to 7 kg CO2e/ m2/yr

CO2e limit corresponding to 6 kg CO2e/ m2/yr

CO2e limit corresponding to 5 kg CO2e/ m2/yr

phase of the voluntary sustainability class in 2020, which includes a requirement for LCA calculation.

The policy is all the more remarkable in that it was backed with cross-parliamentary support, including the Social Democrat-led coalition of centre left, left and socialist green parties, as well as all main opposition parties, including centre right and populist right parties. The negotiation of the agreement among such a broad range of political parties should ensure its stability, with the parties to the agreement committing to meeting again in 2023, 2025 and 2027 to tighten embodied CO2e targets based on the latest knowledge and data.

The announcement follows progress from a number of European countries in tackling embodied carbon, which is estimated to contribute 11 per cent of global greenhouse gas emissions annually.

The Netherlands was the first country in the world to require life cycle assessments on new buildings, in a regulation which came into force in January 2013, with France and the Nordic countries subsequently developing regulations on embodied carbon in buildings. •

Advertise with us.

94% say the adverts in Passive House Plus are relevant to them*

Contact us for more information on how your brand can feature in our next issue.

To enquire about advertising, contact Jeff Colley on +353 (0)1 2107513 or email jeff@passivehouseplus.ie

www.passivehouseplus.ie *source, Passive House Plus Irish edition 2019 reader survey

COLUMN

DUNCAN SMITH

Is Enerphit the key to decarbonising existing homes?

With increasing attention turning to cutting carbon emissions from existing homes to meet carbon reduction targets, Duncan Smith, housing asset and energy strategy manager at Renfrewshire County Council, argues that approaches which improve comfort and dramatically reduce energy bills must be front and centre.

O

ver the coming weeks and months, governments here in the UK and Ireland will start to plan the phased return to normality out of lockdown. There is an opportunity that presents itself as we emerge from the pandemic and dust ourselves down. An opportunity to change the dynamic and build a better retrofit model.

Within housing we need to look at the systems and practices that we use and ask if they are value for money both now and into the future. In many parts of the UK the cost of energy to heat a home is expensive. For those living in social housing the cost can be between £1,700 and £2,200 a year. That’s almost double the gas-grid average across the UK. This simply cannot be sustainable, not just for the environment but for households too.

So, if we carry out retrofit works to a home and it doesn’t move the cost in any way that the householder is able to see the benefit, are we doing the right thing? We need to aim for a significant reduction in energy consump-

have already delivered Enerphit or near Enerphit projects in the UK and Ireland over the last couple of years, including Portsmouth City Council (Wilmcote House) and Queens Cross Housing Association (Cedar Court), along with Dún Laoghaire-Rathdown County Council’s Rochestown House and Dublin City Council’s St Bricin’s Park.

In terms of costs, it is more expensive to take a home to Enerphit than a standard, or “cosmetic” retrofit approach. However, recent unpublished research in Scotland estimated that cost may be £25,000 on average if carried out at scale. But what does it save long term? What are the physical and financial benefits?

From a monetary value to the resident, it’s possible that it could reduce the costs of heating a home by 90% to under £200 on average. A typical saving on a heating bill – excluding electricity and hot water – could be £1,000 a year.

For occupants, this could have a significant impact on their lives – especially for those in social housing. Warm, dry homes

buildings and addressing their efficiency. For all this to happen, individuals, companies, specifiers, designers, buyers, providers and most crucially end users must be convinced by the argument and become advocates of change for an Enerphit approach. An approach that reduces demand for energy to the minimum and provides the residual demand through renewables. An approach that looks beyond the cosmetic and looks at value and the long-term benefits.

Let’s not go back to business as usual. Let’s not settle for more of the same. Let’s develop a new norm, one that delivers real benefits to all households. One that builds a sustainable future across society and the economy, and that addresses climate change.

If Covid has taught us anything, it is that real and significant change is possible in a short space of time. We shouldn’t squander this opportunity to change. We shouldn’t revert to the tired old ways of doing things.

They didn’t work before; they won’t work now. We should embrace the possibilities that change could bring. n

There is an opportunity to not only improve the living conditions within households across the UK and Ireland, but to address climate change and eradicate fuel poverty. tion, allowing the remainder to be provided by renewables.

This can only really be done through building fabric improvements and fundamentally increased airtightness levels. In some urban areas we can look at heat networks, but we still need to do all we can to improve the fabric. We can’t address climate change unless we address how much heat we need to keep our homes warm.

One way of doing this could be through adopting an Enerphit model as standard. To do this we need increased fabric improvements, higher specification glazing and airtightness levels comparable/better than current new build standards.

I believe Enerphit can be a catalyst for change and a number of social landlords

will have a transformational impact on the lives of those living in them. Of course, not everything can be retrofitted to Enerphit standard and where we can’t we need to look at where low carbon heat networks can bring value.

We shouldn’t use heat networks to offset fabric improvements, rather to compliment them. It’s not one or the other – it must be both. Together with fabric improvements and renewables there is an opportunity to not only improve the living conditions within households across the UK and Ireland, but to address climate change and eradicate fuel poverty.

But there is also an opportunity to invest in our industry, to upskill our workforce; to develop new ways of thinking about our

This piece was written in a personal capacity and does not represent the views of Renfrewshire Council.

ph+ | duncan smith column | 15

MARC Ó RIAIN

COLUMN

1970s Arkansas & Illinois prototypes: progress towards passive house In his latest column, Dr Marc O’Riain looks back at two American prototypes for the passive house standard that embraced heat pump technology as well as principles of superinsulation and airtightness.

(above) The Illinois Lo-Cal house from the Small Homes Council-Building Research Council, University of Illinois at Urbana-Champaign.

A

s Europe demonstrated its response to the first oil crisis with research projects at the Copenhagen Zero Energy House (1974-75) and Philips Experimental House in Germany (1974-76), the US, also excited by the potential for a new space heating technology in the heat pump, was actually building low energy houses for sale and occupation.

The Arkansas Project (1974) by Tschumi, Blades and Holzclaw (for the US Department of Housing) became the first of such residential projects to improve housing energy conservation and underpin a market for heat pumps. This testbed involved the construction of dozens of insulated houses with walls insulated with six inches of fibre glass batts to achieve an R-value of R-19 on raised heel trusses that came to be known as Arkansas trusses.

The project focused on airtightness and insulated envelopes, to reduce demand enough to make the limited capacity heat pumps viable. Richard Bentley patented the timber frame ‘double wall’ house (1974), allowing Wayne Shick to advance the design solution of the Arkansas Project and create the first ‘Lo-Cal’ or low‐calorie houses in Illinois.

The Lo-Cal house would be the first to coin the phrase superinsulation, which was used in conjunction with optimal solar orientation — supplemented by passive shading — and good airtightness using limited air-to-air heat exchange. The team even managed to minimise thermal bypass before thermal bridging would be ‘discovered’ in 1977 by a group of researchers known as the ‘Princeton house doctors’. The overall design of this timber frame structure is remarkably close to passive house detailing, which was not to be introduced until 1988.

The Lo-Cal structure’s design had incorporated Bentley’s insulated double wall

16 | passivehouseplus.co.uk | issue 37

construction, with a minimum number of connecting elements between interior and exterior wall surfaces, minimising thermal bridging, with an assumed 0.25 to 0.5 air changes per hour provided via infiltration, although this cannot be compared against modern airtightness test results. As the project predated the use of blower door tests, an experimental method was employed using tracer gasses to estimate leakage rates in normal weather conditions.

The house also adopted triple glazed windows on south (85 per cent of glazing) and west (15 per cent of glazing) facades with no windows on the north and east walls.

Windows were 1270 mm high (50”) set below a 760 mm (30”) overhang sitting 400 mm (16”) over the window head. The south windows are exposed to sunlight in the winter and are shaded in the summer to reduce overheating, a strategy well-established by Frank Lloyd Wright and Fred Keck up to 1933.

The very good window energy conservation performance was complimented with a 0.82 shading factor, maximising solar radiation gain in winter. Shicks’ team also remarkably carried out computer modelling for shading using deciduous trees to the east, south and west of the house.

The design included ambitious U-values and used a polyethylene vapour barrier on all exposed surfaces, with ventilation dependent on manually opening windows. The design also included one fixed forced-ventilation point for supply and return with 85 per cent per cent efficient heat recovery, including switch operated forced-ventilation of kitchen and bathrooms.

These passive measures resulted in a 53 per cent reduction in space heating demand while the active measures contributed to a further 13 per cent reduction, resulting in a house that could be heated for two-thirds less than

a standard house in 1976 and a third less than the 1974 Arkansas houses.

The designers and researchers did admit that electric heaters with thermal controls located under the windows would have been more cost effective than a heat pump. Also, the very low air changes resulted in high humidity requiring the constant use of a dehumidifier, leading to additional plug loads. The houses suffered from increased solar heat gain (33 per cent) from the south windows despite the large eave overhangs. This seems to echo contemporary issues with some passive houses today (Finegan et al 2019i).

The design of the Lo-Cal house is very close to passive house principles and detailing, without the use of augmented whole house mechanical assisted ventilation, which Shick later admitted to being a shortcoming of the design. However, researchers were starting to establish the key criteria for building zero energy housing in the mid-1970s and consumers were buying them.

But what about retrofitting existing buildings which would represent 99 per cent of the building stock every year? In the next article we will review retrofit energy conservation in the late 1970s and the discovery of thermal bypass or thermal bridging. n Comparative analysis of Passivhaus simulated and measured overheating frequency in a typical dwelling in Ireland, Finegan, E et al, Building Research & Information, Vol 48 2020 Issue 6.

i

Dr Marc Ó Riain is a lecturer at the Department of Architecture at Cork Institute of Technology, one of the founding editors of Iterations design research journal and practice review, a former president of the Institute of Designers in Ireland, and has completed a PhD in low energy building retrofit, realising Ireland’s first commercial NZEB retrofit in 2013.

UNPARALLELED CHOICE OF PASSIVE CERTIFIED PRODUCTS – OUTWARD OPENING, INWARD OPENING, UPVC, ALUMINIUM, ALUCLAD

GROUND BREAKING U-VALUES FROM AS LOW AS 0.47W/M²K

T. 0845 3098007 E. info@munsterjoinery.co.uk

www.munsterjoinery.co.uk WINDOWS & DOORS

DR PETER RICKABY

COLUMN

Shooting

the moon The concept of building back better and greener, popular early in the pandemic, is now in danger of being abandoned in the rush to return to ‘normal’ — but we always have the power to shape what normal is, writes Dr Peter Rickaby.

O

n Norah Jones’s debut album Come Away with Me is a beautiful, melancholy song that looks back from autumn to a summer of lost romance. The song is called Shoot the Moon. Looking at the moon one evening recently, I was reminded of that song as I looked back to the summer in which we hoped to start to ‘build back better’ after the pandemic.

As I write this, there seems very little political or social will to pay more than lip service to building back better. The most common aspiration seems to be to get vaccinated, forget 2020 and return life to the way it was in 2019.

Build more roads. Construct a new runway at Heathrow Airport. Restore the aviation industry to growth. Restore every industry to growth. Install more wind turbines to avoid retrofitting. Hope vainly that hydrogen will save us. As the song says, last summer we tried to shoot the moon – but missed completely.

But perhaps not completely. There are green shoots, as people around the world rise to the challenge of climate change every day, in different ways. Many former office workers, now working from home, are reluctant to return to the daily tidal commute on crowded trains. We have learned from our children to interact with each other using technology, instead of travelling to meetings. We have learned to study online, and to shop online and get things delivered. We have learned to appreciate the open spaces near our homes.

We are also beginning to understand how we might decarbonise our industries, our vehicles and our buildings. But the numbers don’t add up, and the pace of change is not sufficient – time is running out, and it is becoming evident that the effects of climate change will be much, much worse than the pandemic. We are not just facing heat waves, wildfires, storms, rising sea levels and the flooding of most of our coastal cities. There

Normal is always new. Aspiring to build back better is normal.

18 | passivehouseplus.co.uk | issue 37

will also be droughts, crop failures, famine, conflict, mass migration, refugees and more pandemics.

In this context I find it difficult to understand why anyone would want to put everything back the way it was – except perhaps a few individuals who were doing well at everyone else’s expense. For those who don’t aspire to build back better, two thoughts occur to me.

First, even a cursory study of history reveals that after a crisis nothing ever returns to the way it was. Even without a crisis, we inexorably move on. Generation by generation, people’s new knowledge, experience and understanding drive aspirations to better politics, better economies, better technology, better education, better healthcare, better environments, better societies and better opportunities.

The lives of my children, mostly born in the early years of the twenty-first century, bear almost no resemblance to the lives of their grandparents, born in the first quarter of the twentieth century. So, unless you are Jacob Rees-Mogg, why aspire to go back? Normal is always new. Aspiring to build back better is normal.

Second, nature doesn’t care. It really doesn’t. We might survive the coming crisis, and a few more, and go on to explore space, populate the galaxy and reach new heights of understanding and social development.

Or we might fail to appreciate what our lives depend on, destroy our ecology, fall into conflict, succumb to the next pandemic, and for one of many possible reasons, become extinct. Science teaches us that there is no such thing as destiny. If we disappear, nature won’t notice. Nature is indifferent to the fate of humanity: our future is down to us.

Returning to a shorter, less philosophical and more political perspective, the COP26 conference in Glasgow in 2021 may nurture ‘build back better’ and lead us in a new direction. Perhaps we will get another shot at the moon, but I keep remembering the famous cartoon in which a climate conference delegate asks: “What if climate change is all a hoax and we build a better world for nothing?”

If we want another shot, we must be resolute, work together, and heed the words of Greta Thunberg: “nobody is too small to make a difference”. n

Unless you are Jacob Rees-Mogg, why aspire to go back?

Dr Peter Rickaby helps to run the UK Centre for Moisture in Buildings (UKCMB) and the Building Envelope Research Network at University College London. He also chairs the BSI Retrofit Standards Task Group and was technical author of the new domestic retrofit standard ‘PAS 2035: Retrofitting dwellings for improved energy efficiency — specification and guidance’. He is currently working on ‘PAS 2038: Retrofitting non-domestic buildings for improved energy efficiency — specification’.

The views expressed here are his own and not necessarily those of UKCMB, UCL or BSI.

Passivhaus Certified MVHR Systems PRE HEATER • • • •

BYPASS • • •

Double soft sealing lip Guiding vanes for equal Maintenance free DC motor

Larger surface (cooling ribs) Double safety switch max temp New aerodynamic design Guiding vanes for equal air-flow over heat exchanger

DISPLAY • • • • •

TFT Colour touch-screen New clear menu structure Installation Wizard for quick and proper commissioning Filter wizard with instructions on how to clean and replace Filter/error messages, also via LED

FAN • • •

•

Highly efficient EC backward curved radial fan Constant flow fan Ultra precise and fast flow measurement done by VaneAnemometer Spare part contains complete fan (easily replaceable)

HEAT EXCHANGER • • • • • •

Holmak TST 35 Larger surface area Lower pressure loss (Pa) Higher Thermal Effeciency Material: PETG or B2 class Guiding sleeves (long term air-tightness)

THE ADVANTAGES AT A GLANCE • • • • • •

Most modern communication options Comprehensive control options Useful installation and maintenance wizards Optimum balance between thermal efficiency & energy consumption Very quiet operation Constant flow motor with integrated anemometer ensures precise control of air flow

CVC offers free detailed 3D plans and specifications for all its projects.

This process is created by our in house design team so any modifications or adjustments can be revised to suit as required

CVC stocks a range of ventilation units and ducting systems. Including Passivhaus certified MVHR units. We carry ample stock and are able to supply nationally and short notice.

CVC has a team of national installers positioned around the UK and we can provide installation of all our systems wherever your build may be.

 01491 836 666  info@cvcdirect.co.uk  www.cvcdirect.co.uk

O S T R O PA S S I V H A U S

CASE STUDY

BOXING CLEVER STRIKING STIRLINGSHIRE PASSIVE HOUSE IS A TRUE LABOUR OF LOVE

This all-wood passive-certified home in the village of Kippen was built directly by its architect owners, who not only achieved the passive house standard but did so with an ecological approach that sought to use building materials ultra-efficiently and make it easy to deconstruct and recycle the building at the end of its life.

Words by John Cradden

20 | passivehouseplus.co.uk | issue 37

CASE STUDY

O S T R O PA S S I V H A U S

ENERGY BILLS

£20

PER MONTH FOR SPACE HEATING ONLY, EXCLUSIVE OF CHARGES Estimate, see ‘In detail’ for more.

Building: 170 m2 detached home and office Build method: Stick-built timber frame Site & location: Village site, Kippen, Scotland Standard: Passive house classic certified Budget: £250,000 (build costs)

ph+ | ostro passivhaus case study | 21

O S T R O PA S S I V H A U S

CASE STUDY

PARAPET LEVEL : ± 7500

ROOF LEVEL : VARIES 1ST FL CEILING : ± 5900

FIRST FLOOR FFL : ± 3163

GND. FL CEILING : ± 2800

GND FLOOR FFL : ± 0

NORTH ELEVATION AS PROPOSED

PARAPET LEVEL : ± 7500

ROOF LEVEL : VARIES 1ST FL CEILING : ± 5900

FIRST FLOOR FFL : ± 3163

GND. FL CEILING : ± 2800

GND FLOOR FFL : ± 0

EAST ELEVATION AS PROPOSED

PARAPET LEVEL : ± 7500

ROOF LEVEL : VARIES 1ST FL CEILING : ± 5900

FIRST FLOOR FFL : ± 3163

GND. FL CEILING : ± 2800

GND FLOOR FFL : ± 0

SOUTH ELEVATION AS PROPOSED

PARAPET LEVEL : ± 7500

ROOF LEVEL : VARIES 1ST FL CEILING : ± 5900

FIRST FLOOR FFL : ± 3163

GND. FL CEILING : ± 2800

GND FLOOR FFL : ± 0

T

he term ‘self-build’ can be a little vague these days — even meaningless — when you can class as a self-builder anyone who plays some sort of significant role in the construction of their new build home.

As a self-builder you might have a lot to do with the day-to-day aspects of the project either by getting stuck in or project-managing the work yourself, but you can also have very little to do with it by farming out all the work to the professionals.

Mhairi Grant and Martin McCrae certainly rolled up their sleeves when it came to building Ostro, a hugely striking two-storey, detached timber framed and clad passive house located near Stirling, Scotland. In fact, the sheer amount of work that they did themselves makes this a self-build in the truest sense of the word.

This includes building the timber frame (stick-built, no kit or panel system), installing all of the ground floor and wall insulation, applying all the airtightness products, doing all the plumbing and general joinery, laying the floors, fitting all the plasterboard and other internal linings, the kitchen and bathroom fittings and tilings, and all the decorating.

They also did the external drainage for the ground floor slab, the external timber cladding, all the external landscaping and the sedum roof covering.

22 | passivehouseplus.co.uk | issue 37

WEST ELEVATION AS PROPOSED

So what did they not do? They didn’t do the site excavation and preparation, the pouring of the slab, the fitting of the windows, the roof insulation and waterproofing, the wall-plastering, the specialist interior carpentry, the electrical work and the installation of the solar PV and solar thermal systems.

The result of their highly resourceful endeavours – all on a budget of £250,000 – is a very distinctive, box-shaped certified passive house with lots of hallmarks of Scandinavian architecture in its use of natural timber cladding, unfussy details and a clear, simple shape.

It’s no surprise to learn that the couple run an architectural and design company – Paper Igloo – that now specialises in sustainable and passive house projects, and designed Ostro between themselves. But the fact that it took some six years from start to finish doesn’t diminish the scale of their self-building triumph, particularly when you learn what their primary motivation was.

“It was due to a combination of three things,” says Mhairi. “We wanted, and needed, to keep the costs down as we wanted to be mortgage free. Like most people who are either self-employed or have a small one or two-person company, our monthly income is variable, which makes large fixed costs such as a mortgage very difficult and stressful to manage.

“Secondly, we enjoy the hands-on aspect ELEVATIONS : PROPOSED

of building as a contrast to our daily design work, which involves time spent mostly on a computer. And finally we also wanted to learn more about the passive house aspects of house building that would let us be more informed when designing them for other people in the future.”

Before moving to the semi-rural conservation village of Kippen, near Stirling, the couple lived in a nice old tenement flat in Glasgow that they had renovated themselves but in which they struggled to get the room temperature above 14C in winter. They were considering renovating another flat when Mhairi attended a half-day course in passive design, “which I thought was incredible – I couldn’t understand why all new buildings weren’t built to this standard”. She then qualified as a passive house designer.

They searched for a suitable plot for a few years before finding one in Kippen and broke ground in 2014 — though not before talking to loads of people and driving all the way down to Totnes in Devon to stay in Adam Dadeby’s passive house B&B to experience the reality of heat recovery ventilation.

“So we stayed overnight, I remember the first thing we did when we went into the room, we were trying to find the valve to put our hands up to it, to see if there’s a draft and to listen to it and that kind of thing,” recalls Mhairi. So as

CASE STUDY

well as talking to other architects, “you want to know that the physical reality of it is going to live up to the science, and that it’s actually going to be as comfortable”.

At the start of the project, it helped that the couple had a bit more free time on their hands, and they did the most work in the first two years. This included Martin taking 12 weeks off at one stage to build the timber frame with two joiners. They estimate that this alone saved them tens of thousands on the build, but another factor in that decision was that they couldn’t find carpenters at the time who would do an I-Joist wall or twin frame to enable thermal breaks, never mind factory-built timber panels.

“Six years ago there was hardly anyone,” says Martin. “We couldn’t find anyone to be able to build a passive house frame, whereas now we’ve worked with Eden Insulation and other companies quite a lot and they’ll do something for you. So what we built in that time, they will build you on site in four days.”

The couple were able to cover-off a number of jobs individually. For instance, Martin did the aforementioned timber frame, while Mhairi did all the plumbing and tiling, but they worked together on jobs for the most part.

“When it came to things like plasterboard and insulation fixing, and so on, we just did that together because a lot of jobs require two people for manoeuvring materials, all that kind of thing,” Martin says.

After the first couple of years, the couple spent another four long summers on the distinctive timber cladding. “That was really what we did for four years, which seems incredible when you look back now,” recalls Mhairi. “But it didn’t really occur to me until our neighbour said last year after we had finished, ‘You’ll be so looking forward to summer this year because you won’t have to clad anything. And I

Photos: David Barbour

O S T R O PA S S I V H A U S

thought, ‘Oh yeah, it’ll be really nice’.”

Martin admits that, aside from them being busier at work by that stage, one of the reasons the cladding took four long years was the decision to mount it diagonally, which is much trickier than placing it horizontally or vertically. The cladding is mounted on vertical battens but “when you get to a small triangle at the corner of the wall, there’s nothing to support it. So I had to prefabricate triangles with stainless steel straps screwed on and then offer it up as a unit. It was a tiny little thing, but time consuming.”

He did ask a builder to quote to finish the job at one stage, but the builder wouldn’t do it.

Part of the problem with living in central Scotland compared to somewhere like London, he says, is that finding a contractor interested in executing finer detail work is far harder.

The couple had sold their Glasgow flat much quicker than they anticipated and rented various flats in Kippen for a couple of years before moving into a caravan next to the site for nine months as the build progressed.

During one miserable winter spent in the caravan (which had to double as their office) they discovered that not only was their mattress going mouldy, but they received a £2,000 top-up electricity bill for the four-bar electric heater that was running almost permanently.

So they decided to move into their unfinished but weather-proofed, warm and dry building next door in 2016 and essentially camp in it.

They plaster-boarded one room and not long after got the kitchen fitted.

One useful reference for the couple was the book Details for Passive Houses published by IBO, the Austrian Institute for Healthy and Ecological Building. Although most of the tips were more relevant to masonry construction with external insulation, “it did open my eyes to perimeter insulation and how you might GROUND FLOOR PLAN : PROPOSED

FIRST FLOOR PLAN : PROPOSED

ph+ | ostro passivhaus case study | 23

O S T R O PA S S I V H A U S

CASE STUDY

WANT TO KNOW MORE? The digital version of this magazine includes access to exclusive galleries of architectural drawings. The digital magazine is available to subscribers on passivehouseplus.ie & passivehouseplus.co.uk

achieve continuity at certain junctions,” says Mhairi.

They must also have been taking careful notes regarding airtightness given the impressive score the house achieved of 0.19 air changes per hour. This did prove among the biggest challenges of the build, however, particularly the job of incorporating the membrane during the timber frame construction.

“We were really pleased… that was quite a nice moment,” says Mhairi.

Mhairi praises Niall Crossan and his team at Ecological Building Systems for the tips and advice that they received while doing one of the company’s workshops in Athboy, Co Meath.

“They’re so interested in promoting better buildings and better construction, and so we found them really helpful for things like that.”

The couple were keen from the beginning to use as many natural materials as possible, starting with the PEFC/FSC-sourced, untreated timber frame and cladding but also wood-fibre insulation which, Mhairi notes, “is much more pleasant to work with than phenolic insulation or mineral wool and creates, in conjunction with the other wall products, a vapour open construction.” The flat roof has a sedum covering for biodiversity and water-saving. Mhairi and Martin also salvaged materials from other sites for landscaping, and kept a tight control on construction waste, so much so that no skips were required during the build.

With the projected energy use of their home based on PHPP (Passive House Planning Package) calculations, the couple felt confident enough that the heating demand could be met by something really simple and modest. So instead of a heat pump, they opted for infra-red heating panels (all individually thermostatically controlled) with a back-up post heater in the ventilation supply ducts, while most hot water is provided by good old-fashioned evacuated tube panels.

“It still amazes us how much solar input we get from the evacuated tube panels, says Mhairi. “They are quite aggressive, even in the shoulder seasons. We are often surprised how much dedicated solar thermal seems to be overlooked in Scotland as a viable renewable technology, with many people preferring to use PV [for electricity]. For a house such as ours with only a small PV array, no heat pump and no battery, solar thermal still makes a lot of sense for hot water demand.”

As well as monitoring electricity consumption, which has been in line with their projections, they have also installed temperature and humidity sensors in various places to validate what they are feeling in their bones as they occupy the space.

“We have found that the temperature, as you might expect, is extremely stable – hovering around the 20 C mark internally. We have

Martin did the timber frame, while Mhairi did the plumbing and tiling.

24 | passivehouseplus.co.uk | issue 37

CASE STUDY

had some days down to about -4.4 C externally recently. What has surprised us is that we thought there would be more variation and stratification at the top of the double height, however this is also quite stable within a range of a couple of degrees.”

Indeed, Mhairi comically notes that when they lived in their old flat, she found herself wearing bed socks most nights, and extra jumpers for “when the boiler goes off at 10 o’clock at night”. And that now they often have to physically open the door to figure out how cold it is outside, and whether they need hats and gloves.

The couple have no regrets about all the specification decisions they made over the course of the six-year build. But Martin admits that one thing they might change if they had the chance to turn back time is to go for a mono-pitched roof so that they could mount more PV panels and qualify as a passive house ‘plus’ and therefore charge, for practically nothing, the electric car they are planning to buy.

While they weren’t able to find contractors willing to do things like the cladding or any other complicated or detailed work, they did manage to find a cabinet maker who made their beautiful staircase and a rather neat drinks cabinet with a very slick opening mechanism. “That was quite a nice little moment in the project where, for what felt like the first time ever in our lives, we actually commissioned someone to do this,” says Mhairi. “It was so interesting to be the client and very pleasurable after spending about five years slogging it out.”

O S T R O PA S S I V H A U S

CONSTRUCTION IN PROGRESS

1

2

3

4

5

6

SELECTED PROJECT DETAILS Clients: Martin McCrae & Mhairi McCrae (nee Grant) Architect: Paper Igloo Structural engineer: Clyde Design Partnership Energy consultant: Paper Igloo Passive house certification: Etude Main contractor: Client self-build Electrical testing: Knowire Ltd Airtightness testing: Stuart King Architecture & Design Timber supply (for stick-built frame): Rowan Timber Supplies Wood fibre insulation: Gutex, via Ecological Building Systems Additional wood fibre insulation: Steico, via Passivhaus Store Green roof system: Bauder Additional roof insulation: Knauf Airtightness products: pro clima, via Ecological Building Systems Windows & doors: Unilux Roof windows: Lamilux Larch cladding: Rowan Timber Supplies Internal wall board: Fermacell, via SIG Linoleum flooring: Forbo Self-build insurance: Titan Insurance Services Space heating: Yandiya IR panels, via Edensprite MVHR: Paul Heat Recovery Scotland Wastewater heat recovery: Recoup Lighting controls: Schneider Electric Heating controls: Salus & Nest Water-saving fittings: Crosswater Bathroom fittings: Martin Craig Bathroom Design Studio

1 Self-builders Martin and Mhairi, together with their friend, architect Eamon McGarrigle (centre), installing the Isoquick EPS insulated formwork system; 2 the 300 mm reinforced concrete slab was power floated to form floor finish throughout ground floor; 3 erection underway of the stick-built timber frame walls; 4, 5 & 6 the walls were built with a doublestud timber frame, with wood fibre insulation to both studs, and a further 60 mm in between the studs to form a thermal break.

ph+ | ostro passivhaus case study | 25

O S T R O PA S S I V H A U S

CASE STUDY

CONSTRUCTION IN PROGRESS

1

2

3

4

5

6

1 Wood fibre insulation to the inner studs; 2 pro clima Intello Plus vapour control membrane to ceiling; 3 Spano Durelis Vapourblock airtight vapour control board to walls; 4 airtightness taping around wire penetrations; 5 continuous external wrap of 100 mm thick wood fibre insulation boards; 6 airtightness detailing around windows.

Designing for deconstruction & embodied carbon Words by Mhairi Grant (architect, builder and client)

O

ne of our ambitions for the design of Ostro was to create a dwelling with low environmental impact. While embodied carbon wasn’t a direct consideration, it is interesting to realise retrospectively that a number of our ecologically driven decisions resonate well with a low embodied carbon approach.

We gave a lot of consideration to our construction method and the materials used to create the building, such as our choice of timber frame, wood-fibre insulation and untreated timber cladding. Our aim was one of reduction – to make all of the layers within the construction work as hard as they could and ideally perform more than one function so as to reduce the overall quantity of materials required.

One example of this approach would be the ground floor construction: we dispensed with a floor covering on the ground floor, which might typically have included an additional screed with a timber, tile or carpet floor finish, and instead

26 | passivehouseplus.co.uk | issue 37

exposed our power floated structural slab throughout.

The choice of a twin-wall timber frame with loose-batt wood-fibre insulation was a consequence of two decisions. Our aim of achieving sustainability gold level in the Scottish government’s technical standards meant we had to pay attention to the Scottish Ecological Design Association’s guide to designing for deconstruction.

We wanted to use an insulation material that could be readily separated from the structural frame at some point in the future should the building ever need to be deconstructed. This approach allows either component to be replaced without destroying the other, and therefore each can potentially be re-used or recycled.

Secondly, we wanted to work with a material that was non-toxic, formed from a by-product, and relatively dense to better the decrement delay of the building fabric.

When we were considering the outer

skin of the building, our selection of untreated timber cladding boards stemmed from a desire to use a durable, long lived and low maintenance material, and importantly, one which we could apply ourselves without specialist training.

As the years have passed we have become more aware of the environmental importance of reducing embodied carbon within our designs, and so we recently decided to engage Tim Martel of PHribbon to undertake an embodied carbon calculation on our completed building (see graph). We found the outcomes really interesting: in particular a comparison of our chosen construction method with a more common form of construction, such as cavity wall. Another point of note was the RICS assumption regarding current practice of incineration of post-construction timber in the UK. This has opened our eyes to the impact that incorporating a more circular approach to construction could have on the industry as a whole.

CASE STUDY

O S T R O PA S S I V H A U S

ph+ | ostro passivhaus case study | 27

O S T R O PA S S I V H A U S

CASE STUDY

ɝ­ĩĈ {ŴƇĭŋÝń ­ĩĈŸŋÝń ŸĭāġĈ GŸĈĈ GŕƍōāÝƇĭŕō ¤ŕńƍƇĭŕōɝ ɫ ­ĩĈ ÝžžĭƣĩÝƍž UōžƇĭƇƍƇĈ ¤ƍĭƇÝùńĈ ğŕŸ ƇĭŋùĈŸ ğŸÝŋĈɕ U"Gɕ ¤U ž Ýōā ŋÝžŕōŸƪ ³ ƣÝńƍĈž ʛȾɚȿƤɠŋɀŀ GÝžƇ Ƈŕ ĭōžƇÝńńɕ ûŕžƇ ĈğğĈûƇĭƣĈ

ȾȿɀȾɀ ɇȾɇ ȿȾɃ

28 | passivehouseplus.co.uk | issue 37

ĭōğŕʭùƍĭńāĩŕŋĈžùĈƇƇĈŸɚûŕɚƍŀ

ĭžŕŷƍĭûŀɚûŕɚƍŀ

O S T R O PA S S I V H A U S

CASE STUDY

Embodied Carbon: Ostro Passivhaus

remain in the building, whereas the same house built with typical cavity wall construction would store 128 kg CO2e/m2 (certain timber use is common to both approaches, including the timber cladding, timber floors, etc).

And with an extraordinary house like this – due to the combination of architectural quality and robust detailing – the CO2 emissions sucked out of the atmosphere and stored in those timber products must stand a strong chance of staying out of the atmosphere far beyond the assumed 60 years, buying humanity vital time in the great climate fight.

< Carbon Stored

kg CO2e/m2 TFA

Carbon Emitted >

Embodied Co2e: Cradle to Grave As built emissions

400 300 200 100 0 -100 -200 -300

Module A

Stored CO2e

Module B

Module C

Embodied Co2e: Cradle to Grave Carbon Emitted >

is the Forbo Marmoleum flooring, which had an Environmental Product Declaration (EPD) confirming that the product’s embodied carbon emissions were just 23 per cent of the total for linoleoum from the Inventory of Carbon and Energy – a reflection of the kinds of improvements progressive manufacturers can make in some product areas.

Other areas to target may include reducing the 42 kg CO2e to transport materials to site – perhaps a reasonable target even without localising supply chains given progress in EVs – and the estimated 29 kg CO2e related to the construction process itself – a figure which may be much lower in this case, given the amount of direct labour involved. If all of these changes were made, it’s possible the building would beat the 2030 Climate Challenge target of 300 kg CO2e m2 TFA. The analysis also looked at the building’s external walls in isolation, and compared them to cavity wall construction (assuming 100 mm concrete blocks internally and externally) to achieve the same energy performance. In this case, if we compare the cradle to factory gate emissions for materials only, it tells a very different story – in spite of the fact that the cavity wall comparison ignores the extra concrete that may be required in the foundations in this case.

The upfront CO2e emissions for the asbuilt timber frame walls come in at 8.43 tonnes of CO2e, whereas the cavity wall version would be 15.25 tonnes of CO2e. Meanwhile, the as-built walls also include 33.8 tonnes of CO2e sequestered in the timber and wood fibre insulation, compared to 5 tonnes of stored CO2e in the cavity wall – a benefit that arises from the assumption of timber cladding being used in that case.

Life cycle assessment rules state that while sequestered CO2 can be considered in cradle-to-grave analyses, the end of life must be factored in too. To an extent it’s a moot point: the applicable standard for EPDs, 15804+A2, specifies that even if CO2 sequestering materials are recycled at the building’s end of life, the sequestered CO2 is passed on to this future use and thus ‘lost’ from the building’s embodied carbon score – a fact which may actively discourage consideration of deconstruction and disassembly in the design process.

But the fact remains: the house as built includes 299 kg CO2e/m2 stored in timber and timber-based products for as long as they

kg CO2e/m2 TFA

he embodied carbon score of Ostro passive house varies depending on how you assess it.

For this article the as built-house was compared to the same spec with one difference: substitution of the timber frame external walls with a cavity wall build-up to achieve the same thermal performance.

The as-built house scored a cradle-tograve embodied carbon figure of 439 kg CO2e/m2 of the treated floor area, falling well short of the RIBA 2030 Climate Challenge’s embodied carbon target for dwellings of 300 kg, but surpassing the 2020 (600 kg) and 2025 (450 kg) targets.

One obvious target for further reductions is stage B, the emissions associated with projected component replacements during the building’s assumed 60 year life. The stage B figures assume that elements like the roof, windows, roof window and floor covering will each be replaced once within the building’s life. In the case of well-detailed, high quality windows and roof windows – both of which are aluminium-clad – a considerably longer lifespan may be possible.

As Wolfgang Feist and colleagues found in a monitoring study of the first passive house scheme 25 years after its completion, the original triple glazed windows were found to have less than a 5 per cent loss in insulating value (U-value), and the frames were expected to last at least another 25 years. Their report noted advances in glazing technology in the intervening decades, and referenced a functional service life for glazing in excess of 40 years.

Conceivably, the windows at Ostro may not need to be replaced within 60 years. If some of the main assumptions around replacements during the building’s projected lifespan were altered – assuming no replacements of windows or roof windows, and one rather than two replacements of the solar PV array – the cradle to grave embodied CO2e score would drop to 383 kg CO2e.

Additional savings from the concrete foundations are limited by the fact that the as built insulated foundation system had already significantly reduced cement use compared to strip foundations, but substituting 70 per cent of the Portland cement in the concrete foundations with GGBS would lower the total to 338 kg CO2e.

Some savings come from just having independently verified data. A case in point

Words by Jeff Colley

< Carbon Stored

Embodied carbon explained T

Cavity wall comparison

400 300 200 100 0 -100 -200 -300

Module A

Stored CO2e

Module B

Module C

kg CO2e/m2 TFA

600 400 200

333

390

439

Module A: A5 Construction

469

Module A: A4 Transport to site Module A: PV

0

-128

-200

-299

-400 Cradle to practical completion As built house

Cradle to grave Cavity wall comparison

Stored CO2 in Timber

Module A: Oil Based Module A: Inert Module A: Concrete Module A: Composite Stored CO2e: Timber Stored CO2e: Timber Based Module B: Use Module C: Demolition & Disposal

ph+ | ostro passivhaus case study | 29

O S T R O PA S S I V H A U S

CASE STUDY

Putting people and the planet first Environmentally friendly building products from renewable resources Insulation

Sealing

Construction

CERTIFIED SAFETY

STEICO Building System

Sheathing and sarking boards for new-build and refurbishement

Flexible insulation batts made from natural wood fibres

Air injected insulation made from wood fibres or cellulose fibres

Insulation systems for rendered facades or curtain walls

Light and efficient I-joists for wall, floor, and roof constructions

Laminated veneer lumber with high load-bearing capacity

STEICO are the worlds largest producer of integrated construction and insulation systems made from wood.

We have been manufacturing ecological and environmentally-friendly construction materials for over 30 years.

Supported by our UK insulation distributors:

Find out more about how you can make a difference at: www.steico.com Sealing system for the building shell

30 | passivehouseplus.co.uk | issue 37

CASE STUDY

O S T R O PA S S I V H A U S

IN DETAIL Building type: 170 m2 (treated floor area) detached two-storey timber frame house.

Location: Kippen, Stirlingshire, Scotland Completion date: January 2020 Budget: Approx £250,000. Includes professional fees & VAT where applicable.

Does not include significant labour cost due to self-build nature of project.

Passive house certification: Passive house classic certified Space heating demand (PHPP): 15 kWh/m2/yr Heat load (PHPP): 11 W/m2 Primary energy renewable (PHPP): 37 kWh/m2/yr Primary energy non-renewable (PHPP): 79 kWh/m2/yr Heat loss form factor (PHPP): 3.48 Overheating (PHPP): 4 per cent of year above 25 C Number of occupants: 3 (from PHPP) Environmental assessment method: Section 7: Sustainability ‘gold’ Level; assessment method as per Scottish Technical Standards Airtightness (at 50 Pascals): 0.19 air changes per hour Energy performance certificate (EPC): A 94 Measured energy consumption: 6,392 kWh or 37.59 kWh/m2/yr measured annual energy consumption (October 2019 to October 2020) based on electricity meter readings.

Thermal bridging: Continuous external wrap of 100 mm thick Gutex woodfibre insulation, external and internal window / door reveals insulated, thermally broken window frames, continuity of wall-to-ground insulation, continuity of wall-to-roof insulation, SVP insulated.

All junctions were numerically analysed in PSI Therm software and calculated thermal bridge values entered into PHPP. Energy bills (measured or estimated): Based on projected figures for final energy demand (delivered energy) for space heating in PHPP, uSwitch.com suggests an annual space heating bill of £239.70, or £19.98 per month, using the cheapest tariff available of 17.967p per kWh. This is exclusive of VAT and standing charges, which increase the total to £351.72 annually, or £29.30 per month.

Ground floor: Minimum 600 mm compacted Type 1 sub-base laid in 150 mm deep layers, followed above by 50 mm cleaned and compacted stone blinding, 300 mm thick Isoquick EPS insulated formwork system, 1200 gauge Visqueen ‘Ecomembrane’ DPM (100% recycled polyethylene), 300 mm reinforced concrete slab power floated to form floor finish throughout ground floor. U-Value: 0.122W/m2K.

Walls: Stick-built on site twin-wall timber frame with 20 mm thick Siberian larch cladding (untreated & unfinished) externally, followed inside by 45 x 50 mm deep treated timber vertical battens forming drained and ventilated cavity, 100 mm thick Gutex Multitherm tongue and groove wood fibre insulation boards, 12 mm thick Spano Durelis Populair vapour diffuse racking board, 45 x 95 mm deep vertical timber studs with 100 mm compressed Gutex Thermoflex flexible wood fibre insulation in between, 60 mm continuous layer of Gutex Thermoflex flexible wood fibre insulation forming thermal break, 45 x 145 mm deep vertical timber studs with 160 mm compressed Gutex Thermoflex flexible wood fibre insulation between (9 mm thick plywood gussets holding two timber leafs together), 12 mm thick Spano Durelis Vapourblock airtight vapour control board, joints and all screw holes taped with Pro Clima Tescon Vana tape, 45 x 45 mm timber battens forming service cavity, and 12.5 mm plasterboard internally. Note: in double height areas construction matches above except for the inner stud is 245 mm deep and filled with 260 mm compressed insulation. Average U-values: 0.1 W/m2K for 145 mm stud walls & 0.086 W/m2K for 245 mm stud walls.

Roof: Flat roof with 1° fall finished with Bauder XF301 extensive sedum blanket on Bauder SDF drainage mat, followed beneath by Bauder Plant-E felt capping sheet, on Bauder KSA-Duo felt underlayer, on 120 mm Bauder PIR insulation, on 140 mm Bauder PIR FA-TE insulation, on Bauder DS1-Duo torch-applied vapour barrier, on 18 mm plywood, on min.

25 mm deep x 45 mm wide firring battens to create 1 degree fall fully filled with Knauf Eko Roll mineral wool insulation, on 18 mm plywood deck, on 300 mm deep JJI 300B+ I-Joists to form roof structure with static airspace between, on pro clima Intello Plus AVCL to ceiling, with 15 mm TE Wallboard plasterboard to form ceiling. U-Value: 0.072 W/m2K. Roof has fully insulated parapet to perimeter finished in matching felt Bauder waterproofing system.

Windows & external doors: Unilux triple glazed aluminium-clad thermally broken timber frame windows, with argon gas filling. Overall whole-window average U-Value for the project of 0.82 W/m2K.

Backup 2 kW post heater on MVHR system thermostatically controlled using Nest thermostat on first floor.

Hot Water: 4 m2 Solfex CPC 12 OEM evacuated tube solar thermal panels on ballasted frame on flat roof connected to 300 litre Gledhill solar hot water cylinder with back up 3 kW electric immersion heater.

Ventilation: Paul Novus 300 heat recovery ventilation system; certified efficiency in this dwelling of 91.2% (PHPP). Supply ducts insulated due to installation of post heater.

Water: Recoup Pipe +HE waste water heat recovery unit to master bedroom shower. 54% dynamic efficiency of system calculated in PHPP. Low flow fixtures and fittings throughout in accordance with section seven of the Scottish building standards technical handbook (sustainability water use efficiency). Sedum roof attenuates approximately 40 per cent of rainfall to roof with remainder carried to purpose-built raingarden with final discharge to burn on site.

Electricity: 9.9 m2 Solarworld solar photovoltaic array (6 x 250 W panels) on ballasted frame on flat roof with total installed capacity of 1.5 kW. Green materials: All timber from PEFC / FSC-certified sources, untreated timber cladding and decking, sedum roof covering for biodiversity & water saving, wood fibre insulation throughout all walls (including internal partitions), recycled damp proof membrane, Fermacell board throughout internal partitions and ground floor ceilings, Marloleum & reclaimed parquet flooring for upper floor coverings. Landscaping: recycled slate salvaged from neighbour’s build chipped on site for landscaping, stones from excavations on site utilised in landscaping, salvaged local sandstone from architect’s other projects used in landscaping to create rockery / feature borders, upcycled brick from previous veterinary surgery on site used upcycled to create gabion retaining wall and seating.

Green measures: Waste tightly controlled during construction: no soil / excavated material taken off site, no skips used for duration of build. All packaging recycled, all waste non-treated timber provided to family member for use as fuel. Design for future deconstruction.

Roof windows: Lamilux CI System Glass Element F Energysave triple glazed aluminiumclad thermally broken rooflights pre-installed to proprietary insulated upstands for flat roofs. Passive House Institute certified (phA component). One of the two units is Passive House Institute certified (the other, which provides roof access, is not). Average U-Value: 0.96 W/m2K. Space heating: Direct electric heating provided by 3 x 800 W and 1 x 500 W infrared heating panels, spread throughout ground floor, all thermostatically controlled using Salus controls.

ph+ | ostro passivhaus case study | 31

ANGLE HOUSE

CASE STUDY

P L AY I N G A L L THE ANGLES FABRIC-FIRST LONDON INFILL USES SMART DESIGN ON A TRICKY SITE

Angle House in north London is a wonderful example of sustainable urban housing: modest in scale and built on a run-down site in the heart of north London, it boasts a passive approach to energy efficiency and some beautiful design touches.

Words by David W Smith

32 | passivehouseplus.co.uk | issue 37

CASE STUDY

ANGLE HOUSE

ENERGY BILLS

£35

PER MONTH FOR ALL HEATING & ELECTRICITY (includes feed-in-tariff, see ‘In detail’ for more) Building: 110 m2 detached home and office Build method: Brick & clay block cavity wall with timber frame elements Site & location: Urban infill site, Tottenham, London Standard: Fabric-first low energy dwelling (no specific standard) Budget: £325,000 (build costs)

ph+ | angle house case study | 33

ANGLE HOUSE

CASE STUDY

The house was the winner of the dwelling prize at the 2020 New London Awards.

T

he award-winning Angle House is a low energy dwelling sandwiched between Victorian terraces on a previously neglected site in Tottenham. The two-bedroom home and office was co-designed by Italian architect Andrea Carbogno and his partner, French architect Sophia Ceneda.

Although the couple now live there contentedly, transforming the original run-down plot into a comfortable home took longer than expected and provoked much stress. Not only did the narrow site present design constraints, but there were long delays, and the build stretched the project out.

“There were times when it was one of the most stressful experiences I’ve ever had. We were so invested in it as our personal project. But now it is all over living in the house is great,” says Andrea. “The interiors are modern and it’s very functional. Everything is open space, and all the transition spaces are made use of, and are user-friendly. It’s big enough for large gatherings of family and friends, but not too big for two of us. We’ve designed it with lots of natural light and it’s tightly enclosed.

But there are views out to back gardens on one side and at the front there’s a little courtyard with greenery.”

Both Sophia and Andrea had always wanted to build their own home. In part this was to take advantage of their skills, but it was also for

34 | passivehouseplus.co.uk | issue 37

cultural reasons. “I’m French, but my family is all from Italy, where it’s a longstanding tradition to build your own house,” says Sophia.

“My grandfather built an incredible house in France and I always thought I’d build my own home. I just never thought it would be in Tottenham!”

Neither Andrea nor Sophia began their working lives as architects. Andrea studied accountancy in Italy, before leaving the picturesque Dolomites for London in 2000. For a couple of years, he worked in bars and restaurants. Then, in 2003, he enrolled at the School of Architecture at London Met, where Sophia was taking the same course. She had arrived in London with a background in geopolitical studies and worked for human rights groups.

But like Andrea, she found herself drawn to architecture, especially sustainable design.

Before striking out on his own, Andrea worked for a decade for a London firm designing high-end residential homes. Then in 2014, the couple founded Carbogno Ceneda Architects, in Tottenham. Sophia still works full time as architect and sustainability lead at Glenn Howells Architects, but helps Andrea with business development and some design.

Angle House was the first time they designed a house together.

The couple began to look for a site to develop eight years ago while they were living

in Sophia’s Tottenham flat. Her rule of thumb was that the combined cost of the land and the build should be “no higher than it would cost to purchase and refurbish a house in the same area”. Based on these parameters, they needed to find a bargain, but Tottenham was gentrifying fast and prices were escalating. The best site they could find for £100,000 was a section of the garden at the end of a row of terraces.

It required a lot of imagination to see beyond the debris. “It had been sold 14 years earlier to a man from Birmingham doing shop-front glass glazing. There was a massive prefab concrete structure wrapping around a caravan, where he slept when he came down to work.

There were lumps of concrete strewn on the floor,” says Andrea.

The site had a poor history in planning terms, and it became clear that it would be a challenge to get planning permission even for a modest two-storey structure. In 2013, the couple submitted a simple design that focused on massing, layout and orientation for outline planning permission. There was an agonising wait for planning, and once it was granted, the sale was rushed through.

Andrea and Sophia spent the next six months refining the original design in their spare time.

In general, there was a lot of harmony between their ideas, and few disagreements. However, Sophia insisted on a staircase in the middle

CASE STUDY

of the dwelling and Andrea refused to have any corridors. Sophia took charge of the sustainable elements. Having taken courses at the Centre for Alternative Technology (CAT) in Wales, she was cognisant of passive house principles.

Sophia opted for a zinc roof, although it was more expensive, and a smaller 20 square metre green roof at the back which is made of fibreglass and will eventually be covered in wildflowers. The couple opted for a hybrid construction, with a brick-and-clay block fullfill cavity wall on the ground floor, and on the first floor, a mix of this build-up plus timber frame wherever the footprint is set back from the ground floor wall. The house also achieved airtightness of 1.87 m3/m2/yr, though this was prior to completion, and it has not yet been retested.

All of these measures raised the energy performance to near the passive house standard.

“We aimed for passive house space heating at 15 kWh/m2/yr, and we ended up slightly above it at 27, which is 85 per cent less than a standard UK house,” Sophia says.

The tightness of the site demanded some ingenuity. The road is L-shaped, and the house lies at the short end. It’s the only home on that side fronting the street. Immediately to the left, there is a terraced house, and to the right, there is a row of houses. The planners wanted the couple to set the front of the house back from the road, but they saw this as being against urban design principles, and during a redesign they had to negotiate the extent of this setback.

“It’s like extending the street of terraced houses by adding a new unit at the end, however the unit is pushed back due to the triangulated shape of the site, because it’s too narrow at the front. We replicated the gable wall geometry of the end terrace to our street elevation, so there’s continuity to the sequence of angled

Photos: Agnese Sanvito ©

ANGLE HOUSE

roofs. Our house is subservient to the terrace which, as a design strategy, helps comply with planning guidelines,” says Andrea.

Most of the neighbours were excited when the two architects presented their plans. One of the neighbours said it was like watching an episode of Grand Designs right on their doorsteps. One woman whose garden overlooked the new house was a bit concerned about light.

“But when she checked the design on the planning portal, she could see how the green roof would be set back from the rear elevation so it wouldn’t block out the light. Her response was ‘it will be much nicer than overlooking a dump yard’.”

In June 2014, the couple submitted their revised plan and received approval 12 weeks later. However, work did not begin on the development until October 2015. The initial expectation was that the build would take between 12 and 18 months. In the event, it went on for two-and-a-half-years and the couple didn’t move in until June 2018. “It was another stressful period. As architects, you are in control until a certain point, then you hand over the execution and so many points of conflict can erupt,” says Sophia.

The main contractor for the structural works hired a team of builders based in Reading, over fifty miles from Tottenham. This restricted their time on site, and the truncated days meant the build dragged on. Sophia praises the contractor for executing the works well, “despite the builders being out of their comfort zone with a fabric first design like this”. There were also some delays due to a series of misunderstandings, such as when the builders assumed the ground floor slab was ground-bearing, when it was in fact suspended.

As planned another contractor was brought on to carry out the M&E works and internal finishes including the stunning staircase, but

ph+ | angle house case study | 35

ANGLE HOUSE

CASE STUDY

there were further delays. Sophia believes contractors in London often stretch themselves thin across multiple jobs, which can lead to delays. “These were the only times Andrea and I had arguments as we didn’t always have the same strategy for dealing with the contractors.

However, on the whole the works carried out was well executed.”

The couple finally moved their belongings across to Angle House in the summer of 2018.

After a few days sleeping on Sophia’s floor while the electricity supply was connected, they were finally able to sleep in their new 110 square metre home. The more spacious ground level is 75 square metres and would work as a self-contained one-bedroom flat. “An elderly couple could easily live downstairs as there’s a bedroom, bathroom and wheelchair access,” said Andrea. Upstairs there is a further 35 square metres of space, which is enough for a second bedroom with a bathroom and an office space that is separated from the stairs by timber slats. It could also be transformed into a third bedroom. “It’s not a large house, but it uses the space efficiently,” he says.

Sophia’s awareness of passive house principles paid dividends. Even when temperatures fell to zero in January this year, the couple only needed to switch the heating on for a couple of hours a day, and their annual bill for gas and electricity is a modest £400, excluding charges.

The couple very rarely use the bathroom radiator upstairs, or the portable electric radiator they bought for the office.

Though Sophia took the lead in developing the low energy aspects, Andrea is also passionate about sustainability. He recently took his exams as a passive house designer and intends to take his tutors’ advice to test the house using PHPP software against the Passive House Institute’s low energy building standard (a less onerous alternative to the classic passive house standard). “I’m hoping the course will

It’s possible to deliver low-energy buildings without relying overmuch on technology.

Ground floor (above left) and first floor (above right) plans for Angle house.

36 | passivehouseplus.co.uk | issue 37

CASE STUDY

ANGLE HOUSE

We’ve designed it with lots of natural light and it’s tightly enclosed.

set me up to expand the services we can offer.

I was drawn to passive house because it’s possible to deliver low energy buildings without relying overmuch on technology. But I’ve got a lot more detailed knowledge now,” he says.

The house was the winner of the dwelling prize at the 2020 New London Awards, and was shortlisted for small project of the year at the Building Awards last year too. The couple also achieved Sophia’s goal of not spending more than they would retrofitting a property. The overall cost was £425,000, including a £325,000 mortgage in addition to the £100,000 cost of the yard. In 2018 the house was valued at £650,000. “We’ve proved you can still do something really nice in London for under £500,000, and the house is a case study demonstrating our skills as sustainable designers too,” says Sophia.

WANT TO KNOW MORE? The digital version of this magazine includes access to exclusive galleries of architectural drawings. The digital magazine is available to subscribers on passivehouseplus.ie & passivehouseplus.co.uk

SELECTED PROJECT DETAILS Clients: Sophia Ceneda & Andrea Carbogno Architect: Carbogno Ceneda Structural engineer: engineersHRW MVHR (design & supply): Green Building Store Energy consultant: Fenton Energy Consultants Airtightness consultant: Alex Whitcroft Clay blocks: Porotherm Wall, roof & floor insulation: Knauf Thermal blocks: Marmox Airtightness products: Ecological Building Systems Windows & entrance doors: Internorm Roof windows: Abbey Glass Joinery: Thorsen Joinery Sustainable drainage systems: Aco Drain Finance: Ecology Building Society Gas boiler: Valliant Underfloor heating: Wavin Solar PV: Athena Electrical Lighting: Delta Lighting Heating controls: Heatmiser Lighting controls: Schneider Electric Water conserving fittings: Aston Matther Sanitaryware: Catalano Brick: Bespoke Brick Company Paints: Dulux

ph+ | angle house case study | 37

Specify responsibly

ANGLE HOUSE

CASE STUDY

Wraptite® Construction membranes may be hidden after the project is complete, but their role in ensuring proper heat, air and moisture movement through the building envelope and safeguarding the health of the building and occupants is essential.

Wraptite is a unique BBA-certified external airtightness solution for walls and roofs.

This membrane not only provides airtightness and vapour-permeability, its self-adhering installation method reduces programme length, installation costs and material waste.

Specify responsibly:

It’s what’s on the inside that counts.

01250 872261

38 | passivehouseplus.co.uk | issue 37

www.proctorgroup.com

CASE STUDY

ANGLE HOUSE

CONSTRUCTION IN PROGRESS

1

2

3

4

5

6

7

8

9

1 The run-down plot had an existing prefab structure and other debris which had to be disposed of; 2 Coredesk Cellcore Plus insulation was installed under the ground floor; 3 wall build-up showing 90 mm bricks externally, 200 mm Knauf Earthwool insulation, and 100 mm Porotherm clay blocks; 4 the use of low thermal conductivity Teplo-L-Wall ties minimises thermal bridging; 5 the first floor timber frame with an opening for a roof window; 6 insulated cavity closer; 7 175 mm Knauf Earthwool rafter roll within roof rafters; 8 & 9 airtightness measures including Intello membrane and taping around windows.

ph+ | angle house case study | 39

ANGLE HOUSE

CASE STUDY

Harris Academy Sutton Largest UK Passive House School Architect: Architype Main contractor: Willmott Dixon Air pressure test result: 0.30 AC/H @ 50 Pa Primary energy demand: 133 kWh/m2/year Photographs by Jack Hobhouse

Achieve your vision ...with our support For industry leading building products and expert advice, visit our new website

ecologicalbuildingsystems.com

40 | passivehouseplus.co.uk | issue 37

Brand used: Pro Clima

CASE STUDY

ANGLE HOUSE

IN DETAIL Building type: 110 m2 detached two-storey masonry & timber frame house.

Location: Tottenham, London.

Completion date: Summer 2018.

Budget: £325,000 excluding site, landscaping & joinery.

Passive house certification: Not assessed.

Space heating demand (Measured): 27 kWh/ m2/yr (Figure derived from actual gas bills from January 2019 to January 2020, considering boiler efficiency of 89.6 per cent and excluding estimated 10 KWh/m2 for domestic hot water).

Overheating: Less than 2 per cent of the time recorded with temperature above 25C. On very hot days, overheating is averted with the help of cross-ventilation.

Number of occupants: 2 Environmental assessment method: House designed to be aligned with Code for Sustainable Homes level four, passive house principles in terms of fabric efficiency and heating requirements, and Lifetime Homes criteria.

Airtightness (at 50 Pascals): 1.87 m3/m2/yr one year prior to completion on 15/08/2017 (note: as this result passed building regulations the airtightness was not re-assessed post completion).

Energy performance certificate (EPC): A 92 Measured energy consumption: 50 KWh/ m2/yr (5 Dec 2018 to 4 Dec 2019) based on actual energy bills for electricity and gas & considering boiler efficiency of 89.6 per cent (actual KWh/m2/yr usage as shown in bills is 54.3 KWh/m2/yr). Similar values were reported for previous year.

Energy bills (measured): Gas and electricity energy bills from January to December 2019 inclusive, totaled £578.80 (or £397.70 excluding VAT & standing charge). Subtracting the £150 solar PV feed-in-tariff gives an annual bill of approx. £429, or £35 per month. Based on the estimated space heating demand above,

USwitch.com suggests a cheapest available gas bill for space heating only at this address of £94 annually, before standing charges and VAT are added, and not including the feed-in-tariff (£195 total for space heating with charges).

membrane, 22 mm softwood sheathing boards, 50 mm ventilation gap with 50 mm x 50 mm purlins, 175 mm Knauf Earthwool rafter roll within rafters, 75 mm Knauf PIR laminate, 12.5 mm plasterboard to ceiling. U-value: 0.13 W/m2K

Thermal bridging: Use of low thermal conductivity Ancon Teplo-L-Ties wall ties, thermally broken window frames, Marmox thermal blocks. Y-value: 0.0776 calculation based on construction details and ACDs.

Flat green roof: Wildflower blanket externally, followed underneath by 100 mm growing medium, filter fleece, reservoir board, Ecomat, PE foil, waterproofing, 5 mm fiberglass, 18 mm PEFC marine ply, 160 mm Kingspan Styrozone insulation H350 R, 18 mm PEFC plywood, 50 x 200 mm deep timber joist. U-value: 0.13 W/m2K

Ground floor: Concrete pile foundations (2,000 mm), hardcore on existing clay soil, 50 mm sand blinding, followed above by 160 mm Cellcore Plus 7/10 insulation, damp proof membrane, 200 mm reinforced concrete slab, self-adhesive membrane by Visqueen (to guarantee against any DPM damage during construction), 200 mm thick Knauf Polyfoam Eco floorboard, 70 mm sand and cement screed with underfloor heating pipes, Ditra matting, 11 mm thick ceramic tiles on adhesive.

U-value: 0.13 W/m2K WALLS Ground floor (typical): 90 mm bricks externally, followed inside by Ancon basalt resin Teplo-L-Tie wall ties, 200 mm Knauf Earthwool DriTherm 32 slab insulation, 100 mm Porotherm clay blocks, 3 mm Porotherm Ecoparge, 2 x 12.5 mm plasterboards on dabs internally. U-value: 0.15 W/m2K First floor part masonry (as above) and part timber frame as follows, from outside in: 90 mm bricks externally, 30 mm airgap, Ancon basalt resin Teplo-L-Tie wall ties, 100 mm Knauf Earthwool DriTherm 34 slab insulation, Tyvek SUPRO breather membrane, 15 mm PEFC plywood Sheathing Board, 90 mm Knauf Earthwool FrameTherm 35 slab between 50 x 90 treated timber studs, pro clima Intello Plus airtight vapour control barrier and tape adhesive, 2 x 12.5 mm plasterboard internally.

Timber frame U-value: 0.16 W/m2K Note: Wherever electrical services were needed on an external wall, the wall build-up includes a 50 mm service cavity to prevent any puncture in external fabric.

Main roof: Standing seam zinc roof externally, followed underneath by weatherproof roof

Windows & external doors: Internorm triple glazed low emissivity, thermally broken, powder coated aluminium / timber windows and doors (to garden/courtyard). Internorm timber aluminium Passive House Institute certified entrance door (model HT400).

U-values of 0.5 to 0.67 W/m2K for windows; 0.58 W/m2K for entrance door.

Roof windows: Abbey Glass triple glazed low emissivity broken powder coated aluminium perimeter frames: U-value: 0.75 W/m2K & 1.0 W/m2K. Heating system: Vaillant ecoTEC pro28 condensing gas boiler supplying underfloor heating (GF) and hot water. Time and temperature zone controls with delayed start thermostat. Electric wall radiators for bathrooms installed but rarely used, provision for future radiator connections on first floor.

Ventilation: Paul Focus F200 heat recovery ventilation system. Passive House Institute certified heat recovery rate of 91 per cent / EN 308 certified efficiency of 93 to 95 per cent.

Water: Rainwater harvesting (for plant watering), low flow fixtures. Actual consumption pre-Covid-19 (Mar 19 to Mar 20) 80 litres per person/day (post Covid approx 95 litres/p/day).

Electricity: 8 m2 solar photovoltaic array (2.12 kW power) with average annual output of 1,988 KWh. Annual feed-in-tariff income £150.

Green materials: Timber frame (first floor), clay Porotherm blocks, PEFC certified plywood, Scottish larch (sarking, landscaping and fencing).

ph+ | angle house case study | 41

BARNA HOUSE

CASE STUDY

ENERGY BILLS

€18

PER MONTH FOR SPACE HEATING & COOLING ONLY (Estimated, see ‘In detail’ for more) Building: 246 m2 detached passive house Build method: Cavity wall Site & location: Barna village, Co Galway, Ireland Standard: Passive house classic certified, A1 & NZEB

42 | passivehouseplus.co.uk | issue 37

CASE STUDY

BARNA HOUSE

S P E C TAC U L A R V E R N AC U L A R CONNEMARA HOME FUSES MODERN, LOCAL-ROOTED DESIGN WITH LOW ENERGY EXCELLENCE

ph+ | barna house case study | 43

BARNA HOUSE

CASE STUDY

A new passive house on Galway Bay beautifully blends vernacular design with touches of Arts & Crafts while still appearing thoroughly contemporary, but under its neat exterior is the thinking of an architectural practice striving to reduce the environmental impact of its buildings, inspired by the Architects Declare pledge.

Words by Jason Walsh / Additional reporting by Lenny Antonelli

W

ith clients influenced by the Arts & Crafts movement and a demand to meet passive house standards, a new dwelling in the village of Barna, just west of Galway city, combines the contemporary with a west of Ireland vernacular.

Designed by Helena McElmeel Architects, Carraig Breac (meaning ‘speckled stone’) was motivated both by the clients’ desire to have a home that crossed the boundary from modern to finely-detailed traditional while making no compromises on energy efficiency.

A detached, two-storey house, completed in November 2019, the roughly L-shaped dwelling addresses the road with a strong angular facade. The north-facing elevation here means the relative absence of glazing on the front acts as much as a sound barrier as an energy-conservation measure.

‘It’s quite a busy road so the front elevation has to be sensitive to that, acting almost as a buffer,” says principal architect Helena McElmeel, who is also a certified passive house designer. However, as a result, the building’s real focus is to the sides with large windows on other elevations flooding the beautifully detailed interior with light.

The aesthetics, both inside and out, had specific points of reference: one international and one global.

“The main driver in this was to look at Arts & Crafts, particularly in the UK with things like the

44 | passivehouseplus.co.uk | issue 37

gable,” said McElmeel. “We had some freedom so that we could play with that gable. There’s also a celebration of the porch in the Arts & Crafts movements in both the UK and US, and we reflected that.”

Arts & Crafts was a design movement that developed in the late nineteenth and early twentieth centuries, and which advocated for traditional craftmanship and emphasised romantic or folk styles of decoration.

However, acknowledging the local vernacular was of course also a consideration from the planning stages, meaning that this architect-designed house pays homage to the forms and materials commonly used in the region.

“On the road from Galway west there are not that many new houses, newer pieces of architecture or architect-designed houses there, so there was an opportunity to do something that was contemporary but acknowledged the vernacular, like pitched roofs,” says McElmeel.

The end result is a house that, depending on how you look at it, or indeed from which angle, could be described as either striking or understated. This respect for local forms also dictated the material choices.

“We’re not going to put bricks on a house in Barna. We do try to work with a lot of render in this area, as a closer reference to the vernacular, [and] it has a natural slate roof.”

McElmeel said that even items that may not strike the viewer on first sight were subject to

There was a lot of detailing and, in order to get passive house certification, there was a lot of work.

CASE STUDY

BARNA HOUSE

similar considerations. For example, the discreet downpipes were a reference to styles common in Galway and Connemara.

Inside, timber and herringbone also hark back to Arts & Crafts, with regular rhythms and a staggered arrangement of markings also hinting at Frank Lloyd-Wright.

Niall Dolan, founder and director of contractor GreenTec, said the biggest challenge was meeting the demands of the passive house standard with a cavity wall design. “This one was very testing. There was a lot of detailing and, in order to get passive house certification, there was a lot of work,” he says.

As its name implies, GreenTec has a history of low energy construction, and Dolan says that given the popularity of blockwork with Irish buyers the key is good designing and planning.

“A lot of Irish people just like blockwork [but] the drawings were good, Helena had very good detail, as did the engineer, so while it was a difficult build that made it easier.”

Site conditions also posed issues for the construction process. “We had to pile the foundations just to get going,” he said. “It was a difficult site: rainwater was coming in from the road and there was water coming down from the hills.”

Nonetheless, as his tenth passive house, Dolan said GreenTec was ready for the challenge. Indeed, as GreenTec now moves into deep retrofits he expects to encounter new challenges. Dolan began to focus on low energy construction following the 2008 economic crash.

“In the last recession, I just got interested in training myself up; the company is 20 years old, and was rebranded about twelve years ago.

I was building my own house and went to a HomeBond course and they were talking about airtightness. I ended up going to Germany to look at construction methods.”

Since then Dolan has seen enormous

Photos: Kelvin Gillmor

ph+ | barna house case study | 45

BARNA HOUSE

CASE STUDY

The end result is a house that could be described as either striking or understated.

changes in the Irish construction sector, both in terms of regulation and customer demand. “Everyone now kind of has passive standard in their heads, but price is a factor. One in every four would come in with an architect and say they want passive and stick to it [whereas] two or three would scale back.”

On the whole the self-build market, he said, still largely avoids blockwork when it comes to passive house standard.

“A lot of self-builds go timber frame. They like the fully airtight package being handed over. The issue at the minute is that blocklayers are expensive and hard to get.”

For Helena McElmeel, the job is not over simply because the house has been completed.

A period of monitoring indoor air quality, temperature and energy use is now underway.

McElmeel has also signed-up to the global Architects Declare pledge, which states that the “twin crises of climate breakdown and biodiversity loss are the most serious issue of our time”, and that “for everyone working in the construction industry, meeting the needs of our society without breaching the earth’s ecological boundaries will demand a paradigm

46 | passivehouseplus.co.uk | issue 37

CASE STUDY

shift in our behaviour”. Architects who sign the pledge commit to a series of actions aimed at mitigating climate breakdown and biodiversity loss.

“Currently our team is working on a significant number of both residential and non-residential projects designed to the passive house standard, as we believe it is a robust methodology to ensure low carbon buildings from an operational perspective and quality assurance,” McElmeel says.

She has also found the performance metrics in the 2030 Climate Challenge from RIBA, the Royal Institute of British Architects, particularly useful for evaluating the environmental impact of her buildings.

“It would be excellent if the RIAI [Royal Institute of the Architects of Ireland] could produce a similar standard, defining ambitious, yet achievable carbon, health and wellbeing standards to ensure better building in Ireland over the next ten years,” she says.

Carraig Breac has been occupied for over a year now. McElmeel says the data so far shows the dwelling performing within the health metrics of the RIBA 2030 Climate Challenge, which advises indoor carbon dioxide levels of less than 900 parts per million, and indoor temperatures rising above 25 C for just one per cent of occupied hours.

McElmeel’s firm is also a partner practice for the BUS (building use studies) methodology. BUS is a standardised way of evaluating how satisfied occupants are with a building.

The occupants at Carraig Breac, who wished to remain private for the purpose of this article, indicated that they were highly satisfied with comfort levels in the house. They were also very satisfied with its perceived effect on their health, and with the building design overall.

In their survey comments, they described the house as very comfortable, hassle free and economical, with no draughts. They stated that all dwellings should ideally be passive. They did, however, question the extent of petrochemical-based insulation used in their new home.

“This is our present challenge as a practice, to better address the embodied and whole life carbon impact of our buildings,” McElmeel says. “To date, many of our low energy and passive buildings have relied too heavily on higher environmental impact, unsustainable buildings materials and processes. In keeping with our Architects Declare commitment, we are investing a lot of resource in training and educating ourselves in this area.”

Indeed, the firm has signed up to an Irish Green Building Council pledge to request environmental product declarations (EPDs) from suppliers, and to specify more materials with EPDs. EPDs are an independent way of declaring the environmental impact of construction materials across a range of parameters, including global warming potential, natural resource depletion, acidification and ozone depletion.

McElmeel says: “After we manage to reduce the whole life carbon of our buildings, the next challenge will be to go much further — to adopt more regenerative design principles to deliver spaces and buildings that go beyond net zero carbon, buildings that actually help to repair ecosystems and our environment.”

BARNA HOUSE

SELECTED PROJECT DETAILS Client: Private Architect: Helena McElmeel Architects Contractor: GreenTec Building Civil & structural engineer: S Hanniffy & Associates BER: 2eva.ie Passive house certification: Earth Cycle Technologies Building services contractor: Western Energy Systems Electrical contractor: F&H Electrical Wall & roof insulation: Kingspan Additional roof insulation: Isover Airtightness products: Partel Windows & doors: Internorm GGBS: Cannon Concrete Fit-out: Geraghty Joinery Flooring: Barefoot Flooring Heating & ventilation: Nilan Ireland Solar PV: Caldor Energy Solutions Lighting: Wink Lighting

WANT TO KNOW MORE? The digital version of this magazine includes access to exclusive galleries of architectural drawings. The digital magazine is available to subscribers on passivehouseplus.ie & passivehouseplus.co.uk

This is our challenge — to better address embodied and whole life carbon.

ph+ | barna house case study | 47

BARNA HOUSE

CASE STUDY

Harris Academy School Sutton, the first Passivhaus secondary in the UK. The 2020 winner of Education Estates’ Architect of the Year, CIBSE Project of the Year.

We have complete confidence in

Architype Awards: Education Estates’ Education Architect of the Year 2020

Ecomerchant to deliver a genuinely

CIBSE Building Performance Winner 2020

sustainable and low-lifecycle carbon

AJ100 Sustainable Practice of the Year 2015, 2016 and 2019

project.

Ben Humphries

By carefully selecting the products they

RIBA FRICS

supply, they ensure their whole range is

Director, Architype

ethical, natural and, importantly, healthy.

SUSTAINABLE BUILDING MATERIALS FROM FOUNDATION TO RIDGE

www.ecomerchant.co.uk info@ecomerchant.co.uk 01793 847 444

@pbs_icf 48 | passivehouseplus.co.uk | issue 37

CASE STUDY

BARNA HOUSE

CONSTRUCTION IN PROGRESS

1

2

3

4

5

6

7

8

9

10

11

12

1 The ground floor features reinforced concrete slab and ground beams on piled foundation; 2 Mannok Aircrete were used blocks on the first three courses of each cavity inner leaf to form a thermal break; 3 Armatherm thermal pads under steel columns to eliminate thermal bridging; 4 cantilvered ring beams for the corner window; 5 wraparound airtight detailing around the hollowcore concrete floor for the first floor, with taping around the end of steel beams; 6 Alma-T thermally broken door threshold; 7 construction of the roof underway; 8 Partel Izoperm Plus airtightness & vapour control membrane lapped & taped behind internal render at eaves; 9 Isover Metac insulation in ceiling void; 10 Tegral Torres natural slate & clips to pitched roof; 11 airtightness taping at windows; 12 ductwork for the Nilan Compact P ventilation and heating system, encased in the Gyproc CasoLine MF ceiling system.

ph+ | barna house case study | 49

BARNA HOUSE

CASE STUDY

50 | passivehouseplus.co.uk | issue 37

CASE STUDY

BARNA HOUSE

IN DETAIL Building type: Detached two-storey 246 m2 cavity wall house.

Location: Lacklea, Barna, Galway Completion date: November 2019 Budget: Private

Thermal bridging: Thermal bridges calculated to the specific construction details used in the house. First three courses of Mannok Aircrete blocks, thermally broken windows & doors, insulated window reveals, Armatherm thermal pads under steel columns, and Alma-T thermally broken thresholds. Y-value 0.01 W/mK (passive house calculation method / boundary conditions).

Passive house certification: Certified Space heating demand (PHPP): 14 kWh/m2/yr Heat load (state calculation tool, e.g., PHPP): 11 W/m2 Primary energy demand, non-renewable (PHPP): 69 kWh/m2/yr Primary energy renewable (PHPP): 38 kWh/m2/yr

Energy bills (estimate): Taking the cheapest per kWh tariff suggested by Bonkers. ie (12.97c), this property would have an estimated bill for space heating & cooling of €217 annually or €18 per month, inclusive of VAT, but exclusive of standing charges and Ireland’s PSO levy. These figures are based on final energy demand (delivered energy) figures from the PER sheet in PHPP. However, this cheaper per kWh price would also come with a standing charge of approximately €203 for the year, plus a PSO levy of €78, both exclusive of VAT.

Heat loss form factor (PHPP): 3.58 Overheating (PHPP): 9 per cent of year above 25 C Number of occupants: 3 Energy performance coefficient (EPC): 0.154 (< 0.30 = NZEB) Carbon performance coefficient (CPC): 0.145 (< 0.35 = NZEB) BER: A1 (23.11 kWh/m2/yr) Environmental assessment method: n/a Measured energy consumption: not available Airtightness: 0.6 ACH at 50 Pa

Ground floor: Selected floor finish on 75 mm thick liquid floor screed with underfloor heating pipes, followed beneath by polythene sheet, 170 mm Kingspan Thermafloor Insulation with 50 mm thick strip of the same insulation vertically around perimeter of external walls, radon barrier/DPM over reinforced concrete slab and ground beams on piled foundation to engineer’s specification. U-Value: 0.125 W/m²K Walls: 100 mm blockwork outer leaf with sand cement render to smooth float finish, followed inside by 200 mm cavity and 215 mm blockwork inner leaf. Proprietary cavity closers to window and door openings. 150 mm Kingspan Kooltherm K8 cavity wall insulation (0.020 W/mK) to cavity. 15 mm internal plaster render with gypsum hardwall finish. Mannok

Aircrete Seven thermal block to engineer’s specification to first three courses (two courses laid on edge) of each cavity inner leaf to form thermal break. U-Value: 0.124 W/m²K Roof: Tegral Torres natural slate & clips to pitched roof, on treated battens and counter battens, on Tyvek Supro breathable membrane fully sealed and taped with eaves strip protection, followed underneath by 225 x 75 mm rafters to engineer’s specification fully filled with 220 mm Kingspan K7 Insulation (0.020 W/ mK), Partel Izoperm Plus airtightness & vapour control membrane lapped & taped behind internal render at eaves, 150 mm void fully filled with Isover Metac insulation (0.034 W/mK).

12.5mm Gyproc CasoLine MF ceiling system & Gyproc skim coat finish. U Value: 0.081 W/m²K Windows: Internorm aluminium clad Studio HF410 passive house certified windows. Triple glazed with argon filling. Overall U-Value: 0.80 W/m²K. Heating system & ventilation: Nilan Compact P XL (430 m3/hr) unit which combines heat recovery ventilation along with air heating & summer air cooling through balanced ventilation ductwork. Passive House Institute certified. Effective heat recovery efficiency: 80% (PHI). The Compact P is backed up with a Nilan air-to-water heat pump (Air9) which provides weather compensated hot water to zoned underfloor heating circuits. Seasonal coefficient of performance for Compact P and Air9 (variable speed compressor output power) 511%, Ecodesign A+++.

Electricity: 8 x solar PV panels (260 W each with an estimated yearly contribution of 1,787.14 kWh/yr) with inverter and battery.

Green materials: 50 per cent GGBS cement.

ph+ | barna house case study | 51

COLLEGE VIEW

CASE STUDY

ENERGY BILLS

€25.50

PER MONTH FOR SPACE HEATING & HOT WATER ONLY (Estimate, see ‘In detail’ for more) Project: Deep retrofit of 12 x 38 m2 one-bedroom bungalows Build method: External insulation to solid walls Site & location: Wexford town, Co Wexford, Ireland Standard: NZEB – A2 & A3 rated (building energy ratings) Budget: €368,000 including fees & VAT

SENIOR COLLEGE DEEP RETROFIT TRANSFORMS WEXFORD SHELTERED HOUSING

The extensive energy and ventilation upgrade of 12 run-down bungalows at College View sheltered housing scheme in Wexford town not only transformed the lives and comfort of residents, but an extensive period of post-occupancy study has yielded important lessons for future projects.

Words by John Hearne

I

t’s now three years since Wexford County Council completed the retrofit of 12 one-bed social housing units off South Davitt Road in Wexford town. At the time, it was only the second development to be grant-funded under the Sustainable Energy Authority of Ireland’s 2017 deep retrofit pilot scheme.

The development has transformed the thermal comfort of the houses, and in at least one case, the improvement in indoor air quality has had a substantial positive impact on the health of the occupant. What’s more, the experience of the tenants provides some salutary and compelling lessons for anyone contemplating a retrofit of this nature. The performance of the units has

52 | passivehouseplus.co.uk | issue 37

been monitored over the last three years by a team led by Dr Shane Colclough in University College Dublin (UCD), and research drawn from those results makes for fascinating reading.

First, the development itself. Before building work commenced in September 2017, College View would not have featured among the county council’s most desirable properties. From the front, the terrace presented a neat if uninspiring row of 1970s single-storey dwellings. Inside however, there were a number of problems.

Colm O’Mahony is an energy engineer with the Three Counties Energy Agency (3CEA), which partnered with the local authority on the project. He explains that the buildings lacked in-

sulation and were very difficult to heat, with energy ratings for all units ranging between F and G. The building fabric in many of the houses had deteriorated, and extensive damp and mould issues testified to the prevalence of thermal bridging at key junctions.

There was a mix of heating systems, you had old oil boilers and open fires as well as storage heaters,” says O’Mahony. “They were cold, draughty and just not comfortable to live in. On top of that you had very poor indoor air quality and a very poor aesthetic.”

Michael Doyle of Wexford County Council adds that in addition to the mix of heating types, different tenants used their heating in different

CASE STUDY

College View resident Peter Fay

ways. “Some had prepay power, some hadn’t.

One tenant had an oil boiler but hadn’t put oil in it for years. And there were huge damp issues, and subsidence in the floor in one unit.”

Tenants at College View are mostly older, and some have learning or other disabilities. It was critical, from the council’s point of view, that all were consulted with, and that they understood how the project would affect them. This was deep retrofit; staying in their homes during the works was not considered an option. Moreover, the changes envisaged by the design team would transform the homes they had lived in for many years, both functionally and aesthetically.

Michael Doyle explains that he went to each tenant in turn, sat down with them and talked them through the retrofit and how it would affect them. In some cases, he arranged to have a social worker present to make sure that the tenant fully understood the impact of the project. The hotchpotch of existing heating systems were to be replaced with 4 kW Daikin air-to-water heat pumps. Due to space restrictions, these had to go in the living rooms.

“I explained the pros and cons,” says Doyle.

“We talked through how they were heating their homes, and what it was costing them. They were buying X bags of coal in the week, or X bales of briquettes. With the storage heaters it was electricity. I went through those bills and explained how much the new systems would save them over time. The only downside was that we had to put a unit the size and shape of a fridge freezer in the sitting room, and that it was going to be obtrusive.”

The use of the Daikin unit meant that in addition to providing tenants with cheap space heating, electric showers and immersion heaters could also be dispensed with; the heat pump and fitted tank would provide them with constant hot water.

The county council held workshops in collaboration with 3CEA where all of the planned work was discussed with tenants. The fabric first approach was explained, as was the necessity of window and door upgrades, layout changes and the expected improvement of the air quality in their refurbished homes. Colm O’Mahony says old habits die hard, and some tenants were reluctant to give up heating systems that they had relied upon for years.

“People are used to their oil, their coal or gas boiler, and tend to be a bit set in their ways, but we had done projects in Wexford before, so we had case studies from people of a similar age who’d had heat pumps installed, and those helped a lot.

These houses – small at 31 m2 – looked identical from the outside, but once the work began, it became clear that each needed individual attention. In addition to the mix of heating types, some houses had faulty pipework, blocked vents, damaged roofs and damaged guttering.

One in particular had a very significant mould problem.

External wall insulation became the central strategy for dealing with the thermal bridge issue. Wall cavities were insulated too. Pitched roof insulation was beefed up, but the design team decided that ripping up the existing solid floor would add too much disruption and cost, so that remained as before.

Prior to the refurbishment, ventilation came courtesy of opened windows, chimneys and cracks in the wall. These were replaced with a demand-controlled ventilation system. All of the ductwork in unheated spaces was insulated to prevent heat loss and mitigate the risk of condensation. There were also measures taken to avoid fan or duct-borne noise.

Airtightness is always the big challenge on

COLLEGE VIEW

projects like this, and Colm O’Mahony credits the contractors for achieving an average airtightness rate of 4.77 m3/hr/m2, just below the threshold of 5 that is deemed “advanced” airtightness under the NSAI’s code of practice for retrofit, SR 54.

Though there were no extensions involved in the work, some additional non-energy works were necessary, such as improvements in back gardens, the removal of oil tanks, access works and the kind of general maintenance and improvement work that old buildings require.

The development has been very successful on a number of fronts. First and foremost, the tenants report high satisfaction levels.

“It’s fabulous,” says resident Peter Fay, who is now in his second winter in the refurbished house. In particular he loves the air quality and the fabric improvements. “Number one is the triple glazing. When I was growing up, we were lucky to have one pane of glass in the window, plus the fact that it’s completely insulated from head to toe. So, it’s very warm. I only use the heating in the morning to get the chill out.”

Michael Doyle in Wexford County Council zeroes in on one resident who had been living in the house with the worst damp issues. He had been suffering from respiratory problems for years. “There’s no easy way of saying this but the mould and the fungus and the damp feeling in the house was terrible.”

Six months after the tenant moved in, Michael went back to see him again. “He told me that there wasn’t a bit of mould anywhere in the house. He said that he would normally be on his third or fourth course of antibiotics but that winter, he hadn’t been to the doctor once. He was convinced that that was all down to the warmth and the indoor air quality.”

Though the local authority has no intention of selling the houses, they commissioned a valuation from local auctioneer Dolores Power, who estimated that the retrofit – which cost €25,000 per unit – had delivered a €35,000 increase in price. This may not all be down to assumptions about increased comfort and lower energy costs,

ph+ | college view case study | 53

COLLEGE VIEW

CASE STUDY

of course. One of the benefits of external wall insulation is the fact that it gives old buildings a facelift. Add in the new windows and PV panels on the roofs and the houses look like new builds.

‘High satisfaction ratings’ A research paper, co-authored by Shane Colclough of UCD as part of the NZEB 101 project, has looked at key indicators for the development including indoor environmental quality, energy consumption and occupant satisfaction levels, in the context of the requirement that all new dwellings constructed in the EU meet the nearly zero energy building standard (NZEB). At College View, ten of the 12 dwellings meet the NZEB energy and carbon targets, even though as retrofits they weren’t required to under the building regulations.

Eight of the twelve residents participated in an occupant satisfaction survey conducted as part of the research, using what many regard as the gold standard in post occupancy evaluation, the building use studies (BUS) methodology. This recorded high satisfaction levels in relation to the locality, the overall functional performance and appearance of the houses. Satisfaction with the size and layout of the rooms was patchier; the small kitchen was a particular bugbear. Thermal comfort, by contrast, scored much more highly.

The report says: “Overall, the winter indoor environmental quality is perceived as being of a high standard, with four of the occupants giving the highest rating for satisfaction, one giving the second-highest, and two giving the third highest rating.”

Occupant satisfaction levels are even higher in summer, with six of the seven occupants giving the highest score and one giving the third highest. Six of the seven scored maximum points for overall comfort.

The data recorded by the post occupancy monitoring indicates what the occupant feedback on thermal comfort translates to in actual energy use. For all but two of the dwellings, living room temperatures were above 20 C for 75 per cent of the time. The warmest dwelling had median temperatures of between 23.4 C and 25.2 C across the four seasons. The coolest dwelling had median winter and spring temperatures of 15.2 C and 18.8 C respectively. However, even in these outlying dwellings, the occupants report high levels of thermal comfort, indicating that the buildings are performing as the occupants require. Meanwhile, carbon dioxide levels in all living and bedrooms (except one) are below 1,000 parts per million for more than 75 per cent

54 | passivehouseplus.co.uk | issue 37

of the time, indicating the ventilation system is maintaining a healthy indoor environment.

But in all units, the energy use predicted by the DEAP software is wildly out of line with real world consumption. That excess runs from a low of 29 per cent to a high of no less than 138 per cent. After the retrofit, these twelve buildings were all assigned A2 and A3 building energy ratings, but the actual energy use implies poorer performance.

The report says of their ‘real world’ energy ratings: “The BER [building energy rating] band is “A” in three cases of the eight studied, with one dwelling consuming energy equivalent to a C1 BER, and the remaining four operating within the B1 band.’

Why is this the case? It would appear to stem from the assumptions DEAP makes about occupancy. The software assumes that the living room is heated to 21 C for two periods during the day, 7am to 9am and 5pm to 11pm, and that the rest of the dwelling is heated to 18 C for the same periods. The reality of course is that these houses are occupied almost all of the time, and by people for whom thermal comfort requires higher temperatures.

The report puts it like this: ‘It was found that the temperatures were significantly different from those expected during the heating periods, and that the temperatures remained high outside of the heating period. This is a significant finding and reflects high levels of occupancy during the day and a desire for continuous heating, even during the period 11pm to 7am.”

The fact that the DEAP software is configured for a standardised occupancy profile is clearly a problem. It cannot distinguish between an occupant who is out at work all day and one who spends most of their day in the house, and who has higher thermal requirements. Moreover, since the pandemic, we are all spending more time in our houses, and it seems likely that home working is going to become the norm for a lot more people. Clearly, we are left with two options: either our building rating tools need greater flexibility if we are expecting them to reflect different occupancy patterns, or we have to accept that the approach of one-size-fits-all ratings may be of limited value.

The post-occupancy evaluation of College View was undertaken by the NZEB101 project, which is supported by SEAI and is monitoring the real-world performance of 101 domestic and non-domestic NZEB buildings.

(above) Daikin heat pumps and Weatherglaze triple-glazed windows were installed at the dwellings.

Why is energy use higher than predicted? These houses are occupied almost all of the time, by people who require higher temperatures.

See www.nzeb101.ie for more.

Photos: Patrick Browne / Browne’s Photography

CASE STUDY

COLLEGE VIEW

CONSTRUCTION IN PROGRESS

1

2

3

4

5

6

7

8

9

1 College View prior to the deep retrofit; 2 & 3 the development had a mix of different heating types prior to retrofit, including oil boilers and storage heaters; 4 the dwellings had no ventilation prior to retrofit besides windows, chimneys and some hole-in-the-wall vents; 5 the walls were insulated externally using an Enewall external insulation system with 100 mm of platinum EPS insulation; 6 the external insulation starter track at DPC level; 7 a verge trim caps the external insulation system at gable ends, where it protrudes beyond the roof line; 8 & 9 the walls were finished with external render system.

ph+ | college view case study | 55

COLLEGE VIEW

CASE STUDY

WANT TO KNOW MORE? The digital version of this magazine includes access to exclusive galleries of architectural drawings. The digital magazine is available to subscribers on passivehouseplus.ie & passivehouseplus.co.uk

SELECTED PROJECT DETAILS Client: Wexford County Council Energy consultant: 3CEA Project management: 3CEA Main contractor: DCI Energy Efficient Solutions Post occupancy evaluation: University College Dublin Airtightness consultant: Jeff O’Toole External insulation system: Pw Thermal Building Solutions Ltd Roof insulation: Isover Windows & doors: Weatherglaze Energy credits: LCC Group Heat pump: Daikin Demand controlled ventilation: Aldes Solar PV: ACTIV8 Solar Energies

When I was growing up, we were lucky to have one pane of glass in the window.

College View resident Peter Fay in his retrofitted home.

80

1200 Temperature (ºC)

70

Humidity (%)

CO2 (ppm) 1000

60 800 50

40

600

30 400 20 200 10

5 Nov 2019

22 Nov 2019

15 Dec 2019

15 Jan 2020

(above) An anomaly in the data: while the homes at College View generally showed high temperatures in line with the comfort requirements of their elderly occupants, one house went to the opposite extreme. While in part this can be explained by occupant behaviour – some people have ingrained habits of underheating homes – another major factor seems to be apparent in the CO2 data, which dropped significantly for prolonged periods, indicating substantially reduced occupancy.

56 | passivehouseplus.co.uk | issue 37

CASE STUDY

COLLEGE VIEW

Estimated and recorded space heating and hot water primary energy consumption {kWh}

9000

8047.48

8000 7000 6000

5879.496 5295.30928

5000 4000

3416.39

3745.26

5555.5464 4781.11664 3330.99

4483.6704 3416.39

5580.61664 4641.5216

4301.23 3380.22

3097.68

3000

3055.19

2000

Recorded

1000 0

nZEB22

nZEB23

nZEB24

nZEB25

nZEB26

nZEB27

nZEB30

nZEB33

DEAP (calculated)

Estimated and recorded primary energy consumption for regulated loads (space heating, hot water, ventilation, lighting, pumps and fans) in eight of the dwellings. Note that these figures exclude the calculated contribution from solar PV.

ph+ | college view case study | 57

CPD Cert in Building Energy Modelling Using PHPP COLLEGE VIEW

CASE STUDY

April 30th 2021

100 hours online learning 6 week course PHI points Only £870 / €980 APPLY NOW AT WWW.AECB.NET

58 | passivehouseplus.co.uk | issue 37

CASE STUDY

COLLEGE VIEW

IN DETAIL Building type: 12 x 38 m2 one-bedroom bungalows, solid wall construction, constructed in the 1970s.

Location: Wexford Town, County Wexford Budget: €368,000 including fees & VAT Completion date: February 2018 ENERGY RATINGS

Before: All units F & G rated (ranges from 403 to 1,158 kWh/m2/yr) After: All 12 units A2 or A3 (ranges from 25.14 to 65.2 kWh/m2/y, average of 43.45 kWh/m2/yr) Carbon performance co-efficient (CPC): Ranges from 0.054 to 0.38. Only two dwellings are outside the NZEB target of 0.35.

Energy performance co-efficient (EPC): Ranges from 0.056 to 0.27 – averaging.

All are inside the NZEB target for new homes of 0.3.

Measured energy consumption (eight of the twelve dwellings): Measured primary energy consumption ranges from 51 kWh/ m2/yr to 167 kWh/m2/yr, with an average of 85.4 kWh/m2/yr (figure includes space heating, hot water, ventilation, and fixed lighting). This compares to a predicted average primary energy demand in DEAP of 38.38 kWh/m2/yr.

ENERGY BILLS

Before: Three tenants gave figures for the cost of running their primary heating system pre-retrofit, and these averaged €1,416.

Based on the BER predictions and the cost of coal and electricity, the projected cost in the dwellings pre-retrofit was €1,361.

After: As part of the NZEB101 project Loop CT meters were installed to monitor heat pump energy consumption, while immersion consumption was monitored too. The average combined figure across eight dwellings for

space heating & hot water consumption was 2,360 kWh. The lowest available tariff available on Bonkers.ie indicates this will cost €306 per year, or €25.50 per month (at 12.97c per kWh including VAT). This ranges from €241 €463/yr for the homes which used least and most heat energy, respectively. These figures assume no contribution from the PV arrays – each of which is calculated to generate 2,950 kWh/yr of electricity which serve household needs – with no battery storage – and provide excess back into the grid. In reality, even in the absence of battery storage this is likely to significantly further reduce the heating and overall energy use, given the occupancy profile at College View – the energy use and indoor environmental quality data suggests homes that are being used and heated throughout the day, all year around – meaning the occupants may be making above average use of PV energy.

Number of occupants: 1 per dwelling AIRTIGHTNESS (AT 50 PASCALS)

Before: 6.623 m3/hr/m2 After: 4.769 m3/hr/m2 GROUND FLOOR

Before: Uninsulated solid floor construction, no insulation. U-value: 0.83 kWh/m2/yr After: Same as pre-retrofit – floor not upgraded during retrofit works.

WALLS

Before: 300 mm cavity wall construction. No insulation. U-value: 1.95 kWh/m2/yr After: 100 mm of Kingspan Aerowall Platinum external insulation, thermal conductivity 0.030 W/mK, with a finished external render.

While some dwellings were of solid wall construction any wall cavities were pumped with bonded bead insulation. Average U-value: 0.27 kWh/m2/yr ROOF

Before: Pitched roof (cold roof construction) with roof tiles followed underneath by

felt, timber rafters, 0 mm-200 mm Isover insulation between existing ceiling joists.

Plasterboard and skim coat finished ceilings.

Average U-value: 0.84 kWh/m2/yr After: 400 mm Isover Metac Insulation installed (200 mm between ceiling joists, with 200 mm over ceiling joists), thermal conductivity 0.044 W/mK. Insulated and draught sealed attic hatches, including attic closers/latches, to ensure an airtight seal.

U-value: 0.13 kWh/m2/yr WINDOWS

Before: Double glazed, PVC, air filled, 12 mm gap. U-value: 2.8 kWh/m2/yr After: Weatherglaze A-rated triple glazed windows (low e). Whole-window U-value: 0.80 kWh/m2/yr HEATING SYSTEM

Before: Mix of storage heaters & oil boilers 20+ years old, 65-80 per cent efficient (HARP database). Open fire back boiler (30 per cent efficient).

After: Daikin 4 kW air-to-water heat pump & 180 litre buffer tank. Space heating efficiency 530%. HW eff 213 per cent. Fully Integrated controls. 2kW immersion heater to each dwelling too. Electric showers replaced with Thermos units to reduce DHW consumption.

VENTILATION

Before: Openable windows, in addition to the air entering through the existing chimney and also infiltration through gaps, cracks etc.

After: Aldes demand-controlled ventilation systems – humidity-controlled whole house extract ventilation. SFP 0.29 W/m2. Humidity sensors and controls upgrade. All ductwork in unheated spaces insulated to prevent heat loss and the occurrence of condensation in the ductwork. Adequate measures implemented to avoid fan or duct borne noise or noise transfer.

Renewables (after): 11.6 m2 solar photovoltaic array per dwelling, (6x 285 W Suntech STP 285S panels).

ph+ | college view case study | 59

RETROFIT TRAINING

INSIGHT

R U N AWAY T R AI N IRELAND’S DEEP RETROFIT UPSKILLING DRIVE GATHERS STEAM

Following its commitment to retrofit one quarter of dwellings in the country by 2030, the Irish government has now announced the establishment of four new centres of excellence for retrofit training, building on the training approach developed to help the industry meet the NZEB standard for new buildings. Workers from state-owned company Bord na Móna are among the first to undergo training as the company transitions out of peat extraction.

Words by Jason Walsh

above Bord na Mona workers undergo retrofit training at Mount Lucas national construction training centre in County Laois.

A

s energy efficiency has become the norm in Irish construction, first through one-off homes built by the interested few, and then through regulatory change, the overall quality of the country’s building stock has, naturally, improved. What has remained is the challenge of the existing stock.

Recognising this, the Irish coalition government set a target of 500,000 retrofits to at least a B2 energy rating by 2030 as part of the programme for government it agreed last summer. To deliver that, large numbers of workers will need to be trained to deliver high quality retrofits that genuinely cut energy use while safeguarding the structure of buildings and improving indoor air quality.

Deep retrofit is a complex process that

60 | passivehouseplus.co.uk | issue 37

involves understanding the physics of how heat and moisture interact with the structure of buildings. Done poorly, for instance without proper attention to ventilation, it can even exacerbate condensation and dampness. But done well, it can transform the comfort and health of occupants.

In December, Simon Harris, minister for further and higher education, announced the establishment of four new retrofitting centres of excellence in Ireland, as part of a drive to train workers in the skills needed to deliver these retrofits. The centres will be at based at four education and training boards (ETBs) across the country: Limerick & Clare, Sligo, Laois & Offaly, and Cork.

Speaking at the time, Harris said: “Today, I am announcing we will establish four cen-

tres of excellence – four centres to train 2,000 people in retrofit skills, including near zero energy buildings (NZEB) skills. So, if you are a worker in the construction area and you want to upskill in the area of green skills, then this could be for you.”

As per EU rules, Ireland’s version of the NZEB standard came in time for the 2020 deadline for new buildings, requiring higher standards of energy efficiency in Part L of the building regulations, and a shift towards mechanical ventilation in Part F. The four new centres come in addition to the pioneering work undertaken at the Waterford and Wexford Education and Training Board (WWETB) to establish training courses in NZEB at its Enniscorthy training centre, including a new course in the design, installation and commis-

INSIGHT

RETROFIT TRAINING

above The sample house at WWETB’s NZEB training centre in Enniscorthy, Co Wexford. sioning of ventilation systems to Part F of the building regulations. Expanding this type of ventilation training nationwide will be critical to ensuring that the coming retrofit rollout is done to a high standard.

The good news is that the retraining of workers won’t just create jobs, it will create well-paid, high-skill jobs rooted in building physics, meaning a focus on both careers and climate action, through hands-on training.

The truth is, though, that in order to meet its targets, Ireland will need to create an industry almost out of thin air. Harris acknowledged this in December when he said: “The government has set ambitious targets to retrofit 500,000 homes by 2030 but we need to ensure we have the workers to deliver it.”

Unfortunately, and perhaps unsurprisingly given the pandemic and attendant lockdown, 2020 was not a great year for retrofit in Ireland. Sustainable Energy Authority of Ireland (SEAI) figures show the retrofitting programme output fell by 31 per cent in 2020.

While 2019 saw 24,700 retrofits, this fell to 16,955 in 2020. Of those, only 196 were deep retrofits; a small number, but at least progress on 2019’s figure of 112 and an indicator, however faint, of movement in the right direction.

The big picture WWTEB is not just a national hub for low energy building in Ireland, it is now an international one too. Along with New York, Pittsburgh, Brussels and Vancouver, Wexford is also now a centre of excellence as part of the United Nations Economic Commission for Europe’s high performance buildings initiative (despite its name, UNECE also includes North America).

Scott Foster, who heads the sustainable

energy division at UNECE, believes that retrofitting buildings to a high standard also means helping to solve several fundamental problems abroad in society today. “It’s not only climate; it’s jobs, it’s comfort, it’s quality of life, it’s reducing poverty,” he says.

“You need a lot of people to do all this work, and you’re not giving money to some centralised organisation. You’re putting money into the hand of the local guy, as well as the local economy.”

The logic behind establishing international centres of excellence like Wexford is to have local centres of training, local examples of best practice, and local leaders who can spread the word about deep retrofit. Pitched correctly, which is to say not as a wagging finger, a mobilisation of retrofitting could have near-universal appeal, Foster says. “This [is the kind of thing that] works under a Biden administration and it works under a Trump administration, and you can’t say that about a lot of initiatives.”

Leading passive house expert Tomas O’Leary of MosArt Architects and Passive House Academy — and the self-builder of Ireland’s first passive house, built in 2004 — has helped WWETB to develop its NZEB trainings programmes, and the national skills specification it created for NZEB new builds and retrofits.

“New-build is sorted now: the standard is good in terms of insulation, for example.

But 40 per cent of carbon emissions globally are from building, and most of that is from existing building stock,” O’Leary says.

O’Leary points to the evidence before our eyes: almost everyone in Ireland knows what it is like to live in a house that is difficult to heat, and many live with mould and high energy

bills, even in dwellings built in recent decades.

“With the benefit of hindsight we know they weren’t built correctly,” he says.

But O’Leary says if we rush the retrofit process we risk doing a subpar job. Instead, every retrofit should be a carefully executed, full and deep retrofit.

“As we embark on retrofitting we have a choice: do you want to do quality or quantity?

My fear is we have to come back in 30 years’ time and do it again. A deep retrofit is disruptive and people are going to be discommoded [so] they won’t want to go through that trauma again.”

above Retrofit enthusiast Scott Foster, head of the sustainable energy division at the United Nations Economic Commission for Europe.

ph+ | retrofit training insight | 61

RETROFIT TRAINING

INSIGHT

MO R E TH AN JU ST TU RF

O

ne major business that has taken notice of the changed environment is Irish semi-state company Bord na Móna, which until recent times developed and extracted large quantities of peat from bogs in the Irish midlands for power stations, domestic fuel and other products.

The company ended peat harvesting operations last year as part of its ‘brown to green’ strategy. In truth, this move has been on the cards for some time.

In July 2019, unions estimated 800 turf jobs would be lost at the company, while in October 2019 then minister for communications, climate action and the environment Richard Bruton told RTÉ there would be a “package of measures that will look at supports for workers”.

If this was to mean more than redundancy payouts, then how it was to be done if Bord na Móna was to become, in the words of its chief executive Tom Donnellan, a “climate solutions company”, was less clear.

A year and a half later some clues have begun to emerge. Although it was already working alongside the Department of Climate Action, SEAI and Irish Rural Link (IRL) to inform people about deep retrofitting, the company has now taken a step further by offering training in retrofit to outgoing staff, in association with Laois and Offaly Education and Training Board, which will become one of the new retrofit centres of excellence.

Thomas Fox has spent thirteen years with Bord na Móna, where he currently works as community liaison. Having left his position working in peat, Fox took a deep retrofitting course offered to Bord na Móna workers.

“We knew it was going to happen at some stage, but maybe it’s a bit sooner than we expected. I’ve been the community liaison for a year and a half; I’m out explaining what’s happening on the ground,” he says.

A plumber by trade, Fox joined Bord na Móna in the wake of the 2008 economic crash. Now, he says, new opportunities are presenting themselves.

“The climate change agenda has given rise to new career paths. There were 24 of us at the first stage in Mount Lucas [National Construction Training Centre]. There would have been a lot of people with a construction background working on the bogs in Bord na Móna so for someone who has taken redundancy it’s a fantastic opportunity.”

The practical nature of the training served to underscore its utility value for those looking to change careers, he says. “It’s a fantastic course, [trainers] MosArt were fantastic. It was physical and on-site, you can see what you’re doing.”

Ciaran Butler, learning and development specialist at Bord na Móna, says the training is designed to give people choices, and made sense for a changing Bord na Móna.

“It’s just an option for them. It’s all about

62 | passivehouseplus.co.uk | issue 37

reskilling and upskilling all workers affected by decarbonisation. Retrofitting aligned with government strategy and we’ve been upskilling a lot of people who are exiting.”

Butler signed up for the course himself, and echoes Fox in praising the way the course mixes the theoretical with the practical.

“I went through the course myself, I wouldn’t send somebody through a course without assessing it. I feel like I learned a lot through it, in terms of building physics, NZEB, new requirements in the building industry and so on.”

That includes working on typical building styles workers are likely to encounter on the job. “They build mock houses based on Midlands housing stock, so if one of our workers went out they’d know exactly what they were seeing. It really is theory and practice,” he says.

The instructors seem equally pleased.

“We’ve been delivering training in China; we’re very active in America; to be standing there with these Bord Na Móna workers is amazing,” says Tomas O’Leary.

“We’ve a bit of education to do… we need to do more to educate people that this is not a low tech, low paid job. On a personal level, delivering these courses is one of the most satisfying things I’ve ever done.”

The NZEB retrofit training programme had its genesis not in the Midlands, but at WWETB, where innovation and development manager Michael O’Brien — himself a physicist — says that necessity was the mother of invention.

“We knew nothing about this stuff until we started attending conferences in 2017; we’re very involved in training apprentices and I could see straight off that there was a need

above Retrofit training rigs at the Mount Lucas national construction training centre.

INSIGHT

RETROFIT TRAINING

for training and in particular for upskilling in the trades.

“We set about seeking a training programme, as we normally would, only to very quickly realise there was nothing. And in fact there were no learning outcomes or skills specifications.”

Supported by further education agency Solas, WWTEB set about changing this by developing skills specifications and building a training centre in Enniscorthy. It then began delivering courses at the end of November 2018, initially aimed at five trades as well as site supervisors.

Since then the cohort attending has expanded greatly, in spite of Covid. New courses have been developed, including one that aims to meet a new requirement in the Irish building regulations for competent persons to design, install and commission ventilation systems. Training is offered to anyone involved in building.

O’Brien says that this is because there is more to a building than building.

“We felt it was really important that people like auctioneers, people working in sales at building suppliers, and people working on a building site, at any level, understand NZEB and Part L,” he says. “We’ve gone from something that was non-existent to having about ten [training] programmes.”

Beyond individuals moving into the construction sector as retrofit specialists, there is also the possibility of Bord na Móna moving wholesale into retrofit now.

Certainly, this would both align with government strategy and meet Tom Donnellan’s stated green aims for the business. In order for it to happen, though, government policy will have to support it. If it does, local authority housing could start to be transformed, particularly in the Irish Midlands, which has some of Ireland’s highest levels of rural deprivation.

“Yes, we’re looking at the viability of Bord na Móna getting into retrofitting with local government partnerships. There’s been discussion of that at government level but it’s only discussion so far. There’s a lot of work to be done before it’s something that Bord na Móna would look at as a major project,” says Butler.

If it does happen, though, it could help to address the biggest issue facing the sector and homeowners: a lack of scale.

“One of the problems with the retrofit industry [today] is it is a cottage industry,” Tomas O’Leary says, “delivering it at scale will bring the costs down.”

above Top photo and inset: Bord na Mona workers training at Mount Lucas; middle and bottom sample wall types and the ventilation training setup at WWETB.

It’s all about reskilling and upskilling all workers affected by decarbonisation.

ph+ | retrofit training insight | 63

MARKETPLACE

PA S S I V E H O U S E +

Marketplace News Liquid membranes transforming airtightness work — Blowerproof UK

L

iquid airtight membranes are revolutionising airtightness works in public and commercial buildings, according to leading supplier Blowerproof UK, because of their ease and speed of application especially direct to block, brick and concrete, and inherent ability to deliver airtightness around difficult junctions.

Blowerproof was used as the primary airtightness layer on the UK’s most airtight building, the Imperial War Museum archive in Duxford.

“Since its introduction Blowerproof has been widely used by self-builders and contractors to seal difficult corners and junctions, but it has significant potential to serve as the primary airtightness layer on projects of scale,” said Will Kirkman of Blowerproof UK. “For example, Blowerproof has been used as the primary airtightness layer on over 270 passive-standard schools in Belgium to date, typically being applied externally.”

Kirkman said that this method, where the airtight membrane is applied to the external side of the inner leaf with insulation subsequently fixed directly to the membrane, has been comprehensively tested and proven as reliably secure with no loss of airtightness.

“The Belgian Schools of Tomorrow program recognised the benefits of eliminating internal detailing issues and the cost savings of using Blowerproof in this way, and the scheme established a common practice for achieving airtightness at scale across much of northern Europe,” said Kirkman.

Blowerproof is a VOC-free, water-based, flexible polymer that is brush, roller or spray applied to create a permanent airtight seal.

Manufactured in Belgium by Hevadex, Blowerproof was brought to the UK in 2016 by leading sustainable building materials supplier Ecomerchant, the product’s UK distributor.

Blowerproof is BBA and Passive House Institute certified. To date Hevadex has manufactured enough of the product to cover 2,000,000 square metres. The company also estimates that it has been used on approximately 1,000 certified passive builds globally.

Perhaps the most high-profile project to use the product to date is the Imperial War Museum’s (IWM) rich paper collection in Duxford, which was designed to the passive house standard and achieved an airtightness score of 0.03 air changes per hour - the best airtightness test result in the UK to date, and joint best in the world, as far as Passive

House Plus is aware.

The 1,238 square metre IWM building is approximately twenty times more airtight than the target for certified passive buildings and 200 times tighter than the current UK requirements for non-domestic buildings.

The warrantied installation of Blowerproof at IWM was completed by Ultimate Coatings Limited (UCL), Blowerproof’s appointed application contractor.

The building was designed by Architype with Nick Grant as passive house consultant and Fabrite acting as the main contractor.

“The IWM store has been a great way for us to demonstrate the capacity of liquid applied membranes to secure high levels of airtightness on budget and on time. These results clearly demonstrate what a professionally applied and warrantied application of Blowerproof can achieve in terms of airtightness,” said Kirkman. See www.blowerproof.co.uk for more. • (above) The IWM building in Duxford, which achieved a world-beating airtightness score of 0.03 ACH @ 50 Pa; Blowerproof being applied to the outer face of a masonry building, prior to fitting the external insulation layer.

New profile Progression window gets passive certification T he new profile Progression passive-certified range of triple glazed timber windows, with glass reinforced plastic (GRP) cladding, recently received its A-rated passive house component certification.

The Progression range is supplied in the UK by Green Building Store and is manufactured in the Czech Republic. Progression is a popular choice among passive house designers because of its high performance (Uw 0.68 W/m2K) and ‘frameless’ contemporary aesthetics with minimal sightlines, maximizing daylighting and passive solar gain when needed.

For more information see www.greenbuildingstore.co.uk. • (right) The new profile PROGRESSION window from Green Building Store has received A-rated passive house component certification.

64 | passivehouseplus.co.uk | issue 37

PA S S I V E H O U S E +

VIESSMANN LAUNCH VENTILATION SYSTEM TO TACKLE COVID IN SCHOOLS

MARKETPLACE

New embodied carbon rules for large London projects B

V

iessmann has launched a new ventilation solution to combat the spread of Covid-19 in schools. The company’s new hybrid ventilation unit, the Vitovent 200-P, provides closed rooms with constant air circulation of filtered air. This greatly reduces the risk of occupants breathing in contaminated aerosols which can spread across indoor spaces and hang in the air for hours, especially in winter when windows are more likely to be closed, the company said.

Viessmann said that the Vitovent 200-P counteracts the danger of contaminated aerosols by applying the principle of displacement ventilation. This works by providing a constant supply of filtered fresh air into the room at low velocity through diffusers close to the floor, then extracting the air near ceiling height after it has risen due to heat exchange with occupants’ bodies.

According to Viessmann, good air quality and a comfortable learning atmosphere are ensured by the constant supply of fresh air with heat and moisture recovery, the continuous air circulation, and the extraction of air containing CO2 and VOC (volatile organic compounds) pollution.

Viessmann’s Co-CEO, Maximilian Viessmann, commented: “As a 103-year-old family business, we are committed to designing living spaces for generations to come. Right now, it is crucial that we quickly and pragmatically safeguard our children to maintain a part of their social life and access to education in these challenging times.”

The company said that the effectiveness of the Vitovent 200-P was proven in a pilot project at the Hans-Viessmann-School, a vocational training institution with about 1,000 students in the town of Frankenberg, Germany. Work has since begun on supplying the system – which can be easily and inexpensively retrofitted by replacing a window panel – to a further 50 schools and social institutions in Germany. A separate announcement will be made when the Vitovent 200-P becomes available in the UK. •

uilding life cycle assessment (LCA) experts Bionova have advised architects, developers and contractors to be aware of their LCA obligations under the Greater London Authority’s new London Plan, which came into effect on 2 March. The London Plan is the spatial development strategy for the Greater London Authority (GLA).

Under the new plan, all residential developments of more than 150 units or over 30 metres in height, or commercial buildings covering more than 2,500 square metres floor area, face new LCA rules.

The plan requires all referable planning applications to calculate the whole life carbon emissions of the project and demonstrate actions to reduce it. This must be done in three stages: at pre-planning an outline of the expected emissions of the project must be submitted, at planning stage applicants must submit a whole life carbon assessment, while carbon emissions must also be reported post-occupancy.

The new London Plan also requires a circular economy statement to be submitted with each referable project. Proposals must set out how three core principles will be achieved: sustainable sourcing of materials and resource efficiency, designing for elimination of waste and ease of maintenance, and the sustainable management of any waste that does arise. The plan says projects should be designed for easy maintenance, accessibility, longevity, adaptability and disassembly.

Speaking to Passive House Plus, Panu Pasanen, chief executive of Bionova, said the company’s One Click LCA software offers the tools to meet these requirements.

“When it comes to the whole life carbon requirements, One Click LCA can support you on all stages of the submission from pre-application stage to post-construction,” Pasanen said. “One Click LCA’s carbon designer tool allows you to compare the carbon footprint of building types at design stage, while at planning stage our Building LCA software provides reliable, powerful and user-friendly LCA based on RICS guidance and tailored to GLA reporting requirements. One Click LCA also facilitates post-occupancy assessment.

“For your circular economy statement, One Click LCA’s building circularity tool offers mass-based assessment of building materials, and helps you to calculate the amount of reused and recycled materials and determine end of life processes and the benefits to designing for adaptability and disassembly,” Pasanen said.

“The GLA guidance requires that assessments should be carried out using a nationally recognised assessment methodology and One Click LCA is proud to be one of the tools approved by GLA. ” For more information see www.oneclicklca.com. •

(above) The Viessmann Vitovent 200-P ventilation unit.

ph+ | marketplace | 65

MARKETPLACE

PA S S I V E H O U S E +

Calsitherm boards to be rebranded ‘Red Board’

AERECO AWARDED AGRÉMENT CERT FOR DEMAND CONTROLLED VENTILATION

C

alsitherm and Redstone, two of the largest providers of calcium silicate based interior insulation and mould prevention products, have joined forces, with the Paderborn-based family business Calsitherm taking a majority stake in Bremen-based Redstone. Ecological Building Systems has exclusively supplied the Calsitherm range of calcium silicate boards and ancillary products to Ireland and the UK for the past 15 years.

In the course of the merger, the strategy team led

by Calsitherm managing partner Dr Tobias Hölscher commented: “With this step we are strengthening both companies and expanding the product portfolio to continue to provide all building materials related to healthy living and sustainable construction.”

Ecological Building Systems will continue to exclusively import and distribute the range of Redstone Calsitherm boards, which will be re-branded as ‘Red Board,’ and ancillary products to Ireland and the UK. More information can be found at www.ecologicalbuildingsystems.com. • (below) Calsitherm calcium silicate boards, supplied

by Ecological Building Systems, will now be rebranded ‘Red Board’.

A

ereco has become the first company to receive an NSAI Agrément certificate for ventilation, while also achieving a new ISO 9001 quality management standard for its Irish subsidiary.

“Aereco continues to drive standards in the ventilation sector and are delighted to announce that two big pieces of work with the NSAI have now been finalised,” said Simon Jones, Aereco’s commercial director for the UK and Ireland.

“Firstly, the Irish subsidiary has added to the Aereco group’s long-standing ISO 9001 commitment to quality with a local certification, assuring our commitment to quality at all levels of the business.

“Secondly, after many years of hard work and an exhaustive process, we have achieved the first NSAI Agrément cert in Ireland for demand controlled ventilation, or indeed any type of ventilation system. Not only is it confirmation of the effectiveness of our system in meeting and exceeding regulations, it also significantly streamlines the commissioning and validation process.”

The Agrément certificate applies to all of Aereco’s demand controlled mechanical extract systems and provides a dedicated pathway for the company’s constant pressure systems to be validated under the NSAI scheme.

“We are delighted with both achievements and hope it provides assurance to our customers of our commitment to excellence,” Jones said. “Aereco have been trusted partners for many over the last decade and this is a big step in assuring that partnership for the next decade.”

Jones continued: “This is something we never take for granted. The ventilation industry is developing rapidly and if the last year has taught us anything, it is that that we neglect indoor air quality and ventilation performance at our peril. At Aereco we are constantly improving and innovating the business, and importantly the installed performance of our systems. It’s my hope that these new certifications, along with the recent release of our control indicator as part of the updated regulations for Part F, cement that commitment.” • (above) Aereco has been awarded an NSAI Agrément cert for its demand controlled ventilation systems.

66 | passivehouseplus.co.uk | issue 37

PA S S I V E H O U S E +

Manchester passive ICF house gets 0.31 ACH The airtightness test underway at Passive Building Structures’ Manchester passive house.

MARKETPLACE

Partel’s Izoperm Plus achieves passive house ‘A’ cert

A

new passive house in Manchester, built by Passive Building Structures, has achieved an airtightness test result of 0.31 air changes per hour at 50 Pascals on its final blower door test, easily beating the passive house airtightness standard of 0.6.

Passive Building Structures works throughout the UK and Ireland and specialises in a whole-building-fabric approach using insulated concrete formwork (ICF) walls with an insulated raft foundation, plus a lightweight SIPs roofing system.

“Airtightness is an inherent property of our ICF walls because of the monolithic nature of the concrete layer,” Pearce McKenna of Passive Building Structures told Passive House Plus. “However, to get down to the passive house standard, careful planning, attention to detail and quality control on site are critical.

“Airtightness is responsible for a considerable amount of energy loss in typical buildings, and controlling the movement of air is an integral part of the overall reduction of energy demand. The positive effects of high insulation levels and tripleglazed windows are compromised where there is uncontrolled air movement, so controlling unwanted air leakages and then introducing fresh air ventilation is crucial.”

McKenna said that the company utilises the inherent properties of concrete for the performance of its buildings. so careful considerations are made around the concrete design mix, the rate of pour and adequate vibration to ensure consolidation.

McKenna praised Green Building Store, who installed their Progression passive house certified windows on the project, for the quality of their workmanship. “Delivering this level of airtightness performance requires a collective effort from all the trades,” he said.

He also emphasised that a good blower door test result is an indicator of more than just airtightness. “It’s a very important performance indicator in terms of construction quality, workmanship, and envelope integrity,” he said. “It is one of the only performance indicators that is tested on site rather than being based on design figures or assumptions.”

He added: “We will continually strive to improve, make adjustments and further develop our own skills to ensure we consistently deliver on quality and achieve these low levels of airtightness.”

The 5,000 square foot house in Didsbury, Manchester is expected to be completed this summer, and the owner is planning to submit the project for passive house certification. You can follow this project and others on the company’s Instagram page @pbs_icf, or see www.pbsltd.co.uk. •

P

artel’s Izoperm Plus airtightness system has achieved phA certification from the Passive House Institute, the highest level of component certification, following recent testing.

The full system includes Partel’s Izoperm Plus vapour control membrane plus the Conexo Multiseal and Vara Seal single-sided acrylic tapes, and Acrabond liquid solvent-free joint adhesive. The latter three products are used for membrane overlaps, OSB-to-OSB junctions and for airtight connections to concrete respectively.

Testing of the system resulted in an air permeability value of 0.01 (±0.002) m³/(hm²), standardised for a test pressure of 50 Pascals. This is well inside the baseline requirement for phA certification of 0.10 m3/ (hm2) at 50 Pascals.

“Our goal is to innovate in technical products that ensure the efficiency of project’s performance, and certification plays a fundamental role in this process. This must meet Partel’s rigorous quality standards to advance sustainable product development,” said Hugh Whiriskey, founder and technical director at Partel. The Izoperm Plus airtightness system is developed by Partel and supplied in Ireland, the UK and North America.

Izoperm Plus membrane together with Conexo Multiseal and Vara Seal tapes were used on the Barna passive house project featured in this issue of Passive House Plus. For more information on this airtightness system see www.partel.ie. •

ph+ | marketplace | 67

MARKETPLACE

PA S S I V E H O U S E +

Good design key to heating & cooling via MVHR – CVC Direct

Steico set for major expansion with new factory

L A

big part of a comfortable household is having good indoor air quality and a comfortable air temperature. Mechanical ventilation with heat recovery (MVHR) is an efficient way of providing the necessary ventilation with little heat loss.

However, can MVHR be used for space heating and cooling? The answer isn’t as straightforward as you might think, according to leading MVHR experts CVD Direct.

“There are normally two limiting factors that might hinder the suitability of these solutions,” said Vitor Roriz, technical consultant with CVC Direct. “One is that there is only a limited amount of heat that can effectively be transferred with air, and passive house guidelines suggest we should keep the number of air changes per hour for an MVHR system to a minimum in order to reduce heat losses, so effectively we have a low amount of air volume to carry the heat.”

“However, for a passive house with a peak load of only 10W/m2, using your MVHR system to provide both heating and cooling seems like a really good idea, as this is a system that is already required due to the airtightness of passive houses. There are ways of using your MVHR system to provide total environment control, but such solutions should only be used in passive dwellings where the PHPP calculations show that heating or cooling via the MVHR is feasible.”

The second factor limiting the suitability of using MVHR to provide heating and cooling is humidity control. “Heating the incoming fresh air can lead to the supplied air having a very low relative humidity, which can cause discomfort to the occupants,” Roriz said. “On the other hand, if you cool down the air then you need to be careful about condensation. For these problems, and if the project assessment shows that special care is required for relative humidity control, there are several different solutions that guarantee that the indoor air is always between the ideal comfort levels of 40 to 60 per cent relative humidity.”

“To summarise, either you are looking to supplement your heating system or you are looking for total environment control with heating and cooling through your MVHR,” said Roriz. “If correctly designed, this can be achieved through your MVHR and here at CVC Direct Ltd we are prepared to discuss all the possible solutions to make your project work.” • (above) The Brink Renovent Sky 200 MVHR unit, as installed by CVC Direct.

Delivering full indoor environment control through MVHR is feasible in passive houses, but requires careful design.

68 | passivehouseplus.co.uk | issue 37

eading wood fibre insulation manufacturer Steico has announced plans to build a new factory with three production lines at its recently acquired site in Gromadka, Poland.

“Two lines will be built for flexible wood fibre insulation mats, with a combined total annual capacity of over one million cubic metres,” the company said in a statement. “Another line with an annual capacity of around 500,000 cubic metres will produce stable wood fibre insulation boards using the dry process.”

Construction on the €75 million plant is scheduled to start in mid 2021, with insulation production set to begin at the end of 2022. “The possibility of further expanding capacity in future is already included in the current project design,” the company added.

The Gromadka facility is located about 70 km east of Görlitz on the A4 motorway, and is part of a former airport that is being converted into an industrial estate. Steico acquired the site in November 2020.

Steico said that it is responding to the “rapidly increasing demand for wood fibre insulating materials” by expanding its manufacturing facilities. This includes expansion of production capacity for a range of product lines — including flexible, rigid and air-blown wood fibre insulation — at its existing manufacturing facilities in France and Poland.

“The Steico Group aims to use these investments to significantly expand its position as the global market leader for wood fibre insulation materials, and to continue the profitable growth it has enjoyed to date,” the company said. • (above) In addition to planning a new Polish factory, the Steico Group is responding to increased demand by expanding production at its existing facilities, including its Castlejaloux site in France.

PA S S I V E H O U S E +

MARKETPLACE

A Proctor Group call for consideration of moisture balance issues A

Proctor Group (APG) have stressed the importance of taking account of the HAMM (heat, air, moisture movement) principles when designing buildings, taking account of the effect of insulation type and placement along with the vapour permeability of the various layers. According to APG technical director Iain Fairnington, a balance of factors is key to producing a healthy building envelope that protects the occupants.

“One of the features of balancing these principals can involve calculations to assess condensation and / or moisture risks,” said Fairnington. “Glaser calculations can do this but can have limitations, which a WUFI calculation can help overcome – for example with rain and drying out of residual moisture in the construction.” Fairnington said that a WUFI calculation to BS EN 15026 can help establish the effect that different vapour control layers (VCL) can have on the structure, and on whether a VCL is critical in a given case. “It’s difficult to argue that a VCL isn’t a good thing but similar to the first Covid-19 vaccination injection, a VCL may reduce the moisture risks to acceptable levels but shouldn’t be relied upon as the sole method of protection. Remember a VCL is a vapour control layer,” said Fairnington, “not a vapour barrier – an antiquated term that led to its over reliance.

“Generally, where the insulation is placed externally a VCL is less critical, especially where the airtightness layer is considered in the external vapour permeable membrane, compared with insulation solely between

framing behind the sheathing board,” said Fairnington, adding that this has led to the introduction of externally applied, self-adhered, vapour-permeable yet airtight membranes like Wraptite.

“It is these properties of Wraptite – a selfadhered, airtight, yet vapour permeable membrane – that allows it to be placed on the external face of the sheathing board,” he said.

“This allows for temporary water protection, airtightness and long-term vapour permeability, which along with the correct balance of insulation, means a VCL may be less critical.

But it’s important to assess this fully on a project-by-project basis.”

Fairnington said that while there is little doubt that VCLs – especially in the case of variable resistance membranes – can help to reduce the moisture flow through a building envelope in many applications, they become less critical in some areas, depending on insulation placement. “For example, when placing insulation purely in between the frame of a timber frame building, the moisture risk may be too high to omit the VCL and therefore should be used to reduce vapour progressing through the structural frame,” he said. “However, if this is balanced with insulation placed external to the structural frame, the dew point potential is reduced due to the warm frame and the VCL becomes less critical. But it’s still good practice.”

“A good appreciation of the key balancing of heat, air and moisture movement can work together for the benefit of the industry,” Fairnington said. “APG have many VCLs in

our range, one being a variable VCL, and it is not our position to persuade the industry not to use them. Our stance is to show people that VCLs should not be relied upon solely to reduce moisture build up but can have benefits when balanced with other factors.”

APG now have Wraptite and Procheck Adapt passed as certified passive house components, tested by the Passive House Institute.

APG’s technical back up service includes Glaser and / or WUFI calculation services where appropriate to show the robustness of the proposed constructions, along with toolbox talks (virtual if required), specification guidance and site visits (dependant on Covid restrictions), which can give a compliance report showing areas that are well installed and areas of improvement in the installation. • (below) Wraptite was specified for Ceres House, a mass timber house designed by level-ak architects in rural Victoria, Australia.

Want to see your ad in the next issue of the magazine?

To enquire about advertising, contact Jeff Colley on +353 (0)1 210 7513 or email jeff@passivehouseplus.ie

www.passivehouseplus.ie

ph+ | marketplace | 69

T O BY C A M B R AY

COLUMN

Measuring humidity, the old school way A chance purchase on eBay leads buildings physics expert Toby Cambray to admire the aesthetics and mechanics of old scientific instruments.

A

few months back, I was browsing eBay in an idle moment, and came across something so wonderful I could not resist buying it immediately. It helped that it wasn’t very expensive. It’s a hefty chrome plated scientific instrument with an aesthetic somewhere between art deco and steampunk, about 400 mm long.

The object in question is pictured here, and I popped a photo on Twitter for a guessing game, eventually won by passive house consultant Nick Grant.

What on earth is this infernal device that so beguiled me? It has a key at one end for winding a clockwork (none of that new-fangled electricity) mechanism that whirrs and ticks in the most delightful way, driving a small fan within the casing. The fan draws air down a tube connected to a pair of tiny trumpet flares; in the middle of each there nestles the bulb of a simple mercury thermometer. What is the purpose of such an instrument?

which is then wetted.

As seasoned hillwalkers know, wet socks are bad news. Your feet get cold to an extent out of proportion with the temperature of the rain or puddles. This is due to the loss of latent heat – the water evaporates away from your feet but takes a certain amount of heat in doing so. This effect is turned to advantage in the hygrometer: the wet sock reduces the temperature of the wet-bulb thermometer and by comparing it with the dry bulb temperature, the humidity can be inferred.

This is because the reduction in temperature caused by the evaporation depends on humidity. If the humidity is 100 per cent, no evaporation can take place because the air can’t hold any more moisture, but at 0 per cent humidity, the evaporation is maximised.

The rate of evaporation and subsequent reduction in bulb temperature is a bit complex and depends on a number of things including air velocity, so each make and

To operate my device, it requires the addition of a tiny sock over one of the thermometers, which is then wetted.

Nowadays, if we want to measure humidity there are a plethora of inexpensive electronic sensors, most of which work by measuring the change in capacitance of slivers of special materials as they take up and release moisture from the air (yes, they’re hygroscopic like Jaffa Cakes). But go back several decades and such technology was unavailable, or at least unaffordable or imprecise – not that one can rely too heavily on relative humidity measurements, even today. So, in the absence of a handy miniaturised sensor, how could you measure humidity?

One answer is stylishly demonstrated by my mysterious device. You may have come across the term ‘dry bulb temperature’ as a measure of air temperature. In isolation this might seem slightly odd to a twenty-first century reader, unfamiliar with the low-tech measurement of humidity. If it occurs to you that the term dry bulb implies a similar metric called wet bulb, you’d be right, and this explains the pair of thermometers. To operate my device, it requires the addition of a tiny sock over one of the thermometers,

70 | passivehouseplus.co.uk | issue 37

model of these old-fashioned hygrometers comes with its own empirical look-up tables to convert the temperature readings to humidity. If you’re familiar with the idea of wet-bulb hygrometers, you might be better acquainted with the style that looks like an old-fashioned football rattle, and is waved around the same way. The advantage of the fan is to ensure a more consistent air velocity and therefore a more repeatable measurement, as well as looking like a space pirate’s double-barrelled blunderbuss.

While modern devices might be a fraction of the price, more reliable, convenient and accurate, and have capabilities far outstripping old technology, there’s something charming about vintage scientific equipment, all mahogany and little brass plaques.

My dad, an ex-science teacher, has a study filled with obsolete demonstration kit, salvaged from various school clear-outs, and it’s this element of education that also makes these old things interesting – you can figure out how they work, and learn a great deal along the way. n

(above) The clockwork-powered, mechanically aspirated psychrometer/ hygrometer that Toby Cambray bought on eBay.

Toby Cambray is a founding director at Greengauge and leads the building physics team. He is an engineer intrigued by how buildings work and how they fail, and uses a variety of methods to understand these processes.

PROGRESSION

GRP

ThERmOwOOd

‘Frameless’ and contemporary, our Passivhaus-certified PROGRESSION triple glazed window has a whole window U value of 0.68 W/m2K. The PROGRESSION range is now available with two low maintenance cladding options: GRP (fibreglass) and Thermowood (thermally-modified timber).

C all us o n 01484 4 6 3 3 3 6 or e ma i l w i n d ow s @ gre e n b u i l d i n gs t ore . c o. u k fo r m o re info r m ati on or t o ge t a q u ot a t i on .

®

making buildings better P ro duc ts a nd supp or t f or Pa s s i v h a u s & l ow e n e rgy b u i l d i n gs

t : 014 8 4 4 6170 5 | www.g reenbuilding sto re.co .uk ph+ | editor’s letter | 71

Whole Life Carbon

Your next business opportunity

DELIVER

results for London Plan, RICS, BREEAM, PAS 2080

WLC assessment from IES-VE, Revit, Tekla, Rhino

Get a free consultation for your London Plan, RICS, BREEAM, PAS 2080 projects 72 | passivehouseplus.ie | Issue 21

AUTOMATE

Dave Jones +44 7879 991889 Johanna Jarvinen +44 7464 350081

GENERATE

early-stage carbon & cost reduction options

START A FREE TRIAL oneclicklca.com