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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

SEA CHANGE

Zero energy passive houses on Devon coast

AIRBORNE COVID THREAT

The stimulus measure of the moment?

“We can launch a new eco Renaissance”

UN director lays out low energy case

Issue 34 £5.95 UK EDITION

Deep retrofit


2009597010-08.eps NBW=80 B=20

Will poor ventilation risk a second wave?


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 Reponse / 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 Marc Ó Riain doctor of architecture Peter Rickaby energy & sustainability consultant Fionn Stevenson professor of sustainable design David W Smith journalist

EDITOR’S LETTER

editor’s letter T

he past few months have been an extraordinarily trying time. Still, I have to remember to check my privileges, put my exceptionalism in my pocket and remember that many people have had it far worse than the team at Passive House Plus. With that perspective in mind, our struggles at this magazine, as they are, aren’t worth divulging. But some readers may have noticed a delay in this magazine arriving, so I feel duty bound. When the lockdown began in March, just after our last issue was finished, it posed immediate problems for our business, as it did for countless others around the world. At first advertising, which provides the overwhelming majority of funding for a magazine such as this, fell off a cliff. This was not something we could afford to happen – we’ve never been a profit-oriented company, and when we’ve turned a profit we’ve always invested it into the magazine, to reach as many readers as possible, and to provide the best service we can. So we have focused our efforts on finding new ways to help our clients, including hastily arranging to post magazines to readers at home to help see them through the lockdown, and dropping the paywall on the digital edition in an effort to substantially increase our readership. Thankfully, our readers have responded in droves. If you value this magazine, and the work we do to inform and educate on the detail of how to build and retrofit to high standards of sustainability, I’d strongly urge you to show your appreciation to the advertisers

ISSUE 34 in this issue, and to the companies who have backed us on our online Marketplace+ portal recently. While we would never begrudge the companies who couldn’t justify advertising since Covid-19 struck — we understand the hard decisions that many companies have had to take — we have been humbled by the loyalty so many organisations have shown us. Many of these companies made a point of backing us because they see that Passive House Plus has a role to play to help show the industry how to build and retrofit better. The feeling is mutual: we try to be as picky as possible about the kinds of advertisers we promote. If we are to have any chance of delivering the low energy, healthy, low environmental impact buildings the world so badly needs, we cannot afford to lose the hard-won expertise and capacity that has developed in this sustainable corner of the industry. The accumulated knowledge and skills will not be easily replaced. Rather we need these kinds of companies to grow, so that proven sustainable solutions are applied on all new build and retrofit projects. So, I implore you: while I hope you find inspiration and detailed learning in the articles published in this issue, please also reach out to the advertisers in these pages and the Marketplace+ portal on our website — either directly or collectively via our online enquiry form at www.passivehouseplus.co.uk/enquiries — and see what role they can play to help you build better. Regards, The editor

Print

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

Cover

Seaton Beach passive house apartments Photo by Dug Wilders / Norrsken

Publisher’s circulation statement: Passive House Plus (UK edition) has a print run of 11,000 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.

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CONTENTS

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CONTENTS COVER STORY

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Good stock Stylish Stockport retrofit achieves radical energy savings

This inspiring project may be exactly what the deep retrofit sector needs: an example of how to turn a bog standard, cold suburban home of little architectural merit into a climate champion delivering outstanding levels of energy performance, comfort and health, all while transforming the building architecturally.

INTERNATIONAL This issue features the passive house ‘plus’ certified headquarters of Métropole Rouen Normandie, located on the banks of the Seine in Rouen, France, and designed by Jacques Ferrier Architecture.

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NEWS

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COMMENT

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Sea change Luxury zero-energy passive apartments rise on the Devon coast

Built mostly with clay blocks and sited above the sandy shores of Seaton, on the Devon coast, this new development of eight high-end apartments not only meets the passive house ‘plus’ standard — meaning it pairs the requisite ultra-low energy fabric with a substantial amount of renewable energy generation — but it also boasts serious attention to the use of ecological and healthy materials.

A new report questions long-held assumptions about heat recovery ventilation, UK climate committee says deep retrofit should be central to a green economic recovery, and Passive House Plus sees a big spike in digital readership.

Dr Marc Ó Riain takes a look at the relationship between collapsing ecosystems and the emergence of new infectious diseases; Professor Fionn Stevenson calls for better ways to measure the environmental impact of buildings; and Dr Peter Rickaby says that Covid-19 has inadvertently given us a glimpse of what sustainable living patterns might look like.

CASE STUDIES

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Northern exposure Deep energy retrofit transforms northfacing Dublin seaside semi

Even though its stunning views lay directly northward, simple design, good detailing and lots of insulation have turned this 1960s semi on the edge of Dublin Bay into a warm and light-filled low energy home.


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Pilot light Pioneering Donegal deep retrofit a roaring success

A rundown 1970s scheme of one-bedroom, singlestorey social housing units in Ballyshannon, Co Donegal, has been transformed into a pioneering development of cosy, A-rated, NZEB-busting homes. The pioneering project – the first completed under Ireland’s deep retrofit pilot scheme – also breathed new life into an unloved green area and is expected to help fuel a regeneration project in the town.

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CONTENTS

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In the early stages of the Covid-19 crisis, there was little official recognition that airborne transmission was a risk. Has that view changed, and what role will building ventilation play when winter approaches?

INSIGHT Deep retrofit & stimulus Is an upgrade revolution the economic tonic to tackle Covid?

With governments across Europe looking for ways to jump start their economies following the early impact of Covid-19, attention is increasingly turning to deep retrofit. But while there is strong evidence that deep retrofit could play a major role, the devil will be in the detail – and the challenge of dramatically upscaling a nascent industry shouldn’t be underestimated.

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We can launch a new eco Renaissance

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The UN’s Scott Foster says deep retrofit of our building stock, and a sustainable built environment, should be at the heart of our recovery from the Covid-19 pandemic.

Dead air Airborne Covid-19 and poorly ventilated buildings

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

The science of filters

How do ventilation filters work, and can they help to protect us against Covid-19? Toby Cambray, cofounder of Greengauge Building Energy Consultants, weighs in on the physics of a subject that is more complex and interesting than you might expect.

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INTERNATIONAL PASS I V E & EC O B UIL D S F R O M A R O UND THE WO RL D

IN BRIEF Building: 8,300 m2 public building Architect: Jacques Ferrier Architecture Method: Double-skin glazed façade with concrete elements Standard: Passive house ‘plus’ certified

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FRANCE

Photos: Luc Boegly / Myr Muratet / Ferrier Marchetti Studio

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

MÉTROPOLE ROUEN NORMANDIE HEADQUARTERS, FRANCE

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etween 1892 and 1894, Claude Monet obsessively painted the façade of Rouen Cathedral, capturing how the ever-changing light and weather altered the mood, colour and texture of the cathedral’s gothic façade in a series of more than 30 paintings. These artworks inspired architect Jacques Ferrier in his design of a new metropolitan headquarters for the town, situated on the banks of the river Seine, which he clad in colour-shifting glass ‘scales’ to create an iridescent façade that reflects the ever-changing light and weather. Even more remarkable than the chromatic façade is that the building is certified to the passive house standard. Indeed, experienced passive house designers might baulk at the extent of glazing here — glass covers more than 60% of the building’s façades. So-called ‘sensible glazing ratios’ are typically at the heart of good passive house design — the idea being that you put the right amount of glass, in the right places, to capture heat and natural light from the sun, but avoid the summer overheating and winter heat loss that is often associated with excessive glazing. Ferrier may have shunned these norms but has also created a rather remarkable building. Rouen’s new town headquarters not only meets the passive house standard but the passive house ‘plus’ benchmark, which means it must generate about as much energy on site (from renewables) as the building consumes. Because covering the roof in solar PV panels would not have been enough to achieve this on its own, the project

decided to create a double-skin façade, with solar photovoltaic panels — coated with dichroic films that reflect different colours — forming the outer skin on much of the south face. On the north façade, which overlooks the river, the outer skin is comprised of glass scales coated with metal oxides, again to reflect different colours. This double-skin is also designed to provide insulation and prevent overheating in summer but allow more sunlight in during winter (the panels are angled to limit high-angle summer sun, but to receive more low-angle winter light). The building also has 35 geothermal probes connected to two heat pumps that provide heating and cooling, but demand is minimal, and within the passive house standard of 15 kWh/m2/yr for each. Meanwhile an atrium slices the building in half, bringing daylight deep into the heart of the plan, and also creating a series of internal terraces for staff and members of the public. The roof also boasts a large terrace with views over the city and River Seine. The building’s oblique shape is designed to mimic the silhouettes of cranes on the dockside, and the bows of passing ships. It may not be a traditional interpretation of passive design — and we will be curious to see how comfortable indoor temperatures remain as the climate warms — but it is nonetheless a spectacular piece of architecture. “The building’s appearance transforms throughout the day,” say the architects. “With the light shining through, it appears to float on the quay.”

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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

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FRANCE

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

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Eco-friendly refrigerant R32


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

NEWS

NEWS

Passive House Plus launches new UK website

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assive House Plus has launched a new version of our website specifically for UK readers. The new site, at www.passivehouseplus.co.uk, contains a focus on UK news and stories. It also has a UK-specific version of our Marketplace+ sustainable building directory. All of our main project case studies, in-depth guides and feature reporting appear across both our UK and Irish sites, but news, blogs and comment are now tailored to each country’s audience.

“We believe that having a dedicated UK site, as well a UK-specific version of our Marketplace+ directory, will provide much more relevant content for our UK readers, as well as a more tailored platform for UK brands in the sustainable building sector to get their message across,” said Passive House Plus editor and publisher Jeff Colley. Passive House Plus was launched in 2012 following the rebranding of Construct Ireland magazine, with separate editions for the UK and Ireland printed from the second edition onwards. •

New report questions long-held MVHR assumptions

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new report by the Passivhaus Trust has questioned the common assumption that mechanical ventilation with heat recovery (MVHR) is inappropriate in dwellings with air permeability worse than 3 m3/m2/hour. It is common practice not to recommend the installation of MVHR systems in such homes, but the new report, titled ‘The case

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for MVHR’, says there is “no clear up-todate evidence” behind this rule. It said this benchmark is based on “outdated information and flawed assumptions”. Written by Passivhaus Trust policy director John Palmer, with input from a range of other leading experts, the analysis critiques some of the common assumptions behind the rule, such as the view that

above 3 m3/m2/hour MVHR becomes inefficient due to increased electrical load or less efficient heat recovery. “This analysis has shown that MVHR systems result in improved ventilation and lower carbon emissions for all levels of airtightness,” it says. “There is a compelling case for MVHR systems to be fitted in all new dwellings and to be strongly encouraged in retrofits where significant reductions in energy demand are being targeted.” There is growing relevance to questioning the 3 m3/m2/hour rule given questions over whether SARS-CoV-2, the virus that causes Covid-19, can spread more easily in poorly ventilated spaces. REHVA, the Federation of European Heating, Ventilation and Air Conditioning Associations, has advised that all ventilation systems that recirculate air should be switched off, and replaced with as much fresh air ventilation as possible. MVHR systems provide 100% fresh air by default. The Passivhaus Trust stated: “MVHR systems extract warm but potentially stale, dirty, and humid air from bathrooms, kitchens and utility rooms before passing it over a heat exchanger which transfers the heat to fresh, filtered air from outside the building. Extract and supply air streams are fully separated, eliminating contamination risk.” The full report is free to download at www.passivhaustrust.org.uk. •


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

NEWS

Deep retrofit crucial to green recovery, climate committee says Advice also calls for upskilling for retrofit & low carbon heating

•  L  ow-carbon retrofits and building. The CCC said that there are “vital new employment and reskilling opportunities across the country if governments support a national plan to renovate buildings and construct new housing to the highest standards of energy and water efficiency, to begin the shift to low-carbon heating systems, and to protect against overheating”. It also called for the rollout of “green passports” for buildings, and of local area energy plans. •  T  ree planting, peatland restoration, and green infrastructure. “Investing in nature, including in our towns and cities, offers another quick route to opportunities for highly-skilled employment, and outcomes that improve people’s lives,” the committee said. •  E  nergy networks must be strengthened to support electrification of transport and heating, the CCC said. “New hydrogen and carbon capture and storage (CCS) infrastructure will provide a route to establishing new low-carbon British

industries, while fast-tracked electric vehicle charging points will hasten the move towards a full phase out of petrol and diesel cars and vans by 2032 or earlier,” the report added. •  Infrastructure to make it easy for people to walk, cycle, and work remotely. “Dedicated safe spaces for walking and cycling, more bike parking and support for shared bikes and e-scooters can help the nation get back to work in a more sustainable way,” the committee said. “For home working to be truly a widespread option, resilient digital technology (5G and fibre broadband) will be needed.” •  Moving towards a circular economy. The CCC stated: “Within the next five years, we can not only increase recycling rates rapidly but stop sending biodegradable wastes to landfill. Local authorities need support to invest strategically in a good-quality, low-carbon services for waste collection and disposal and to create new regional jobs.”

•  Targeted science and innovation funding. The CCC said: “Kick-starting research and innovation now in low-carbon and adaptation technologies will facilitate the changes needed in the decades ahead and build UK competitive advantage.” “Covid-19 has shown that planning for systemic risks is unavoidable,” said chair of the CCC’s adaptation committee, Baroness Brown of Cambridge. “We have warned repeatedly that the UK is poorly prepared for the very serious impacts of climate change, including flooding, overheating and water shortages. “Now is the moment to get our house in order, coordinate national planning, and prepare for the inevitable changes ahead. The UK’s domestic ambition can be the basis for strong international climate leadership, but the delivery of effective new policies must accelerate dramatically if we’re to seize this chance.” The full report is available to read at www.theccc.org.uk. •

The CCC said that there are also opportunities to support the transition and recovery by investing in the UK’s workforce, and in lower-carbon behaviour and innovation, such as through:

Photo: Chris McAndrew/UK Parliament (CC BY 3.0)

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inisters must seize the opportunity to turn the Covid-19 crisis into a defining moment in the fight against climate change, the Committee on Climate Change (CCC) has said, as it called for a major drive to retrofit the UK’s building stock. In its annual report to parliament, the CCC provided comprehensive new advice on delivering an economic recovery that accelerates the transition to a “net-zero emissions” society and strengthens resilience to the impacts of climate change. “The UK is facing its biggest economic shock for a generation," said CCC chairperson Lord Deben. “Meanwhile, the global crisis of climate change is accelerating. We have a once-in-a-lifetime opportunity to address these urgent challenges together; it’s there for the taking. The steps that the UK takes to rebuild from the Covid-19 pandemic can accelerate the transition to a successful and low-carbon economy and improve our climate resilience. Choices that lock in emissions or climate risks are unacceptable.” The committee assessed a wide set of measures and gathered evidence on the role of climate policies in the economic recovery. Its report highlighted five “clear investment priorities”:

•  Reskilling and retraining programmes. The CCC said: “The net-zero economy will require a net-zero workforce, able to install smart low-carbon heating systems and to make homes comfortable; to design, manufacture and use low-carbon products and materials; and to put carbon back, rather than taking carbon out, from under the North Sea. Now is the time to build that workforce and to equip UK workers with vital skills for the future.” •  Leading a move towards positive behaviours. “There is a window for government to reinforce the ‘climate-positive’ behaviours that have emerged during the lockdown, including increased remote working, cycling and walking. The public sector must lead by example by encouraging remote working. It also needs to innovate in order that customer service can be provided effectively remotely,” the committee said.

(above) Baroness Brown, chair of the CCC’s adaptation committee, said that the delivery of new policies on climate change “must accelerate dramatically”.

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NEWS

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

NEWS

New drive to Passive House cut VAT on Plus sees digital MVHR systems spike during Covid

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new campaign is aiming to encourage more sustainable property refurbishment through tax incentives for people to adopt passive, or near passive, building standards. The petition proposes that mechanical ventilation with heat recovery (MVHR) be treated as an energy saving measure, and thus be eligible for a reduced rate of VAT. If it achieves enough signatures, the petition will be debated by parliament. Petition founder Eliot Warrington of Solarcrest said: “Anyone keen on passive house comfort, health and environmental benefits knows that achieving airtightness is key, and that makes MVHR mandatory rather than optional. The problem is, unless yours is a new build you’re looking at a hefty VAT bill on the MVHR for your trouble, often over £1,000. “Penalising people who ‘go green’ voluntarily is both unfair and illogical when you’re trying to reduce carbon emissions. For some strange reason heat recovery is not deemed an energy saving measure so is not eligible for the reduced rate of VAT. We think it’s about time that position changed, hence the petition.” He continued: “A reduction in the VAT payable on MVHR would remove a barrier that currently deters some people from making their property airtight and therefore low energy. Instead it would encourage people to adopt a technology that improves health by removing damp and pollution from the home.” Passive House Plus has lent its support to the campaign, with magazine publisher and editor Jeff Colley stating: “MVHR works by recovering waste heat from outgoing air, and using it to pre-heat fresh incoming air, so it is an obvious candidate to be classed as an energy saving technology. “Clearly, people may be reluctant to make their homes airtight if they find ventilation systems, which go hand in hand with airtightness, too expensive. Reducing the VAT on MVHR is an obvious way to encourage the move towards low energy, airtight properties with quality mechanical ventilation systems providing fresh air. Such homes will have smaller energy bills, a smaller carbon footprint and be healthier and more comfortable for occupants.”

To lend your support, please visit: https://petition.parliament.uk/petitions/300597. •

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he digital edition of Passive House Plus has seen a significant increase in readership during the Covid-19 crisis, in addition to the magazine’s market-leading print circulation. The standing total for digital reads of the Spring 2020 UK edition of Passive House Plus is 4,402 reads, compared to a standing total of 747 reads for the previous issue. Back issues of Passive House Plus tend to accumulate digital reads slowly over time, typically averaging circa 3,000 reads after a year or two. The magazine’s ABC audited average circulation for the print version of the UK edition averages 8,971 copies, with an average of 1.99 readers per copy (based on the 2019 Passive House Plus reader survey) indicating a print readership approaching 18,000 people. The spike in digital readership resulted from a decision to drop the paywall on the digital edition, as part of a strategy to increase readership and boost exposure for advertisers feeling the effect of the Covid-19 lockdown, while providing readers with access to the magazine at a time when they may have scope to catch up on reading. In order to enable readers to receive the magazine at home during the lockdown, a form was setup on the Passive House Plus website for readers to request a free copy to be sent to their home address. “We’ve elected to keep the paywall down for this issue too,” said editor Jeff Colley. “If our print and digital edition readership is combined, the total would be over 22,000 readers (assuming no duplication between print and digital reads). We’re delighted to be able to reach such a large and loyal readership, and to inform as many people as possible about the detail on how to build or retrofit to the highest standards of comfort, energy efficiency and indoor air quality.” The spike in performance was also evident with the Irish digital edition of Passive House Plus. The standing total for digital reads of the Spring 2020 Irish edition of Passive House Plus is 5,847 reads, compared to a standing total of 819 reads for the previous issue. The magazine’s ABC audited average circulation for the print version of the Irish edition averages 6,424 copies, which stands as the 2nd largest circulation of any B2B magazine in Ireland. With an average of 2.08 readers per copy (based on the 2019 Passive House Plus reader survey), the Irish edition has an estimated print readership in excess of 13,000 people. •

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DR PETER RICKABY

COLUMN

Will we ever return to normal? Covid-19 has inadvertently given us a glimpse of what sustainable living patterns might look like, and we must seize this opportunity for long-lasting positive change, says Dr Peter Rickaby.

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n one of my early columns here I recalled asking my students to imagine hovering above a city for a day, and to describe what they would see. They described tides of commuters on bicycles, in cars, on buses and metros, and on trains, flowing to work in the morning and flowing home again to suburbs, hinterland towns and beyond, in the evening. They remarked on the numbers of people and the distances involved – commutes of fifty miles each way being common. Some also described cross-commutes between sub-centres, and local commutes into sub-centres and hinterland towns, to work and school. Overlaid were inter-city journeys to attend meetings, conferences or exhibi-

strong, and even in London we have spent ten years building apartments and raising densities as fast as we can. Nevertheless, it is still the case almost everywhere that as households become more affluent they vote with their wheels to live at the edge of the city or beyond, where densities, air pollution and crime rates are lower, schools are often perceived to be better, and open space is more accessible. This was the settlement trend of the twentieth century, facilitated by cheap fuel, carelessness about emissions and complacent attitudes to the environment, and it has only recently begun to change. Now we suddenly find ourselves in different circumstances. A global pandemic

We have been given a glimpse of a sustainable future. tions, and journeys to deliver materials and distribute goods. My assignment question associated with this exercise was, “do you think what you have described is a sensible pattern of settlement?” Most students responded that it was not, some that it was clearly unsustainable, one (emphatically) that it was insane. Subsequently, we talked about the trade-off between energy use in buildings and in transport, the advantages of higher or lower densities (the jury is still out on that), the integration of agriculture with urban activities, and what a sustainable pattern of settlement might look like. In a recent column, I pointed out the nonsense of referring to the Bloomberg building in London as ‘sustainable’ when it has a huge carbon footprint associated with those who work there commuting to and from their distant homes. My point in both these examples is that the physical separation of our urban places of work from suburban and hinterland homes is at the heart of the problem of sustainability. This applies particularly to cities in the UK and USA, and perhaps elsewhere, but many cities in Europe and Asia have higher residential densities and smaller commuter catchments, so the tides there are smaller, although still significant. In European cities the tradition of urban apartment living is

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and public health emergency left many of us locked down at home. We are now working, meeting, teaching, learning and shopping online, and getting many of the things we need delivered. Commuter trains are much less crowded, bus services have been cut and roads are no longer congested. Almost nobody is flying anywhere. Energy use in transport and commercial buildings is down (though up slightly in domestic buildings), carbon dioxide emissions are down, urban air quality is much improved. It is not all great of course – we are not visiting family and friends, taking holidays or weekends away, watching or playing sport, drinking in pubs and bars, or eating out at restaurants. Notwithstanding these inconveniences, we have been given a glimpse of what a sustainable future could look like. We are learning which activities need to be centralised and which can be networked, that working or studying from home are good options for many, and that online media can provide social cohesion for everyone, not just for teenagers. When the emergency is over (if it ever is), conservative, populist politicians, bankers and big business will want to return everything to the way it was before – to restore their profits and our former ‘way of life’, even if it was wasteful and unsustainable. Even if healthcare was under-funded,

migrants were under-valued, homeless people slept on our streets and our environment was being destroyed. However, I predict that many will resist. Encouraged by David Attenborough, Greta Thunberg, and Extinction Rebellion, we will have the opportunity go further towards a sustainable way of living and working. Employers will trust their staff to work from home, facilitating team cohesion by events like morning and evening online meetings. Employees (especially parents) will value the flexibility associated with working from home. Homes will slowly be modified to make home-working easier. Cars will become intermittently-used public services, and with no ‘peaks’ public transport will become cheaper, more flexible and more comfortable. How sustainable will the outcome be? That remains to be seen, but I suspect that things will never be quite the same again. Going back is not a sustainable option. n

Dr Peter Rickaby is an independent energy and sustainability consultant. He helps to run the UK Centre for Moisture in Buildings (UKCMB) at University College London, chairs the BSI Retrofit Standards Task Group, and is active in training building professionals in retrofit coordination and risk management.


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FIONN STEVENSON

COLUMN

We need better building

performance metrics The way we currently do post-occupancy evaluation of buildings is inadequate, says Professor Fionn Stevenson — we need new ways to measure the environmental impact of buildings, and how resilient they are to climate change.

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here is an increasing expectation that a robust performance evaluation is carried out on the buildings we design, once they are completed and again after they have been occupied for some time. These results are regularly reported in this magazine. Post-occupancy evaluation (POE) methods are well known, and in the European Union there is a requirement to publicly display energy use and carbon emissions for public buildings under the Energy Performance of Buildings Directive. However, there is a serious concern about whether the right metrics are being used to make this evaluation. Is kWh/m2/yr really good enough? What about total energy use? What about adaptive comfort consid-

floor area. When you multiply the energy demand per m2 by the floor area, you get the total energy in use demand, which is the more useful figure for understanding the overall impact of the building. The floor area significantly influences embodied energy and carbon emissions too. Looking at total demand forces us to answer difficult questions such as: do I really need all this space? Am I occupying this home efficiently? These questions matter, because it is the overall impact of our buildings that ultimately affects climate change, not the rate of energy use on its own. A new mandatory metric in performance evaluation that addresses total energy and carbon emissions

Four-and-a-half million homes are already overheating in the UK each summer. erations? Is climate change future-proofing even considered in POE? In my recent book on housing performance, I address the issue of ‘sufficiency’ – the need to take account not of just how well our homes perform, but what their overall impact is in terms of resource use. In Passive House Plus issue 33, we had a couple of new homes illustrated at around 150 m2 floor area, with primary energy demands predicted to be 44 and 96 kWh/ m2/yr, and another home at around 276 m2 with a demand of 39 kWh/m2/yr. The interesting thing here is not just the difference in energy demand – it is the huge difference in

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in use is needed to address this gap. Another major issue remains unaddressed in current POE metrics: how many people actually live in the home. Why does this matter? If a home designed for a family of five with three bedrooms only has two people living in it, then it is underutilised and causing profligate resource use. While passive house and other useful environmental performance standards address the performance of a home, they do not address how people use it. Another new POE metric is needed, to compare the number of people living in a home with the number it was originally

designed for. This can work both ways, of course, and reveal when a home is over-occupied too, with more people living in it than sensibly designed for. This can be particularly useful in rented housing, when rogue landlords are overfilling homes. It can also provide realistic figures of occupancy for understanding what is really going on in housing in terms of the amount of energy used to house people. Then there is the burning question of whether homes are resilient in relation to climate change. Four-and-a-half million homes are already overheating in the UK each summer. This is partly related to poor design which prevents natural cross ventilation at night or creates inadequate MVHR [mechanical ventilation with heat recovery] systems. While some building performance evaluation tools, such as the passive house software PHPP, factor in overheating for design purposes, there is currently no requirement to future-proof the performance of our homes in relation to global temperature increases, increased rainfall and other storm factors. An additional performance metric is needed at the design stage to ensure that all essential factors related to climate change have been taken into consideration. In summary, we need better metrics for housing performance evaluation, related to the reality of space use, occupancy and future-proofing. Fortunately, there is good work going on in the UK Building Performance Network to develop better performance evaluation methods, and there is also a chance to influence the forthcoming new British standard that is being developed for POE in relation to retrofit. n

A fully referenced version of this article is online at www.passivehouseplus.ie Fionn Stevenson holds a Chair in Sustainable Design at the University of Sheffield. She is a founder member of the Building Performance Network, and an advisor to the Royal Institute of British Architects on POE policy. She is author of ‘Housing Fit for Purpose: Performance, Feedback and Learning,’ published in 2019 by the RIBA. Twitter: @fionnstevenson


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MARC Ó RIAIN

COLUMN

Are we the virus? Taking a temporary detour from his series of columns on the history of sustainable building and renewable energy, Dr Marc Ó Riain takes a look at Covid-19 from the perspective of Gaia theory, and at the relationship between collapsing ecosystems and the emergence of new infectious diseases.

D

iverting from my usual column I have taken the opportunity of solitude to review some academic papers and books relating to the development of Covid-19 in an environmental context. James Lovelock’s Gaia theory (1972 & 2009) proposes that the planet is a complex interacting system much like a single organism. In this vision, humans are the virus making the organism unstable, and thus Gaia’s immune system will find ways of fighting the virus... in our case with a virus, and it is not the first example. The Spanish flu, Covid’s most appropriate antecedent, lasted three years, and was caused by the conflagration of war, mixing of French soil, multinational armies, poor quality living conditions, stress, fear and the use of chemical gases, with its virulence aggravated by the repatriation of soldiers, creating a true global pandemic . Although in a different context, our increasing travel, trade, industry, population, pollution and expansionist agriculture has placed an ever-increasing pressure on the fringes of regional biodiversity. This is scientifically linked to a “a rise in disease emergence and the potential for pandemics” according to researchers . The rate of detection of these novel and

We disrupt ecosystems, and we shake viruses loose. epidemic-prone diseases, like Covid-19, is increasing in frequency, and they are increasingly difficult to manage; H1N1, SARS, MERS, Ebola, Zika, Yellow Fever... Between 2011 and 2018, WHO tracked 1,483 epidemic events in 172 countries. The increase in novel diseases is emerging from the fringes of our societies along the edges of biodiversity “hotspots” such as tropical rainforests and bushmeat markets in Brazil, Africa and Asia, but driven by the northern hemisphere’s demand for meat, minerals and materials. According to the Centre for Disease Control in the US, approximately 75% of emerging infectious diseases and 60% of all pathogens that infect humans have originated in animals. David Quammen (2012) prophetically warned 20 | passivehouseplus.co.uk | issue 34

Newly emerging and re-emerging infectious diseases (National Institute for Allergies & Infectious Diseases, USA)

us: “we cut the trees; we kill the animals or cage them and send them to markets. We disrupt ecosystems, and we shake viruses loose. A parasitic microbe, thus jostled, evicted, deprived of its habitual host, has two options— to find a new host or a new kind of host... and often, we are it.” In 1997, epidemiologist Donald S Burke at the University of Pittsburgh identified that the coronavirus (CoV) has a proven ability to cause epidemics in animal populations and intrinsic evolvability to recombine to cause pandemics in the human populations. Burke argued that world governments and NGOs needed to be actively monitoring remote places to identify local spill-overs of CoV, with field capabilities to suppress the disease before it becomes a regional outbreak. An interesting example of such monitoring is the research carried out by the Global Viral Forecasting Initiative (GVFI), which blot tested bush meat in high risk areas for emerging viruses, in a systematic effort to stop the next pandemic before it begins to spread. This is exactly the type of research that needs to be funded and broadened to arrest pathogens in small clusters, thus eliminating the virus in human populations before they get a more widespread foothold. The development of these novel viruses is part of a larger pattern, one which we are responsible for, one where Gaia is defending herself against us. Perhaps we need to flatten the curve of population growth, sooner rather than later, as the force of population expansion

is pressuring environments, creating the opportunity for viruses to jump species. Although world population is projected to stop growing by the end of the century, per capita energy consumption and CO2 emissions have steadily increased over the past 50 years, thus the pressure on habitat may still exist. We need to start protecting our naturally biodiverse regions, retaining them as the lungs of the planet but also to contain the potential pathogens that may bring us to our knees again. The northern hemisphere also needs to take responsibility in returning biodiversity to parts of our farmlands, and by financially supporting the protection of tropical ecosystems. We reap what we sow, in terms of the terrible consequences of lives lost and economies shut down. We need to wake up and start to anticipate the next environmental shock, change our behaviours and our laws before the planet works out how to live without us. n A fully referenced version of this article is online at www.passivehouseplus.ie 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.


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CHURWELL

CASE STUDY

ENERGY BILLS

£28

PER MONTH FOR GAS BILL (estimate, see ‘In detail’ for more)

Building: Deep retrofit & extension of 1960s brick house into 150 m2 near-passive home Location: Stockport, Greater Manchester Standard: AECB Standard

22 | passivehouseplus.co.uk | issue 34


CASE STUDY

CHURWELL

GOOD STOCK STYLISH STOCKPORT RETROFIT ACHIEVES RADICAL ENERGY SAVINGS

This inspiring project may be exactly what the deep retrofit sector needs: an example of how to turn a bog standard, cold suburban home of little architectural merit into a climate champion delivering outstanding levels of energy performance, comfort and health, all while transforming the building architecturally. Words by David W Smith

ph+ | churwell case study | 23


CHURWELL

CASE STUDY

CONSTRUCTION IN PROGRESS

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1 The derelict 1961 suburban house was bought in a sealed bid in March 2016; 2 & 3 floor to wall junction, with 150 mm Dow Styrofoam and damp proof course at underside of external wall insulation; 4 airtightness detailing around windows, with windows to sit within the external insulation layer; 5 roof to wall junction, showing Rockwool insulation meeting the external insulation, and airtightness taping; 6 close-up of the 280 mm Graphite EPS external wall insulation, bonded to existing brickwork with min 10 mm continuous adhesive to form airtight layer; 7 & 8 airtightness detailing and insulation to Lindab ductwork, for the mechanical ventilation with heat recovery system; 9 Tescon Vana breather membrane lapped out under the roof with tiles, with external insulation being installed.

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wo architects relocating from London with a young family took on the challenge of converting a derelict 1961 suburban house in Stockport, Greater Manchester into a passive house. Russel and Anna Hayden were excited about imposing their modern vision on what was then an ordinary property with brick and block cavity walls, in the hope of creating a replicable example that could be copied up and down the length of the country. The house they created has bright and spacious modern interiors that belie its relatively ordinary facade. And although the couple narrowly missed achieving the Enerphit standard for passive retrofits, their house performs superbly well and meets the slightly less demanding AECB Standard. “It was disappointing not to achieve passive house as I’m a great supporter of the thoroughness of the process, but we only just missed it. We achieved 1.18 air changes instead of the target of 1.0 and it doesn’t change the fact that the house is comfortable

24 | passivehouseplus.co.uk | issue 34

and pleasant to live in,” says Russel, who self-managed the project from his parentsin-law’s house across the road. “We also love the timeless Scandi simple look, and we’ve reused lots of things from the original house. We turned the rails on the stairs into door handles, and we sandblasted the cedar cladding from the dining room and put it in the hall.” The thermal performance of the retrofitted property has also easily surpassed that of the couple’s previous house in London – in both winter and summer. Two years ago, when temperatures rose into the mid thirties outside, the inside of their new house was no more than 25 or 26 degrees. “The roof light at the top of the stairs makes a huge difference as it creates a stack effect, so we only need one or two windows open downstairs to keep it cool,” Russel says. “Even when it’s less than five degrees outside, the one radiator downstairs is enough, and it barely comes on. Upstairs, the radiators are never needed.”


CASE STUDY

The clean indoor air has improved the sleep of Anna, who had bouts of insomnia in London. “It was noticeable as soon as we switched on the MVHR and felt the trickle of cool, filtered air that we both enjoyed deeper sleeps and vivid dreams. I’ve read scientific research suggesting the effect is caused by lower CO2 levels,” Russel says. Without dust, he adds, there are no spiders and even their dog’s hairs don’t settle and are easily sucked into the vacuum cleaner. Meanwhile, the triple glazing makes it so soundproof that the couple barely notice planes going overhead, and even slept right through a police car chase that ended in the garden of their next-door neighbour. The Haydens bought the derelict property for £310,000 in a sealed bid back in March 2016. It was in the popular Heatons area of Stockport, in Greater Manchester, which Russel says, “ticked a lot of millennial boxes”. “It’s green and leafy, with a good sense of community, but it’s a bit more suburban than nearby Didsbury. It was also opposite Anna’s parents’ house and they kindly allowed us to move in there while we got everything sorted,” he says. The couple hired a local builder who began ripping out the insides in April 2016. After he

had demolished all the internal walls and stripped out all the fittings, it left an empty shell. In the summer of 2016, the family left London, where Russel had worked for Nicholas Hare Architects, and Anna for Stanton Williams. They moved into the house of Anna’s parents, with their two children, Dexter, now eight, and Zoey, now five. To make the project affordable, Russel project-managed the retrofit from over the road. Meanwhile, Anna took a job as project director for the special exhibitions gallery at Manchester’s Science and Industry Museum, and the couple rented out their London property. The cost of converting the house came in at £170,000, but it would have been far more without Russel’s DIY skills. He had acquired a theoretical knowledge of techniques from the AECB CarbonLite Passivhaus Designer course and had shown a keen interest in sustainable design at his practice in London. “I procured all the materials and agreed with the builder what to do each day. I did all the taping as the sequencing is so critical and later on I did all the finishing off. The local builder was a fantastic help, spending many evenings on YouTube researching passive house techniques. That was a real bonus

CHURWELL

for us as it’s hard to describe accurately what’s required when builders haven’t done passive houses before. It’s one of the biggest challenges in the industry,” he says. Russel developed the design closely with environmental consultancy Enhabit, who provided passive house design services, airtightness testing, the MVHR system and the windows, and who have subsequently merged with fellow passive house specialist suppliers Green Building Store. “Russel didn’t need as much guidance as most of our clients because he was already knowledgeable,” says Akta Raja, director of Enhabit. “But one course doesn’t teach everything you need to know about the building physics of passive houses and getting all the detailing right. We helped Russel to build the PHPP model.” Even with the help of Enhabit and a design plan in place before they moved to Stockport, the practicalities of self-managing the project were far from straightforward. “I didn’t realise at the time just how passive house workmanship has to be a level above what the average builder is used to achieving. The course gave a flavour of how to do taping, for example, but it’s not the same as working on a whole house. You can

To make the project affordable, Russel project-managed it from over the road.

Photography: The Modern House

ph+ | churwell case study | 25


CHURWELL

CASE STUDY

have drawn every detail before you arrive on site, but lots of things crop up unexpectedly,” says Russel. Russel spent a lot of time over the Christmas period of 2016 laying industrial parquet flooring throughout the house while it was still empty, spending late nights sanding and re-sanding. “The floor is a key element as it provides a sense of unity throughout the house. The spaces all meld into one, which is lovely,” he says. As soon as he had finished installing the floor, the family moved into their new property in February 2017. Although it felt quite cold during that winter, the installation of 280 mm of thick expanded polystyrene to the exterior transformed the feel. The house has not been significantly altered structurally, which helped to keep costs down. The couple removed both kitchen walls and a chimney breast in order to create a large, open-plan space downstairs, with living room, dining area and kitchen. Upstairs they rebuilt partition walls in order to create three better-proportioned bedrooms, a bathroom and an en suite. Part of the large garage was converted into a shower room and utility space as part of a new timber-framed studio extension downstairs, which doubles up as an extra bedroom for guests. The extension is clad with cedar square-edge boards that Russel collected from a sawmill in Hereford and then air-dried naturally in the back garden. The same boards were used to clad the replaced tumbledown porch. On the roof, the old 1960s tiles were stripped off. New Larsen-truss type beams were fixed to the side of the existing rafters to make up the depth for almost 400 mm mineral wool insulation, before installing the new concrete tiles. On the ground floor, Russel and Anna opted to keep the existing slab and apply the insulation and screed on top, then the oak parquet flooring, which reduced some of the head space. To gain back some head space, they left the plasterboard off the ceiling joists, which also provided a more rustic feel. “It raised a few eyebrows, but we like it as it’s gnarly and a bit rough,” Russel says. “We also had to jet-blast the joists and underside of the floorboards [above ground floor] and paint them with intumescent paint to satisfy fire regulations.” Having not quite reached the Enerphit target for airtightness, Russel spent a day looking for small holes. But he soon realised that fixing the issues would require unpicking a lot of the structural work and cost a fortune. The primary air barrier for the original walls was the layer of continuous 10 mm thick adhesive that joined the external insulation to the brickwork (for the new extension walls it was 18 mm SMARTPLY OSB 3 board taped at junctions). “Our weak point was where the garage and the extension joined onto the rectangle of the house. There were quite a few areas where we didn’t have the parge coat. Next time, I would pay more attention to the continuity of the outer later, especially where you have the roof [of the extension] coming into the

26 | passivehouseplus.co.uk | issue 34

CONSTRUCTION IN PROGRESS

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1 & 2 Construction of the new roof with 325 mm deep OSB ribs creating cavities for the installation of new Rockwool insulation; 3 insulation and airtightness work around the opening for a new triple-glazed Fakro rooflight; 4 construction of the new timber-frame extension with 150mm studs waiting for insulation; 5 Insula structural thermal break under steel column; 6 Lindab spiral galvanised ducting for the Paul MVHR system.


CASE STUDY

cavity wall,” he says. “Once the air gets in there, there’s nothing you can do. When we dry lined the interiors, we could also have made them even more airtight as a second line of defence in case the outer one wasn’t working perfectly.” Enhabit’s Akta Raja sees the project as a great success. “It’s tricky when you’ve never done it before and you’re project managing, to achieve passive house, especially with an existing building. But it’s a great way of setting a target and there’s no reason to feel a failure if you don’t quite reach it. The energy consumption is still 90 per cent better than it would have been otherwise and all that carbon annually will be saved for the rest of a lifetime. Russel and Anna have created a genuinely brilliant house which is comfortable to live in and has great indoor air quality,” she says. She believes the AECB Standard is an excellent alternative to passive house. The AECB, of which the Passivhaus Trust is a subsidiary – was instrumental in bringing the passive house standard to the UK. Based on the same methodology but recognising that meeting the passive house standard can prove too challenging in some situations, the AECB Standard specifies good low energy performance via a fabric-first approach, utilising the passive house methodology and design software, PHPP. “Not only is it easier to meet, but members of the AECB are able to self-certify, which saves them the extra costs of passive house accreditation,” she says. “The project was a good learning experience and [Russel] has brought his deeper understanding of energy performance to his new work.” The AECB told Passive House Plus it is now poised, however, to allow only certified passive house designers and other suitably qualified individuals to self-certify projects to improve on quality assurance. Others will be able to hire qualified individuals for certification. Russel Hayden now works as an architect out of the house’s studio extension. The project was a good learning experience and he has brought his deeper understanding of energy performance to his new work. “Typically, I’ve been designing kitchen-diner extensions on the back of leaky Victorian semis. Clients like the juxtaposition of contemporary designs with the older house. I’ve also been involved in retrofitting older houses to make them more energy efficient. To date, I’ve not been commissioned to do a passive house, but I have the understanding now and I’d jump at the chance,” he says.

CHURWELL

SELECTED PROJECT DETAILS

Client: Anna & Russel Hayden Architects: Hesketh Hayden Passive house designer, M&E engineer, windows & doors: Enhabit Main contractor: Beswick & Son Electrical contractor: McDermott’s Electrical Services UK Airtightness testing: Peak Acoustics & Enhabit Mechanical contractor: David Holden Plumbing & Heating EWI installer: Pegasus Externals External wall insulation: S and B EPS Ltd External insulation system: JUB Systems UK Wall & roof insulation: Rockwool Floor insulation: Kingspan Sub-DPC insulation: Dow Thermal breaks: Insula Roof windows: Fakro Cedar cladding: HW Morgan and Sons Screeds: Foggs Floors Flooring: UK Wood Floors Radiators: Stelrad MVHR: Paul Ventilation ductwork: Lindab Sanitaryware: Duravit Roofing materials: Burton Roofing OSB: MEDITE SMARTPLY

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.co.uk

A VERY MODERN HOUSE

L

ast year, Anna and Russel’s house was featured on the online journal of leading estate agency The Modern House, who kindly provided us with the main set of images that accompany this article, and who are effusive in their praise of the property. The Modern House has been credited by Esquire magazine as “rewriting the rulebook on estate agency,” and the agency says it “helps people to live in more thoughtful and beautiful ways”. “We profiled Anna and Russel at their home in Stockport as part of a series looking at wellbeing in the home,” The Modern House’s senior content editor Charlie Monaghan told Passive House Plus. “What we found was that, for Anna and Russel, building to passive house standards not only contributed to their feeling of physical wellness but came with immeasurable mental benefits too.” The agency also sees sustainability as growing considerations in the hous-

ing market. “Sustainability and energy efficiency are becoming increasingly important factors in a buyer’s decision to purchase a home as awareness of environmental issues are raised and buyers become more mindful of their carbon footprint,” says the company’s commercial operations director, Rosie Falconer. And while she says that the nature of a property and its location are still the most important factors for buyers, environmental concerns are gaining more weight. “The environment is becoming more prevalent in the social consciousness and design is always a response to society’s collective concerns. As such, we are noticing an increased focus on energy efficiency particularly in new builds, which we only see as strengthening over the coming decade.” You can read The Modern House’s interview with Russel and Anna at tinyurl. com/russelandanna.

Passive house workmanship has to be a level above what the average builder is used to.

ph+ | churwell case study | 27


CHURWELL

CASE STUDY

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28 | passivehouseplus.co.uk | issue 34

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CASE STUDY

CHURWELL

IN DETAIL Building type: Deep retrofit to link-detached two-storey house built 1961, plus new single-storey timber frame extension to rear. Finished floor area 150 m2. Location: Heaton Moor, Stockport Budget: £170,000 project cost Completion date: November 2017 Space heating demand (PHPP): Before: 423 kWh/m2/yr After: 25 kWh/m2/yr Heat load (PHPP): Before: 143 W/m2 After: 13 W/m2 Heat loss form factor (PHPP): 3.6 Overheating: 0% of year above 25C Number of occupants: 4 + dog Primary energy demand (PHPP) Before: 578: kWh/m2/yr After: 92 kWh/m2/yr Environmental assessment method: N/A Energy performance certificate (EPC) Before: G After: N/A Measured energy consumption: Before: N/A After: 69 kWh/m2/yr (Jan-Dec 2019, based on meter readings for electricity use) Energy bills Before: N/A After: £338 on gas annually (Oct 2018 - Oct 2019); £628 on electricity annually (Oct 2018 Oct 2019) Airtightness (at 50 Pascals) Before: 14 air changes per hour (ACH, estimated) After: n50: 1.18 ACH. Air permeability: 1.123 m3/ hr/m2. Both at 50 Pascals.

Ground floor: Before: Uninsulated concrete slab with embedded underfloor heating. After: Existing concrete slab (underfloor heating no longer used) followed above by 100 mm Kooltherm K3 insulation, 80 mm Retanol Xtreme screed, 25 mm industrial oak parquet finish. U-value: 0.187 W/m2K. Existing walls Before: Existing brick/concrete block walls with empty 70 mm cavity. U-value average: 2.03 W/m2K After: 280 mm Graphite EPS external wall insulation with JUB silicone render finish to existing walls. Insulation installed in one layer; bonded to brick with min 10 mm continuous (not dabs) adhesive to form airtight line. Mechanical fixings are 335 mm EJOT STRU 2G countersunk screws with insulation cover at 7/m2. U-value: 0.120 W/m2K. Below ground: 150 mm Dow Styrofoam from damp proof course (DPC, at underside of EWI) down to footings. Existing roof Before: Concrete tiles on battens on felt, no insulation After: Concrete tiles, battens and c/battens followed underneath by Pro Clima Solitex underlay (wind-tight line), continuous 60 mm Rockwool Hardrock DD slabs; roof structure built up with 325 mm deep OSB3 ribs fixed to side of rafters; 330 mm Rockwool Flexi between ribs, 18 mm SMARTPLY OSB3 boarding to underside of rafters, joints taped with Tescon Vana (airtight line). U-value: 0.111 W/m2K Extension floor: New 125 mm concrete slab with 200 mm Kooltherm K3 insulation, 80 mm Retanol Xtreme screed: U-value: 0.097 W/m2K. Extension walls: Vertical cedar cladding on battens and counter battens externally, followed inside by Solitex Fronta Quattro breather membrane, 140 mm Rockwool DD slabs, 150 mm timber stud frame with 150 mm Rockwool Flexi between, 18 mm SMARTPLY OSB3 boarding (airtight line), battens and plasterboard as service void. U-value: 0.119 W/m2K.

Extension flat roof: GRP waterproofing system on OSB3 tongue & groove decking externally, followed underneath by firring battens forming vented zone, Solitex Plus membrane with Tescon Naidec taped joints (wind-tight and waterproof line), 60 mm Rockwool Hardrock DD slabs, 300 mm deep OSB3 ribs with 310 mm Rockwool Flexi between, 18 mm SMARTPLY OSB3 boarding (airtight line), battens and plasterboard as service void. U-value: 0.179 W/m2K Windows & doors Before: Single glazed, timber windows and doors. Overall approximate U-value: 2.48W/m2K New windows & doors: Enhabit Scandinavian Slimline windows. Timber with aluminium cladding. Average U-value of glazing: 0.54 W/ m2K. Average U-value of frame: 1.29 W/m2K. Average g-value: 0.52 Roof window: Fakro FTT U6 triple glazed roof windows with thermally broken timber frames. U-value: 0.81 W/m2K Heating system Before: Underfloor heating to ground slab and open fireplace. Upstairs unknown. After: Viessmann 200-W 19kW system boiler with Vitotronic 300-K weather compensator; radiators with thermostatic valves. 250L Stelflow S250T twin coil cylinder with cylinder stat and backup 3kW electric immersion heater. Ventilation Before: No ventilation system. Reliant on infiltration, chimney and opening of windows for air changes. After: Paul Novus 300 heat recovery ventilation system, with Lindab spiral galvanised ducting. Passive house certified heat recovery efficiency of 94-94%. Green materials: Cedar cladding from Hereford, timber frame to extension, parquet flooring. Items re-used from original house include internal cedar cladding, balustrades as door handles, steel storage shelves as fence panels, old brick walling as hardcore.

ph+ | churwell case study | 29


DEVON

CASE STUDY

SEA CHANGE L U X U R Y Z E R O - E N E R G Y PA S S I V E A PA R T M E N T S RISE ON THE DEVON COAST

Built mostly with clay blocks and sited above the sandy shores of Seaton, on the Devon coast, this new development of eight high-end apartments not only meets the passive house ‘plus’ standard — meaning it pairs the requisite ultra-low energy fabric with a substantial amount of renewable energy generation — but it also boasts serious attention to the use of ecological and healthy materials. Words by David W Smith

30 | passivehouseplus.co.uk | issue 34


CASE STUDY

DEVON

ENERGY BILLS

£0.91

PER DAY FOR ALL ENERGY USE* *One apartment, based on 10 months monitored data Building: Five-storey block of eight luxury apartments, 101 m2 to 138 m2 each Location: Seaton, Devon Standard: Passive house plus certified

ph+ | devon case study | 31


DEVON

CASE STUDY

T

he county of Devon has been a hotspot for passive house development for more than a decade. Exeter City Council, in particular, has backed numerous schemes, including affordable housing schemes and a leisure centre with a swimming pool. Recently, the £3 million Seaton Beach development on Devon’s coast became the first multi-unit residential building in Britain to achieve passive house ‘plus’ certification. The project also won awards for best sustainable residential development in the UK and best apartment in Devon (for its top-floor penthouse) from the International Property Awards. The presence in Exeter of passive house architects, Gale & Snowden, has helped to accelerate the trend for large scale passive

32 | passivehouseplus.co.uk | issue 34

house development in the area, and the five-storey Seaton Beach was no exception. Although the original design was produced by a different architect, Gale & Snowden later worked on the passive house elements. At the outset, however, Mike Webb, managing director of Seaton Beach Developments Ltd (SBD), had not intended to build to the passive house standard. Webb simply wanted to develop a block of eight luxury apartments with sea views in this small coastal town, near Lyme Regis. “Seaton Beach was a rare chance find for a speculative development. We were visiting friends in Devon in May 2015 and happened to walk past a large Victorian property for sale on the sea front. We quickly formed a development company with a friend who backed the

venture, and bought it for £515,000 two weeks later,” says Webb, who lives in Tenbury Wells, in Worcestershire, where he and his wife own rented properties and a solar installations company. The rather downtrodden and unremarkable old building was knocked without issue, and Webb’s co-directors, Mike and Anne Dowling, selected Exeter architects Clifton Emery Design to produce plans for the new tower. Webb was happy with Clifton Emery’s design, describing it as “beautiful, curved and artistic”, but the local planning officer was less enthusiastic and, consequently, the planning committee denied permission by one vote in July 2016. Their concerns centered on the height and depth of the building and its relationship to the properties adjoining the


CASE STUDY

DEVON

It’s an attempt to look at the living environment more holistically.

narrow site. But Webb believes they “failed to see the regenerative potential”. The battle for planning permission went on for several months. In the end, SBD turned to the local design review panel for support. The panel endorsed the scheme and, finally, East Devon District Council approved planning in November 2016. At this point it became clear that the south-facing orientation and form factor made it possible to build to the passive house standard. “Over the years I’ve become passionate about passive houses and it seemed a great way to leave a legacy to the earth,” Webb says. “I realised this development was the best chance I would ever get to do that.”

Photography: Norrsken / Dug Wilders

To be confident of achieving the standard, Webb needed a practical specialist in passive house design to complete the work started by Clifton Emery. In February 2017, when Webb met architect Tomas Gaertner – the man he dubs “the German genius” – he knew he had found the right man. Gaertner was at that time a director at Gale & Snowden. He had trained and worked as an architect in Germany, the birthplace of passive house. But he had only designed a handful of residential passive houses there before moving to the UK in 2007. Gartner’s arrival in Exeter proved timely, as his skills in energy efficient design were in great demand. The influential Emma Osmundsen, managing director at Exeter City Living

ph+ | devon case study | 33


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34 | passivehouseplus.co.uk | issue 34

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CASE STUDY

group — the local authority’s development arm — provided the political clout that made a lot of passive house development possible. Gaertner’s first passive house scheme in Exeter was the influential Knights Place affordable housing scheme, in 2010. Now working for SE3Design, he has continued to collaborate with Osmundsen, mainly on larger commercial developments (Gaertner left Gale & Snowden part way through this project and Lawrence Millyard took over as project architect). Gaertner did not need to make major structural changes to Clifton Emery’s design for Seaton Beach. His main role was to take charge of the passive house detailing. “There were no drastic changes, although the final design was a bit higher to allow for [more] insulation in the penthouse, and to make space for the roof terrace,” he says. Clifton Emery’s plan, however, had proposed using a concrete frame for the entire structure, but Gaertner says this would have been more expensive and made the detailing of airtightness junctions more difficult. Instead, Gaertner proposed building the ground floor in concrete, using poroton clay blocks from the first to the third floors, then installing a timber frame for the penthouse on the fourth floor. He explains that with a concrete frame, structural elements such as columns and floors are separated from the space-enclosing elements (i.e., the external walls) by movement joints and gaps between infill wall panels and ceilings, to allow for deflection. For airtightness, this would require flexible junction details using membranes and tapes. “Tape details — especially in a wet, dusty

construction — are higher risk as substrates are often not adequate and tapes are prone to delaminate and fail,” Gaertner says. “The block construction allowed for a simple plaster detail for airtightness without any junction tapes.” The poroton blocks are also aerated and thus provide insulation, which appealed to Gaertner as it meant he could avoid the use of plastic insulation for most of the building. The top floor steps back from the rest of the building below, so to reduce its weight and allow it to be built without additional steel beams or lintels, it was built with a timber frame. Gaertner’s approach to passive houses has been influenced by building biology, the construction philosophy that emerged in Germany in the 1960s. “It’s an attempt to look at the living environment more holistically. We consider the impact of the materials on both the living environment and the ecological environment. We try to be energy efficient and use renewables, but at the same time not compromise on materials. It’s about avoiding poor air quality and mould. We also follow the World Health Organisation’s standards for healthy indoor environments,” he says. At Seaton Beach, for example, the use of monolithic clay block follows the principles of building biology. “It’s highly hygroscopic [meaning it can absorb and release moisture] and moves moisture around in the building, which will help to regulate internal humidity,” Gaertner says. Another feature of Seaton Beach in keeping with building biology was the use of AURO natural mineral paints. “They contain no additives, such as fungicides. The higher lime

DEVON

We try to be energy efficient, but not compromise on materials.

ph+ | devon case study | 35


DEVON

CASE STUDY

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CASE STUDY

content means the paint acts as an anti-fungal and doesn’t create a chemical problem. In contrast, when you use non-permeable emulsion paints, the moisture cannot move into the walls quickly enough. The only way to get rid of it then is with ventilation. It’s especially important in winter to have the buffering potential in the walls.” Following building biology principles is easier in the south west of England than in some other parts of the UK because the region has a mild climate, Gaertner says. This means it’s possible to reach the passive house standard with less insulation. “It’s inevitable when you push for higher insulation levels, especially on commercial developments, that you end up using some petrochemical materials because the projects otherwise become too expensive,” he says. “With the milder climate, we can get away with much less insulation… [the poroton walls here for example have a U-value of 0.26).” Rather than install a lot of insulation at Seaton Beach, Gaertner maximised the free energy savers from the block’s good orientation and form. It was especially critical to pay attention to the window detailing. The original design had curved triple glazed windows, which had to be replaced with straight-edged ones. The biggest problem with the original design was a three-metre-high, three-sided glass window in the penthouse. It provided beautiful sea views but would have acted like a greenhouse. Gaertner designed a lot of solar shading to prevent overheating, reducing the glazing to a more sensible proportion while retaining the views. That solar shading was provided by the defining aesthetic feature at Seaton

Beach – the building’s generous curved sea-facing balconies from Surrey-based specialists Balconette – including curved glass balustrades and marine grade chrome handrails to make the most of the sea views. This feature serves as a striking counterargument to the notion that the passive house standard, which is easier to achieve with simpler, box-like forms, leads to prosaic buildings, even where the envelope remains box-like, as in Seaton Beach. Good architecture embraces restrictions. With a little design ingenuity, and the use of Schoeck Isokorb thermally broken balcony connectors, a box-like building is wrapped in beautiful yet functional curves, while enhancing rather than compromising the building’s energy performance. A mechanical ventilation system further enhanced energy saving. “All these various measures meant we were able to compromise on the U-values and use materials with benefits for the environment, ecology and health,” he says. Each apartment has a Genvex Combi 185 BP combined ventilation and air-to-air heat pump, which can heat up 185 litres of stored water. To back it up, there are three electric towel rails and two wall-mounted electric radiators in case of extreme weather. On the roof, there are 49 solar PV panels with a maximum output of 16kW and an annual yield of 14,234 kWh. The addition of the solar panels along with the Genvex heat pump took the PHPP calculations into the “plus” category. Webb attributes the success of the Seaton Beach project to what he calls “education and collaboration”. The “collaborative” element

DEVON

SELECTED PROJECT DETAILS Client: Seaton Beach Developments Architect: Gale & Snowden Initial/planning architect: Clifton Emery Design M&E engineer: Gale & Snowden Passive house & building biology consultants: Gale & Snowden M&E contractors: Total Home Environment & Fords of Sidmouth Civil & structural engineer: StructureHaus Main contractor: Classic Builders (SW) Ltd Quantity surveyors: Randall Simmonds Mechanical & electrical contractor: Fords of Sidmouth Airtightness tester: New Barton Contracts Heating & ventilation system: Total Home Environment Passive house certifier: WARM Timber frame: Allwoods Cellulose insulation: Warmcel, via Smart Construction SW External wall insulation: McCarthys Contractors Ltd Poroton blocks: Wienerberger Thermal break: Schoeck Balcony systems: Balconette Floor insulation: Dow Airtightness products: Green Building Store Airtight OSB: MEDITE SMARTPLY Windows & doors: Norrsken Roof windows: Velux Shading: RSL Roller Shutters Zinc cladding: Pace Roofing & Cladding Carpets: Axminster Carpets Roofing: Bauder Solar PV: Wind & Sun Ltd Lighting: Fords of Sidmouth

ph+ | devon case study | 37


DEVON

CASE STUDY

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38 | passivehouseplus.co.uk | issue 34


CASE STUDY

DEVON

CONSTRUCTION IN PROGRESS

1

2

3

4

5

6

7

8

9

Detail showing Isokorb thermal breaks where the balconies meet the Porotherm clay block walls

1 Work begins on the project with the knocking of the existing structure, a large, unremarkable Victorian property on the seafront; 2 & 3 construction under way of the ground floor structure, which features 300 mm Dow XPS insulation; 4 the bulk of the structure was built using poroton clay blocks, which are aerated and thus provide insulation; 5 plastering of this blockwork internally provided a straightforward way to make the walls airtight; 6 windows are Norrsken composite timber and marine grade aluminium triple glazed units, with solar shading provided by the defining aesthetic feature at Seaton Beach – the building’s generous curved sea-facing balconies; 7 the fourth floor penthouse apartment was built with a timber frame, and steps back from the rest of the building below to reduce its weight; 8 ductwork for the Genvex combined ventilation and air-toair heat pump, installed in each apartment; 9 the roof of the building, five floors up, is insulated with Warmcel cellulose insulation and finished with a Bauder membrane; also seen are the openings for two Velux tripleglazed rooflights.

ph+ | devon case study | 39


DEVON

CASE STUDY

came from the close cooperation of all parties, many of whom had already worked together on other passive houses. Meanwhile, the “education” of the on-site workers in how to build passive houses was important because the building contractor Classic Builders SW was not an experienced specialist in the field. At the start, Webb took a team of 30 building workers for a day’s training with the passive house specialist Peter Warm, in Plymouth. “It taught them everything they needed to know about building passive houses, which put everyone’s minds at rest as they were under a lot of pressure to deliver,” he says. Additionally, Robin Pike, the Classic site manager, took on the role of airtight champion and delivered some exceptional airtightness results. Webb also engaged quantity surveyors Randall Simmonds and structural engineers StructureHaus, who had previously worked with Tomas Gaertner in Exeter. Despite the well-informed team, the project overran by six months. It was completed after 18 months in October 2019. Some of the delays were down to the strong, squally winds that blew in from the sea. “One example was when five articulated lorries arrived from Bristol in March last year carrying concrete planks, but we had to send them back as it was too windy to lift anything,” Webb says. “Using

40 | passivehouseplus.co.uk | issue 34

higher quality products drove up the price and led to time overruns, but we wanted to use the best materials, such as the zinc shingles that clad the penthouse.” Webb already had several years’ experience of working with renewable technologies and qualified as a passive house consultant during the build. He acted as clerk of works, travelling regularly from Worcestershire to Devon. In July 2019, one of the apartments became a show home and in August, the first permanent resident moved in. Webb also decided in January 2020 to turn the penthouse apartment into an art gallery, partly to showcase local artists, but also to attract potential buyers. To date, Webb has sold five of the eight units, and another potential sale is on hold because of the fallout from Covid-19. The penthouse was put on the market in time for summer, but again it had to be postponed due to Covid-19. Once the Covid-19 crisis is over, Webb will resume his plans for more passive house developments near his home in Worcestershire. He also acts as a consultant for potential passive-house builders. “With everything I’ve learned on the Seaton Beach project, I could save people a fortune on architects’ fees and help them work closely with the designers of their homes,” he says.

With the milder climate, we can get away with less insulation.

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.co.uk


CASE STUDY

DEVON

IN DETAIL Building type: Five-storey new build apartment block of 8 units with 870.7 m2 total floor area. Apartments ranging in size from 101 m2 to 138 m2. Location: Seafront site in Seaton, Devon Completion date: November 2019 Budget: £3.5 million (inc. site purchase of £515,000) Passive house certification: Passive house plus certified Space heating demand (PHPP): 12 kWh/m2/yr Heat load (PHPP): 11.2 W/m2 Primary energy demand (PHPP): 100 kWh/m2/yr Primary energy renewable (PHPP): 54 kWh/m2/yr Overheating (PHPP): 1% of year above 25C Number of occupants: PHPP based on 20.1. Actual to date 6-10 as some are second homes. Airtightness (at 50 Pascals): 0.5 ACH Energy performance certificate (EPC): All units A-rated (97-99) Measured energy consumption: Unit X is occupied full time by a single person and from 4 August 2019 to 4 June 2020 (10 months) total electricity imported was 2,009 kWh. A further 744 kWh was used direct from the 2 kWp solar PV array. When PV production exceeded the apartment’s demand, a further 1,184 kWh of PV produced electricity was exported. The other apartments & the communal areas can use this first, before being exported to the grid. From the 10 months actual consumption (and

applying May data for June and July), an annual use of 2,753 kWh can be forecast. The Genvex Combi MVHR & heat pump unit in Unit X uses 1,457 kWh/yr (121 kWh per month avg). The remaining 1,295 kWh includes 3 x towel rails which are designed to meet 50% of heat demand. See below for solar PV electricity production. Energy bills: For Unit X above, the total annual energy costs are £333. Thermal bridging: All thermal bridges were numerically modelled to demonstrate compliance with the passive house standard. Ground floor: 250 mm compacted base followed above by 25 mm sand blinding, 1 mm DPM, 300 mm Dow XPS insulation, separating layer, 200 mm reinforced concrete slab, 10 mm acoustic mat & 65 mm screed. U-value: 0.141 W/m2K Walls Ground floor: 16 mm Alsecco render externally followed inside by 200 mm Neopor EWI, 215 mm concrete block, 15 mm plaster. U-value: 0.194 W/m2K First to third floors: 16 mm Alsecco render externally followed inside by 365 mm Poroton T10 block by Wienerberger, 15 mm Plaster. U-value: 0.259 W/m2K Fourth floor: Factory-built timber frame by Allwoods with marine grade zinc cladding externally on 22 mm ply, followed inside by 50 x 50 mm treated battens and counter-battens, pro clima Solitex Plus membrane, 12 mm OSB board, 180 mm Warmcel-filled TJI stud, 15 mm taped and sealed Smartply Propassiv, 50 mm service cavity and 15 mm plasterboard & wet plaster skim internally. U-value: 0.141 W/m2K Roof: Factory-built timber frame by Allwoods with Bauder membrane externally on 22 mm ply, followed inside by 50 x 50 mm treated battens, 22 mm ply, 310 mm Warmcel-filled TJI stud, 15 mm taped and sealed Smartply Propassiv, 50 mm service cavity and 15 mm

plasterboard & wet plaster skim internally. U-value: 0.081 W/m2K Windows & external doors: Norrsken composite timber and marine grade aluminium triple glazing, with argon filling and an overall U-value of 0.82 W/m2K average. Roof windows: 3 x Velux GGU triple glazed roof windows. U-value: 1.01 W/m2K Heating & MVHR combined system: Genvex Combi 185 BP MVHR unit combined with micro air source heat pump (330W) with 2 x 71W fans provides 50% of heat demand. This is topped up by 3 x 150W direct electric towel rails & then for extreme weather 2 x Dimplex wall-mounted radiators. The Genvex Combi unit also heats 185L of stored hot water & also has a 1 kW immersion for faster recovery. The Genvex Combi 185 is Passive House Institute certified to have heat recovery efficiency of 71.2%. Water: Above ground rainwater harvesting tanks, low flow fixtures in all areas. Electricity: 49 panel REC 320W solar photovoltaic panels (covering 80.2 m2) with maximum output of 16 kW & annual yield of 14,234 kWh. The array feeds the 8 x 2 kWp inverters, one for each apartment. Sample unit: Based on the first 10 months data – again with May data applied to June and July - Unit X is projected to produce 2,034 kWh of electricity, of which 1,184 kWh is exported to other units/ communal facilities before any excess is exported to the grid. The full building receives a £1,000 feed-in tariff each year which is used to subsidise residents’ service fees. Green materials: Recycled wood from demolished house used for pergola, stone from demolition used for boundary wall, Warmcel cellulose (recycled newspaper) insulation, Auro natural paints, 100% wool carpets locally sourced from Axminster carpets, all timber from PEFC certified sources, clay blocks recyclable at end of life.

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COUNTY DUBLIN

CASE STUDY

ENERGY BILLS

€125

PER MONTH FOR ALL ENERGY (estimate, see ‘In detail’ for more)

Building: Deep retrofit & extension of 1960s cavity wall house Location: Blackrock, Co Dublin Standard: A3

42 | passivehouseplus.co.uk | issue 34


CASE STUDY

COUNTY DUBLIN

NORTHERN EXPOSURE Deep energy retrofit transforms north-facing Dublin seaside semi

Even though its stunning views lay directly northward, simple design, good detailing and lots of insulation have turned this 1960s semi on the edge of Dublin Bay into a warm and light-filled low energy home. Words by John Cradden

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COUNTY DUBLIN

CASE STUDY

I

f you’re an experienced architect who has taken the opportunity in recent years to learn about building performance and energy efficiency, the chances are it will have a seismic impact on the way you design any future projects. One upshot is that projects like this attractive retrofit of a 1960s four-bed semi-detached house in Blackrock, Co Dublin, are all about achieving an equal balance between quality design and thermal performance. The rear of the house is north facing but with probably one of the best views anywhere of Dublin Bay, taking in the iconic red and white twin chimneys of the Poolbeg power station all the way over to Dun Laoghaire harbour. When Ruth and Tom Jenkinson fell in love with and bought the original property in 2017, it was an E-rated dwelling with a small 1980s style extension that hadn’t been lived in for some time. But they quickly commissioned Trevor Dobbyn of Fabrica Architects with a brief for a modern, well-insulated house that maximised the view, and which needed minimal maintenance. It also needed to be adaptable to living on the ground floor. The accommodation brief was achieved

The rear of the house is north-facing but with one of the best views of Dublin Bay.

44 | passivehouseplus.co.uk | issue 34

by a short, single-storey extension to the front and a generous two-storey extension to the rear, while also being retrofitted to an A3 building energy rating (BER). Naturally the aim was to open up those amazing views, so the primary challenge was how to offset the large amount of glazing that would be needed at the north-facing rear with the potential for heat loss. “Therefore, the overall performance of the building was of equal importance to the quality of the interior looking out onto Dublin Bay,” says Dobbyn. Having worked for the prestigious Dublinbased practice de Blacam & Meagher Architects since qualifying in 1997, Dobbyn was one of the first to enroll in DIT’s diploma in thermal bridge assessment in 2013, which he followed up in 2016 with the same institu-

tion’s professional energy skills in NZEB course, and also the RIAI environmental accreditation. “It’s very difficult to un-see a thermal bridge once you’ve learned about them,” he says. Before that, “the kind of physical performance of the building would have been further down the list originally when you’re doing designs, so when you learn that kind of skill, it lends itself to trying to balance a building that’s as efficient as possible but is also aesthetically pleasing. “So, there’s a bit of a trade-off depending on what you’re trying to achieve... some bits you might feel the design is worth pushing more than the thermal performance and vice versa. You’re trying to detail it so you’re not causing thermal bridges... and you can be kind of restricted in how it looks if you’re


CASE STUDY

just purely going for thermal performance.” This approach explains details like the slender pillars at the front, supporting the large canopy and covered entrance that gives vital shading at the south-facing facade, but which lightens the look and closely matches the shape and feel at the rear. “The use of shading canopies and projections allows the front and rear elevations to be broken into more slender forms,” Dobbyn says. “They are outside the insulation envelope so they can be much lighter. While the rear canopy is technically not for solar shading, it is angled to face Dun Laoghaire harbour, and allow the owner to have his morning coffee in shelter, while also allowing me to hide the parapet above the sliding doors.” The 1960s semi-D is of a solid-block construction, so in order to maintain the consistency in terms of the construction materials and method, it made sense to opt for a masonry build for the extension, with the whole shell wrapped in EPS external insulation, finished with an acrylic external render. Other fabric measures included passive certified, triple glazed timber alu-clad

Photography: Artur Sikora

windows all round (with exception of the rooflights), and insulated stone floors with underfloor heating, while the pitched roof was rebuilt with new counter battens, airtight membrane and Xtratherm insulation boards. The garden is fairly small, but another touch was to install a pillarless safety glass wall at the end to preserve the view, particularly from a sitting position. A 12 kW Panasonic Aquarea air source heat pump handles the heating duties, while a Lunos E2 demand-controlled heat recovery system looks after ventilation. Supplied by Galway firm Partel, it’s a decentralised ventilated system with automated humidity control. It was chosen because it is a ductless, self-contained system, mitigating the need to do extensive modifications to install ductwork, particularly given the steelwork required for the extension. Coming from a traditional gas boiler and central heating system, the adjustment to this new heating-and-ventilation arrangement took a while for the Jenkinson’s. “It is simple to operate. You choose the temperature you want at each room thermostat and

COUNTY DUBLIN

the machine does the rest,” says Ruth. “It takes longer to build up or reduce the heat than a gas boiler system.” She adds that the ventilation certainly enhances the air quality but is audible . The final airtightness test was delayed pending the arrival of a new front door, so results were not available at the time of writing, but Dobbyn reports that while access to the relevant points in the building for airtightness measures was OK, some areas were a little tricky to get at, such as where there the roof rafters met the adjoining property, and the existing first floor joists. In all, the build progressed fairly smoothly starting in May 2018 and finishing in April 2019, although the completion was delayed because the windows were some six weeks late. “We were thrilled with the layout, ambience and the modern comforts,” says Ruth. “We were particularly pleased with the upstairs sitting room and the added brightness it gives to that level of the house. “Living in it has been a joy. We installed solar panels but we’re not sure how cost effective they are and perhaps we need

ph+ | county dublin case study | 45


COUNTY DUBLIN

CASE STUDY

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46 | passivehouseplus.co.uk | issue 34


CASE STUDY

COUNTY DUBLIN

CONSTRUCTION IN PROGRESS

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9

1 & 2 The front and rear facades of the 1960s semi-detached house prior to renovation; 3 work underway on removing the existing small extension and windows at the rear of the house; 4 works carried out during the renovation included rebuilding the original pitched roof; 5 the new two-storey extension at the rear was designed to maximise the spectacular views across Dublin Bay, despite being north-facing; 6 underfloor heating installed throughout the ground floor; 7 & 8 pro clima Intello membrane to extension ceiling and roof window opening, with airtightness taping; 9 new alu-clad triple-glazed sliding doors were installed to the garden extension.

more panels. We certainly have a warm and comfortable home and the bills reflect a modern build.” Dobbyn is happy that the final result has achieved that vital balance between energy performance and design that completely fulfils the brief. “The clients have confirmed no issues with the storms during the year with the extent of glazing to the rear, and the view is just incredible,” says Dobbyn. If the Jenkinson’s have been confined to this home during the Covid-19 lockdown, you can certainly think of worse places to be.

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.co.uk

SELECTED PROJECT DETAILS Architect: Fabrica Architects Heat pump & underfloor heating: Base Engineering Ltd Civil & structural engineer: OBA Consulting Main contractor: Mark Whelan Building Services Mechanical contractor: John Thompson Plumbing Electrical contractor: Action Electrical Contractors Airtightness products: Ecological Building Systems External insulation: Green Zone Products Windows & doors: Passive Window Systems Ltd Roof lights: Cubo Screed: Ultraflo Flat roofs: Laydex Building Solutions Wood stove: Heatco Decentralised MVHR systems: Partel Solar PV: Base Engineering

We were thrilled with the layout, ambience and the modern comforts.

ph+ | county dublin case study | 47


COUNTY DUBLIN

CASE STUDY

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CASE STUDY

COUNTY DUBLIN

IN DETAIL Building type: Deep retrofit & extension to 147 m2 existing semi-detached house from 1960. New converted roof space, and single-storey extension to front. Finished floor area 183 m2. Location: Blackrock, Co Dublin Budget: Undisclosed Completion date: April 2019 BER Before: D1 (251 kWh/m2/yr) After: A3 BER (55.5 kWh/m2/yr) Energy performance co-efficient (EPC): 0.393 Carbon performance co-efficient (CPC): 0.285 Energy bills (after): The Jenkinson’s told Passive House Plus that their total electricity bill for 2019 (the house is all-electric) was approximately €1,500, which averages out at €125 per month for all heating, lighting, ventilation and appliances. Airtightness (at 50 Pascals): Incomplete, awaiting new front door to complete test. Ground floor Before: Uninsulated concrete floor & uninsulated suspended timber floor throughout. After: New insulated stone floor with underfloor heating throughout; 15 mm vein cut roman travertine on de-coupling matt, followed beneath by 55 mm Ultraflo liquid hemihydrate screed with underfloor heating & 30 mm edge insulation, 200 mm Ballytherm BTF floor insulation, 150 mm concrete slab & 40 mm edge insulation. U-value: 0.9 W/m2K

Walls Before: Solid concrete block walls with no insulation. After: 100 mm enhanced Atlas EPS insulation and acrylic render finish externally, on 215 mm hollow block or solid blockwork (proposed and existing), on 8 mm cement coat to inner blockwork to form airtight layer, on 38 mm Xtratherm Thin-R Insulation boards bonded with 12.5 mm plasterboard + skim finish. U-value: 0.19 W/m2K Party wall: Scratch coated & insulated with 50 mm Gutex woodfibre insulation in recesses to either side of the large chimney breast. U-value: 0.38 W/m2K Roof Before: Pitched roof with concrete roof slates on battens, on sarking felt, on existing joists, 100 mm insulation laid on flat between ceiling joists. After: Reused or replacement concrete roof tiles on new counter battens, on new sarking felt. Rafters replaced with new 150x44 mm C16 rafters with 100 mm Xtratherm Thin-R Pitched Roof rigid boards between. Intello Plus airtight & vapour control membrane to underside of rafters. Followed inside by 38 mm Xtratherm Thin-R boards + 12.5 mm plasterboard with skim finish. U-Value: 0.19W/m2K New flat roof: Resitrix CL roof membrane on 12 mm WBP, on 60 mm rigid Ballytherm PIR insulation, on 19 mm OSB/3 ply laid to falls on firring pieces, on 175x44 mm C16 joists with full-fill Gutex Thermoflex insulation, on Intello Plus airtight & vapour control membrane to

underside of rafters, on 35 mm services zone with 12 mm ply painted black, on 25 mm yellow pine battens white washed. New U-Value: 0.13W/m2K Windows & doors Before: Double glazed UPVC windows throughout. New triple glazed windows & sliding doors: Passive Window Systems triple glazed alu-clad windows & doors throughout, (4-16-4-16-4) U-value of glass: 0.6W/m2K Roof windows: Cubo double glazed roof windows on insulated timber upstands. Overall U-value: 1.2 W/m2K Heating system Before: Gas boiler & radiators throughout entire building. After: Panasonic Aquarea 12Kw air to water heat pump, with 200L buffer tank. Underfloor heating to ground floor and low temp aluminium radiators to first floor & converted attic space. Ventilation Before: No ventilation system. Reliant on infiltration, chimney and opening of windows for air changes. After: Lunos E2 decentralised demand-controlled heat recovery system with automated humidity control. Electricity 9.4 m2 solar photovoltaic array with average annual output of 2.2kW.

ph+ | county dublin case study | 49


DONEGAL

CASE STUDY

P I LOT LIGHT

PIONEERI NG DO N E GA L DE E P RE T R OF I T A ROARI NG S U C C E S S

50 | passivehouseplus.co.uk | issue 34


CASE STUDY

DONEGAL

ENERGY BILLS

€23

PER MONTH FOR ALL ENERGY (estimate, see ‘In detail’ for more)

Building: Deep retrofit of 1970s social housing scheme Location: Ballyshannon, Co Donegal Standard: Nearly Zero Energy Buildings (NZEBs)

A rundown 1970s scheme of one-bedroom, singlestorey social housing units in Ballyshannon, Co Donegal, has been transformed into a pioneering development of cosy, A-rated, NZEB-busting homes. The pioneering project – the first completed under Ireland’s deep retrofit pilot scheme – also breathed new life into an unloved green area and is expected to help fuel a regeneration project in the town. Words by John Hearne

West Elevation

East Elevation

South Elevation

North Elevation

Floor Plans

ph+ | donegal case study | 51


DONEGAL

CASE STUDY

P

rior to its refurbishment, the Ernedale Heights scheme of social housing in Ballyshannon, Co Donegal, presented a rogue’s gallery of problems. The three terraces of 11 homes were dark and cold. Despite the fact that they sat on a site that enjoyed a lot of southern sunshine, they faced north, away from the green areas that lay between them. Poor ventilation led to condensation, damp and mould growth – a major health concern for the elderly residents, and this was exacerbated by leaky roofs and insulation-free walls. The only heat sources were solid fuel fires and storage heaters, while the cramped design caused a raft of accessibility issues. Brian Carey of Clúid, the housing association which refurbished the homes, explains that conditions were so bad that five of the houses were uninhabitable and had been boarded up. “You’re talking single glazed windows and zero insulation. These were built back in the 1970s, and nothing had been done with them since then apart from emergency repairs. You had black mould along the tops and bottoms of the walls and no south-facing windows, so they were very cold and dark. Even though they’re small – no more than 35 m2 – they were very poorly laid out and did not make the most of the space.” Though the houses were not designed for older people, most of the tenants had been in situ for many years, and the majority had passed retirement age. So, the residents spent most of their time inside, leading to a very high heat demand. Heating bills were astronomical – as much as €4,000 per year for a three-room house (that’s three rooms, not three bedrooms), and the dwellings also required near-constant maintenance. Despite all this, residents loved the area. The estate is centrally situated – less than five minutes from the centre of Ballyshannon. Between the coastal location and the strong sense of community, there was a great appetite from the tenants to stay put and make the most of what they had.

52 | passivehouseplus.co.uk | issue 34

Brian Carey explains that the houses were originally owned by Donegal County Council, and that Clúid reached an agreement with the council to take ownership of the estate and regenerate it. The tenancies would transfer to Clúid on completion. The uninhabited houses would be filled with people from the council’s waiting list. In 2015, Clúid – the largest housing association in Ireland – started to look into the feasibility of addressing the shortcomings of the houses. Given the extent of the issues, a piecemeal solution was never going to work. The conclusion was that a refurbishment programme could be undertaken, albeit within very tight budgetary constraints. “We considered demolition,” says Carey, “but there were two reasons why it didn’t happen, the cost and the model. A new build would have been way out of our budget. Planning conditions would have required an increase in size from 35 to at least 52 m2. That on its own would have driven costs higher.” In addition, he explains, refurbishment was the preferred choice of Donegal County Council. They wanted to maintain the connection with these long-established houses and saw the project as a kind of pilot. The entire area had become quite run

down in the intervening years and Ernedale Heights could act as a standard bearer for a broader regeneration programme. Clúid funds its activities through a combination of private and public loan finance. The former comes from the Housing Finance Agency, while the latter takes the form of a capital advanced loan facility (CALF) direct from the Department of Housing. There is a rigorous approval process to qualify for these loans, and all financing has to be in place before the go ahead is given to begin work. The budget is always the starting point of a project of this nature, says Carey. “We don’t start with a lovely set of drawings. We see that we have X amount of money and ask, ‘What can we do with it?’” Next, Clúid and the county council began a series of consultative meetings with residents. “We wanted them to be part of the story,” says Carey. “These were the houses that they had been living in, and that they would return to. There was no point rebuilding the houses unless we dealt with the issues they had. We got them to list their problems, and there was a common thread. Cold, damp, lack of light, uneconomical and so on. This became our starting point.” Gary O’Connor of project architects,

Photography: Kelvin Gillmor


CASE STUDY

DONEGAL

CONSTRUCTION IN PROGRESS

1

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1, 2 & 3 The Ernedale Heights scheme of social housing prior to refurbishment. The 11 homes were dark and cold, and faced north, away from the green areas that lay between them; 4 the original wall cavities were uninsulated; 5 the slopes of the original roofs were too shallow, so they had to be taken down and rebuilt; 6 Ballytherm PIR insulation was installed where bathroom floors were taken up to create level access; 7 looking into the original 70 mm wall cavity before it was insulated; 8, 9 & 10 an external wall insulation system from Pw Thermal was chosen instead of internal drylining, thereby improving thermal performance without reducing internal space. It features 100 mm Kingspan Platinum EPS insulation, with a wet dash finish; 11 & 12 installation of the new front door — all windows and doors are double glazed units from Munster Joinery.

ph+ | donegal case study | 53


DONEGAL

CASE STUDY

SELECTED PROJECT DETAILS

Rhatigan Architects, takes up the story. “The consultation process allowed us to ascertain the good and the bad of living in those houses, what were the items that they felt needed addressing, what inherent problems did the houses have. We had another forum once we developed our design and presented it to the residents. We outlined the works that we were going to do and got further input from them.” The consultation process, combined with a detailed survey of the houses, made it clear that they would need to be gutted to achieve even the most basic compliance. Apart from the absence of insulation, the slopes of the roofs were too shallow, and they had to be taken down and rebuilt. The extent of these works meant that given budgetary constraints, the design team couldn’t be too ambitious. They aimed for a C1 building energy rating (so between 151 to 175 kWh/m2/yr of primary energy demand, excluding plug loads). It was at this point that the SEAI announced its deep retrofit pilot programme. Clúid approached SEAI, and this ultimately became the first project in the country to secure funding under the scheme. This enabled the team to go much further than their original design. “All of a sudden, we were able to look at external wall insulation, heat pumps and PV panels. PV panels don’t suit everyone, but these tenants are in their houses all day, and so are in a position to use the power as it’s generated.” The original plan had been to pump the cavities and dryline the internal walls. While these measures would have brought wall U-values to regulation levels, it would have meant shaving precious inches from an interior that was already very small. Now, in addition to pumping the cavities with bonded bead insulation, the design team had the resources to opt for an external wall insulation system from Pw Thermal instead of drylining – in this case a polymer modified NSAI Agrément certified system that replicates the traditional wet dash finish, chosen to thereby deliver much better thermal performance without reducing internal space.

54 | passivehouseplus.co.uk | issue 34

Heating bills are now a fraction of what they were. Airtightness in the original houses was very poor; in excess of 12 air changes per hour on average. Gary O’Connor says that the walls were re-plastered internally with care taken to seal all penetrations, as well as new airtight roofs being installed. These measures delivered a final average result of 3.0 air changes per hour. Given that the site is in a windy, coastal area, this makes a huge difference to comfort levels. The tenants were kept up to speed with what was happening throughout the build phase. Most were rehoused locally, and often came to see how things were progressing. Opening up the design to address the accessibility and orientation issues was of course key to the refurbishment. “We looked closely at the living spaces,” says O’Connor, “working out how to maximize the benefit of the passive solar gain within. We decided to re-orient the houses so that they were facing south. We put in double doors that opened out to a generous patio, and that connected both sides of the houses. We also made them dual aspect, so that they linked to their neighbours.” In addition to those vital solar gains, the re-orientation addressed one of the key problems the tenants had identified during the consultation phase – the fact that the houses were so dark. In turning them to face the sun, the architects were also able to make all of the spaces accessible, replacing internal and external steps with ramps. The front entrances are now much more accessible, and visible too, which gives a greater sense of security to the residents. Inevitably, fresh challenges arose as the construction team began stripping the buildings down. The need to replace the roofs was discovered early on. In order to secure

Client: Clúid Housing Association Architect: Rhatigan Architects M&E engineer: Doran Professional Services Civil & structural engineer: CHH Consulting Engineers Main contractor: PJ Treacy & Sons Quantity surveyor: Kilfeather QS Mechanical contractor: Emmet Travers Plumbing, Heating & Gas External insulation system: PW Thermal Building Solutions Ltd EPS insulation (bead and boards): Kingspan Insulation Insulation contractor: B Donaghey & Sons Ltd Roof insulation: Knauf Windows & doors: Munster Joinery Roofing: Conwell Roofing Heat pumps: Daikin, via Northern Refrigeration Services Ventilation: Aereco, via Northern Refrigeration Services Solar PV: Future Renewables BER assessor: Nationwide Energy Consultants

adequate airtightness and remove thermal bridges, the chimneys were also removed and the fireplaces blocked up. One of the big issues with the original layout was that the green spaces between the three blocks were not overlooked. Brian Carey says: “To say that these were unloved would be putting it mildly.” There were no paths linking the green areas, and no planting to soften their barren look. “For that reason, people didn’t engage with them. They didn’t meet here or go for walks or anything, so we put in little footpaths between the terraces, and each row is now connected through these well-tended lawns, which feature plants and flowers.” The south-facing patios now look over these landscaped areas. The introduction of new boundary fencing and landscaped boundaries gives ownership of these spaces to tenants, and helps to stop others taking shortcuts through the site. The tenants moved back in in December 2018, and so far, the reaction has been universally positive. Each Clúid scheme has a dedicated housing officer to deal with any issues that the tenants may have. During normal times, he or she visits on a weekly basis to check in with tenants, and Clúid puts in place a planned maintenance programme too. Despite the sophistication of the technology – Aereco demand controlled ventilation, PV panels and new Daikin air-to-air heat pumps, the tenants are confronted with simple controls – they only need to specify the temperature they require on a simpler digital controller, and there have been no issues as a result. “We’ve learned,” says Carey, “that you need to make it simple for people. Heating bills are now a fraction of what


CASE STUDY

DONEGAL

they were. The dwellings even meet Ireland’s new build standard for nearly zero energy buildings (NZEBs), with energy and carbon performance coefficients all under 0.3 and 0.35 respectively, as required by the 2019 version of Part L of the building regulations (see ‘In detail’ for more). “The difference between these houses, before and after, couldn’t have been more different – they were completely reconfigured,” Carey says. “All of the tenants were delighted with how they turned out. I called up a couple of weeks after they moved in and a couple of them were out on their patio drinking coffee. They were delighted to be back.”

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.co.uk

IN DETAIL Building: Deep retrofit of 11 x 1970s single-storey houses, all approx. 38 m2 floor area. Location: Ernedale Heights, Ballyshannon, Co Donegal Budget: €950,000 Completion date: May 2018 Space heating demand (DEAP, post-retrofit, sample dwelling): 28 kWh/m2/yr Number of occupants: 1-2 per dwelling Building Energy Rating (DEAP) Before: Average of G (736 kWh/m2/yr), ranging from 409 kWh/m2/yr (F) to 866 kWh/m2/yr (G), the large range caused by differences in heating systems and the fact some dwellings had double glazing and some had single. After: Average of A3 (56.50 kWh/m2/yr), ranging from 54.24 kWh/m2/yr to 58.91 kWh/ m2/yr) Energy bills (measured or estimated Before: Using the estimated pre-retrofit delivered energy for an average dwelling at Ernedale Heights, Bonkers.ie suggests an annual electricity bill of at least €1,773 (cheapest suggested plan) at May 2020 electricity prices. This assumes equal use of day and night rate electricity. Figure includes VAT and standing charges. In reality, residents were not likely to have been using this much electricity as this assumes the house is heated to 21ºC in living areas & 18ºC elsewhere, which would probably not have been the case in practice. After: Bonkers.ie suggests a cheapest annual available plan of €278 (€23 per month) based on average post-retrofit delivered energy (DEAP). This assumes equal use of day and night rate electricity. Figure includes VAT and standing charges.

Energy performance coefficient (DEAP): Average of 0.223, ranging from 0.217 to 0.23. Note 0.3 or lower is required to comply with Ireland’s definition of NZEB (Part L 2019). Carbon performance coefficient (DEAP): Average of 0.213, ranging from 0.208 to 0.22. Note 0.35 or lower is required to comply with Ireland’s definition of NZEB (Part L 2019). Airtightness (at 50 Pascals) Before: Average of 9.32 m3/hr/m2 (ranging from 7.95 m3/hr/m2 to 9.76 m3/hr/m2) After: Average of 2.83 m3/hr/m2 (ranging from 2.44 m3/hr/m2 to 3.66 m3/hr/m2) Ground floor Before: Uninsulated concrete floor After (if upgraded): No general ground floor upgrades were undertaken within the scope of works, however in places where radon sumps were installed or bathroom floors were taken up to create level access, Ballytherm PIR insulation was installed. Walls Before: 100 mm rendered concrete block outer leaf and inner leaf with un-insulated 70 mm cavity. After: 100 mm Pw Thermal Building Solutions external wall insulation with 100 mm Kingspan Platinum EPS insulation, followed inside by 100 mm original rendered block outer leaf, 70 mm cavity pumped with Ecobead cavity insulation, 100 mm masonry original inner leaf with new plaster finish. U-value: 0.17 W/m2K Roof Before: Insulation deteriorated to 25 mm.

After: Roadstone Donard flat pan interlocking roof tiles, on Tyvek roofing membrane, on new prefabricated timber trusses. Insulation was installed on the flat at joist level with 300 mm Knauf Earthwool fibre insulation with a thermal conductivity of 0.044W/mK laid in two layers; between joists and over joists to give a U-value of 0.13 W/m2K. Windows & doors Before: Single glazed, timber windows and doors. Overall approximate U-value: 3.50 W/ m2K New windows: Munster Joinery double glazed windows and doors, with 6 mm clear float, low-emissivity coating, 16 mm Argon filled cavity, 6 mm solar control outer pane. Overall U-value of 1.20 W/m2K. Glazing oriented to south in renovated dwellings. Heating system Before: Open fire and portable electric heaters. After: 1 x external Daikin air-to-air heat pump connecting to 2 x Daikin internal air conditioners per dwelling, one in the bedroom and one in the living room. Controlled via infra-red remote controller with temperature & timer function. Ventilation Before: No ventilation system. Reliant on infiltration, chimney and opening of windows for air changes. After: Aereco demand controlled mechanical extract ventilation. Electricity Renusol VarioSole on roof system with 6 JA Solar – JAM6 60/265 with a rated output of 1,590Wp was installed to the roofs of each unit.

ph+ | donegal case study | 55


GREEN STIMULUS

INSIGHT

DEEP RETROFIT & STIMULUS IS AN UPGRADE REVOLUTION THE ECONOMIC TONIC TO TACKLE COVID? With governments across Europe looking for ways to jump start their economies following the early impact of Covid-19, attention is increasingly turning to deep retrofit. But while there is strong evidence that deep retrofit could play a major role, the devil will be in the detail – and the challenge of dramatically upscaling a nascent industry shouldn’t be underestimated.

Words by Kate de Selincourt 56 | passivehouseplus.co.uk | issue 34


INSIGHT

I

n April, the Financial Times gave the world’s governments a grave warning. “The Covid-19 pandemic has shown the lethal folly of ignoring expert warnings about the need to be ready for calamity... This should be uppermost in leaders’ minds as they struggle to rebuild stricken economies.” The leader writers urged governments to use their spending power “to help stimulate a recovery… that does not lock in a fossil-fuelled economy. The situation could not be more urgent; for the world’s beleaguered workforces, and also for the climate.” The coronavirus pandemic is expected to cost the global economy between $6tn and $9tn; this prediction doubled between April and May. The International Labour Organisation predicted cutbacks equivalent to nearly 200 million full-time workers would take place between April and June of this year. The UK and Ireland, who in common with much of Europe both had severe lockdowns lasting several weeks, are suffering major economic stress. And climatologists are predicting that 2020 could be the hottest year ever recorded. The last 12 months have seen accelerating ice melt and record temperatures near both poles. Carbon dioxide levels have just topped 416 parts per million, probably the highest level for 800,000 years. The FT leader joined an international chorus calling for green rebuilding. The United Nations told governments to “build back better” — more sustainable, resilient and inclusive. The International Energy Agency is urging nations to make clean energy technologies, and energy efficiency in particular, a key part of stimulus packages. In the EU a “green recovery alliance” of most member states, including Ireland, and a slew of large corporations, has signed a joint statement warning that “Covid-19 will not make climate change and nature degradation go away” and that running to panicked economic fixes that lock in fossil fuel use would be counterproductive. In Ireland, there is a clear focus on construction – retrofit and new build – to restart the economy. Business confederation Ibec is campaigning for its Covid recovery plan ‘Reboot and Re-imagine’, which calls for government support for new construction, in particular social housing, and for “an ambitious national deep retrofit programme” with a new delivery and financing model to upgrade buildings to B1 and A energy ratings. And as Passive House Plus went to print, a draft programme for government had just been agreed between Fianna Fáil, Fine Gael and the Green Party that contained a commitment to retrofit 500,000 homes to at least B2 rating over five years. Just transition In the UK, the Committee on Climate Change (CCC) wrote in May to the four UK governments urging them to rebuild

after Covid-19 “whilst delivering a stronger, cleaner and more resilient economy”. Covid has hit disadvantaged communities harder, in multiple ways, and the CCC was forthright, calling on UK governments to embed fairness as a core principle of a green recovery. “The benefits of acting on climate change must be shared widely, and the costs must not burden those who are least able to pay, or whose livelihoods are at risk,” the CCC’s letter said. CCC chief executive Chris Stark, and Julie Hirigoyen, chief executive at the UK Green Building Council, both point out that construction and retrofit is one of the best ways to create jobs, per £1 or €1 invested. “Energy efficiency is ‘shovel ready’ – with labour-intensive projects rooted in local supply chains,” Hirigoyen says. A report for the International Energy Agency (IEA) agrees, stating: “When homes are upgraded to higher efficiency standards, more than half of the total investment typically goes directly to labour.” A very comprehensive analysis of the value of green versus ‘standard’ stimulus packages by the Smith School of Enterprise and Environment, at the University of Oxford, confirmed that boosting green construction is a highly effective way to create jobs, and thus repay the investment long-term. A team of 230 economists from around the world was asked to rate 700 stimulus packages implemented after the 2008 financial crash. They found construction projects retained more of the investment locally, adding that clean energy in particular (both renewable generation and energy efficiency work) was “helpfully very labour intensive in the early stages” with up to three times as many jobs being created per £1 invested, compared to investments in fossil fuel. Unconditional airline bailouts, by contrast, “performed the most poorly in terms of economic impact, speed and climate metrics.” Wider benefits As well as creating jobs, construction-focused green stimulus brings numerous other benefits, in particular to the least well-off. This was highlighted in a report last year by the Irish Congress of Trade Unions, calling for a just transition for Irish households and workers affected by the planned closure of carbon-intensive peat-burning power stations in the Irish midlands. The group quotes the Sustainable Energy Authority of Ireland, which estimates that tackling the one million older Irish homes that need deep retrofit could add €35 billion to the Irish economy: “This represents a significant opportunity to improve health and well-being for the occupants, particularly the significant numbers suffering from energy poverty… as much as 28 per cent of households in 2015.” New housing, particularly the construction

GREEN STIMULUS

of well-designed, low energy social housing, also brings large social returns. When social housing is constructed, new tenants enjoy lower rents, better living conditions, and more security than the average tenant in the private rental sector – and far better than in temporary accommodation. Tenants and the community at large benefit, including economically, as research by HACT (the Housing Associations’ Charitable Trust) illustrates. People moving into social housing are likely to enjoy improved mental and physical health, to be better able to find and retain a job, they are less likely to be a victim of crime, and their children will be able to stay in the same school, benefiting their education, this research shows. How to finance a green rebuilding Funding energy saving work through utility bills, as has been done in the past ten years or so in the UK, is popular with governments because it is “off balance sheet” (i.e. kept out of the state’s own budget). But funding via energy bills is regressive. It hits the poorest hardest and has become politically unpopular as a result. An expanded, ambitious programme of the kind that is needed to meet carbon targets cannot realistically be imposed on bill payers, many of whom will see little or no financial return. Yet governments seem to have had a bit of a blind spot with regard to green construction. Regarding retrofit in particular, the case has repeatedly been made that deep retrofit should be seen as a national investment — it is effectively an infrastructure programme. And it works economically in those terms. Medium-to-long term, investment in green construction pays back amply to the state, many researchers have concluded. Verco and Cambridge Econometrics examined this for UK climate change think tank E3G in 2014, and calculated that a 15-year programme of deep energy retrofit would return £1.25 to the government per £1 invested, from the increased tax take resulting from job creation as well as from supply chain activity, increased household disposable income, and a lower state welfare bill. This positive rate of return makes government borrowing justifiable as an approach for funding energy efficient construction – in the same way that any national infrastructure investment is justified. For big infrastructure projects, governments generally like to leverage private sector finance, to increase the total size of the programme. Given that energy efficiency work improves the value of a property, property owners can be expected to contribute something, either at the time of the work, or at the moment of property sale. However, incentives are generally still required to overcome initial resistance, compensate for the costs of disruption, and also to ensure uniform, high standards of work. In Ireland, Paul Kenny of Tipperary

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Energy Agency, who runs the SuperHomes deep retrofit scheme, believes grants of 35% or so are necessary to catalyse homeowner investment. Tax incentives (for example stamp duty relief) are one way of managing this, as are direct cash contributions to the work. Another incentive, which could be complementary, is to offer subsidised lending. This can be organised as a rolling loan fund, which has worked well in pilot schemes in the UK in the past. Low cost finance is offered along with support to ensure the work carried out is properly designed and project managed. MEP Ciaran Cuffe suggests that in Ireland, the European Investment Bank could support something similar, and back a state guarantee for loan finance for deep retrofit. There is also the option of independent finance through the private sector. Energy retrofit is a market that is reportedly of growing interest to private investors who are seeking ‘green’ and future-proofed investments. Analysts are warning investors that oil stocks are no longer safe, as fossil fuels are increasingly identified as problematic – a trend that if anything is accelerating in the Covid crisis. Lending into future-proofed, low-carbon property is starting to appear attractive, though investors will however be anxious to see quality assurance of the work they are backing (this was one of the drivers for developing the UK retrofit quality protocol, PAS 2035). ‘Ethical’ investors are also being courted by the social housing sector. According to the Financial Times, a group of large housing associations, investors and financial experts is actively looking for ways it can raise money by quantifying what they do in terms of environmental and social performance, to attract so called ESG (environmental, social and governance) investment. One of the criticisms levelled at infrastructure investments like airports or high speed rail is that they do not always distribute benefits to the most in need. Construction work, as we have seen, is jobs-intensive, and wherever there are people, there are houses to retrofit and new houses to build. However, there are still concerns that to maximise community-wide benefits of any regeneration and retrofit programme, there also needs to be local control. The UK Green Building Council has proposed a couple of structures that could enable a national retrofit programme to be fine-tuned to suit each area, such as local authority funds and community social enterprises. Do as much as you can do well The calls to ‘green stimulus’ action emphasise the urgency of the Covid and climate crises, and the need for ramping up of action to match. The International Energy Agency, for example, at first glance seems to be promoting a gung-ho approach to green

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Above clockwise from top left: Irish Green Party MEP Ciaran Cuffe; Julie Hirigoyen of the UK Green Building Council; UK Committee on Climate Change chief executive Chris Stark.

energy and retrofit: “Early action can create jobs quickly by focusing on what is already in place and ready to be scaled up.” But they go on to warn: “Supply chains and capacity will be crucial. If new programmes quickly increase demand, can the market respond? Are good products available? Are installers ready to meet demand at sufficient levels of quality and safety?” Jonathan Atkinson, manager of the Manchester People-Powered Retrofit programme, fears they are not – and says that changes at many levels are needed. In a blog for the Centre for Alternative Technology he warned that the existing model for procuring energy efficiency work in the UK has led to a ‘race to the bottom’ in terms of costs and quality. “Poorly planned energy supplier-funded works delivered to unrealistic timescales by badly trained staff led to widespread damage, leaks, poor quality home environments and aggrieved residents.” As the IEA put it: “Governments in a hurry to generate activity can be tempted to lessen the focus on technical standards or required efficiency levels, but this can be a false economy in the longer term.” This is not a mistake we can afford to make. The UK’s new PAS 2035 retrofit standard represents a major step forward in assuring quality in retrofit. Requirements include design by appropriately qualified professionals, and an insistence on effective ventilation whenever there is a risk of inadequate air exchange. At national level though, it has not yet been formally adopted. In order to overcome the dangers of inadequate and even harmful installations, there is wide agreement that more and more appropriate training is urgently needed.

Even in the small pilot whole-house retrofit schemes currently being funded by the UK government, demand from homeowners risks outstripping the supply of suitably qualified advisors and installers. Manchester’s People-Powered Retrofit programme is one of these pilots, and Jonathan Atkinson is concerned. “There is a skills shortage that has to be addressed to enable safe and effective retrofit to be delivered. There is no point in ramping up funding for retrofit unless it can be delivered properly,” he writes. “Luckily there are great, practical training models out there that can be replicated. Investing in the people doing the work absolutely must go hand in hand with investing in the work itself, or we will be storing up all kinds of trouble.” In new build too, construction to genuinely low-energy standards requires particular skills and knowledge: one of the reasons passive house projects often show higher costs is because clients are effectively investing in skills training on behalf of the whole construction sector — the necessary skills and knowledge aren’t part of mainstream construction education and apprenticeships. Experience has shown that many construction workers adapt readily once the time and resources have been found for training, so there is a clear opportunity during a construction slow-down to support workers to remain in the industry and to gain the skills needed to “build back better”. One group who could be targeted are those same young people whose skills training and job prospects are most impacted by an economic crisis. The damage is already occurring: reportedly just 20% of UK


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apprenticeships due to start in April came to fruition. Research by the Resolution Foundation shows that remaining in education or training offers long term benefits to job market entrants, compared with trying to go straight into work in a depressed job market. The foundation has called for extra support to be put in place urgently, so young people can gain an extra six months of training – something many currently struggle to afford. The Green Party in Ireland has similarly called for the introduction of fast track apprenticeship programmes, to train the 20,000 workers its estimates are required to adequately retrofit the national housing stock. The programme for government that the party agreed with Fianna Fáil and Fine Gael, just as Passive House Plus went to print, contains a commitment to overhaul apprenticeships and training to ensure there is a skilled workforce for delivering mass retrofit. Politically popular? According to recent news reports, polling shows a clear majority of the population in each of the 14 major economies, from China and India, to Russia, the US and Brazil, thinks climate change is as serious as coronavirus. And in the UK, 70 per cent are in favour of accelerating climate action by moving the government’s zero-carbon target from 2050 to 2030. People are also questioning economic norms: polling has found a majority of the UK public, for example, wants ministers to focus on improving health and wellbeing over economic growth, even after the immediate threat from the coronavirus has passed. Nick Robins from the London School of Economics (LSE), one of the authors of the Smith School study, pointed out that after the global financial crisis of 2008 a massive proportion of ‘recovery’ investment was in his view misdirected into fossil fuel projects. In an interview, he told the BBC: “If we have any hope of combating climate change, we must make absolutely sure we do it better this time.” So often the argument is heard that we can’t afford to invest in more sustainable approaches to building and upgrading our homes, schools, shops and offices. It is becoming increasingly clear that we can’t afford not to – and that the world’s ordinary people understand this perfectly well. Failing ourselves, and young people in particular, on either a Covid rescue, or on climate rescue, would be unforgivable.

A fully referenced version of this article is online at www.passivehouseplus.co.uk

WILL EC ONOMIC GR OWTH SAVE U S? ‘Green stimulus’ or ‘green recovery’ generally has its goals framed in terms of boosting or restoring economic growth. Yet at the back of our minds, many of us are aware that the headlong striving for growth at all costs may be what has got us into the climate crisis in the first place. An exception to the ‘growth growth growth’ agenda is the city of Amsterdam. In the Covid recovery plan the city produced in April, its main goals, unusually, weren’t about growing the economy or increasing gross domestic product. Rather, they were about making the city better for people and the planet, in an analysis based on the principles of ‘doughnut economics’, a concept developed by the Oxford economist Kate Raworth. The doughnut envisages society flourishing in a sphere between a

basement of minimum, decent living standards for all and a ceiling of ecological limits (see diagram above). Instead of using the gross domestic product as the measure of society’s success, doughnut economics enables policymakers to visualise numerous dimensions of wellbeing – economic, health, social, environmental – on an equal basis. They can identify where there is a shortfall in basic needs for citizens, and where there is excess that is taking too much from the rest of the world, or threatening its future. “It gives us the opportunity to put those other values — like social interaction, health and solidarity — much more in the forefront of how we’re going to recover from this shared crisis,” Amsterdam’s deputy mayor Marieke van Doorninck explained.

Above Visual representation of the ‘doughnut economics’ concept, by economist Kate Raworth (CC BY-SA 4.0).

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WE CAN LAUNCH A NEW

ECO RENAISSANCE

The UN’s Scott Foster says deep retrofit of our building stock, and a sustainable built environment, should be at the heart of our recovery from the Covid-19 pandemic.

Words by Lenny Antonelli

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cott Foster has a great green vision for our post Covid world. Over the past few years, Foster has made something of a name for himself as a global champion of passive and low energy buildings. Foster is director of the sustainable energy division at the United Nations Economic Commission for Europe (UNECE), which promotes economic co-operation between UN member states (UNECE includes the US, Canada, and the former soviet states, as well as Europe). Passive House Plus first spoke with Foster in February about retrofit, the carbon footprint of building materials, and more besides. We intended to run the piece in our spring issue but decided to delay its publication until summer. Then the Covid-19 outbreak became a global pandemic, and suddenly our original interview felt dated. So, in April we reached out to him again by email, to discuss how the global response to Covid-19 could be an ecological one. Foster pointed to anecdotes of how lockdowns had caused a dramatic reduction in pollution — “CNN reports that people in the northern Indian state of Punjab can now see the Himalayas, more than 100 miles away, because of reductions in air pollution,” he said — but he also stressed the pandemic had come at a devastating economic cost, and could lead to a dangerous deflationary cycle. “Plummeting demand for products at some point will lead to drops in prices. As

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that effect becomes generalized, an economy will move into a deflationary, self-reinforcing spiral as people delay purchases in anticipation of lower prices. The money multiplier of economic growth becomes a money divider as economies shrink – deflation is considered to be much worse than inflation because of the deep damage it can do.” He expressed hope that this effect would be temporary but added: “The implosion of the world’s economies is extraordinary, and as confinement continues the duration of deep repercussions becomes increasing unknowable. It is an urgent imperative to get the world’s economies back to work. Jobs, health, security, food, investments all depend on our getting back to work, though all the while ensuring that we do not relaunch the pandemic in the process.” What is needed, he said, is a global economic “renaissance plan” with green principles, and deep retrofit of buildings, at its heart. The Renaissance, which marked the transition from the Middle Ages to modernity, was associated with “great social change and strides forward intellectually and culturally”, arguably just what we need now to confront the climate and ecological emergencies. “If we simply re-launch economies by reverting to the model that existed before December 2019, then we are simply re-treading paths that take us to the wrong destination,” Foster said.

‘A holistic vision for the role of buildings’ While promoting energy efficiency in buildings is just one part of his job, it’s the one where Foster believes he can make the biggest difference. To underpin that belief, UNECE has developed ‘framework guidelines’ on energy efficiency in buildings, a set of common principles for UN nations to strive for. These advise limiting the space heating and cooling requirements in buildings to 25 kWh/m2 per year, and total energy use to 90 kWh/m2 annually. 
 But in general the guidelines are aspirational rather than prescriptive: they say that building design and construction should be sciencebased, and that building performance should be subject to ongoing measurement. Buildings should also be affordable, be built using sustainable materials, and integrated with their surrounding environments. They should also have advanced, networked building information systems (you can read the principles in full at unece.org/energyefficiency).
 Speaking on the phone from Geneva in February, Foster said the guidelines “go way beyond what building standards do so far, in that they don’t deal with a house on a component by component basis, they deal with a building as an entire system, which is embedded in a community, which is its own system. Which is embedded in a city.” “This goes way beyond simply ‘passive house’. It creates a holistic vision of the role


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that buildings are going to play in a complex urban environment.” And he thinks these principles could be at heart of a post-Covid, or indeed intra-Covid, economic stimulus. Deep energy retrofit of buildings has been flagged as one of the effective ways to stimulate the economies post-Covid (for more see our feature on retrofit and stimulus elsewhere in this issue). Retrofit cuts carbon emissions, creates lots of jobs for every euro spent, and when done well, improves health and wellbeing for building occupants too. The challenge has always been how to make it happen at scale. Cheaper finance for low energy renovations is part of the solution, Foster believes, as is direct government funding — which will hopefully receive a boost via Covid stimulus packages. Another key step is getting property valuations to reflect the quality of buildings in a more holistic sense — including, for example, whether they are good or bad on occupant health. ‘Agents of change’ But we also need to change the way we pay for energy, he says. “If I move from paying for energy as a commodity to paying for energy as a service, instead of me sending you a bill for the number of kilowatt hours you’ve consumed, you and I enter into a subscription relationship, and you’re going to pay me to make sure the temperature in your house is 18C. You get the lighting you require, and air quality standards are met. My business model becomes one of looking at your entire dwelling as the complex system that it is and making needed investments to reduce my costs of delivering the energy services you require.” This approach, called energy service contracting, works well in theory, though in practice it has been hindered by tricky contracting issues — such as the fact the consumers cannot easily change energy supplier under such arrangements. But Foster believes the concept is essentially sound. He says we need to see energy suppliers, rather than property owners or tenants, as the “agents of change” to scale up retrofit. But we should also remember how important new build energy standards are going to be, especially in the global south. “If you think of a world with 9 billion people [as

The agents of change are at the city and local level. is predicted for 2050] and you imagine, as is expected, that 70% of those are going to live in cities… that is the equivalent of adding 235 new cities the size of Paris to the planet. So, when you look at the developing world, new building is extremely important to get right.” Cutting the embodied carbon of buildings is key too, and Fosters calls for methodical new ways of recovering materials from existing buildings to help avoid extraction of new raw materials in future. We should look at the built environment itself as a source of materials, he says. “So if you’re going to demolish a building or trash a car, or whatever the object is, there needs to be some way to track all of the components that went into it, either its batteries or copper or steel… some mechanism for using digital processes for keeping inventories of what materials have gone into what objects, so when you go to dispose of it, you know what’s there, and you know how to access it.” Pricing carbon But he says that carbon taxes are a key underlying mechanism to make all of this happen. “I am not talking about €20, €30 or €50 per tonne of carbon, I’m talking north of €120. So, it’s a big number if you want to have a serious effect.” Without a carbon tax, the only choice is to try to regulate the climate impacts of each individual material or sector. “I’m not convinced of the effectiveness of prescriptive regulations in a market as complex and diverse as the global supply chain for buildings.” In such a complex system, Foster says people working on the ground are most critical. To that end UNECE has developed its High Performance Buildings Initiative, partnering with New York, Pittsburgh, Vancouver, and Ireland to establish international centres of excellence in high performance building, to spread the good word at grassroots level among designers, tradespeople, and local decision makers.

SCOTT FOSTER

These centres will provide training in low-energy design and construction, share best practice, and work to build public support for high performance buildings. In Ireland, the Waterford Wexford Education & Training Board has opened an NZEB (nearly zero energy building) training facility in Enniscorthy. It runs courses in low energy building skills for trades, including carpenters, bricklayers, electricians, plasterers, and plumbers. “Wexford is a national initiative that is likely to have Ireland-wide effects, and we’re hoping to have Ireland then have an effect across the EU,” Foster says. “The agents of change are at the city and local level. Government policies are obviously very important — but I do find that it is critically important to talk to the people with the hammers in their hands, they’re the ones who are going to make things change.” Fosters believes pumping in money and support at this level is crucial to any retrofit stimulus. “Getting cash into the hands of the tradespeople — the carpenters, the plumbers, the contractors, the architects, and the rest of the building supply chain — would reinvigorate local economies rapidly while delivering on long-term quality of life for everyone (climate, affordability, health, comfort),” he wrote to us. ‘An existential threat’ Foster is unequivocal on the state of our planetary emergency. “The world is not on track for 1.5 degrees or 2 degrees [of warming]. Right now, we are barrelling down the highway for between 4 and 6 degrees and that is, as a species, the existential threat that we’re facing,” he says. “And by the way we’re screwing up life for a lot of other species in the process, too.” Facing this crisis will require global cooperation, and a recognition of our inter-dependence. Foster believes this has been lacking in our response to Covid-19. “If governments had been open and transparent about the challenges they faced and collaborated on the solutions, the now pandemic could have been contained better by staying at the personal transmission level and not a community transmission level. Had they shared experiences on what was working and what was not, they might have flattened curves much earlier on,” he wrote to us in April. “So, yes, I firmly believe that nations and states acting alone do not work as well as collaboration based on science and facts. Mutually beneficial interdependence requires trust, and that seems to have gone missing.” Trust, and co-operation will certainly need to be rebuilt, if Foster’s vision of a green global economic renaissance is to bear fruit. But his vision is still a vivid one. “We have an opportunity with this pandemic to catalyse a modern renaissance, a re-birth of nations and economies in a way that delivers quality of life sustainably at global scale.” Left Participants at an NZEB training course run by Waterford Wexford Education & Training Board, one of the latest UNECE centres of excellence for high performance buildings.

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DEAD AIR

 I RBO R NE C OV I D-19 & P OORLY A V ENT IL ATED BUILDI N GS

In the early stages of the Covid-19 crisis, there was little official recognition that airborne transmission was a risk. Has that view changed, and what role will building ventilation play when winter approaches?

Words by Jeff Colley

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he World Health Organisation (WHO) has long maintained that Covid-19 is not airborne, but its position becomes less clear when subjected to scrutiny. On 28 March, the agency made strong assertions in posts on Facebook and Twitter: “FACT: #COVID19 is NOT airborne,” the WHO account tweeted. A WHO article published the next day was less unequivocal, stating that the virus was “primarily transmitted between people through respiratory droplets and contact routes”, while conceding that airborne spread “may be possible in specific circumstances and settings in which procedures or support treatments that generate aerosols are performed,” such as intubating a Covid patient. The article acknowledged that research existed indicating airborne spread, but cautioned that it had not yet been subject to peer review, and proposed no additional precautions about airborne spread. Passive House Plus contacted the WHO to ask, in light of the contradiction between its unequivocal Facebook and Twitter posts ruling out airborne Covid-19 on 28 March and its more nuanced position on 29 March, if it would unpublish the social media posts in question. The agency reiterated its position: “Covid-19 is primarily transmitted between people through respiratory droplets (for instance produced when a sick person coughs) and close contact with sick people or contaminated surfaces. These droplets are too heavy to hang in the air. They quickly fall on floors or surfaces. This is why WHO recommends that everyone continue to follow basic protective

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measures against Covid-19.” “In health settings during certain procedures, it is possible for the virus to be airborne under some conditions. This is why WHO recommends precautions for health workers.” The WHO response referenced a WHO guidance document on preventing Covid transmission in healthcare settings. In a section on contact and droplet precautions, the guidance states that “patients should be placed in adequately ventilated single rooms. For general ward rooms with natural ventilation, adequate ventilation is considered to be 60 l/s [litres per second] per patient”. For airborne precaution rooms, the target is set at 160 l/s per patient. There is an apparent contradiction in the ventilation target for wards. If the WHO’s position is that Covid quickly falls on the floor or surfaces, and that one metre of distancing between beds is sufficient mitigation, then why specify a ventilation rate – and a high rate of 60/l/s/patient at that? Linsey Marr, the Charles P. Lunsford professor of civil and environmental engineering at Virginia Tech agrees. “Recommending improved ventilation in buildings implicitly acknowledges that airborne transmission is important. Otherwise, social distancing alone would stop transmission,” says Marr. In responding to Passive House Plus, the WHO revealed plans to imminently publish revised advice on ventilation as part of its Covid-19 infection prevention and control (IPC) guidance in healthcare settings, while also issuing a statement to the magazine on

airborne Covid-19. The statement, which is published in full on the Passive House Plus website, outlines the WHO position that there is no evidence of airborne transmission of Covid-19 outside of aerosol generating procedures, and that evidence of the virus in air samples did not demonstrate that the virus could be transmitted in this way. “So far there is no evidence of “transmission” of the virus as an airborne pathogen (such as TB),” the agency said. “This is different from finding the virus in air samples or showing that aerosol particles can be generated from bigger droplets when people cough, sneeze or talk loudly.” According to Prof Jose L Jimenez, a fellow at the Cooperative Institute for Research in Environmental Sciences, this statement reflects a very narrow, binary definition of “airborne”. “It is like measles or TB, or it is not airborne at all. Makes no sense,” he says. “Why are there only those two possibilities, what is that assumption based on?” Charles Haas, LD Betz professor of environmental engineering at Drexel University is equally vexed. “The dichotomy between ‘aerosol’ and ‘droplet’ is ancient and outmoded,” he says. “The problem with WHO is that initially they conveyed too much of a sense of certitude and they have had difficulty backing off.” The WHO statement argues that the virus reproduction number in various countries, “does not indicate a typically airborne pattern of transmission. The occurrence of airborne transmission would have resulted in many more cases and even more rapid spread.”


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Prof Jimenez calls this assertion “totally bogus”, adding that the reproduction rate “is not an indicator of aerosol transmission,” adding that Anthrax or hantavirus have a reproduction rate of zero, but are only transmitted via aerosols. Jimenez adds that unlike more efficient airborne diseases like measles and TB, Covid-19 is “opportunistic airborne”, and needs crowding, low ventilation rates and duration in order to spread. Shelly L Miller, professor of mechanical engineering at the University of Colorado Boulder argues that the WHO are “demanding much more rigorous proof of airborne transmission compared to surface/touch transmission. Where has it been definitively proven that contact with contaminated surfaces got people sick? Yes, we find the virus on surfaces but also in the air.” Replying to Passive House Plus in May, Prof Marr made a similar point: “I don’t think we can rule out airborne transmission of Covid19, especially in close contact situations and in spaces with poor ventilation for the number of people present,” said Marr. “In fact, there is mounting evidence that airborne transmission is occurring. There isn’t actually any direct proof of transmission by large droplets either.” The sense that the WHO and the medical community in general are not engaging sufficiently with aerosol scientists is palpable. The WHO told Passive House Plus it “convenes a group of more than 30 international experts in the fields of infectious diseases, epidemiology, public health and infection prevention and control” to regularly review the evidence. “The set of people at the table […] is narrow,” says Prof Haas. “Where are experts in engineering, ventilation, risk assessment? They have always had too narrow of a net that they cast for expertise.” If the emerging consensus among aerosol scientists is right, then airborne transmission of Covid-19 is a significant factor – in particular in crowded, poorly ventilated buildings. The issue, then, of how we ventilate our buildings comes into sharp relief. The aforementioned 60/l/s and 160/l/s per patient targets for hospital wards and airborne precaution rooms – expressed as minimum hourly averages – comes from a 2009 WHO document, titled ‘Natural ventilation for infection control in health-care settings’. It notes that this guidance, “only applies to new health-care facilities and major renovations,” an apparently implicit recognition that existing hospitals will have sub-optimal ventilation rates in airborne precaution rooms, and consequently higher risks of infection spread. The guidance also states: “The design must take into account fluctuations in ventilation rate”, and adds that “when natural ventilation alone cannot satisfy the recommended ventilation requirements, alternative ventilation systems, such as hybrid (mixed-mode) natural ventilation should be considered, and then if that is not enough, mechanical ventilation should be used.” Consulting ventilation engineer Mich Swainson points out that the ventilation rate

required to maintain good indoor air quality in non-domestic buildings is typically taken as a minimum of 10 l/s, as per UK building regulations, CIBSE Guide A, and the Department of Health document, ‘HTM 03-01 A’. However, HTM 03-01 notes that a general ward or single room should have an air change rate of six air changes per hour (ACH). “Relating 6 ACH to a dwelling, purge ventilation in a room is achieved by opening the windows, this aims to achieve a minimum of 4 ACH,” says Swainson. “Purge ventilation is deemed to be intermittent. The WHO and HTM 03-01 respectively indicate that a ventilation rate of 60 l/s/patient and 6 ACH is required, 24/7. Unless a natural ventilation system had been specifically designed to achieve such rates, in a single room this would require a significant window area to be open 24/7, and in a general ward could only be achieved with cross ventilation through large openings. In cool, windy or wet weather, the use of windows would be impractical to achieve such high flows, without significant impact on the thermal comfort of the occupants.” As Dr Chris Iddon, chair of the CIBSE natural ventilation group, explains, the ability to deliver high levels of natural ventilation through window openings in hospitals may be considerably reduced from the design intent by window restrictors installed to stop patients escaping. “Window replacement is also an issue,” he adds, “as the tendency is to focus on Part L rather than whether the windows can help achieve the flow rates under Part F.” Iddon warns that achieving higher ventilation rates may prove trickier in the coming months, given the tendency of occupants to close windows and vents during colder weather. “We’ll be coming to wintertime. We need to think about what amount of air we can reasonably deliver whilst not unduly increasing any transmission risk.” “If you’re in your household bubble I think you have to think less about ventilation than in a public building,” says Iddon, reasoning that surface spread and large droplets will already make virus transmission highly likely in households. Iddon is more concerned about public buildings. “A lot of those buildings are probably well ventilated, but a lot aren’t. I’m not surprised we’ve seen large viral transmission events in halls, given how high up and inaccessible the windows tend to be.” Iddon said CIBSE’s position has been to err on the side of caution, and try to maximise ventilation as much as reasonably possible, but to revisit this as we move in to autumn . “In a lot of circumstances where the ventilation is poorer than it should be, there seems to be an increased risk of infection,” he says. But can natural ventilation be relied upon to satisfy a specific ventilation requirement? Useful insight on this point can be found in a 2015 review of 168 academic papers published since the year 2000 on ventilation and health, and which subjected 48 of these to more detailed analysis. It found that higher ventilation rates were generally associated with reduced adverse health outcomes, and that acute health symptoms

COVID-19

tended to be lower in mechanically ventilated buildings. The picture on mechanical ventilation was mixed with regard to asthma and allergy symptoms, but the findings on natural ventilation bear repeating in full: “Ventilation rates in naturally ventilated buildings can only be characterized with a high level of uncertainty because they depend on outdoor conditions and activities and on the behaviour of building occupants. Instantaneous (spot) measurements or even weekly averages may not be able to capture and represent the true variability and may not be representative of actual rates. Consequently, exposures that are related to ventilation may not be properly estimated and may not reflect the actual exposures. They may simply be too low or too high compared with the actual levels.” Barring feats of ventilation engineering, it would appear misguided therefore to expect natural ventilation to reliably meet a minimum ventilation rate, except when backed up with the safeguard of mechanical systems in mixed mode designs. There’s also evidence that occupants tend to close or permanently block natural vents. A Scottish study of 40 naturally ventilated airtight homes found that 63% of vents in bedrooms and 63% of vents in living rooms were stated to be “closed and never opened”. Meanwhile, a 2010 study of natural ventilation in 22 airtight English homes found that 60% of vents were closed, while a 2005 BRE study of 37 homes found that trickle vents were fully open in only four of the study homes, and fully closed in 13 homes. The Scottish study, which was conducted from January to March 2014, calculated that the average per person overall ventilation rate was 3.1 litres per second per person and the range was from 0.9 l/s/p to 6.0 l/s/p. The BRE study involved monitoring ventilation rates in 37 naturally ventilated, leaky homes during winters and summers over two years. The measured air change rates were considerably lower in winter: 0.44 air changes per hour in winter, versus 0.62 air changes per hour in summer. The main reason given was increased opening of windows and trickle vents in summer months. Homes where windows were open ‘most or all of the time’ had significantly higher ventilation rates than other homes, both in winter and summer. House type was also an apparent factor: flats had lower ventilation rates than other house types. Bearing all of this in mind, there is reason to fear that the conditions will be ripe for the airborne spread of Covid-19 as winter approaches, due to people spending more time indoors and the near ubiquitous reliance on natural ventilation via background ventilators and window opening – ventilation strategies that many people are inclined not to use during winter. To view the CIBSE guidance on emerging from lockdown, including ventilation guidance, visit: www.cibse.org/coronavirus-covid-19/ emerging-from-lockdown.

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Marketplace News WHY SHADING IS A MAJOR HEALTH ISSUE IN OUR HOSPITALS

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aylighting, overheating, glare and lack of natural, insect-free ventilation remain significant issues in UK hospitals and may be hampering the ability of patients to recover, and hospital staff to properly care for them, according to UK solar shading manufacturer Smartlouvre. Smartlouvre managing director Andrew Cooper said that many UK hospitals are prone to overheating and glare, which in turns leads to stuffy indoor environments that are sub-optimal for both patients and staff, as emphasised in the latest CIBSE guidelines on ventilation. “In a healthcare environment the occupants need natural daylight and air more than ever,” he said. “A connection to the outdoors and having access to natural light helps patients heal faster, making for a shorter hospital stay, and in general, the therapeutic environment that is strived for.” But without proper shading, glazing that provides views and daylight can also cause overheating and glare, and discomfort for those inside. Cooper says these are often not considered during hospital design. “All too often they are disregarded, or at least deprioritised and found to be a problem after the building is occupied.” He pointed out that back in 2018, a UK heatwave saw NHS trusts bulk-buying mobile air-conditioning units, fans and bottled water as temperatures climbed to up to 40C inside wards. “This year is predicted to be the warmest year in UK history when we are also dealing with a global coronavirus pandemic, which makes clean natural ventilation essential,” he said. “So why isn’t solar shading prioritised? Or is it the cost of cooling? Or the effect on the environment of air conditioning? Ventilation is crucial, as CIBSE emphasise, especially whilst dealing with the pandemic, but so is heat and light control. Worse still, healthcare trusts that don’t have imminent budgets for new buildings are seeing their running costs rise, year after year, in order to manage temperatures in buildings built when these levels of temperatures weren’t even a consideration.” The UK Committee on Climate Change stated in a recent report that the types of hospital ward that are vulnerable to overheating currently make up 90% of the total stock (by floor area). A recent Cambridge University report found that some £17.5bn of upgrades could be needed to make UK hospitals resilient to overheating through new shading measures and improved ventilation. “Overheating in hospitals is a serious issue.

The general design guidance for healthcare premises as defined by the Department of Health isn’t prescriptive when it comes to solar gain and glare. It simply states that it should be controlled and suggests examples of providing control being through louvres and blinds. Internal or external, it doesn’t say. Furthermore, it suggests that thermal comfort conditions are ‘issues to consider’. Where are the standards? The minimum heat gain and glare, the temperatures acceptable at any given point in the day? Recuperating patients require a lot of sleep, which is interrupted at just 26C, and that’s just the start. “And so, the management of heat and glare is left to shading solutions that at best, remove only some of the problems, or at worst, also remove the benefits of the glazing and the daylight.” “Internal blind systems remove visibility and a connection with the outside world and only protect the room from a minimal amount of heat gain. External shading systems do work but are expensive to install and maintain as well as reducing the quantity and quality of daylight and vision out. Even the most recent advances in glazing technology reduce the view out.” Smartlouvre’s MicroLouvre product consists of a fine bronze allow mesh, comprising 700 tiny ‘bris-soleil’ fins per metre of fabric, measuring only 1.5 mm in depth. It is installed on a frame external to any windows, allowing heat to accumulate on the surface of the metal and then dissipate to the outside before it reaches the window. “You stop the heat and light before it hits the glass, with a metal fabric, with micro fine louvres woven in to dissipate the sun’s heat and energy but not block natural daylight, natural ventilation or vision out,” Cooper said. “This solution works totally differently from traditional external and internal blinds, which reflect, distort and restrict vision and light.” “It doesn’t diffuse daylight, it provides all the benefits but not the negative impact of excessive heat gain and glare. The louvres are micro fine, and angled at a level to ensure optimum light in, and visibility out, whilst protecting the building occupants from the heat, glare and even external viewing in. It’s known as angular selective technology. Testing at Fraunhofer Germany has shown that MicroLouvre, retrofitted on to ordinary double glazing, outperforms even the best solar glasses.” MicroLouvre was recently studied as part of an exercise carried out by Richard Tibenham of Greenlite Energy Assessors to model different solar shading solutions for a

large new student accommodation building in the East Midlands. Tibenham’s model determined that without any solar shading, the building was likely to experience “moderate to severe” overheating issues, even without taking account of future climate change scenarios. He modelled MicroLouvre against two other solar control solutions, namely control glass and high-performance internal blinds. Of the three products, Tibenham concluded that Smartlouvre offered the “highest level of guarantee against overheating concerns over the medium-long term”. He concluded that the product offered a good glare reduction while allowing full daylight spectrum transmittance and a durable service life of 25 years plus, all while reducing overheating to the required target (CIBSE TM59). “MicroLouvre performs better than retrospectively applied solar control films in terms of light transmittance, summertime solar gain reductions and durability,” he wrote. He also stated that in the case of this new build student accommodation, however, it is the more costly option. On a retrofit project however, MicroLouvre would compare more favourably, because its cost would be compared with the need to fully replace existing glazing with a solar control option. Speaking to Passive House Plus, Smartlouvre’s technical product manager Joe Reynolds welcomed Greenlite’s analysis, and recognition of MicroLouvre’s performance. “Now we just need to quantify the effect of full-spectrum daylight, superior glare control and the other added benefits MicroLouvre provides,” he said. To find out more about Smartlouvre go to www.smartlouvre.com.

(above) MicroLouvre is designed to prevent glare and overheating while preserving daylight and maintaining views to the outside.

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ECOLOGICAL LAUNCH NEW WEBSITE AND ONLINE TRAINING

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cological Building Systems have announced the launch of a new website, aiming to support professionals and homeowners alike to achieve better results from their next project. The new site adds e-commerce functionality, enabling online ordering of Ecological’s range of sustainable and energyefficient building products. As well as providing in-depth technical specifications, datasheets and certifications, the site includes a wide range of visual instal-

lation guides, project examples and hands-on product advice aimed at making sustainable building methods more accessible. It includes an advanced recommendation engine to help users quickly identify complementary products and accessories to fit their needs, plus live chat to provide personalised advice where needed. For industry professionals, the website also houses information on Ecological’s range of training and CPD events. While these are usually hosted in Ecological’s on-site training

centres in Carlisle in the UK and Athboy in Ireland, the training offering has recently been expanded to include new virtual webinars and online events in light of the Covid-19 crisis. Penny Randell, UK general manager and director at Ecological Building Systems, said: “At Ecological, we’ve always felt that providing education and support is just as important as selling the products themselves, if not more so. Finding not only the right products but the right accessories and tools for a particular application isn’t always easy, and even then, correct installation can make or break a project. “Our new website is a one-stop shop to help anybody planning a sustainable building project to source the right products for the job, and access information and advice to get the best possible results. We’re delighted to be able to bring so much of our team’s collective expertise online for the first time – it’s the next best thing to having them at your desk.” The Irish division of Ecological Building Systems is in Athboy, County Meath where the company was established in 2000, while the UK division is near Carlisle, Cumbria. Full information on their range of products and services is available on the new website at www.ecologicalbuildingsystems.com. • (above) The new Ecological Building Systems website.

Xtratherm secures EPD for Thin-R boards

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eading insulation manufacturer Xtratherm has become the latest company to receive an environmental product declaration (EPD) under the Irish EPD programme. Xtratherm’s EPD is for its Thin-R range of PIR insulation boards, and the declaration covers Thin-R boards ranging in thickness from 25 mm to 150 mm. EPDs are an increasingly important way for manufacturers to provide standardised data on the environmental impact of their products across a range of different parameters, including global warming potential, acidification, eutrophication and ozone depletion. They are designed to eliminate false and misleading claims about the environmental performance of materials by providing independently certified data. Building materials are assessed according to EN 15804, a standardised method for evaluating the environmental impact of construction products. There is growing focus in the industry

66 | passivehouseplus.co.uk | issue 34

now not just on the energy efficiency of buildings, but on the wider environmental impact of the materials used in them. Speaking to Passive House Plus, Peter Seymour of EcoReview, the consultancy that produced the EPD for Xtratherm, said manufacturers were starting to see the benefits of having EPDs among their range of environmental certifications. “EPDs are now the preferred choice for specification on projects using BREEAM, LEED, and the IGBC’s Home Performance Index,” he said. “It is also a sure thing that the incoming government will put a major focus on the embodied carbon and energy of the built environment, and that EPDs will become the essential vehicle to communicate this data.” Meanwhile Danny Kearney, Xtratherm’s director of technical sales and marketing, commented: “Xtratherm is committed to reducing the environmental impact of our products and we’ve seen the benefits of EPD certification since back in 2018 when we were one of the first companies to

certify. Now more than ever, environmentally conscious customers are demanding transparency in build materials, and we’re happy to be able to provide assurance across the entire production process from raw materials all the way to dispatch.” •

(above) Xtratherm’s Thin-R range of insulation boards has just received EPD certification.


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Partel launches new Size is key for MVHR fire-rated breather membrane — CVC Direct L

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hen it comes to MVHR, size does matter, according to leading system designer and supplier CVC Direct. “All too often MVHR [mechanical ventilation with heat recovery] units are under specified and forced to run at high capacity, and the outcome of this is a noisy and inefficient system,” CVC Direct’s Nicholas Vaisey told Passive House Plus. “Typically we aim for 50-60% of the unit’s maximum capacity for normal ventilation, allowing for sufficient boost ventilation.” CVC supplies Brink MVHR units with constant volume fans, which operate by constantly assessing the system pressure and adjusting the fan to maintain the commissioned airflow. “On this basis it is very important to maintain low system pressures, to help reduce noise and provide an efficient system,” he said. “So, it is just as important to size the ducting correctly and use the correct ducting,” he continued. “Trying to push too much air down a small duct means high velocities, increased pressure on the system and increased noise.

Unnecessary bends, sharp bends and corrugated ducting also result in higher levels of resistance in the MVHR system, which increases the noise from the unit and turbulent noise generated by the airflow. “At CVC we design the air velocities to be below two metres per second at normal operation, to maintain these velocities we recommend the 92 mm semi-rigid ducting, rather than the commonly used 75 mm. If we supply a rigid system, we would use steel rather than a PVC system, for its increased performance characteristics.” Lack of attenuators is another common failure with specifications, Vasiey said. Passive house guidelines outline sound pressure levels of less than 25 dB(A) in living and sleeping rooms, and less than 30 dB(A) in kitchens, bathrooms, WCs and utility rooms. “This should be demonstrated at design stage and if can’t be achieved through attenuators, then the unit selection should be revised. If a rigid system is used, cross talk attenuators should also be specified,” he said. •

(above) Brink MVHR unit with rigid pre-insulated ducting.

ow energy building product supplier Partel has launched a new premium class of protective flame-retardant breather membrane to the UK market. EXOPERM MONO DURO 200, with a Euroclass B fire rating, is designed for external applications within the low energy building sector. “Today, fire-rated breather membranes are the leading solution in planning any type of durable construction,” said Hugh Whiriskey of Partel. “Designers, architects, engineers, and builders are facing critical challenges such as more demanding environmental, health and safety regulations, as well as the need for a higher level of building fire safety that protects the building structure, as well as protecting lives.” Partel’s new EXOPERM MONO DURO 200 membrane is designed to address these challenges and provide peace of mind in any condition. The membrane has been tested in accordance with EN 13501-1, obtaining a B-s1, d0 classification. It is CE-certified according to EN 13859-2 and is ideal for use with both roof and rear-ventilated facades, featuring open or closed joints. It is suitable for use in all building types, from residential houses to high-rise construction, the company said. Based on advanced monolithic TPU technology, EXOPERM MONO DURO 200 provides “outstanding water and wind-tightness properties, excellent ageing resistance while offering constant high performance throughout its useful lives,” Whiriskey said. Thanks to its unique two-layer structure — vapour permeable TPU coating combined with technical PES non-woven fabric — the membrane is designed to: • be highly breathable, reducing condensation risk • provide increased fire resistance, reducing flammability and smoke • offer long-lasting UV protection (the TPU monolithic-coated facade offers long-term UV protection, up to 10 years) According to Partel, the TPU functional film ensures very high resistance of the membrane to stretching and tearing, which positively impacts the safety and speed of the builder’s work, being very easy to handle. The product is underpinned by an extensive 15-year warranty when used with typical vented facades, and a 10-year warranty for open joint facades (maximum proportion of joints 40% and a maximum joint width of 50 mm). “EXOPERM MONO DURO 200 will enable our customers to improve building safety, increase design opportunities and enhance sustainability, making it easier for them to reliably build better, energy-efficient, and more durable construction,” Whiriskey said. For more see www.partel.co.uk.•

(above) Partel’s new EXOPERM MONO DURO 200 fire-rated breather membrane.

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Built Environment completes ‘mammoth’ MVHR installation

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uilt Environment Technology Ltd are supplying an innovative MVHR system with geothermal intake ducts at a luxury new-build home for a private client and his family, in Surrey. With a gross internal floor area of 1,300 m2, the new home has been designed to provide privacy, space and luxury, including a basement swimming pool with spa and sauna, a fully-equipped fitness suite, a cinema and a golf simulation room. The family accommodation is arranged over four floors, with a separate studio flat above the garages, for guests. Completing a new-build house of this size is a mammoth task under any circumstances and one which would normally be undertaken by an appointed main contractor, with designated sub-contractors in their various fields of expertise. In this case, however, the client elected to projectmanage the entire build process himself, directly appointing specialist contractors throughout. Built Environment Technology Ltd was appointed as the mechanical ventilation with heat recovery (MVHR) specialist, with full turnkey responsibility for specification, design, procurement and project management. Vent-Axia Sentinel Kinetic High Flow MVHR units were specified, with five units required to meet the airflow demand, in conjunction with a complex system design. Air quality will be proportionally controlled by an

integral humidity sensor in each unit, with manual boost override in case of need. The client also wished to refine comfort as much as possible, whilst reducing the associated energy requirement, and specified two geothermal intake ducts for the MVHR units. Manufactured by Rehau, ground-to-air heat exchange ducts are designed to eliminate the extremes of outside conditions, by transferring renewable geothermal energy to the intake air. When outside temperatures are very low, therefore, the intake air temperature is naturally raised, and conventional, high-energy frost protection heating is not required. When outside temperatures are very high, however, the opposite takes effect and intake air is naturally cooled. When asked about the challenges of heat recovery on such a big project, senior projects manager at Built Environment, Richard Porteous, said: “We have a great deal of experience with very large properties and this is certainly no exception! Attention to detail is critical over a period of many months and it is a huge team effort, both on and off site. It has been refreshing to work directly for the client, as decisions have been made very quickly, when required. We also look forward to monitoring the geothermal intake performance, as outside temperatures vary throughout the year.” •

(above) One of two geothermal intake ducts for the MVHR system.

New passive vet centre opens in Wigan V

eterinarian and passive house enthusiast Chris Copeman, whose £60,000 passive house retrofit was featured in Passive House Plus issue 29, has built a new veterinary practice in Wigan that is aiming to meet the passive house standard. Bryn Veterinary Centre comprises three consulting rooms leading off a reception space that reaches up to the roof of the two-storey building. The project was designed by PYC Group, who also acted as passive house consultants on the project. The timber frame structure was provided by MBC Timber Frame and insulated using Warmcel recycled cellulose insulation. Green Building Store’s Ultra and Performance triple glazed timber windows and doors were chosen for the project. Green Building Store also designed, supplied and commissioned the MVHR system for the project. A Paul Novus 450 MVHR unit was specified, alongside galvanised rigid steel ducting. The ventilation system at Bryn Veterinary Centre provides a controlled

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amount of ventilation to every room in the building and enables the veterinary centre to extract air from ‘wet’ rooms, such as operating rooms and kennel rooms, to create a healthy air flow and reduce the risk of infection. Using timber frame for offsite construction also speeded up the building process, Copeman added. “Within a week you’ve got a weather-tight building. It’s an incredibly fast building method.” The building achieved an airtightness of 0.33 air changes per hour and it is currently awaiting passive house certification. It boasts a 10kW solar photovoltaic array which has so far generated about 3,700 kWh since opening in October, with about 2,300 kWh of this used on site. Copeman added: “The result is a near carbon neutral build footprint and a building that is 10 times more efficient, generates its own power and gives you full control of every aspect of the environment inside. It is a happy building, full of warm, natural materials, where staff, clients and their pets all seem to thrive.” •


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Remote home monitoring can help in Covid fight – iOpt Assets

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lasgow-based remote home sensing provider iOpt Assets believes its digital monitoring service can help to significantly limit maintenance visits by local authority and housing association staff, reducing one potential avenue of infection spread during the Covid-19 pandemic. iOpt Assets provides a remote sensing service that enables housing stock owners to remotely monitor temperature, humidity and CO2 in the buildings they manage. This dynamic information is then correlated with static information like house type, build method, insulation levels, and occupancy levels, as provided by the landlord. “When combined, this provides a powerful mix of information that can be used to anticipate problems like damp and mould, fuel poverty, poor indoor air quality, changes in occupancy levels, and heating system failures,” iOpt Assets director Dane Ralston told Passive House Plus. “And in the age of Covid-19, we believe this can be hugely helpful in reducing the need for local authority and housing association staff to visit their properties, helping to prevent the spread of infection.” Ralston continued: “Most of our clients start off interested principally in monitoring energy efficiency and temperatures, but quickly realise they can learn a whole lot more about conditions in the properties. It’s not about just about looking at temperature, or CO2, or humidity, but about how these interact with the lifestyle of the occupants, and with the ways the properties are insulated and heated. This provides a very powerful set of data.”

The company provides real time, accurate data on housing conditions, and early warnings of potential issues, to its clients. Three or four wireless sensors are typically installed in an average two or three-bed property. The company’s software platform then interprets the data gleaned from sensors and information about the house to predict when and where issues such as mould growth will arise, using iOpt’s bespoke algorithms and machine learning techniques. Ralston said it was interesting to note that in May 2020, CO2 levels in dwellings it monitors rose on average by about 40% compared to May 2019, because far more people were working at home and staying inside. “We worry that if Covid-19 comes back for a second wave in winter, that will have a massive impact in terms of people spending more time inside, and keeping windows closed, leading to worsening indoor air quality and lack of ventilation.” iOpt Assets uses the LoRa radio network for its remote sensing. “We’re looking at developing our monitoring capabilities further to work at the ’smart city’ level to look at how indoor air quality is impacted by external factors such as traffic pollution.” To find out more see www.ioptassets.com. • (above) The iOpt Assets system combines wireless indoor air quality and temperature sensors with building data, to enable social landlords to remotely monitor buildings and identify risks such as the likelihood of when and where mould growth may occur.

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T O BY C A M B R AY

COLUMN

The science of filters How do ventilation filters work, and can they help to protect us against Covid-19? Toby Cambray weighs in on the physics of a subject that is more complex and interesting than you might expect.

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f you’ve never given it a great deal of thought you’d be forgiven for thinking that filters are very important when it comes to how our buildings can help or hinder the effort against the current pandemic. I certainly did! It turns out (at least in relation to domestic MVHR) that unless you have several infectious people coughing into the intake grille, a filter in your typical domestic MVHR system is not going to do much to protect you from Covid-19 (though it can’t hurt). But filtration is still important, as well as complicated and perhaps interesting… There is more to how filters work than meets the eye; they aren’t simply sieves with tiny holes, although that’s one mechanism by which they work. If you look at them under a microscope, the holes in most filter media (or gaps between their fibres) are bigger than much of what they are intended to catch. Crucially, proper filter media are manufactured with an electrostatic charge applied, so particles tend to stick to the fibres if they get close enough. Above about 0.2 microns, particles tend to travel in straight lines, and in the same way you can’t see through a filter because

microns, which are larger than the MPPS, and more likely to get stopped by a filter. So how good are the different grades of filters at catching these various particles? The answer to this question can be found in the boring-but-important standards on the subject. Anyone who has specified or designed MVHR for a passive house ought to know that the level of filtration required on the intake is F7 (or better). Here, F means fine, as opposed to M for medium and G for coarse (sic), and F7 must on average remove 80 to 90% of particles in the 0.4 micron size. G4 is the standard spec for domestic filters, and what you get if you don’t specify a grade. These are therefore typical in non-passive house applications. However, G filters have an efficiency of less than 40% with respect to 0.4 micron particles, so clearly can’t be relied upon to remove the finer particles that are bad for our health. To be clear, G filters are only really intended to protect equipment from larger particles which could damage fan blades etc. Also, it’s common in commercial buildings to cascade filters, so the incoming air is passed through more than one filter,

but they are generally comparable and should yield better performance because the new test looks at a broader spectrum of particle size. There is a huge amount to this topic and I’ve barely scratched the surface here. Pressure drop is a very important aspect for example, and one reason to avoid over-specification of filters. I started out on this column thinking I’d mug up a bit on filters and write something about the importance of filters in combatting the current pandemic. Instead, I found myself going down a rabbit hole with less relevance to protection against Covid-19 but learning a lot along the way. I can only hope that someone else out there finds this useful, interesting or both! n

It makes sense to have one filter for Covid, and another one for Corvids.

the light hits one or more fibres, a particle travelling in a straight line will simply collide with a fibre. Below about 0.1 microns, a particle starts to behave more like a gas molecule, darting around according to Brownian motion. Once within the filter, all that darting around tends to make it bump into the charged fibres. The cumulative effect of these mechanisms gives an efficiency curve with a dip at about 0.1 to 0.2 microns; this size is therefore known as the ‘most penetrating particle size’ (MPPS) and is used to benchmark filters. It turns out that a Covid-19 virus has a size almost exactly the same as the MPPS, which is bad because it means a virus is the optimum size to penetrate a filter. On the other hand, viruses generally escape the body suspended in droplets of 0.5 to 10

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starting coarse and becoming more fine. This helps the fine filters focus on what they are best at, leaving the job of catching flies, leaves and dead birds to less costly filters. It makes sense to have one filter for Covid, and another one for Corvids. It’s also worth pointing out that the standard setting out the G, M, and F classifications (BS EN 779) has been superseded by one that is more fit for purpose. As usual with changes in standards, it takes time for updates to become widely adopted in practice. Brave souls might summon the energy to wade through the 164 pages that make up BS EN 16890, but failing that, you might consider swapping F7 for ePM1 60% and G4 for Coarse 70% in your documentation. The categories are not directly equivalent because the test method is different,

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.


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ph+ | editor’s letter | 71


Support where and when you need us Xtratherm have updated our resources and technologies to support you in your own changing working situation, to continue to provide the service you can rely on. We are all getting used to communicating online, particularly in the areas of technical support and CPD delivery.

New & Updated Ways to Work: Xi Online Learning Remote Support Live Webinars

For more information call: 0371 222 1055 72 | passivehouseplus.ie xtratherm.com

| Issue 21

We have met many more of you face-to-face for the first time; so that can only be a good thing. Our webinars and consultations are created with you and your team in mind, covering the areas of interest that you are focused on. Let’s keep talking.

Topics include: — Achieving Future Homes Standard — Part L Regs and Passive - where are we? — It’s all in the detail - how to improve thermal bridging — Threshold detailing to avoid bridging — Closing cavities to meet fire, structural & thermal regs — Calculation of Thermal Bridging - what software? — Calculation of U-Values - getting it right — Cut-to-fall roof thermal calculation - not as simple as an average — SAP - an understanding

Profile for Passive House Plus (Sustainable Building)

Passive House Plus (Sustainable building) issue 34 UK  

To ensure anyone who wants to read the new issue of Passive House Plus can do so easily during this time of disruption, we're once again mak...

Passive House Plus (Sustainable building) issue 34 UK  

To ensure anyone who wants to read the new issue of Passive House Plus can do so easily during this time of disruption, we're once again mak...

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