Cut the VAT on retrofit 

MVHR ducting housed in the roof apex at Lower Royd radical retrofitMany of us are having to spend more time in our often not-very-cosy homes during this period of self-isolation.  So, now seems to be a good time to make the case for the removal of VAT on retrofit building work. This would be an important step that the Government could make to help boost the UK economy in these unsettled times as well as acting on the other very pressing emergency of climate breakdown. 

At the moment, we are in the ludicrous position that newbuild build projects have zero VAT but VAT is charged at a rate of 20% on retrofit projects. There are a few exceptions to the rule but generally because of the VAT, build costs are more for retrofit, resulting in a situation where it is usually cheaper to knock down buildings and build new ones in their place, rather than work with existing structures and retrofit them for new, greener use”.[1}  Yet we know that retrofitting results in far lower overall carbon emissions than replacement. 

Two current campaigns are calling on the Government to reduce or zero VAT on retrofits. The Architect’s Journal’s Retrofit First campaign calls for VAT to be cut on refurbishment, repair and maintenance from 20 per cent to 5 per cent. Meanwhile Architect Harry Paticas has set up his own petition calling for zero VAT on eco-retrofits.  

The environmental argument 

Roof under construction at Lower Royds radical retrofitHomes in the UK are responsible for an estimated 15% of total carbon emissions and heating is responsible for over 60% of their energy use. To properly address the existential threat of climate breakdown, there is an urgent need to deep retrofit our homes to radically cut carbon emissions. 

The AJ has set up its Retrofit First campaign  Because construction gobbles up energy and resources at a phenomenal rate: cement, aluminium, steel, plastics and more. It is responsible for up to 40 per cent of the UK’s carbon emissions. The economic model of tearing down existing structures, chucking the debris and building from scratch is hugely wasteful. If we can retain more existing structures through intelligent retrofit, we’ll reduce carbon emissions and embodied energy costs, help conserve resources, and set buildings up for a longer life.” 

 The financial argument 

Radical low energy retrofits can cost between £30-50,000 per dwelling. Despite the significant benefits of lower bills and increased comfort, at present very little retrofit is taking place.  

As Harry Paticas puts it:  

“With the lack of any significant funding for a UK retrofit programme and homeowners (private and social) obliged to pay 20% VAT on all works to existing homes (with only a few exceptions) there is a strong disincentive to carry out deep retrofit works. 

The removal (zero-rating) of VAT on building projects to existing homes that are based on a demonstrable deep, low-carbon eco-retrofit would act as a major stimulus to the market with the potential of achieving significant reductions in carbon emissions.” 

WIN-WIN-WIN-WIN 

Spraying Diathonite into first floor wall junctiom

The airline industry is the latest UK industry to demand a financial bailout from the Government following the financial impact of the coronavirus pandemic. The removal of VAT on retrofit building work would be a less climate-wrecking way to kick-start the economy and would create many new low carbon jobs,  helping us take the crucial action needed to prevent climate breakdown while eradicating fuel poverty and making our homes cosier 

Please support campaigns calling for a reduced VAT on retrofit building work 

Retrofit First: www.architectsjournal.co.uk/opinion/join-our-retrofirst-campaign-to-make-retrofit-the-default-choice/10044363.article 

STOP the VAT on Eco-Retrofit, petition set up by Harry Paticas www.change.org/p/uk-government-zero-rate-vat-on-deep-retrofit-eco-refurbishment-building-works 

 

Chayley Collis, Green Building Store

Chayley Collis, Communications Manager, Green Building Store

Green Building Store: Celebrating 25 years

Green Building Store 25 years
 
Celebrating 25 years of Green Building StoreThe time seems to have gone so quickly but, amazingly, 2020 sees Green Building Store celebrate its 25th year of operation. Originally based in a shed on the side of Director Bill Butcher’s house with 2 staff (and a dog), the company now has 36 staff and a national reputation for low energy building products and expertise. The company has changed and evolved considerably over the last 25 years, illustrated by its switch to promoting the Passivhaus low energy standard in 2009.
 
Green Building Store Directors Bill Butcher & Chris Herring  said: 
“Over the last 25 years we have seen interest in green building grow steadily. The good news is that we are now (finally) finding greater uptake of low energy building by councils, businesses and individual selfbuilders. The bad news is that national Government policy is still not providing the drivers and incentives that are so urgently needed.
We are proud of our role in helping the UK take up Passivhaus and low energy building and look forward to the next 25 years!”

 

25 key milestones

Green Building Store founders 1995

Green Building Store founders 1995

1995 Environmental Construction Products (ECP) launched by three builders frustrated by the lack of availability of green building products. The Ecoplus range of high performance timber windows is launched and made in Huddersfield. Office set up in shed attached to Bill’s house.   Staff: 2

1999 Company moves offices to Meltham centre.  Staff: 7

2001 Trading name changed to Green Building Store launched as trading name of ECP, with launch of online shop selling natural paint and insulation. Slator-Butcher construction incorporated as Green Building CompanyStaff: 16

2001 Green Building Company undertakes full-scale energy-efficient refurbishment of Bridge 5 Mill In Manchester, including training of 15 apprentices in the process.

2004 Launch of a range of products and services specifically for the public and commercial sectors, including water-saving products and commercial window ranges.

2005 Green Building Store’s Ecoplus System range becomes the first UK manufactured range of FSC® certified 100% windows and glazed doors.

2007 Green Building Store moves to its (current) Heath House Mill base.  Staff: 24

2008 Green Building Store’s Ecoplus System window and door range receives a ‘Major Commendation Award’ in the BCE Environmental Leadership Awards 

2009 Green Building Store launches range of Passivhaus products and services to help facilitate the uptake of Passivhaus design and construction in the UK. 

Green Building Store receiving the Queens Award for Sustainable Development 2009

Green Building Store receiving the Queens Award for Sustainable Development 2009

2009 Green Building Store wins Queen’s Award for Enterprise: Sustainable Development 2009, for its ‘pioneering approach to sustainability’.

2009 Bill Butcher contributes the ‘Passivhaus diaries’ blog for BUILDING magazine on the construction of the Denby Dale Passivhaus.

2010 The Denby Dale Passivhaus – the UK’s first Passivhaus built using cavity wall construction – is built by Green Building Store’s construction division and achieves Passivhaus certification. Green Building Store creates a 60-minute technical film on the building of the Denby Dale Passivhaus, with the support of Kirklees Council.

2010 Green Building Store Director Chris Herring helps found the Passivhaus Trust and is appointed Chair.

2012 Green Building Store won the Manufacturer of the Best Green Product category in the Yorkshire Post 2012 Environment Awards for its Ecoplus3 range of high performance timber windows & doors.

2012 Green Building Store develops its Warmer Homes resources to help householders undertake low energy retrofits ,  as part of the  MASTT (Marsden & Slaithwaite Transition Towns) Warmer Homes project in partnership with Connect Housing, and were funded by DECC. 

2013 Green Building Store commits to plant 1000 trees with Trees for Yorkshire over 4 years.

2014 Green Building Store achieves EnerPHit (Passivhaus retrofit) standard at the Cre8 Barn at Yorkshire Wildlife Trust’s Stirley Community Farm in Huddersfield. The project goes on to win ‘The Legacy Award – Sustainability’ at Constructing Excellence Yorkshire & Humber Awards 2014.

2015 Green Building Store commits to switch over to triple glazing for all its standard window specifications, so that triple glazing is sold as standard for its window and door ranges.

UK Passivhaus Awards 2015 Small Projects category

2015 Cre8 Barn wins ‘Retrofit Project’ category in UK Passivhaus Awards 2015.

2016 Golcar Passivhaus project certified and shortlisted for UK Passivhaus awards 2016

2016 Cumberworth radical retrofit project pioneers breathable internal wall insulation (IWI) solution in the UK. 

2017 Lower Royd radical ‘whole house’ retrofit project wins the #RISE2017 Award for ‘Vision & Sustainability’.

2019 Green Building Store’s online store selling airtightness products, MVHR filters and insulation is re-launched.  Staff: 36

2019 Green Building Store wins ‘Highly commended’ in BusinessGreen Leaders Awards Small Business category.

2019  Goldsmith Street project for Norwich City Council receives RIBA Stirling Prize for architecture. Green Building Store supplied and commissioned all the MVHR systems on the project.

 

Heidelberg Passivhaus conference: Achieve Better Buildings May 2019

View of HeidelbergThis year’s international Passivhaus conference was quite different from any I have previously attended.  There did seem to be some confusion about the status of the conference, and I know some Passivistas did not attend, believing it was to be a German conference.  However this conference was always intended to be the doppelganger of the big event this year: the international conference to be held in Gaobeidian in China in October. 

Gaobeidian

Holding the main event in China makes sense.  The scale of construction in China and developing countries is on a different scale from anything we will see in Europe or North America – think multiple new cities the size of London within a relatively few years from now as the twin drivers of population growth and urbanisation continue to accelerate early in this century.  Where China leads other developing countries will follow, so the Passivhaus Institute has been working very hard to support Chinese colleagues in their aspiration to develop Passivhaus at a scale we can only begin to imagine in Europe.  Gaobeidian, where our doppelganger conference is to be held, is a complete new city being developed entirely to the Passivhaus standard. 

Travelling by train to the Passivhaus conferenceHowever I am not going to China.  While we undoubtedly need to share knowledge across the world, we also have a moral responsibility to consider flying very carefully.  I believe in Sweden this is now called ‘flygskam’ (flight shame), and while our individual actions cannot on their own fundamentally solve the climate crisis we now face, I have no doubt that taking some personal responsibility for our carbon footprint does if nothing else, create some ‘peer pressure’, which can only help to increase awareness and ultimately the dialogue in our society about these key issues.  Personally I have been inspired by friends but particularly by Professor Kevin Anderson, one of the UK’s leading and most outspoken climate scientists, who has said that he will only fly if it is important enough for him to do so.  Since the early 2000s he has found nothing important enough, and hasn’t flown.  I cannot say that I will never fly, but I will certainly only do it when absolutely essential.  So, of course my journey this year to Heidelberg was by ferry from the north of England, and wonderful European trains.  In fact I am writing this blog while speeding up the Rhine valley – what could be more delightful!

So, the Heidelberg conference felt quite different from any of the others I have attended since my first in 2007.  Instead of the 1000+ delegates, we had 300-400, and instead of a modern ‘messe’ venue, we had a lovely old conference centre right in the centre of Heidelberg Altstadt. 

The climate & environmental emergency

However, for me the really big difference was the context.  While most thoughtful people, and certainly I am sure everyone attending a Passivhaus conference, will have long been aware of the developing crisis presented both by climate change and species extinction, something has changed.  For me the change has been the deep emotional acceptance of the message that this is an existential crisis for humanity which will have fundamental impact not in some difficult-to-visualise distant future, but for immediately following generations.  I look at my young grandchildren and can only wonder about the world they are inheriting.  This is a crisis which has its origins back in the industrial revolution, or arguably much earlier in the way some of human society has framed our relationship with the natural world.  But it has really developed since the immediate post war period, which means over the course of my own lifetime.  The IPCC 1.5 C report late last year, the rise of Extinction Rebellion, the extraordinary impact of a 16 year old Swedish schoolgirl – who could have even imagined this a year or two ago? And, as I write we have the publication of the report from the Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services, cataloguing the devastating impact we humans have had on natural systems and the potential for catastrophe in our planetary systems.  So the huge question facing us all is: can we reverse all of this within a handful of years.  We no longer have the luxury of time.  As Professor Piers Forster, one of the IPCC lead authors, has said ‘we have to do everything, and we have to do it now’.

So for me the framing of this conference was the urgency of the challenges we now face.   We know that Passivhaus has the lessons to address at least some of the issues in the built sector.  Can we get that message over, and can we do it in a handful of years?  If not, Passivhaus is a virtuous hobby, no more.  It is only change at large scale that can now address the depth of crisis we face. My question, coming to Heidelberg, was what is there to learn from what others are doing.  Were others seeing things the same way I was?  What can we do to scale up what we are doing?

 

Introduction to the conference by Wolfgang Feist

I was heartened by Wolfgang Feist’s introduction to the conference programme, which I thought so plangent that it was worthwhile sharing below: 

“We live in times that are confusing to many, where scientific facts are called fake news and fundamental ethical principles are called into question.  Such phases have happened time and again throughout history and it is necessary to remember that the resulting totalitarianism has never contributed to the solution. 

The science today shows us that we are overusing natural resources and on the brink of irreversibly changing the planet’s climate in a way in which a reasonable civilisational coexistence can no longer function.  This analysis may not suit us, but it does not make it wrong. 

A gradual transition to a sustainable economy can work: presuming, however, that we start now at the latest.  This means no new fossil fuel power plants…., no new vehicle lines with internal combustion engines, and in the long run no more fossil fuelled heating systems in our buildings.”

I would argue that we need much more.  We need a fundamental rethinking of the way our economy works, of capitalism and growth.  And we absolutely need to consider ‘sufficiency’ as well as ‘efficiency’.  This was a strand picked up particularly by Professor Michael Braum, in the plenary session, where he emphasised that ‘sustainability is more than living in an energy efficient building’.  It is no good cycling and having solar panels, while still flying and wanting lots of technology.  ‘Society has to change its mindset’.

Much-needed inspiration

But we are all human, and we all need inspiration, as well as sobre (and in many ways bleak) analysis of the situation we face.  And there was a lot to inspire us at this conference.  We heard an inspiring introduction from Franz Unterstellar, Minister for Environment and Energy of the State of Baden Wurttemberg. These political introductions are usually a necessary but often rather dull start to any conference.  This was different.  Franz gave a clear and critical analysis of where we are, emphasising that climate change was already affecting his region, while then going on to talk about some of the measures being undertaken in the region.  He was followed by Professor Eckart Wurzner, Lord Mayor of Heidelberg, who is an environmental expert deeply committed to making Heidelberg a pioneer in climate protection.  Of course we knew this, which was the reason we were in Heidelberg.  The Bahnstadt project has been the largest scale Passivhaus project in the world (although I suspect this status has been, or will shortly be, eclipsed by Gaobeidian).  But there was much more going on here, from making it the second most bicycle-centred city in Germany, to having reduced the average citizen’s carbon footprint to 8.5 tonnes CO2 per person per annum.  There are subsidies for retrofitting old buildings, an innovative heat storage system, an innovation park where they are about to produce organic solar cells through 3D printing (if the simultaneous translator got this right!), to a whole new section of the city – the Patrick Henry village – building on the success of the Bahnstadt.  So much to learn for our own cities and local government, particularly for those like mine which have declared climate emergencies.  And yet so much more to do to bring that carbon footprint down to 2 tonnes CO2 or even less!

Of course a conference is not just about the big picture, but also an opportunity to learn, and to share knowledge about the details.  And then there is the networking, which is always an invaluable aspect of a get together like this.  So I will just highlight a few of my key strands.  Others will inevitably have different stories to tell.

 

The Bahnstadt

The Bahnstadt HeidelbergThe Bahnstadt HeidelbergNaturally I wanted to know much more about the Bahnstadt, and I wasn’t disappointed.  The big lesson here was that Heidelberg took control.  By purchasing large areas and setting up its own development company, it was able to place planning requirements for the Passivhaus standard on all development here.  At first there was no contractor from Heidelberg interested in building or able to build here and the initial buildings went to outside contractors.  Now the picture is quite different.  As the Lord Mayor said, cities must be pioneers in climate protection and to show leadership, as we have also seen in the UK for example in Exeter and Norwich. 

That leadership was also shown by Christiane Staab, mayor of the nearby city of Walldorf.  While much smaller than Heidelberg, Walldorf has also shown leadership with all Passivhaus new build, and ambitious retrofit programme among other measures.  Again as Christiane said, ‘municipalities must be the pioneers’ to inspire their citizens.  Climate protection is akin to fire protection – both absolutely essential.  And if anyone doubts it in Walldorf she recommends they take a trip into their local forests, which are now dying.

On Sunday afternoon I had the opportunity for a short guided tour of the Bahnstadt, and while extensive construction and landscaping work is continuing, I think no one could fail to be impressed by the scale and ambition of this inspiring project.

As Ralph Bermich, who has led the Bahnstadt initiative, summarised towards the end of the conference, we really have to take these issues seriously and ‘walk the talk’.  The Bahnstadt can certainly inspire all of us to do so.

 

 

 

Near Zero Energy Buildings

Several sessions I attended looked at different faces of NZEB.  To be effective we know that Passivhaus understanding needs to sit right at the centre of this.  I was, I have to say, quite shocked to find Germany, the great economic and moral driver of the EU, is actually failing to meet its mandatory targets and is likely to be subject to major fines over the next few years.  Politics is never simple and never linear, but with the extensive municipal interest in Passivhaus it seems very surprising that greater traction has not been gained with the federal government.  There was a very interesting (reportedly) debate covering this issue, which unfortunately I was not able to attend.  But the message I heard was that the German government would not risk compromising the construction of new houses by introducing higher standards.  A story which is sadly all too familiar in the UK. 

While thinking about NZEB, it was interesting to consider the cost issue.  Cost is never far from our awareness with Passivhaus construction after all.  Some interesting work was reported by the Affordable Zero Energy Buildings project (www.azeb.eu) looking at the key drivers to increased costs, and how these can be reduced.  Not surprising perhaps that the key message was one very familiar to those involved with Passivhaus – involving all parties at as early a stage as possible in the design process and including partnership working, thinking NZEB from the very beginning, the importance of getting the contract right and of including performance guarantees within it.  More interesting analysis is available at the website, which looks well worth investigating.

 

Scaling Passivhaus

I came to the conference with the scale of the crisis we face and the need for scaling of what we do firmly at the front of my mind.  Building better buildings is clearly an essential building block in meeting that challenge.  Hence the title of our conference. This must mean rapid scaling of Pasivhaus both in the market, but perhaps more importantly through engaging with policymakers.  This was undoubtedly a strand that wove through and underlay this conference.  As speakers said throughout the conference, and Helmut Krapmeier emphasised while chairing the final session, we need more government policy uptake and that means more lobbying. 

 

IPHA – The International Passive House Association

The International Passive House Affiliates Council

Here, I think national organisations, and the International Passive House Association have vital roles to play.  So following the conference, it was a privilege to chair the Affiliates Council of the International Passivhaus Association where we considered just that: how to develop Passivhaus at scale in our own countries, but also how to respond to the likely upsurge in interest.  Are we ready for both as organisations?  We are on the brink of irreversibly changing the planet’s climate as Wolfgang Feist said, with catastrophic consequences.  What is interesting is that complex systems do not change in linear ways, so we really do need to be ready for the societal tipping points where things change rapidly and unexpectedly.  These tipping points might just give us the opportunity to make the change that we clearly need at this critical time.  We need to be alert to the opportunities both to create policy tipping points and to capitalise on them.

 Are we ready??

Chris Herring is Director of Green Building Store, Chair of the Passivhaus Trust and Chair of the International Passive House Association Affiliates Council.

Low energy newbuild, Yorkshire

ULTRA triple glazed timber windows and doors at low energy selfbuild project Yorkshire
We are delighted our house is now complete and has become a great family home. Green Building Store played a very significant role throughout and their input at all stages has been invaluable, something for which we are very grateful. We couldn’t recommend them highly enough.

Clients

From start to finish the entire Green Building Store team was fantastic. At every stage the advice and guidance was invaluable and I always found a patient, listening ear no matter how many questions I had! Each member of the Green Building Store team share a passion and knowledge for their field. I felt very much that they were all with us on our home building journey.

Clients

AXIS Architecture  has designed a selfbuild low energy home, built on a plot of land in Yorkshire purchased with planning permission. The architects worked closely with the clients and the local planning authority to ensure the subsequent slightly adapted design would continue to satisfy the ‘very special circumstances’ rule, for any new projects on greenbelt land. At the planning stage, a commitment was made to making the property an exemplar of sustainable construction, through the use of low energy technologies and a highly energy efficient building fabric.

The clients had a vision for the house to be as energy efficient and sustainable as practically possible and were interested in the Passivhaus low energy building standard. While developing the construction design, AXIS Architecture undertook a Design Review with Green Building Store’s consultancy service. Owing to the unusual form and generous footprint, which called for a steel frame as the structural solution, the clients were advised by Green Building Store that it would be unrealistic to expect full Passivhaus certification to be achievable. This was partly because of the high area of external envelope relative to the internal building area, but also because of the large expanses of glazing designed to make the most of views of the site and surrounding area and to make the house as naturally light as possible. However, the team were able to work on the detailing of all the junctions within the project to maximise airtightness and minimise thermal bridging.

In addition to Green Building Store’s consultancy and training support, Green Building Store provided ULTRA triple glazed timber windows and doors, Pro Clima airtightness products, MVHR mechanical ventilation with heat recovery design, supply and commissioning for the project.

Landscaping

Set into the hill-side, the house features dry stone wall cladding and the wildflower blanket green roof to blend in and harmonise with its rural setting. This was achieved through careful design of the curved plan form of the house, with a gently sloping green roof, in order to visually blend the house into the rural surroundings by mimicking the site topography.

Design & Planning Challenges

The site was  purchased with planning permission for a single storey dwelling but additional living space was needed, so  Axis Architecture were faced with the challenge of rethinking the internal layout and utilising the roofspace to fit in a further two bedrooms, bathroom and second living room, all without raising the roofline or increasing the massing, in order to satisfy the local planning authority that the amended design would have no greater impact on visual amenity than the original planning approved design.

Building envelope

A commitment was made to design and construct the building envelope to high levels of energy efficiency, requiring particular attention to levels of insulation, thermal bridging and airtightness. Green Building Store’s consultancy service reviewed the various external envelope details and guided the architects in correctly specifying products and materials to reduce the impact as far as possible.  The project aimed for a maximum U-value of 0.15 W/m2K for the external walls, roof and floor.

  • Roof:, 170mm rigid Kingspan insulation, as part of the green roof construction.
  • Floor: 150mm Kingspan insulation, below the screed, which encapsulates the underfloor heating coils.
  • External walls: Constructed using thermally-broken timber Structural Insulated Panels (SIPs) to the inner leaf, with a total 100mm thickness of Ecotherm rigid insulation and 100mm of Knauf Earthwool.

Triple glazed timber windows and doors

Green Building Store’s ULTRA triple glazed timber windows (both inward and outward opening) and doors were specified for the project, including a series of lift and slide doors and tilt and slide doors.  The ULTRA range offers a whole window U value of 0.75 W/m2K. The solid frame windows and doors were made from FSC® certified redwood, finished in a paint colour of RAL 7022. Two FSC® certified oak entrance doors were also specified and finished with a clear finish.

Green Building Store worked with the architects and builder to develop detailing around two of the sliding doors. This involved insulating around the steel rectangular post and then making a bespoke timber cover piece. The team also designed in a Compacfoam block beneath the windows that went alongside the sliding doors, so that they could be made the same height to work with different floor levels.

The clients commented: “We spent a great deal of time researching similar products from several other companies and the quality and design of Green Building Store’s range stood out against the rest.We were able to look at working examples of the windows and doors in their showroom and the performance, clearly visible attention to detail plus the level of customer service meant there was no decision to be made. The very large sliding doors, despite their size and weight move easily and silently, they provide excellent sound-proofing and certainly add to the overall cosy feel of the house.”

 

Minimising thermal bridging

In order to ensure minimal heat loss through the fabric of the building at junctions in the external envelope, including wall to floor, wall to roof, wall to window, the designing out of cold bridging was carefully reviewed which led to the specification of innovative new insulation products.

  • Floor to wall junction

Marmox Thermoblock is a block of load-bearing insulation material which eliminates the cold bridge at the wall/floor junction.  Thermoblock was used in the 65 x 140mm format below DPC level at the base of all external walls and internal loadbearing walls and changes in level.  It was consistently positioned at the level of the floor insulation to eliminate cold bridging .

  • Door thresholds – Compacfoam

Compacfoam is a high strength rigid insulation used for minimising thermal bridging, with a compressive strength and density similar to timber. It is a lightweight thermoplastic foam, based on polystyrene, that offering  excellent thermal insulation. Compacfoam was used below the threshold / cill level of all the external patio doors and full height windows, to minimise cold bridging (and heat loss) through the external wall at ground floor level.

  • Roof overhang

Given that the steel frame was already designed, Green Building Store’s consultancy service advised on ways to reduce thermal bridging at the roof overhang, separating the steel supports from the eaves using Sh’o’ck connectors.

Airtightness

The project called for a continuous airtightness barrier to the external walls, roof, floor, windows and doors. Green Building Store’s consultancy service provided advice on how best to achieve this, alongside onsite construction toolbox talks. The entire internal face of the external walls, and roof, was boarded with 18mm OSB 3 board, to provide a continuous air and vapour barrier.

As all internal plasterboard finishes were fitted separately in front of the OSB board, leaving a clear service cavity for electrics and plumbing pipework, this meant that penetrations through the airtightness barrier could be kept to an absolute minimum.

Pro Clima airtightness tapes, supplied by Green Building Store, were carefully applied around window and door openings by the building team, so as to avoid leakage around the perimeters of the frames. Taping also occurred between internal walls and the polythene vapour control layer beneath the floor screed, to seal this junction. The airtightness detailing, resulted in an airtightness result of 2.34 air changes per hour, at least three times better than Building Regulations.

Mechanical Ventilation with Heat Recovery (MVHR)

Mechanical Ventilation with Heat Recovery (MVHR) allows for sufficient and comfortable fresh air ventilation to all areas of the house, whilst minimising the loss of indoor heat energy. Green Building Store carefully designed the MVHR system to physically fit inside the building, and modelled the system using 3D software to check performance of the system in terms of noise, pressure, balance and airflows.

Ductwork

Ductwork routes were carefully considered at an early stage and AXIS Architecture specified open-web engineered joists (Easi-joists) to allow concealed ducting to be threaded through the ceiling void under first floor, and within a ceiling bulkhead running along the front curved wall of the open-plan living room.  Jameson Consulting Engineers specified circular cut-outs to primary beams in a number of locations where ductwork could not be routed around the steel frame.

Owing to the large size of the house, Green Building Store’s MVHR design team chose to use two PAUL Novus 300 MVHR units, with a heat recovery rate of 93%, to supply the 490m2 project. The two MVHR units were linked so that they were working on the same ducting system rather than having two completely separate systems, reducing the overall amount of ductwork that was needed in the building. However, as a result, much of the ductwork needed to be wider as it was carrying a higher volume of air.

Open Plan

The MVHR system includes the extracts to the kitchen, 4 ensuite bathrooms, and 2 WC rooms within the house. As the ground floor consists of a large open-plan kitchen, dining and living space, it was important to consider the air flow in that space in order to control the spread of cooking smells and air borne grease. The MVHR Design team ensured that the kitchen extract was large enough to drag the supply air from the open plan space rather than the opposite way around. The commissioned extract air flow rate from that kitchen space is 95m3/h on fan speed 2 (standard operation) and 127m3/h on fan speed 3 (boost rate). This is much higher than the building regulations requirement of 47m3/h on fan speed 3, which would not have been sufficient for this space. There are two Touchscreen control panels on the wall in the Kitchen from where the occupants can boost the system if necessary

Commenting on the MVHR system at the house, the clients said:

“This was an area which, whilst we understood the principles behind the technology, was something neither we or anyone we know had any experience of. Essentially we were in the hands of the Green Building Store team to design a system which would add something very significant to both comfort and efficiency of our home. 

The installation of the system was completed by our building team but Green Building Store was constantly on hand to provide telephone support and visits if required. The system was fitted quite easily and we have not been disappointed with its functionality and the fresh air quality it provides. Our house doesn’t suffer from misted bathroom mirrors, cooking smells (despite its very open plan design), hot and cold spots or damp areas. Dust production is significantly less and we simply enjoy a very ambient atmosphere which I guess we now take very much for granted!”

Green Building Store

The clients added: From start to finish the entire Green Building Store team was fantastic. At every stage the advice and guidance was invaluable and I always found a patient, listening ear no matter how many questions I had! Each member of the Green Building Store team share a passion and knowledge for their field. I felt very much that they were all with us on our home building journey and have been genuinely interested in seeing it reach completion.

We had a vision for what we wanted to create but lacked an in-depth knowledge of the intricacies and principles that would allow this to come to fruition. We were educated, guided and supported and couldn’t have asked for anything more. Any follow up advice, purchases, small repairs and additions since completion have been swiftly dealt with in the usual friendly way we have come to expect from Green Building Store.

We are delighted our house is now complete and has become a great family home. It’s proving to be all the things we were promised and more. Green Building Store played a very significant role throughout and their input at all stages has been invaluable, something for which we are very grateful. We couldn’t recommend them highly enough.”

Completed: 2017

Case study: 2018

More information

Axis Architecture www.axis-architecture.co.uk Tel: 0114 249 0944

 

Loch Leven low energy home

PROGRESSION Passivhaus certified windows at Loch Leven low energy house
We chose PROGRESSION for the quality of the window and the narrow sitelines which maximises the glazed area. The insulated frames and increased glazing area meant that they perform well thermally. Visually they’re great – I love the fact the frames are almost invisible.

Kirsty Maguire – Kirsty Maguire Architect Ltd

The PROGRESSION windows also worked well for the large uninterrupted picture windows that we wanted for the project. We have already specified PROGRESSION on another project we are working on.

Kirsty Maguire – Kirsty Maguire Architect Ltd

The ULTRA doors complemented the PROGRESSION windows well , as well as helping keep budget costs down.

Kirsty Maguire – Kirsty Maguire Architect Ltd

Kirsty Maguire Architect Ltd has just completed a newbuild low energy home, designed using the rigorous Passivhaus approach as a basis and design tool including PHPP modelling (Passivhaus Planning Package) to help optimise comfort and performance. The project was designed to create a cosy, light and spacious home maximising the potential of the views across rolling farmland and looking towards Loch Leven and the Lomond Hills. It is designed to meet the AECB ‘Building Standard’.

Green Building Store’s PROGRESSION windows and ULTRA doors were specified for the project.

Design

The clients were keen to create a cosy and energy efficient home that combined contemporary and traditional Scottish design so Kirsty and her team developed the design using stone and timber cladding with pared back detailing reflecting traditional Scottish cottages. The house was built by Craigs Eco Construction using a timber stud frame, stuffed with wood fibre insulation and all clad externally with wood fibre boards for thermal bridge free construction.

PHPP data

Space heating: 25 kWh/m2.annum

Heat load: 14W/m2

Airtightness: 0.52ACH

Passivhaus-certified triple glazed timber windows

Kirsty Maguire specified the PROGRESSION windows, from Green Building Store, for the project: “We chose  PROGRESSION for the quality of the window and the narrow sightlines which maximises the glazed area. The insulated frames and increased glazing area meant that they perform well thermally. Visually they’re great –I love the fact the frames are almost invisible”.

“The PROGRESSION windows also worked well for the large uninterrupted picture windows that we wanted for the project. We have already specified PROGRESSION on another project we are working on.”

Entrance doors

ULTRA triple glazed timber entrance doors were chosen for the project. Kirsty added: “ The ULTRA doors complemented the PROGRESSION windows well , as well as helping keep budget costs down.”

 

Completed: 2018

Case study: 2018

 

More information

Kirsty Maguire Architect Ltd: kirstymaguire.com, email: [email protected]

Craigs Eco Construction www.craigseco.com

Cumberworth radical retrofit: It’s a wrap!

Conservatory outside thermal envelope at Cumberworth radical retrofit

We’re really pleased with how our Cumberworth project has gone. Energy consumption, as modelled in PHPP, has gone down somewhere in the region of 80-90%. The airtightness has radically improved –  from 17 air changes per hour to 2.

Our clients are loving being back in their warm and cosy ‘new’ home. It looks lovely too, especially with the addition of the new conservatory (outside the thermal envelope) adding extra light and space.

 

 

 

Airtightness test

Airtightness testing at Cumberworth radical retrofit

When we embarked on this project we committed to getting the air changes down to 3 ach/ hour. We had an airtightness blower door test recently and it came in at 2.5 air changes/ hour @ 50 Pascals. We went around the house with a thermal imaging camera we found that there were two areas that were a problem although otherwise the house was extremely airtight.

Partition wall

Thermal imaging partition wall

The thermal imaging revealed a problem at the large full height partition wall, which is the old barn gable end wall. We should have treated it as if it was an external wall, because of lateral air movement from the external walls, which are rubble-filled and causing air movement.
We had airtightness measures in place on all external walls BUT we didn’t do the same level on the partition wall. We did parge the partition wall for a metre from the junction with the external wall, including a 400mm layer of Tectem insulation to stop thermal bridging and condensation forming. We should have parged the whole of the partition wall, including around the doorways.

Another area we should have looked at was the airtightness around the floor joists going into the partition wall on the two floors. We could have taped the joists with Tescon No 1 tape to the parged walls OR we could have chopped off the joists and used wall plates (as we did at the Denby Dale Passivhaus) and hung the joists off them.

As we develop our understanding of radical low energy retrofits we are on a steep learning curve and learning on each project. We are becoming more and more perfectionist and any air leaks now feel disappointing so I am kicking myself about the partition wall as we should have been able to foresee the problem.

I think we took our eye off the ball because we were focusing our attention more on the moisture and IWI issues. So..it’s a lesson… We are unable to remedy the issue at this stage as it would be too intrusive and too costly and perhaps unnecessary.

Wood burning stove

Thermal image woodburning stove

Fortunately the second issue was something that we could address.

When I teach on the CarbonLite CEPH course we always stress the importance of scepticism regarding manufacturers’ claims but unfortunately on this occasion I didn’t follow my own advice.

We chose a wood burning stove for the project that was marketed and labelled as ‘Passive’, with only a very small heat output of 4KW, which is what was needed. It had an external air supply which led us to believe the stove was room-sealed. But actually when we did the airtightness test it was leaking the equivalent of up to 0.5 air changes an hour. When we disengaged the stove, flue and supply pipe, and re-did the air test the results came in at 2 ach/ hour, rather than the 2.5 ach/ hour with the stove.

To remedy this we put a call-out on Twitter asking our colleagues in the Passivhaus community for alternative options. Two alternatives were suggested. The Rika Passivhaus stove is airtight and has been installed at the Acomb project in York. The Morso S11 stove also can be suitably airtight, but only after adaptations to the airflow control, and has been used on an EcoArc Passivhaus project in Cumbria.

We have managed to get a full refund on the original stove but we do feel that it is being mis-sold , due perhaps to lack of understanding about Passivhaus. We subsequently found a reference to its lack of airtightness in the stove’s installation instructions, so they’d obviously come across the problem, but this has not transferred over to their marketing department.

We have chosen to replace it with the Morso S11 because it fitted in the aperture that we’d built. The Rika was too big and we’d have had to do a lot of building work to fit it in. The Morso S11 has actually turned out cheaper than the original stove!

Wrap-up

Given the many challenges at the house, we had assumed that the retrofit would never reach the EnerPHit standard. As we weren’t going for certification, our initial PHPP modelling only used assumptions and educated guesses for Psi values (edge losses). The modelling in PHPP suggested that, once improved, the space heating need will be in the region of 65 kWh/m2/ year. This contrasted with the space heating need of the original house , which would be in the region of 497 kWh/m2/year, assuming that the house was heated at a steady 20 degrees in the winter. So the space heating need is looking like an 86% improvement!

The end result is wonderful – a warm and comfortable home for our clients with better airtightness than we originally thought we’d achieve. Congratulations to Jude and all the team for doing such a great job and also a massive thanks to our wonderful clients Sue and Paul for allowing us to try out a ‘whole house’ radical retrofit with a number of new IWI techniques and materials. We will be sharing updates of the ongoing HydroTrac moisture level monitoring and post-occupancy monitoring of the building. Watch this space!

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