A very British Passivhaus

Denby Dale Passivhaus

Green Building Store has succeeded in adapting the Passivhaus approach to British traditional building methods – by creating the first certified Passivhaus in the UK to use traditional cavity wall construction. The Denby Dale Passivhaus project (www.greenbuildingstore.co.uk/denbydalehouse) in West Yorkshire has today (Friday 30th April 2010) received its official Passivhaus certification. The project – built by Green Building Store’s construction division Green Building Company – has pioneered the combination of low energy Passivhaus methodology with standard British cavity wall construction and building materials. Passivhaus design originated in the 1990s in Germany and there are now over 10,000 certified Passivhaus buildings in the world. Typically, Passivhaus buildings are built using timber-frame construction or block work wall with external render.

Bill Butcher, Director of Green Building Store, said:

“We chose cavity wall construction because most British builders are familiar with the technique and materials could be sourced easily from any builders’ merchant. Cavity wall also met Yorkshire planning requirements for stone exteriors and was affordable for our clients. In addition, masonry construction, including cavity wall, offers a ‘cave effect’ which acts as a thermal mass, helping to keep temperatures stable in winter and summer”.

Key features of Denby Dale Passivhaus

  • One of the first certified Passivhaus homes in the UK
  • First certified Passivhaus built with cavity wall construction in UK
  • £141K build costs
  • 118m2 three-bed detached house
  • Costs/m2 = £1194
  • Airtightness: 0.33 ach @ 50 Pa
  • Space heating needs: under 15 kWh/m2/annum
  • Minimal heating – using 90% less energy for space heating than the UK average
  • Heating costs of around £75 per year.
  • Subject of the popular ‘Passivhaus Diaries‘ blog

Bill Butcher added:

“The Denby Dale Passivhaus proves that it possible to build an ultra low energy house using British building techniques and materials, at a low cost. Good simple robust design, knowledge and care in application are all that are needed to achieve Passivhaus levels. Traditional British construction methods can be used to reach the performance levels that you need for 2050 carbon reduction goals”.
Professor Wolfgang Feist – originator of the Passivhaus methodology and founder of the Passivhaus Institut in Germany – has been supportive of the project:

“The Green Building Store team is to be commended for adapting the Passivhaus methodology to British building techniques and for constructing the first Passivhaus using cavity wall construction in Britain. The Denby Dale project has proven that Passivhaus design can be easily adapted to British building techniques. Airtightness is not a myth – the rules of physics are the same everywhere – and wet plaster offers an excellent airtightness barrier for cavity walls, if applied to all surfaces of external walls and connected properly at the joints. The Green Building Store team has done a great job at Denby Dale and also in helping to spread the word about Passivhaus design in the UK. Congratulations!”
As well as using materials from a local builder’s merchant, specialist materials for the project were sourced from Green Building Store’s range of Passivhaus products (including windows, airtightness tapes and membranes, cavity wall ties and MVHR systems) . Green Building Store launched its Passivhaus range early in 2009 to help facilitate the uptake of Passivhaus design in the UK.

The construction of the Denby Dale Passivhaus has been well-documented through Bill Butcher’s popular Passivhaus Diaries blog. For more information on the Denby Dale Passivhaus and to register for a free technical briefing, go to: www.greenbuildingstore.co.uk/denbydalehouse

Notes for the Editor

1. Heating costs

Average UK dwelling stock uses energy at a rate of 278 kWh/m2/annum (Source: AECB yearbook – the Sustainable Building Guide – 2006/7) and space heating makes up 56% of all domestic energy use. (Source: DECC 2007 figures).

Passivhaus houses use around 90% less energy for space heating than the average UK home (15 kWh/m2/annum, as opposed to 155.68 kWh/m2/annum for average dwelling stock). Space heating needs for the Denby Dale Passivhaus are 15 kWh/m2/annum.

As the Denby Dale Passivhaus is 118m2, it will use 1770 kWh/annum for space heating.

1 kWh of gas costs 4.14 p (Source: DECC Quarterly energy prices 2010)

Therefore annual space heating costs of the Denby Dale Passivhaus are expected to be: 1770 kWh X 4.14p = £73.27

2. Certification

The Denby Dale Passivhaus has been certified by Warm Associates, under supervision of the Passivhaus Institut in Germany.
3. Airtightness

0.33 ach @50 Pa measured using the Euronorm and Passivhaus method

Passivhaus requirements are 0.6 ach @ 50 Pa. For Passivhaus certification (and Euronorm methodology), the volume of all internal partitions, stairs, floor void etc are discounted in the airtightness calculations, resulting in a lower overall internal volume (in this case internal volume calculated as 277 m3).

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