Passivhaus Case Studies
Over the last few weeks we have looked at what the Passivhaus Standard is and why people are building to this standard.
Today the UK Passivhaus Conference 2014 is taking place and will be looking at how Passivhaus can be used to deliver near and zero energy buildings and we will be talking more about that in our blog next week. But in this, the penultimate part of our current series of posts about Passivhaus, we take a look at some specific examples of low energy buildings in the UK that have already been built to the Passivhaus standard.
This property in Lena Gardens is a Victorian mid-terrace constructed in the 1870’s. As a retrofit the project posed several issues not commonly found with a new build Passivhaus.
Solid brick walls prevented the use of cavity wall insulation and the building’s location within a Hammersmith conservation area prevented most external alterations. This meant all insulation had to be fitted internally, including on the party walls to prevent heat loss to neighbouring properties.
Kingspan’s Kooltherm range was chosen for the project as, with thermal conductivities as low as 0.020 W/m.K, relatively thin layers of insulation could be used to achieve the very high levels of thermal performance needed.
By combining these measures with a heat recovering mechanical ventilation system, the house now needs less than 15 kWh per m2 of energy to be heated annually, far lower than the UK single family home average of 130 kWh per m2.
London’s largest Passivhaus development comprises a row of three-storey terraces (Block A), two five-storey apartment buildings (Blocks B & C) and a further four mews houses with roof terraces (Block D). Both Blocks A and B have been fully Passivhaus Certified.
A key requirement for this project was to ensure that space on the tight urban site was maximised. A major part of achieving this was by minimising the thickness of the wall build-ups whilst still attaining the high levels of thermal performance required by the Passivhaus Standard. To achieve this the Kingspan TEK building system was specified for the external walls of Block A and D, and Kingspan TEK Cladding Panels were installed on the concrete frame of Blocks C and D. Both build-up’s achieved outstanding thermal performance with final external wall U-values of 0.10 W/m2 .K.
James Pickard, Director of Cartwright Pickard, who were appointed to design the Greenhauses commented: “We are proud to have worked with Octavia to deliver the largest certified Passivhaus scheme in London, proving that Passivhaus dwellings are a viable proposition in urban locations that might previously have been deemed unsuitable. The brick finish and careful detailing demonstrates that eco-homes can be attractive, and don’t have to look idiosyncratic or incongruous.”
The photo at the top of this blog post (courtesy of Octavia Housing) shows 100 Princedale Road, a three storey, Victorian terraced property, situated in a Holland Park conservation area in London. It was the first UK retrofit to be certified to Passivhaus standards.
Similar to Lena Gardens, the conservation area prevented the use of external insulation, but internal space was at a premium so Kingspan Thermawall TW55 was specified on the external walls to minimise the loss of floor area. The other challenge was achieving the air-tightness required for the standards – novel detailing was designed for this. A continuous layer of OSB was used to create an air-barrier at external and party walls, ceilings and basement floor. Doors and windows were connected to the OSB with a tapejointed breathable membrane, in order to maintain air tightness. This attention to detail achieved an airtightness of 0.5m3/hr/m2 at 50 Pa.
These and other innovative design features have allowed 100 Princedale Road to achieve an 83% reduction in CO2 emissions and a 94% cut in energy use; and the building’s heating burden has plummeted to 15Wh of energy per m2 per year (the UK average is 130kWh per m2 per year) – saving the tenants around £910 annually on fuel bills and meeting the demanding Passivhaus low energy standard.
Each of the case studies shows that building or refurbishing a house to the Passivhaus Standard can be a challenging process, requiring inovative design, carefull attention to detail and some good insulation. Further examples of the Passivhaus Standard in action can be seen in our Passivhaus Projects brochure.
And check back next week for our final post in this Passivhaus series, when we will be talking about what we discovered at the Passivhaus Conference.
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