London -- Kingspan Insulation products have recently helped a Victorian terrace house in Lena Gardens, London, become one of only two retrofitted UK properties to achieve the prestigious "Passivhaus" performance standard.
The challenge for low-energy house designers Princedale Ecohaus and Green Tomato was to find solutions which would allow the 3-storey terrace house to perform to the very high levels demanded to meet the Passivhaus standard. This involved designing and developing all of the systems used in the house, including the airtight wall configuration.
As the terrace is in a conservation area, all insulation had to be installed internally, so 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.
To make the house airtight, a continuous layer of) OSB (oriented strand board was installed on the roof, all external and party walls and the lower floor. Airtight tape and breathable membranes was then used to seal the OSB layer to the windows and doors, forming an airtight barrier and allowing the building to meet the required Passivhaus air tightness limit of 0.6 m3/hr/m2 at 50 Pa.
Kingspan points out that this is ten times higher than the standard required by Approved Document £1A of the Building Regulations (England and Wales).
On the external walls, 130 mm and 50 mm thicknesses of Kooltherm K12 Framing Board were fitted either side of the airtight barrier, while on the roof a 130 mm layer of Kooltherm K7 Pitched Roof Board was installed between the rafters, with the airtight barrier and a second 50mm layer of K7 insulation fitted under the rafters.
"Our client wanted to convert his house into a home fit for the future. Installing highly efficient, space-saving Kingspan Kooltherm allowed them to achieve this whilst minimising the loss of internal space," said Tom Pakenham, director of Green Tomato Energy. The property is being monitored to assess its performance in real life.
The finished roof and walls produced outstanding thermal performance with U-values of only 0.10 W/m2K. To further insulate the building a 50mm layer of K12 insulation was also installed on the party walls.
"The benefits of retro-fitting houses to the Passivhaus standard are tremendous," explained Philip Proffit, director of Princedale Ecohaus Ltd: "Not only are the annual heating bills for most houses reduced to less than £100 but the combination of an airtight barrier, insulation and airtight triple glazing and mechanical ventilation mean that nuisance outside noise such as traffic can be easily shut out, creating a tranquil environment within the house".
The house also has a heat-recovering mechanical ventilation system, and now needs less than 15 kWh per m2 of energy to be heated annually, compared with130 kWh per m2 for an average UK single family home.