The 1929 solid block house had some lovely features but no insulation values, it therefore required insulating and an airtight retrofit. A one-storey extension to the side and a two storey extension gave the size and functionality a modern family require.
The walls of the extension feature 220mm deep timber frame studs with blown cellulose insulation, airtightness membrane and a continuous hemp-filled services zone. The aquapanel cladding system (with 60-year agrement certificate) clads the rear and front elevations of the extension. A rendered blockwork outer leaf protects the side walls of the extension.
The extension has under floor heating and timber wide board floors. Good levels of insulation, low thermal bridge junctions and airtightness have been used throughout. Mechanical ventilation with heat recovery was specified to ensure good air quality and a reduced heat load as the heat of the extracted air is transferred to the oxygen-rich air being supplied.
A careful arrangement of windows and rooflights ensure natural light deep into the plan.
All original features, such as picture rails, have been reinstated in original rooms after the dry-lining. These features do not carry into the extension thought the skirting board profile and timber flooring give continuity throughout.
An analysis of the walls of the extension has enabled us assess the carbon emissions of various alternate buildups. Much of the specification comes from a low embodied energy, low carbon and health perspective. The GGBS slab of the extension saved 8.5 tons of CO2.
More can be read on the house and low carbon construction in this article.