Passivhaus Self-Build, Herefordshire

As architects working for the sustainable architecture practice Architype for many years, Polly Upton and Kirk Rushby were in a good position to tackle their own Passivhaus selfbuild project. The resulting corrugated metal-clad 3 bed ‘upside-down’ house was designed in PHPP (Passivhaus Planning Package) and is currently awaiting Passivhaus certification.

21°’s PROGRESSION windows and ULTRA entrance and Lift & Slide doors were specified for the project. 21° also designed, supplied and commissioned the MVHR (mechanical ventilation with heat recovery) system for the project.

Design

The selfbuild site was in a slightly inaccessible plot close to a railway line. By building to the Passivhaus standard Polly and Kirk knew there would be positive acoustic benefits, which would eliminate most of the noise from the railway line.

Timber frame construction was chosen as a more familiar construction methodology and because it was more practical for delivering to site. The house also has a non-concrete compacted gravel foundation. With the constraints of the site, they wanted to avoid the stress of a concrete delivery.

The house was designed ‘upside down’ so that the bedrooms were on the ground floor and the living space above, where the views would be better. The whole of the volume of the roof is utilised with a top ‘half storey’ within the thermal envelope, giving them more usable space, including office space.

Triple glazed timber windows & doors

A ‘mix and match’ of 21° triple glazed windows and doors were chosen for the project.

PROGRESSION fixed and opening windows were chosen alongside entrance doors and Lift & Slide doors from the ULTRA range. Paint finish colours for all windows and doors for the project were RAL 8004 externally, with ‘nature effect’ internally.

A lot of thought was put into the design and specification of the windows and doors at the project. Each window opening was carefully considered and was designed for simplicity and simple sightlines. Polly and Kirk wanted a window arrangement where there were no window transoms or mullions and the visible frame was kept to a minimum from the outside. Daylighting, views, solar gains and cross ventilation (through the openings on the east and west) were all balanced up while also trying to avoid complexity.

On the south side of the house, Polly and Kirk opted for two larger fixed windows which would not open. Opening windows were not needed for cross-ventilation purposes in that location and opting for fixed windows helped keep costs down.

Avoiding overheating

The house has been carefully designed to avoid overheating, through the use of a roof overhang and external shutters.  With the main view out to the west, a manual shading strategy involving roller shutters was employed for their big lift and slide door.

MVHR (mechanical ventilation with heat recovery)

21° designed, supplied and commissioned the MVHR system at the project. A Zehnder Comfoair Q350 MVHR unit was specified alongside rigid spiral wound steel ducting system.