Kingsley Passivhaus

A 1940s semi-detached cavity wall home in Cheshire has been upgraded to full Passivhaus standard in a project led by Architect Gil Schalom of GSD Architecture Ltd. The retrofit of the 3 bedroom home included a loft conversion, external wall insulation, upgraded windows and has a treated floor area TFA of 89.5m2 .

The house has now been lived in for 2 years and the project has recently received full Passivhaus certification. Green Building Store provided ULTRA windows and doors and Pro Clima airtightness products for the project, as well as the design, supply and commissioning of the heat recovery ventilation MVHR system and providing PHPP modelling consultancy services for the project.

Energy use

• Passivhaus software (PHPP) predicted heating demand of 1500 kWh per annum for the house.
• Over the last 2 years the house has used around 2000Kwh p.a. for heating, cooking and hot water and around 1000kwh of electricity whilst generating 3000kwh p.a. from solar panels.
• Typically, in the UK, a house of this size uses 12000 kWh of heating and 4000kwh p.a.electricity

Floor and foundations

The floor was taken up, dug out and replaced with a concrete slab with 30cm of insulation below. The inner walls were underpinned with thermal blocks.

Roof

The roof was stripped and insulation boards were fixed above the rafters, with counterbattens and breathable membrane on top, before the battens, tiles and solar panels were replaced. Sheeps wool insulation was fitted between and below the rafters. Extra glulam timbers and joists were added to the loft to make a new room in the roof.

Airtightness

Plasterwas removed from all exterior walls and Pro Clima airtightness tapes were used to seal round all rafters, pipes and windows before replastering to complete a continuous airtight layer around the whole house. Airtightness tests were performed at two stages showing that the building had been made 20x more airtight than current building regulations and achieved0.27 ach @ 50 Pa. . Green Building Store supplied a range of Pro Clima airtightness products for the project. Selfbuilder client

MVHR heat recovery ventilation

Once the house was airtight, controlled airflow could be added back to the building in the form of MVHRheat recovery ventilation. Ducting was run round the house to supply fresh air warmed by the heat recovered from air extracted from bathrooms and the kitchen. Green Building Store designed, supplied and commissioned the Paul Focus 200 MVHR system at the house.

Triple glazed timber windows and doors

Windows and doors were replaced with triple glazed, tilt and turn, high performance units from Green Building Store’s ULTRA range, with solid frame and whole window U value of 0.75 W/m²K. They were hung outside the masonry walls to reduce thermal bridging from the cold bricks.

The windows were finished in Afzelia wood stain inside and out and were completed with 150mm aluminium sills, which were painted white to match the render.

The window styles chosen were simple, with only 2 windows with mullions, and all the rest without mullions, which helped improve thermal performance and keep budget costs down.

External wall insulation

20cm of External Wall Insulation was attached to the outside walls down to the foundations and up to meet the roof insulation boards to complete 360 degrees of insulation of the house. This was then rendered with a three part cement-based render system.

Consultancy & support

Green Building Store’s consultancy service also provided PHPP modelling support for the project and so Green Building Store has offered a comprehensive ‘wrap-around’ support for the Kingsley Passivhaus project.