Bakers Shaw - Bakers Shaw is designed to Passive House design principles; these include ultra insulated building components, an air tight building envelope, optimal solar gain, reduced thermal bridging and fresh air and humidity controlled by a mechanical heat recovery ventilation system.
Project Details
Treated Floor Area: 558.00m2
Volume: 1306m3
Project U-values by element
Walls: 0.11W/m2k
Roof: 0.108W/m2k
Floor: 0.092W/m2k
Basement Wall: 0.14W/m2k
Windows and Doors: <0.8W/m2k
The project is located in the Chilterns, in an Area of Outstanding Natural Beauty and the building footprint has been designed similarly to that of the previous timber frame chalet bungalow. Planning restrictions regarding the proposed ridge height meant a basement was required to ensure the client could achieve a large family home. The construction of the basement was achieved using the Polarwall insulated concrete formwork system with additional external insulation to meet the required Passive house standards.
The house structure consists of a pre-fabricated timber frame with Hemcrete panels. Hemcrete is a mixture of hemp, lime and water. Hemp is grown in Europe including the UK; it absorbs the CO2 expelled during the cultivation process. Lime releases CO2 during the manufacturing process but re-absorbs CO2 as it cures. Hemcrete is regarded as a carbon neutral, renewable material. Hemcrete has great thermal inertia properties regulating the thermal performance of the building, by reducing quick temperature changes. Clay board is used on second floor instead of plaster board to provide thermal mass reducing.
The roof tiles are made from recycled plastic and are incorporated with the PV tiles, utilising the south facing roof space but effectively disguising the PV. Bakers Shaw recycles rain water by harvesting it from the roof area and using it to flush the toilets. There is a reed bed system designed to purify the outflow from the septic tank providing water suitable for water irrigation and offering bio-diversity to attract wildlife and birds.
Bakers Shaw has a timber framed glazed sunspace entrance attached to the south facing elevation acting as a buffer zone outside the thermal envelope. This buffer zone prevents heat loss and traps the suns energy for use in the house. To achieve this, a duct was connected from the sun space to the MVHR allowing the ventilation system to utilise the heat.
Bakers Shaw has incorporated the following technologies and materials:
- Basement - Polarwall concrete formwork
- Hemcrete timber frame
- Solar PV tiles positioned on the South facing roof - to provide electricity
- Solar thermal tubes positioned on the east and west roof areas - connected to a thermal store to provide hot water
- Woodchip biomass boiler to provide heat to the under floor heating system and top up the thermal store
- Mechanical Heat Recovery Ventilation System: Genvex GES Energy and GE Energy 2
- John Guest - Wet Under-floor heating system installed on the ground floor and in all the bathrooms
- Windows and doors -Internorm Edition ( Passive house certified)
- Windows and doors -Internorm Edition ( Passive house certified)
- Roof tiles - Recycled plastic slates
- Brickwork - Sourced locally, handmade and fired using timber to create a distinctive appearance that matches the style in the area.
- Porch Sun Space - Double glazed timber frame structure to acts as a buffer space for the building
- Clay board on the second floor - to provide thermal mass preventing overheating
- Wet land - designed to purify the outflow from the septic tank providing water suitable for water irrigation and offering bio-diversity to attract wildlife and birds
- Rain water harvesting - recycled rain water collected from the roof area and used to flush the toilets.