We are currently on site in Oxfordshire with an exciting new-build house which is built within the pit of a disused quarry. The site is amazing, nestled between a mature deciduous forest on one side, and open fields on the other. The project was granted permission under Paragraph 79, of the National Planning Policy Framework which requires a proposal’s design to be ‘truly outstanding or innovative, reflecting the highest standards in architecture, and would help to raise standards of design more generally in rural areas’.
The starting point for this project was the materials of the site, stone from the quarry and timber from the forest. The house is conceived as two parts. The lower level is built within the quarry pit and hidden from view. the plan is organised around a series of stone walls which run through the length of the house and connect to stone walls within the sunken gardens and landscape beyond. The upper level is a timber frame construction using both glulam and CLT to provide a cantilevered eaves structure which allows uninterrupted views to the vistas beyond.
The house is organised as around a central double height atrium space, which is flanked by a series of private and semi private space at two levels, each with their own view to the outside landscaping. The construction is designed to Passivehouse standards.
Architect : A-Zero Architects
Giles Bruce, Phillip Toyin, Ross King, Shoichi Sado, Mizue Katayama
Quantity Surveyor : Andrew Morton Associates
Structural Design: Entuitive Consulting Engineers
Contractor : Phillips Build Ltd.
Windows & Curtain walling : Aumaxum
Glulam Timber Frame / CLT : Construkt CLT
Renewables Design & Installation: Solo Heating
Use timber instead of steel
The above ground super structure of this house is almost entirely fabricated of timber – from the glulam structural frame to the prefabricated timber cassettes that form the envelope. The structural timber structure is a glulam frame stiffened by a series of longitudinal CLT panels which run the length of the building. The materials were prefabricated by Hasslacher in Austria and trucked to site where it was assembled over several weeks by a small team. The timber frame is fully internalised, allowed the envelope of the building to wrap around the frame. We used a series of prefabricated timber panels filled with woodwool to achieve the levels of insulation required for Passive House standards., and these two were craned into position in a short space of time.
We also used cross-laminated timber (CLT) panels in one of the out-buildings, assembling a full envelope over a cast in situ ground floor structure. CLT is often criticised as being a wasteful use of timber, but in this instance, the material allowed us to achieve a 9m clear span without using steel.
Aim for Zero
In the climate of the UK, the greatest source of energy consumption is space heating. This house is designed to Passive-house standards, meaning that the energy required to keep it comfortable through the year does not exceed 15kWh/m2 (for comparison a leaky Victorian house would use over 200kWh/m2).
The low space heating demand was achieved through high levels insulation in the envelope, Cordex Filcor structural insulation below ground and a Pavatex wood wool insulation within the timber cassette construction which forms the above ground envelope. All junctions within the construction were simulated to eliminate thermal bridging. High performance glazing by Schucho, is designed to minimises heat loss in winter and solar gains in summer. Infiltration is minimised using an Pro Clima Intello Plus Vapour Check Membrane, and fresh air is provided mechanically, with all heat recovered from out-going air.
The house still needs a source of heat, and this is provided using a heat pump which harvests heat from a 1,400m2 ground collector located 1m below the landscape.
An array of photo-voltaic cells also provides the house with a source of electricity, generating around 3.5 kW in summer.