Birchwood House, Queenstown
Our clients required a highly sustainable, single storey, contemporary, country house. The brief included four bedrooms, each with their own ensuite bathroom, an open plan kitchen /dining/living area, a library, guest toilet, separate laundry, sauna, spacious double garage, with plenty of room for equipment such as a ride on mower, bikes & skis and outdoor terraces for all day use. On our suggestion, a ‘courtyard’ conservatory was added.
The resulting enclosed floor area is 345 m² (including conservatory but excluding decks).
From the house the occupants had to be able to enjoy views to the various surrounding ski mountains.
The design solution was for a layout where all the main habitable rooms have a northerly aspect and the service rooms a more southerly aspect. Bedroom 4 (designed for Airbnb use) has a SW aspect and is separate from the other bedrooms and living spaces with its ‘own’ outdoor roofed space as well.
The roof is designed as two butterfly twisted planes connected by a large central gutter that discharges into water tanks for potable water (back up), garden irrigation and grey water fittings. An existing bore in the area is the main potable water source.
Waste water is treated on site in a sustainable wastewater treatment tank and irrigation field.
The northern part of the roof has been designed for higher ceilings and wider eaves to the open plan living area on the E side, while the eave width and ceiling height reduce towards the W side of the building. The southern part of the roof is also a twisted plain mainly covered in solar PV panels, to provide all power needed for the house.
While the conservatory allows the owners to grow (sub) tropical plants throughout the year, it also acts as a winter heat source for the whole house and provides a shaded ‘outdoor’ area sheltered from the sun and wind in summer.
Although originally driven by functional considerations, the two twisted planes gave the building a lively sculptural shape.
To enhance the sculptural form, a single cladding of stained timber board and batten was chosen, with the aluminium door & window joinery colour to match.
The concrete floor slab has auxiliary hydronic heating embedded in the insulated slab for ‘back up’ as the Passive Solar Design will heat the slab in winter and keep it cool in summer. The concrete floors will be polished and remain exposed except for some rugs in selected areas.
The whole house has high thermal insulation (well beyond the minimum NZ code requirements) and double glazing to store the winter heat and keep out the summer heat.
Natural ventilation is created by giving all habitable rooms high level opening windows, situated below the high part of the sloping ceilings, to induce ‘stack ventilation (as warm air rises).