The Edgar house uses excellent design and conventional construction to achieve a highly energy efficient home at almost no cost increase over a volume built home.
The house uses passive solar design features. A large area of northern windows is shaded by an appropriate eave to allow the entrance of winter sun but not summer sun. The house has a long east-west axis and a deep eastern veranda and a western porch, both of which provide excellent shading. Normal NatHERS 7 levels of insulation are used (R2.7 walls, R5 ceiling insulation doubled in the rooms with raked ceilings) and off-the-shelf double glazed, thermally broken windows are fitted. Thermal mass is provided by the concrete floor slab (edge insulated), internal brick feature walls and 4,500 litres of water distributed in three tanks.
An electronic logging system records 24 parameters, including internal and external temperatures, thermal mass temperatures, interior humidity and so on.
The house is currently in the final stages of construction, with bathrooms and the kitchen yet to be completed.
Over summer 2025-2026, with no air conditioning used, a mid-afternoon interior temperature of 24.9 deg C was recorded on a day when outside it was 44.7 deg C. In spring 2024 , with no heating systems used, the minimum outside temperature was 0 deg C and at that time inside the house it was 18.5 deg C.
The home shows that a highly energy efficient, comfortable house need cost almost no more than a conventional house.
