Image Credit: Peter Reefman / Energised Homes Underground rainwater tanks after they were fully connected and ready for backfill. The driveway features recycled concrete, some of which, Reefman says, comes from driveways that were installed on the wrong side of their respective sites. A cross-ventilation window in the main bedroom. Windows near the top of the home’s cooling tower also open to help keep the interior cool. This photo was taken when the outside temperature was about 96; the interior temperature, meanwhile, was 75, Reefman says. Although the home’s solar hot water system has an electric booster, the system’s three solar panels by themselves usually provide enough hot water during most of the year. The photovoltaic panels in the background generate about 6.5 kW per day, enough to meet all the electricity needs of the house.
It is winter in Australia, and so it is a good time for Peter Reefman, a builder based in the southeastern state of Victoria, to show off the energy efficiency of his recently completed three-bedroom home in the town of Portland.
Through his company, Energised Homes, Reefman has been trying to push the performance level of his homes up while keeping their cost competitive and their contemporary appearance in line with prevailing market preferences. His new house, which he both lives in and uses as a demonstration home, earned an 8.1-star rating under Australia’s Nationwide House Energy Rating Scheme (NatHERS), which uses an assessment scale of zero (the worst) to 10 (the best) and factors in the layout of the home; the construction of its roof, walls, windows, and floors; the orientation of windows and shading relative to the sun’s path and local breezes; and the degree to which these features suit the local climate. As Australia’s Department of Climate Change and Energy Efficiency puts it, the interior comfort of a home with a 10-star rating would require “no artificial heating and cooling.”
Borrowing a strategy
Reefman told the ABC Western Victoria news service that it took a while for him to incorporate solar orientation – a critical component of Passivhaus construction – into his own approach to homebuilding, but once he did, he says, he was immediately impressed by the results. The exterior of the house features generous window space on the north-facing wall, a few small windows on the south wall, very limited window space on the home’s west side.
Reefman installed a polished concrete floor on the first floor of the house, and wood flooring (now covered with wool carpet and rubber tiles) on the second floor. A heat pump helps warm the house in winter. Reefman estimates that heating and cooling costs combined will come in under $19 (U.S.) a year.
Other features of the house include a reflective metal roof, a rainwater harvesting system with a total 9,900-liter capacity, and the use of recycled concrete in the driveway, salvaged wood for the screen fence at the front of the building, and used brick for the facing on the garage exterior.
On the roof, Reefman installed a solar hot-water system and 1.4 kW solar power array, which he estimates will trim the home’s annual energy costs by about $1,500 below those for a conventionally constructed home of comparable size.