From the outside, this exposed house in Brabham, a newly developed suburb in Perth’s east, looks a lot like the other houses in the project on the street with its freshly painted walls and new garden.
But this three-bedroom house has been rated with an energy rating of 9.2 stars under the CSIRO’s Nationwide House Energy Rating Scheme (NatHERS).
This makes it the highest rated two-storey house in the country, according to Mick Fabar, chief executive of Green Homes Australia, which built the house.
The Brabham house is made with a light wooden frame. (ABC Radio Perth: Emma Wynne)
He hopes that having a prototype that people can see for themselves will encourage them to commission buildings that use much less energy.
“That’s why we built this house, so they can come in, come on the hottest day and see what it’s like,” Fabar said.
No experience with air conditioning
The house, which is built with a lightweight timber frame, has all the elements commonly associated with eco-friendly living: a light-coloured roof, solar panels, battery storage and double-glazed windows.
Significantly, it has no air conditioning, only ceiling fans.
The house relies on ceiling fans and the position of the windows for much of its heating and cooling. (ABC Radio Perth: Emma Wynne)
But Fabar said it was the less flashy elements that made the most difference in the house, like the polished concrete floor that runs the length of the ground floor that provides the important thermal mass.
“Concrete is absolutely beneficial; you have to have thermal mass in a house to moderate the temperature whether you’re in a warm climate or a cold climate.
“You need thermal mass to be able to extract energy from the environment, from the living space, and then feed it at night.”
Added thermal mass is achieved with an interior brick wall; the construction team chose to leave it unrepresented when they were told that leaving it would take the house from a 9.1 star rating to a 9.2.
A brick wall was left untrimmed to increase the star rating. (ABC Radio Perth: Emma Wynne)
The second element is the placement of double-glazed windows for passive cooling and heating.
“All the windows have been calculated to be in the right position to not let the summer sun into the home, but the right amount of winter sun into the home, so that’s a critical calculation,” he said. say Fabar.
“We have fans to cool us in the summer, and in the winter the design is really about the winter sun and heating that thermal mass and using it to heat the home.”
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Leakage plug
The design has also focused on an often overlooked element of Australian housing: airtightness, meaning that once the house is heated or cooled, it stays that way.
“You don’t want to create a living environment and then have air escape under doors and under baseboards and through power points and windows,” Fabar said.
“In Australia, we have a terrible history of leaky homes (5, 6, 7 percent) and there’s no standard.”
The display home is intended to have less than 1 percent air leakage.
“It’s really simple building science, but it’s not too hard, it’s just that builders don’t apply it,” Fabar said.
All doors and windows are double glazed with hermetic seals. (ABC Radio Perth: Emma Wynne)
Everyone involved in the project is aware that spending hundreds of thousands of euros on a new house without cooling at the touch of a switch can be a hard sell, especially in an area 20 kilometers inland where the sea breeze ‘summer is slow.
But builders and developers hope the potential savings on electricity bills and the chance to see if it works will be tempting.
Construction cost
Fabar would not disclose how much the home cost to build, but said it was in the low $500,000 range and not significantly more than a comparable home.
“Building an energy-efficient home doesn’t necessarily cost you more money if you design it right,” he said.
“Traditionally, we’re seeing a 2 to 3 percent increase in cost to build an energy-efficient sustainable home.”
But the savings in the coming years are expected to be significant, he added.
“Everyone lives differently. Some people sleep with the lights on or take a two-hour shower, but according to the national average, energy use will be reduced by 70 percent.”
To find further evidence of its efficiency, the house will be studied by researchers from the University of NSW, both as a display house and when occupied to obtain data on real energy use.
The house has a light colored roof and solar panels. (Provided: Birdhouse Media)
Paul Lakey, regional managing director of Peet, the joint developer of the Brabham estate with the State Government, said the current costs of running a home were becoming more relevant to buyers.
“One of the biggest things people have to work on when they’re looking to build a home is the life of the home,” Lakey said.
“If you can save several thousand dollars a year in energy efficiency and annual costs, then that’s a good way to go. Over 20 years of building up.
“The cost of energy isn’t going down anytime soon. That’s a big factor in the rising cost of living right now.
“If you can reduce these recurring costs in a simple way without affecting your standard of living, that has to be a good thing.”