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Home renovations gave one family the chance to completely rethink their domestic energy usage, writes Verity Campbell.

Home renovations gave one family the chance to completely rethink their domestic energy usage, writes Verity Campbell.

When Emily and Hugh Stodart set out to renovate their home in the northern Sydney suburb of North Balgowlah they had comfort and cost saving in mind.

The original home, a 1970s fibro shack raised on brick pillars, was a thermal-comfort disaster. It had no wall or floor insulation, and little in the ceiling. The windows were single-glazed with aluminium frames, allowing the easy loss of heat to the wintry outdoors. To say the house was draughty is an understatement. "Oh, I remember," shudders Emily.

Hot water was supplied by a conventional electric hot water system. Electricity bills showed an average of 16.28 kilowatt hours per day (kWh/day). That figure was below the average of 20.5 kWh/day for a similar northern Sydney household, according to calculations on Energy Made Easy (, but the family still saw plenty of room for improvement.

The couple - who have two young children - had been planning to expand their home, so they decided to embed energy-saving initiatives into the process. They engaged Dick Clarke from building designers Envirotecture. His design took the home from a single-storey, two-bedroom, one-bathroom home, to a double-storey, three-bedroom (plus study), two-bathroom home.

The new building was designed to take advantage of the warmth of the sun through the "thermal mass" of the concrete slab in the new living room. "After insulation, thermal mass is the next most important thing you can do to improve energy efficiency in a home when you're building or renovating," says Clarke.

"North-facing thermal mass, such as a concrete slab floor, stores the sun's heat during the day. At night the heat releases into the home - it's the cheapest heater you could ever hope for."

All elements of the building were carefully chosen to improve the home's energy efficiency. The windows were replaced with timber framed, double-glazed casement windows. Casement windows have a side hinge, meaning they can be fully opened to make the most of cooling breezes.

To stop the house from heating up in summer, Clarke specified pull-down external blinds on the east and west facing windows, which receive the low morning and afternoon summer sun.

"Blinds prevent the heat from entering the building in the first place," he says. "Any other technique can only ever be an attempt to mop up the damage."

A light colour for the new roof and exterior walls was chosen to minimise heat absorption. Insulation was installed in floors, walls and ceilings, and the building was comprehensively gap sealed. Ceiling fans were installed throughout.

Finally, they equipped the home with a 1.5 kilowatt (kW) solar power system, and solar hot water to replace the electric storage hot water system.

"I think the single most effective thing we did was get rid of the electric hot water system," says Emily. After installation of the system Emily's electricity usage dropped by half - overnight.

The solar power system generates enough power to consistently cover more than half the family's electricity usage.

Emily estimates the other energy efficiency measures - insulation, external window blinds, double glazing, ceiling fans, low energy lights and gap sealing - have reduced electricity use in the home by about 1.2 kWh/day - an impressive result, given the house is 25 per cent bigger, with more rooms to heat and cool, and more lights.

Electricity consumption in the home has been slashed by almost 60 per cent, from an average of 16.28 kWh/day to 6.9 kWh/day. The family's combined gas and electricity bills now come in at about $35 a year.

And the house now keeps a nice, even temperature year-round, says Emily. No more stifling summers or draughty, chilly winters.

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