Guide to a zero-carbon home

Simon Black photography

Credit: Simon Black

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Lifecycle matters:

Mark Thomas, an architect and director of Goodhouse (www.goodhouse.co), participated in the South Australian Government’s Zero Carbon Home Challenge at Lochiel Park Green Village in Adelaide. He says it’s important to consider a home’s embodied (building) and operational (use) energy consumption in its assessment, even though the Building Code of Australia doesn’t factor embodied energy into its star rating system.

“To get a truly zero-carbon home, there needs to be a shift in mindset,” he says. Buying lots of new technology and equipment for the home can mean the embodied energy is higher and “you can get a higher carbon footprint on your home by trying to be more sustainable. If you don’t include embodied energy, then you really can’t call it a zero-carbon home”.

Thomas says even though the operational energy of the home his company constructed for the challenge is higher than the embodied energy, the home will become zero-carbon in 12 years after the embodied energy is offset.

If you’re keen to investigate the overall impact of your home before you build or retrofit more efficient technologies, companies like eTool (www.etool.net.au) offer lifecycle assessments. “We follow a product from cradle to grave to determine its environmental impact,” says co-founder Alex Bruce. “The only way to understand if a home is zero carbon is through lifecycle assessment.

He says that every home uses energy differently, so it’s important to quantify your energy use before making any changes. “How much carbon goes into your heater, fridge and hot water system? For example, 35 per cent may go into heating and cooling. Next, prioritise what you’re going to change.”

Entire neighbourhoods of zero-carbon homes are still some way off, but the future is bright. “It can be done to any home, no question,” says Berry.

Lifehouse Design’s Campbell Creek project used a modular design, minimising building waste.

Case study: Lochiel Park Green Village
Adelaide’s Lochiel Park Green Village (www.lochielpark.com.au) is home to 103 (nearly) zero-carbon homes in a near zero-carbon estate that researchers, builders and the South Australian government are using as a template for the zero-carbon homes of the future.

All of the homes follow minimum requirements that include 7.5-star ratings, solar hot water gas-boosted, 1.0 kW peak photovoltaic array for each 100 m² of habitable floor area, high energy- and water-rated appliances, and rainwater harvesting. The energy used and generated at each house is monitored to create an understanding of the building’s performance and how its residents adjust their habits to achieve zero-carbon status.

The first two years of monitoring revealed that Lochiel Park homes use significantly less total energy compared with other recently constructed homes in a nearby estate. Plus, it appears that Lochiel Park homes use less than half the energy for heating and cooling than homes in the same climate zone.

The choice of heating and cooling system appears to be critical to the energy impact of a household. Homes that have installed underfloor heating have a much higher annual energy demand than similar sized households with reverse-cycle heating and cooling systems.

“Underfloor heating is a disaster,” says Berry, who is conducting research at Lochiel Park. “Homes with underfloor heating use far more energy than homes without it. It’s a lovely heat, but a lot of the heat is wasted.”
He says some homes have great hot water systems, while others haven’t installed adequate summer shading. “We can see all this because we monitor the temperatures in different rooms. Simple design strategies could make the houses so much better for very little cost and we see that in the real numbers.”

South Australian-based architects Goodhouse are aiming for zero-carbon building and living.

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