Guide to a zero-carbon home

Green Lifestyle

Experts say there are no technological barriers to building homes that use only as much energy as they produce. Here’s your guide to converting your home to zero carbon.

Simon Black photography

Credit: Simon Black

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From the inefficient homes of our youth to the modern 6-star dwellings of today, sustainable building practices have come a long way. So what’s next – are we on track to construct 10, 20 or even 30-star homes? A new report suggests households can cut their energy use in half and achieve the holy grail of eco-friendly housing: a zero-carbon home.

According to the Zero Carbon Australia Buildings Plan, produced by climate solutions think-tank Beyond Zero Emissions and the University of Melbourne’s Energy Institute, all existing homes can reach zero emissions within ten years. To achieve this, residential energy use is reduced by 53 per cent through a combination of retrofitted technologies such as improved insulation, efficient window glazing, draught-proofing and replacing all lights with LEDs.

Importantly, the upgrade is complemented by the installation of solar power systems, so that each home operates as a self-sufficient energy user and producer. In other words, the home uses only the energy it generates. And the best bit – living comfort is improved, rather than compromised.

Phase zero:

As Australia moves towards more energy-efficient homes, governments, not-for-profits and private companies are experimenting with the concept. Many experts believe our building standards need to move to net zero energy, in line with building codes across Europe, the UK, the US and Asia.

“We should have the goal to reach net zero carbon for all new homes before the end of this decade, and we should be encouraging people to retrofit their houses to that standard,” says Stephen Berry, a University of South Australia PhD candidate who researches zero-carbon homes. “It’s a very doable standard – every year it gets cheaper and easier to do.”

The plan is ambitious, but the barriers to achieving it aren’t technological. “In less than ten years, we went from having nothing to going up three levels of thermal comfort [4-star to 6-star],” says Berry. “That’s a rapid change, a very significant change. It’s time to look at the next level, but it will take quite a few years to build up the evidence base, run the economics to get there – to move towards zero-carbon homes.”

Positive Footprints’ 8.5-star project, Junction House in Melbourne, used passive solar design, top-notch insulation and double-glazed windows, rainwater tanks and solar hot water.

What you can do:

In the meantime, there is a lot that you can do to retrofit your home to a zero-carbon standard. The Zero Carbon Australia Buildings Plan (www.bze.org.au/buildings) recommends a full insulation retrofit, installation of efficient window glazing, better shading, cool roof paint and full draught proofing.

Berry suggests first installing more insulation than you think you need. “It’s the cheapest and best way to reduce your thermal load. If you can eliminate your need for artificial heating and cooling, that’s a pretty big chunk of energy you’ve taken out.”

Next, install double glazing to strengthen the building envelope’s weakest link and fit – or plant – shading to prevent summer solar gain. “A simple rule of thumb is when you change the clocks for daylight saving your shade devices go out and don’t come back in until you change your clocks back,” he says.

If it sounds like sustainable building advice you’ve heard before, you’re right – it’s just that most of the time we implement one or two of the recommendations. With zero-carbon homes, everything matters.

“It’s the comprehensiveness of the whole package and how the whole package works together – it’s that balance of reducing your energy load to as low as is reasonable and balancing that with a solar PV that provides as much as you use,” Berry says. “It’s self-sufficiency. Quite often people only do one or two things, but it’s about doing all the bits and pieces. Comprehensiveness is key to a zero-carbon home.”

Maxa Design’s Nunawading eco-renovation upped the green cred of this home at a low cost.

Passive solar design keeps the Nunawading house cool in summer and warm in winter – without air conditioning.

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