It’s a brick house. But how energy efficient?

By Claire Ginn

Give me a home among the gum trees. Or high rises. Or the suburbs. Give me a metal roof, some brick veneer walls and a concrete floor. That’ll put me on par with the average newly-constructed home in Australia. It seems that that’s where our tastes lie, but how energy efficient are these features?

Around 11.4% of Australia’s emissions can be attributed to households, and with construction continuing at a steady pace, it’s important that we keep an eye on our energy efficiency efforts. We’ve launched the Australian Housing Data (AHD) Portal to do just that and, as always, the truth is in the data.

All the stars

Energy star ratings for homes were introduced in 2001. It’s a scale of 1-10 stars, describing the ‘thermal performance’ of a home – that is, how much heating or cooling is required to make it comfortable. Star ratings are based on information about the home’s design, construction materials and where it’s built. For example, if your home capitalises on local breezes and is positioned to maximise the sun’s path, it may have a higher star rating. But a traditional breezy ‘Queenslander’-style home built in a cooler climate may be rated lower. It’s all about staying comfortable and using less energy when temperature extremes are upon us.

Back in ’01, the energy efficiency of the average home was 1.8 stars. Here’s a progress snapshot of just how far we’ve come since then:

Houses Apartments State Star rating Size (m2) Star rating Size (m2) ACT 6.9 141 7.4 75 NSW 5.9 146 6.3 77 NT 6.3 117 7.7 61 QLD 6.4 125 6.1 82 SA 6.3 134 6.4 69 TAS 6.5 117 7 92 VIC 6.2 155 6.8 61 WA 6.1 148 6.8 75 National 6.2 144 6.4 75

We can see that the average newly-constructed home in 2018-19 had an energy rating of 6.2 stars. If we compare it to the 2001 average of 1.8 stars, this translates to an annual saving of approximately $560 in energy bills and 2.3 tonnes of CO 2 equivalent (tCO 2 -e) in greenhouse emissions per house. Great news for both the hip pocket and the environment.

Kudos is due to the ACT and Tasmania, with both houses and apartments falling well above the national star rating average. The data also shows that Victoria and the Northern Territory are building very efficient apartments, although they are among the smallest in overall size (and built in fewer numbers in the NT).

While star ratings give an overall efficiency rating for our homes, they’re limited to the building itself – not appliance use.

There are a number of other measures that can be taken to ensure we stay comfortable throughout the seasons. Energy consumption by hot water systems, lights or household appliances is not considered in the rating because these fittings are usually replaced several times during the life of the building. We’ve put together some suggestions on staying warm in winter and cool in summer.

Data-driven dreams

In addition to overall energy rating information, our AHD Portal information can be further broken down by design (e.g. dwelling class and floor area), construction (e.g. type of walls and roofing) and fixtures (e.g. solar PV and heating/cooling systems). Another interesting tidbit is that our homes are gradually increasing in size, which may spell the difference if you’re deciding between a 55 or 65” flat screen (the most energy efficient model, of course).

Our Grids and Energy Efficiency Research Director Dr Stephen White said the data shows steady progress in residential sustainability efforts.

“In order to meet national challenges of sustainable energy and resilient cities, it’s vital that we track progress. It’s an important step to ensure emissions goals are met, while seeing where more attention is needed across the industry,” Stephen said.

We’ll update dashboards in the AHD Portal frequently, ensuring it is a relevant and accessible tool for the benefit of residential energy efficiency stakeholders across the country.