How to save money and electricity when renovating — CSIRO's top tips for your home

Many Australians have been jumping at the chance to renovate their properties during the coronavirus pandemic and the extension of the Home Builder Grants Scheme, with CSIRO building experts saying it was a perfect time to lift home energy ratings.

How to save money and electricity when renovating — CSIRO's top tips for your home

By Lexy Hamilton-Smith

What do you do with a 50-year-old red brick home in the tropics of Far North Queensland that is an energy guzzler burdened with a two-star energy efficiency rating?

Key points:

  • The highest rating for energy efficiency is 10 in the Nationwide House Energy Rating Scheme (NatHERS)
  • The average Australian house is rated 2.2 stars and rises to 4.9 stars after renovating
  • Renovating wisely could cut heating and cooling costs by up to 50 per cent

Many Australians have been jumping at the chance to renovate their properties during the coronavirus pandemic and the extension of the Home Builder Grants Scheme, with CSIRO building experts saying it was a perfect time to lift home energy ratings.

For Cairns couple Adam Fletcher and Kim Seccafien, it was a case of going back to the future in a retrofit that would not break the bank, but lifted that rating up to around eight stars.

In the Nationwide House Energy Rating Scheme (NatHERS), the highest rating is 10.

The couple’s power bill has fallen from several thousand dollars a year to around $800 and they hardly ever have to use an air-conditioner to cool down.

Mr Fletcher, who is an environmental scientist, said the aim was “to make it as energy efficient as possible without going to crazy with the cost”.

“We basically retrofitted the ceiling with insulation — went through and redid all the walls as well when they were exposed,” he said.

“Going without air-conditioning most of the time, we utilise ceiling fans, so with a new layout with good ventilation, we have basically got the energy usage of a one person household now.”

But it was a job that required professional advice.

‘Renovating for sustainability not hard really’

Architect and Griffith University adjunct research fellow Belinda Allwood convinced the couple to think outside the box when it came to renovating.

She opened the home up with a breezeway, allowing them to access their backyard easily and moved the bathroom and toilets to an “outhouse style” wet area, making for more living room inside.

“Renovating for sustainability is not hard really,” Ms Allwood said.

“Where we start with clients is looking at existing conditions on the house site and way home works for climate or not.

“Then understanding what it is they need and working out with them how little they really need to live comfortably.

“We can do a full reno and get it working sustainably for the climate typically for less than half of the cost of building a new house.”

She said the house at Edge Hill in Cairns was done two stages.

“The initial budget was $160,000 and we were able to do two-thirds of the work for that — it costs $200,000 all up,” she said.

Ms Allwood said the original house had “good bones” and the owners loved the red brick aesthetic.

It also had a huge yard with established trees, but the house was poorly orientated, with minimal natural ventilation or shading.

“It was hot to live in and felt small and disconnected,” Ms Allwood said.

“We retained the original building fabric, reconfigured the house to ventilate well and connect to the big back yard, recycled materials on-site [timber and brick], added insulation and large openings for cross-ventilation.

“The house is now functioning so much better for the climate — more comfortable to live in.

“We are finding typically for this type of house before renovation with no insulation, small windows and orientation and type of construction, they are typically two-point-something stars rating in the NatHERS rating system.

“But once we finish this sort of renovation we get the house working optimally for climate they could be up to seven or eight stars.”

House now has ‘little micro-climate’

Ms Seccafien said the house was much cooler with the garden helping with shading and a ” little micro-climate”.

Building efficiency experts from the CSIRO have set up an Australian Housing Data website, which shows the average existing house was rated 2.2 stars for energy efficiency.

But after a renovation that often jumped up to 4.9 stars.

It has launched an education campaign to coincide with the continuation of government grants for renovations and the flurry of renovation that began during COVID lockdowns.

CSIRO research leader Anthony Wright said their data showed renovating wisely could represent a 30 to 50 per cent reduction in heating and cooling costs.

Five top tips

Mr Wright said the CSIRO had five top tips that could make a big difference.

“I think most people are unaware how simple it can be to do some of the things that you need to do to be more energy efficient,” he said.

“Seal up gaps and cracks — think about ceiling insulation.

“Topping up your ceiling insulation is one of the best bang-for-your-buck things you can do.”

He said people should use external shading on windows that might get too much summer heat gain.

Mr Wright said people should also look at their household appliances.

“Replacing major appliances like fridges and hot water services can lead to enormous energy savings,” he said.

“Lastly, thinking about some of the more expensive things like double glazing or underfloor insulation or even retrofitting wall insulation.”

He said people were astounded when they realised what sort of energy savings they could make and adjust how much more comfortable their house could be.

“A lot of people living in houses that are quite uncomfortable in winter or in summer and they do the retrofit and find out it didn’t need to be that way,” he said.

Goal for ‘zero carbon ready’ buildings

CSIRO scientist and former architect Michael Ambrose said the average two-star rating for many of Australia’s old homes was “terrible” and very low energy efficiency by world standards.

“What we are doing is collecting data from for every new house built in Australia,” he said.

“For renovations that are done and people get a new energy rating certificate, we collect that data as well, and then do an analysis on it.”

He said they had nearly 800,000 houses in the database.

“From that we can see the types of things that have been put into homes, whether it’s insulation levels or ventilation or more,” he said.

“From that we can get a really good understanding of what the building industry is doing to achieve the energy efficiency savings that are required.”

Australia has set a Trajectory for Low Energy Buildings, setting a goal for “zero carbon-ready” buildings sometime after 2028.

The Australian Building Codes Board is considering increasing the minimum standards for new housing in 2022, but does not take older homes into its zero emissions footprint.

The CSIRO building simulation team believe the huge rise in energy costs has been making homeowners more energy savvy.

‘I would do it all again’

For the Fletcher-Seccafien family their 1969 home, built to government regulations with no air flow or connectivity, was now an open air green space.

“The western side, which is now a bedroom, even on the hottest days it gets the most delightful light and is cool from the shading of the trees,” Ms Seccafien said.

“I would do it all again — we can now show people it is possible because there is a house on their street that has done it.”

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