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Alistair Knox designed over 1000 buildings in Victoria between 1946 and 1986, including this family home in Croydon South.
Originally built in the 1960s, the property is now home to Eva head of design Tom Shaw, Resonant founder Linda Raimondo and their two kids.
The house is filled with the prolific designer’s ‘bush modernist’ flair, characterised by natural materials like brick and timber, and the way these homes embrace their outdoor surroundings.
There’s no denying these sturdy, well-built homes have stood the test of time. But expert energy advisor and author of My Efficient Electric Home Handbook, Tim Forcey, says some of the home’s beautiful retro features are holding it back from being energy efficient and cost-effective to run.
Here are his tips on how Tom and Linda could enhance the house’s performance — without ruining its charm!
Heating and cooling
Tom says overall, controlling the home’s temperature hasn’t been a big issue. They currently use four large, freestanding gas heaters to heat the home, alongside an open wood fireplace. Meanwhile, for cooling, there’s one reverse-cycle air conditioning unit in the living room.
‘It does warm up on the really hot days, but as evening falls you can open up all the sliding doors and the house cools really quickly. In winter, the temperature of the house cools but does warm up once you run the heaters and light the open fire in the main living room,’ Tom says.
Tim says these kinds of gas heaters are very inefficient, and suggests they start using the existing reverse-cycle air conditioning unit for heating as well as cooling. He also recommends investing in more split systems where possible, as these units would be a third of the cost of running the gas heating.
‘Gas is a lot more expensive than it used to be,’ he explains. Plus, using electricity for heating, rather than gas, is better for the environment too.
Draught proofing and insulation
The house’s existing insulation isn’t too bad, but Tim notes that many mid-century homes with flat roofs often don’t have adequate roof insulation due to the limited room in the roof cavity.
A bigger problem is the open fireplace. They are ‘effectively one giant open hole that lets in cold air’, significantly reducing the thermal efficiency of the home. Tim says the easiest temporary fix for this is to create a chimney stopper using a giant piece of foam: ‘You can still take it out if you want to burn the fire a handful of times a year.’
‘Given all the wall vents, the fireplace and the gas heaters, which each have a chimney going up and out of the house, there are a lot of draughts in this house,’ he explains.
‘In the old days, when using wood fire or gas for heating, all these wall vents were needed for ventilation. However, nowadays we should be looking for cleaner heating (like reverse cycle) and reducing the air leaks throughout the house.’
Windows
The sliding glass doors and expansive windows pose a similar problem. They are protected by deep eaves, which is good, but due to the home’s age, they are only single-glazed, creating ‘cold pockets’ in every room.
Tim says this is the flaw with retro homes. Structurally, they are built well, but designers and architects ultimately didn’t have the knowledge and concerns we do now about rising energy prices and climate change.
While it is possible to retrofit double-glazing into existing window frames, so as not to impact the home’s design integrity, it does come at a high cost. The existing thermal-backed curtains hanging from a pelmet do help to trap the heat when closed, but for protection from the heat in summer, Tim says exterior blinds would be more effective.
Hot water system
Tim suggests replacing the gas hot water system with a highly efficient electric heat pump to help save money and limit the home’s reliance on gas. There are plenty of rebates on offer from the state and federal governments, so now’s a good time to make the most of these in case there is a change of government later this year.
He estimates this will cost about $2000 to replace, and recommends brands such as iStore for a base level system, or Reclaim for top of the line options.
The only challenge is a heat pump can’t be installed inside — unlike their current system in a hallway cupboard — so they would need to find a different spot for it outside.
Overall assessment
Tim estimates the current home would score between two-and-a-half to three stars out of 10 on the residential scorecard for energy efficiency — with the typical Melbourne home receiving about three stars.
The family is currently paying around $700 for 60 days on gas bills, and an average of $130-140 per month on electricity. In most cases, Tim says heating is responsible for about 75 per cent of the gas bill, so even making a small change like stopping usage of the gas heating in favour of the reverse-cycle system would create a ‘significant reduction’ of these costs and reduce their carbon emissions.
Next steps
While the family loves their Alistair Knox abode, they don’t feel it’s their ‘forever home’, so they aren’t looking to invest tens of thousands on upgrades like solar panels and double-glazing. Instead, Tom says they will look into installing a new electric hot water system and will trial using their current split system in winter to see how it impacts their bills.
‘I was always under the impression that split systems are expensive to run, so I was surprised that it’s more efficient to use a split system to heat your home,’ Tom adds.
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