In previous decades, builders paid scant attention to energy efficiency, passive solar design and block orientation.
It’s the reason why many period homes in Melbourne have south-facing yards, a poor northerly aspect and draughty windows enabling the free exchange of inside and outside air.
But as both technology and energy efficiency have improved, builders are designing homes so they stay within that Goldilocks temperature zone all year round: not too hot, not too cold, but just right.
In fact, these days to even obtain a building permit, builders must complete a six-star energy report based on the preliminary plans and drawings.
“These reports are conducted by an independent registered energy assessor and are a (government) prerequisite before even signing a building contract,” Hotondo Homes building operations manager Peter Rielly said.
“We’re lucky enough to live in a country where energy efficiency is top of mind for the housing industry.”
Here comes the sun
An energy-efficient home design revolves around the sun, with builders positioning designs to best maximise the sun’s movement from east to west.
A north or northeast-facing living area is highly desirable because it receives sunlight for much of the day, while a south-facing yard can be cold and shaded.
Savvy builders will also place windows strategically to let sun into the home during the winter, and use awnings and shades to keep it out in summer.
“In a cool climate like Melbourne, maximising the existing passive solar heating … can greatly reduce the costs of energy used in a home,” Eight Homes design manager Nathan Thorp said.
Mr Thorp added the power of solar hot water and roof panels was not to be underestimated.
“Appliances that use the natural resources of the sun are the most efficient appliances that builders use,” he said.
Arden Homes director Dean Morrison agreed the right solar orientation in homes was critical.
“The sun is the most cost-effective way to heat your home, and with good design considerations and windows in the right place, it can save you thousands on energy bills,” Mr Morrison said.
He added the company’s Aspire range of homes included sun courts as a standard feature.
“This ensures no matter what orientation your home faces, it has the best solar gain,” he said.
There is a good reason why so many people opt for polished-concrete floors with hydronic heating in their new build.
According to Mr Rielly, the most effective flooring option to manage a home’s temperature is concrete (whether polished concrete or concrete underneath tiling) with underfloor heating.
Timber and carpet, however, are the more cost-effective option and will help keep up the temperature as heat has difficulty escaping.
“If you want to keep the home cooler, vinyl and tiles are the way to go,” Mr Rielly said.
Mr Morrison is a big fan of tiles, which, with the right solar aspect, can be cool in summer and warm in winter.
“In winter when the sun hits the floor tiles and the concrete slab, it stores the heat and will help keep the house warm,” he said. “In summer, tiles remain cooler than other options like timber flooring.”
Mr Thorp said slabs were able to absorb heat from the surface and were more stable than other forms of flooring.
“Waffle slabs with polystyrene pods add additional thermal properties to the slab,” Mr Thorp said.
Seal the deal
The aim of all good design is to keep the home at a stable temperature so there is less need for appliances to regulate the heating and cooling.
A big component of this is insulation, which includes wall, ceiling and floor batts; wall wrap; and double glazing on windows to keep the temperature steady.
“Homes that are not well insulated, and allow leaking of heat, will mean the increased use of heating and cooling appliances just to maintain a comfortable temperature,” Mr Thorp said.
“An important aspect of effective insulation is ensuring that all gaps and penetrations in insulation are well sealed to ensure that the loss of heat does not happen and undermine the effectiveness of the insulation.”
Mr Morrison agreed sealing a home was important, but noted the home must still be able to breathe.
“We need to be careful that we don’t make houses too airtight. In winter, for example, when we have our heating on, it may cause internal condensation that could also lead to mould if the house is not allowed to breathe,” Mr Morrison said.
To counteract this, Arden uses a breathable wall wrap as preferred insulation, with small perforated holes to allow the house to breathe.
Hotondo Homes includes solar hot water systems, draught exclusions and wall and ceiling insulation — both batts and wrap — as a standard inclusion in every home.