Six ways to improve your home’s thermal efficiency

30 January 2019

Intelligent design, orientation and outfitting of your home can save a lot of heating and cooling costs. Here are factors to consider when trying to achieve a high energy efficiency rating.

1. Consider the compass

Orient the living areas of your home to the north to benefit from maximum sunshine and light during the day. Bedrooms are better placed on the south side for cooler sleeping at night.
If you’re building in a sub-tropical or tropical zone and prefer to block the summer sun, face your home to the east and west.
A factor to be considered is the difference between magnetic north and true north. This disparity is about 11-12 degrees in the eastern capital cities, with the geographic pole to the west of the magnetic pole. 

2. Benefit from passive solar

The natural resource of the sun needs to be managed to heat and cool our homes. Smart placement of windows, walls and floors will help collect, store and distribute the sun’s heat during winter and block it in summertime.
Eaves or shallow verandahs over the north-facing windows will protect the house from overhead sun during the summer, while letting in the low-angled rays in winter.
Large windows are great for panoramic views, but can leak a lot of heat in cold weather and may need screening in summer.

3. Watch those windows!

A range of different glazing surfaces are available, including Low-E glass. Double glazing offers much better insulation than single glazing.

The winter performance of windows can be improved with close-fitting curtains with pelmets. Reflective backings on the curtains will aid their heat-repelling ability in summer.  

4. Wrap to stay warm

Energy savings are dependent on home insulation, which acts as a barrier to heat flow and will keep your home warm in winter and cool in summer.  
Insulation can be of two types. Reflective insulation uses a silvery surface to resist radiant heat flow and works best in warmer climates, where reducing heat gain is the priority.
Bulk insulation in the form of batt material resists the transfer of conducted and convected heat and is good for cooler climates where saving heat is important. Bulk insulation usually works equally well in both directions.
Insulation can be added to the roof, ceiling, walls and floor, including underneath suspended floors.
Sealing up the gaps in a home will reduce the power bill. Install draught excluders and doorway seals to keep the heat in.

5. Add to your thermal mass

Thermal mass is the ability of a material to absorb, store and transmit heat energy.
Concrete slabs, particularly waffle pod slabs, have sufficiently high density to soak up heat from the sun during the day and release it slowly during the cooler night.
Well-designed and positioned windows in a home will facilitate this process of heat absorption and release, as will centrally-placed radiant heaters.

6. Go dark on top?

The benefit of a dark-coloured roof in cooler climates is now being recognised. Tiles and steel roofs in Australia tend to be of medium-to-dark colours, measured by the amount of solar radiation absorbed.

A dark roof could be beneficial in colder, heating-dominated climates like Victoria, Tasmania and parts of New South Wales.

The reverse is true in warmer climates, such as Brisbane and further north, where a light-coloured roof will be a significant repeller of heat, even when roofing insulation is fitted.