Six ways to improve your home’s thermal efficiency

19 April 2023 - Six ways to improve your home’s thermal efficiency

Intelligent design, orientation and outfitting of your home can save a lot on heating and
cooling costs. Here are factors to consider when aiming for a higher energy efficiency rating.

1. Consider the compass

In the Southern parts of Australia, orient the ‘living areas’ of your home to the north to
benefit from maximum low winter sunshine and light during the day. Getting sun into the
house during the day will minimize the amount of heating required and prolong the necessity
to turn on the heater until later in the evening.
If you’re building in a sub-tropical or tropical zone it is preferable to block the summer sun
and minimize the effect it has on heating your home, and subsequently the need to crank up
the air-conditioning to cool it back down again.
Ventilation is also important. If you can pick up a cooling breeze then you should consider
cross ventilation in your home and the positioning of windows and doors.
Another factor to be considered is the difference between magnetic North and true North.
This disparity is greater in the Southern states where the geographic ‘solar’ direction is about
11-12 degrees 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.
Shading plays a very important part in the amount of energy it takes to run your home,
and the comfort you experience in your home during the day. The eaves and verandahs work
together to shade a home from the harsh high summer sun, but let the lower winter sun shine
through. Homes with verandahs all around work well in Queensland but are detrimental in
Victoria and Tasmania, where you need to encourage the sun in. Large windows are great for panoramic views but can leak heat in cold weather, and may
need screening in summer to prevent heat coming in.

3. Watch those windows!

A range of different glazing and framing types are available. Glass does not insulate well by
itself, and of course, the more of it you have the greater effect it will have on your home.
Low-E glazing and Double glazing offers better insulation value than standard single glazing.
Timber frames also rate higher than aluminium frames.
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. Insulation 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 a batt material, resists the transfer of conducted and
convection heat by blocking the flow of heat rather than reflecting it. It is good for cooler
climates where saving heat is important. Bulk insulation usually works equally well in both
directions, however if you are in a hot climate it can trap in heat so it’s use is moderated in
the Northern states.
Insulation can be added to the roof, ceiling, and walls. It can also be used underneath
suspended floors. Waffle pod floors will rate better than a straight slab-on-ground floor
because of the air pockets located below the floor surface. 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 have sufficiently high density to soak up heat from the sun during the day and
release it slowly during the cooler night. Thermal mass is more commonly used as a means to
‘store heat’ so if you are in the Northern parts of the country you will do well to keep the sun
off these surfaces, or use elevated floors and decks.
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 recognised as a contributing
factor to the internal temperature of a house. Roofing in Australia tends to be of medium-to-dark
colours, measured by the amount of solar radiation absorbed – the darker the colour the
more solar radiation is absorbed.
A dark roof is beneficial in colder, heating-dominated climates like Victoria, Tasmania and
parts of New South Wales. Whereas the reverse is true in warmer climates, such as Brisbane
and further north where a light coloured roof will repel heat and prevent it from getting into
the house in the first place, even when ceiling insulation is fitted.