Space Heating And Cooling: Home Energy Efficiency

Last Updated: 8th Jan 2025 By Finn Peacock, Chartered Electrical Engineer

Heating and cooling appliances are responsible for around 40% of energy use in the average Australian home – and there are plenty of opportunities here to save some bucks. In this article, we’ll look at the best way to heat or cool your home and how to make the most of what you already have, regardless of its energy efficiency.

In a previous article, we looked at improving the thermal efficiency of your home. But for times you need a helping hand to increase or decrease the temperature; with some exceptions, there is really only one way to go. Let’s take a look at some options and which one stands head and shoulders above the rest.

Gas Heating

Heating with gas is very straightforward, but very inefficient. Much of this is because of the need for a flue or other ventilation to pipe noxious emissions and water vapour outside. This can see the efficiency of gas heaters being as low as 60%, with average efficiency of 70-80%.

Gas heating can also be dangerous to a home’s occupants due to the emissions and fire hazard.

Electric Fan And Resistive Heaters

If you’re using a portable electric heater to keep your home or rooms warm, it’s likely costing you a fortune. These devices are generally 100% efficient at converting electricity into heat; but that electricity is costly, particularly given the times of day when they are usually run. And even if you have solar panels and the heater is run during daylight hours, electric heaters will be chewing up energy that could be used for other applications.

Heat Bank

A heat bank stores thermal energy in dense materials when electricity is cheaper and releases it when required. These can be a good option, particularly if you have solar panels, but they are quite pricey and only heat.

Evaporative Air-Con (Swamp Coolers)

Evaporative air conditioners cool air by passing it over pads saturated in water. This evaporates the water and reduces the air’s temperature. While evaporative cooling systems can be comparatively cheap to run in terms of electricity, a significant amount of water is consumed. And if the area you live in experiences medium to high humidity, they won’t be of much use.

Ceiling And Desk Fans

These can be a good option, summer or winter, particularly if your home is already thermally efficient. In summer, the fan will move air, which has a cooling effect when it hits our skin. In winter, many ceiling fans can be set to go in reverse, pushing heat down towards the living space.

But a fan isn’t a lot of use in particularly humid conditions; and humidity plays a major role in comfort – and they don’t decrease temperature.

Summer Or Winter, Reverse Cycle Air-Conditioning Is King

Reverse cycle air conditioners, also known as air-source heat pumps, can provide both heat and cooling. Instead of using energy to create heat directly, put very simplistically, they move heat around. Even a pretty ordinary reverse-cycle air conditioner will provide around 3.5 kilowatt-hours of heat per kilowatt-hour of electricity consumed – an effective energy efficiency of around 350%.

Solar + Reverse Cycle Aircon = Big Savings

You can save even more if you have a properly sized solar power system working in cahoots with your reverse cycle air conditioner. This doesn’t just apply to when you are home during the daytime. You can try setting a timer so your reverse cycle air conditioner pre-warms/cools your home using solar energy before you get home, therefore using less energy in the evenings. Again, the thermal efficiency of your house will play a major role in how effective this is.

Choosing A Reverse Cycle Air Conditioner

Like anything, reverse cycle air conditioners can be of great, ok, or crappy quality.

A few years ago, the Australian government introduced improved energy efficiency labels for residential-sized split system air conditioners. To learn how to use the new labels to choose the most appropriate and cheapest to run air conditioner in your neck of the woods, see this article.

Quick Heating And Cooling Energy Efficiency Tips

For each degree of extra heating in winter or cooling in summer, energy consumption may be increased by as much as 10%. So, set the thermostat to 18 to 20°C in winter and 25 to 27°C in summer.
Heat or cool only the rooms you need to, and close windows, curtains and doors in those rooms – depending on the heating/cooling device used.
Regular servicing of air-conditioning systems is important to maximise efficiency and perhaps avoid a more expensive repair bill down the track.
Position heaters to avoid draughts and furniture to maximise effectiveness (but not too close to the heater!).
What are you wearing? Dress for the season and you’ll need less external sources for heating and cooling.
While fans don’t reduce air temperature, when used in conjunction with an air conditioner they can reduce the amount of energy needed to feel comfortable.
Open doors and windows to let the cooler air in on summer nights, or warmth during winter days (where viable).
The compressor unit of an aircon system should be protected from direct sunlight, but ensure not to restrict air movement.
If you have a ducted evaporative air conditioner, install covers over the vents to prevent heat escaping during the cooler months.

We’ve mentioned the role of solar energy several times in this article. That’s not just because this is a website focused on solar power, but because of the major role it can play in residential energy efficiency and comfort. If you’re curious about learning more, check out our Solar Panel Guide.