Depending on the climate zone, heating and/or cooling can account for 20% to 50% of energy used in Australian homes.
Choose the most energy-efficient appliances or system that best suits your needs.
To maximise energy savings and personal comfort, seal draughts around doors and windows with weather strips. Roof and wall insulation, as well as good curtains, can significantly reduce cooling and heating loads.
More expensive measures like double glazing need to be assessed for the energy savings they might bring compared to their initial cost and embodied energy. Double glazing may be an unnecessary expense when energy-efficient reverse-cycle air conditioning is installed.
Types of heating and cooling
Most home air conditioners (single phase, non-ducted) display an Energy Rating Label which shows the energy efficiency of the system.
For the householder, the cost-effectiveness and sustainability of heating is greatly improved when the power is sourced from solar panels. Solar battery storage is also becoming more economical to buy and install.
In 2019, a Zoned Energy Rating Label (ZERL) was introduced that provides a seasonal efficiency rating for 3 distinct climate zones across Australia, providing more detailed information regarding an air conditioner’s energy efficiency.
Gas appliances are not regulated by government for energy efficiency. Energy rating labels that appear on some natural gas appliances are part of a voluntary industry-led initiative.
Gas prices are rising, so factor in running costs when making a decision. All but the smallest unflued models also use electricity for running fans and other electrical components, so also factor this into running costs. Gas heaters typically turn only 85% of the gas into useable heat. The rest is lost through the flue, or open windows for unflued products.
- electric reverse-cycle air conditioners (medium to high cost)
- electric or gas portable or installed heaters (low to medium cost)
- ducted gas heating (high cost)
- electric in-slab floor heating (medium to high cost)
- wood fireplaces (medium to high cost)
- heat shifters (low cost)
- ceiling, pedestal and personal fans (low to medium cost)
- electric reverse-cycle air conditioners (medium to high cost)
- electric evaporative cooling (medium to high cost)
- intake of cool night air (free)
- purging of hot air (free)
Seek expert advice when considering a major investment such as ducted heating/cooling or an in-slab system.
Use the Energy Rating Calculator to find the most energy-efficient, cost-effective options for your needs.
Fans improve comfort levels so you feel about 3°C cooler. They have to be blowing on you to feel their cooling effect, as they cannot cool a room. They are a low-to-medium cost to buy, and are very cheap to run at only around 2 cents per hour.
Reverse-cycle air conditioning
This is an electrical climate-control system which provides heat as well as refrigerated cooling. Reverse-cycle air conditioning is 300–600% efficient, which means that it can take one unit of electrical energy and turn it into 3 to 6 times as much heating or cooling energy. Under mild conditions, some products can achieve efficiencies of over 1000%.
Split system air conditioners are made up of 2 units: an exterior compressor and an interior unit. The interior unit can either be non-ducted (such as a wall-mounted unit) or ducted in the roof cavity and connected to various points of the dwelling through ductwork. The 2 units are connected by pipes that carry refrigerant. Ducted systems are not as efficient as the wall units, as a larger fan is used and energy is lost through the ductwork.
Multi-split systems (2 or more interior units connected to one outside compressor) are also available.
A split system with an inverter (which adjusts compressor speed according to outside temperatures) can achieve 30% more operating efficiency than a conventional fixed speed model.
Window air conditioners are installed into a window space. Models can be cooling only or cooling/heating. These systems are generally better suited to smaller rooms or homes.
Buying, installing and maintaining an air conditioner
Get expert advice
See the Australian Refrigeration Council’s air conditioning guides. This will help you when discussing your options with retailers or tradespeople.
Choose an energy-efficient model
Look for the model that suits the layout of your house and has the right capacity for your needs. Non-ducted room air conditioners are required to carry an Energy Rating Label. Look for models that carry the Zoned Energy Rating Label to get a more accurate representation of energy efficiency across a year.
Suppliers may recommend an installer or offer installation. Installation may be included in the cost of a system or negotiated at purchase. Installers should be licensed through the Australian Refrigeration Council and you can do a quick online licence check.
The thermostat and timer provide control for comfort and energy savings.
- Cooling - save up to 10% for each degree that you increase the air conditioner’s temperature.
- Heating - save up to 10% for each degree that you decrease the air conditioner’s temperature.
To ensure the system continues to operate efficiently, servicing should be done by a licensed technician. Cleaning the dust filters will improve efficiency and can be done by the householder.
Portable air conditioners
Portable air conditioners are mostly used for cooling, but reverse-cycle heating/cooling units are also available.
They are not as effective or energy-efficient as installed units, and are noisier to run. They need to be set up with an exhaust duct through an open window.
Portable air conditioners are not subject to minimum energy performance standards (MEPS) and don't carry star rating labels. However, under new regulations that came into force from 1 April 2020, portable, single duct space conditioners will be subject to MEPS and will need to be labelled. Labels for portable air conditioners will always display a zero star rating.
Evaporative coolers are only suitable in low humidity areas such as arid inland regions. Portable and ducted models are available.
Evaporative coolers work by blowing air over a film of water on a filter or sponge, cooling the sponge and the air through the process of evaporation. Outside air is drawn through the evaporative unit (generally on the roof), cooling it via the evaporation process. This air is forced into the house, expelling the hot indoor air through open windows and doors.
Purchase and installation can be expensive, but ducted evaporative coolers use around 50% of the energy consumed by an air conditioner of similar capacity.
This benefit should be balanced against:
- reduced effectiveness on humid days
- water use – up to 25L an hour
Ducted evaporative coolers are also available with inverter-driven fan motors, and these use much less power than those without, especially on the lower fan speeds.
Portable evaporative coolers are of limited effectiveness. If the room they are in has low humidity, they will initially blow cooler feeling air. However, as they are constantly recirculating the indoor air and adding humidity to it, they quickly become very ineffective and can actually start to warm the room through the heat coming from their motors.
Ducted gas heating
A gas heater is installed under the floor, in the ceiling or next to an external wall. Heat is distributed via ducting in the ceiling or under the floor. They are expensive to operate due to significant gas consumption and electricity for the fans.
- Purchase and installation is expensive. However, they provide effective heating and can be zoned to only the rooms where needed.
- Regular servicing and cleaning will ensure the system continues to operate efficiently. Servicing should be done by a licensed technician. Cleaning the air intake filters can be done by the householder.
They can be paired with a ducted evaporative cooler for year-round temperature control, although a reverse-cycle air conditioning system is more practical.
Portable gas heaters
Portable gas heaters are unflued and require ventilation (an open window) for safety. They emit carbon monoxide, nitrogen dioxide and water vapour while burning the room’s oxygen. The ventilation compromises their efficiency and effectiveness, especially on very cold days.
See the NSW Department of Health warning for more information.
Flued gas heaters
Flued gas heaters, where gases are expelled outside, are safer than portable gas heaters. There are 2 types:
- Open-flued models use the room’s oxygen for the combustion process so need ventilation, limiting their efficiency and effectiveness.
- Room sealed, flued gas heaters are the safest, most efficient and effective types but are more expensive to purchase and install.
Fan heaters use convection heating, with the fan a key part of the design. They are more suited to small areas but more powerful models can heat entire rooms.
Oil-filled heaters are a convection heater where the oil is heated and circulated through the appliance to warm the air. The oil is sealed inside the unit so it is not burned off or consumed. They have the safety advantage of no exposed heating element and lower surface temperatures. Some models have a fan to heat rooms more quickly.
Radiant heaters are ideal in small rooms, but are also effective in large cold areas where the need for direct personal heating is important.
Heat lamps designed for bathrooms provide heat quickly and are good for short periods.
Heat shifters move air from heated areas of the house to unheated areas via ducting and a fan. They are cheap to install and run.
Hydronic radiant systems
Hydronic radiant systems recirculate hot or cold liquid via radiator panels throughout a building or piping in a concrete slab. Purchase and installation costs are high but running costs are lower when powered by solar or electric heat pumps. Operation is silent and they don’t distribute dust particles.
An open fireplace is very inefficient with up to 90% of the heat being lost up the chimney. Slow combustion wood heaters are a more efficient option, producing less pollution than a pot-belly stove or open fire. As they burn oxygen from the room they require ventilation which limits their effectiveness. Smoke from wood heaters is a major contributor to pollution so their use may be restricted in some areas.
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Heating and cooling Your Home
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