Heating and cooling

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Depending on the climate zone, heating and/or cooling can account for 20% to 50% of energy used in Australian homes.

Heating, ventilation, air conditioning and refrigeration equipment used more than 65,750 gigawatt hours of electricity in 2020 or around 25% of all electricity produced in Australia that year (Cold Hard Facts 2021).

You can maximise energy savings and reduce cooling and heating loads by doing a few simple things:

choose the right sized appliance for your heating or cooling needs
seal around doors and windows with weather strips (except if you use a flueless or open-flue gas heater as these require adequate ventilation to ensure safe operation).
install roof and wall insulation
install thick curtains.

Double glazing could be assessed for the energy savings in comparison to the cost of installation. For the 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

Electrical

Most home air conditioners (single phase, non-ducted) display an Energy Rating Label which shows the energy efficiency of the system.

For households, 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.

The Zoned Energy Rating Label (ZERL) provides a seasonal efficiency rating for 3 distinct climate zones across Australia, providing more detailed information regarding an air conditioner’s energy efficiency.

Gas

Certain gas heaters are covered by a gas appliances energy rating label, as part of a product certification process required by state and territory Gas Technical and Safety Regulators before they can be legally sold or installed.

See Gas Technical Regulators Committee for more about the certificate process and regulations.

The efficiency of gas heaters varies depending on their design. They lose heat through the flue, or open windows for unflued products. They also use electricity for running fans and other electrical components, so you need to factor this into running costs.

Heating choices

Electric reverse-cycle air conditioners
Electric or gas portable or installed heaters
Ducted gas heating
Electric in-slab floor heating
Wood fireplaces
Heat shifters

Cooling choices

Ceiling, pedestal and personal fans
Electric reverse-cycle air conditioners
Electric evaporative cooling
Intake of cool night air
Purging of hot air

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

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% to 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, because 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.

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

To help you discuss your options with retailers or tradespeople, read the Australian Refrigeration Council’s air conditioning guides.

Talk to an ARCtick registered licensed technician near you and get tips on:

the best position for your unit (inside and outside) including good circulation of air flow internally and shelter from the afternoon sun for the outside unit
how to operate your new unit in the most efficient and cost-effective way
in-home maintenance such as cleaning filters
how often to get your air conditioner serviced and pre-booking the next appointment.

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 information about energy efficiency across a year.

To get a better idea of the size of air conditioner you may need, see the Australian Institute of Refrigeration Air Conditioning and Heating’s (AIRAH) fair air website.

Installation

Suppliers may offer installation by an ARC licensed installer. Installation may be included in the cost of a system or negotiated at purchase. All installers are required to be licensed through the Australian Refrigeration Council and you can verify if they are through the online licence check portal.

Operate efficiently

Good insulation, air tightness and shading around your home can improve the energy efficiency of your appliance.

Keep the indoor air-conditioner units dust free.
Wipe down vents, filters, and louvres (avoid using harsh cleaning fluids).
Get a regular service inspection before peak use (e.g., late spring/autumn).

You can make energy savings just by changing the thermostat. Each degree of extra heating in winter or cooling in summer increases your energy use between 5% and 10%.

Check your manufacturer’s guide for operation and maintenance tips.

Service regularly

Book a regular service by a licensed technician to make sure your appliances operate efficiently. Wipe down and clean filters and dust around the internal and external unit to improve efficiency, in between servicing.

Existing units

For consumer information on your existing product go to your manufacturer’s website or the choice website.

Portable air conditioners

Portable air conditioners are mostly used for cooling, but they are noisy and not as effective or energy efficient as installed units. They need to be set up with an exhaust duct through an open window.

Portable air conditioners have a zero-star rating.

Evaporative cooling

Evaporative coolers are not suitable for all regions. They work well in low-humidity 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 25 litres per hour).

Ducted evaporative coolers are also available with inverter-driven fan motors, and use much less power than those without, especially on the lower fan speeds.

Portable evaporative coolers are less effective. If the room you are cooling has low humidity, they will initially blow cooler air. However, as they are constantly recirculating the indoor air and adding humidity to it, they can actually start to warm the room with the heat coming from their motors.

Gas heaters

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, installation and running costs can be costly. However, ducted gas heating provides 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.

Ducted gas heating can be paired with a ducted evaporative cooler for year-round temperature control, although a reverse-cycle air conditioning system may be more practical.

Portable gas heaters

Portable gas heaters are unflued. Some jurisdictions have banned or restricted the use of unflued gas heaters due to safety concerns.

Unflued gas heaters require ventilation (an open window) for safety. They emit carbon monoxide, nitrogen dioxide and water vapour while burning the room’s oxygen. Ineffective ventilation compromises the operational 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 but are more expensive to purchase and install.

In recent years there have also been safety concerns related to open flue gas heaters. Like unflued gas heaters, open-flue gas heaters must be used in conjunction with sufficient fixed ventilation to ensure safe operation.

See the Energy Safe Victoria for more about heating your home safely with gas.

Electric heaters

Fan heaters

Fan heaters use convection heating, with the fan a key part of the design. They are more suited to small spaces but more powerful models can heat entire rooms.

Oil-filled heaters

Oil-filled heaters are convection units where the oil is heated and circulated through the appliance to warm the air. The oil is sealed inside the unit and therefore is not burned off or consumed.

Further safety advantages are a contained unexposed heating element and lower surface temperature. Some models have a fan to heat rooms more quickly.

Radiant heaters

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

Heat lamps designed for bathrooms provide heat quickly and are good for short periods.

Heat shifters

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.

Wood heating

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 air pollution and their use is restricted in some areas.

Bench testing

The Department of Climate Change, Energy, the Environment and Water engaged 2 lead test facilities to bench test refrigeration and air conditioning equipment.

Our results show that not maintaining systems can increase energy consumption of the appliance.

The study involved bench tests on four pieces of household and light commercial refrigeration and air conditioning equipment to measure the impact of common faults.

We tested a:

non-ducted residential split air-conditioner
ducted roof top packaged air-conditioning unit
walk-in cool room
refrigerated display cabinet.

The faults tested for were:

a blocked condenser
a blocked evaporator
refrigerant undercharge and overcharge
contaminated refrigerant.

These common faults were introduced to each piece of equipment after a baseline record was taken.

The findings indicated that on average there were energy losses between 14% and 20% across most tests. When several faults co-existed, energy use increased substantially, with a high likelihood of system failure if faults were not addressed. Regular maintenance of equipment is likely to reduce the impact of faults on energy use and operational costs over time.

See Bench testing results of refrigeration and air conditioning equipment on the department's website for technical details.

Energy Rating - compare appliances Energy Rating

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Bench testing results of refrigeration and air conditioning equipment Australian Government

Cold Hard Facts 2021 Australian Government