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Understand heating and cooling
On average 40% of the energy we use at home is for heating and cooling. This doesn't include heating hot water. The amount of energy your household uses will vary depending on your circumstances and the climate where you live—as well as the type of heating and cooling systems you install.
Most homes will need heating or cooling at some time of the year, although with a highly efficient well designed home you may be able to avoid the need for additional heating and cooling appliances altogether.
By targeting how best to warm and cool your home you can make your home cheaper to run, remain comfortable all year round and reduce greenhouse gas emissions. In addition to the type of heating and cooling solutions you choose, how you operate and maintain your system will also have a big impact.
Make the best choice for your home by reading up on the heating and cooling options below.
Passive design helps you maintain the interior temperature of your home at a comfortable temperature with little or no mechanical heating and cooling. It's generally cheaper to consider passive design options such as shading windows, installing insulation and draught proofing before you invest in expensive heating and cooling appliances as you'll reduce the amount of energy needed to keep your home comfortable.
You can use passive design ideas when you are planning a new home or for your existing home.
Passive design ideas include:
- insulating the ceiling, walls and floor
- sealing draughts around doors and windows
- allowing winter sun to warm the house through north facing windows
- stopping summer sun from entering the house with good external shading
- using natural airflow to help with cross-ventilation.
Once you've taken advantage of any relevant passive heating options, the next step is to choose appropriate heating for your situation. There are many different types of heating with different sources of energy and levels of efficiency.
Your climate, type of heater, how you use it and even its position in the room can make a big difference to your comfort and heating bills. By choosing the correct size and system for your home you can avoid paying for energy you don't need.
Central heating can often heat a whole house, whereas space (room) heating heats the room (or more in an open plan area) that's in use. Whether you choose central or space heating, there is a variety of heating technologies and options to consider—the best type of heating for you will depend on your circumstances including the size of the rooms being heated, the number of people in your household and your local climate.
- Efficient gas space heaters and reverse-cycle air conditioners (heat pumps) are cheaper to run than standard electric heaters and produce around one third the amount of greenhouse gases. Be aware that it's important to use unflued gas heaters with adequate ventilation as they have the potential to cause indoor air pollution in your home that may affect your health. See the requirements in your state or territory. The NSW Health Factsheet—Unflued gas heaters outlines important health information.
- Ducted central heating systems can use either gas or electricity as the energy source. As they will be heating a larger area of your home, the energy use and running cost will be higher than for space heaters. Zoned systems are available which allow you to limit heating to only certain areas of the home when whole-of-house heating isn't necessary.
- Hydronic central heating systems are usually gas-fired but may use a wood-fired heater, solar system or heat pump. These systems circulate heated water through radiator panels, fan-coil units or in some case indirectly via a concrete slab.
- Reverse-cycle air conditioners (or heat pumps) are the most energy efficient type of electric heater.
- Heat shifters have a fan and ducting to direct warm air to unheated parts of your home. They can be cost-effective to install and low-cost to run.
- Portable electric heaters can be cheap to buy but very expensive to run. Many are not as effective as other methods of heating.
- Electric in-slab floor heating often has the highest greenhouse gas emissions of any heating system and may be the most expensive to run.
As a general rule you should clean the filters on your heating system regularly to ensure that it runs efficiently—follow the manufacturer's instructions. Use thermostats and timers to make sure that you're only heating your room as much as you need and when you require it—saving energy and money.
Research the best type of heating and cooling for your circumstances—our information will help get you started.
Central heating or cooling uses a gas heater, boiler or heat pump to distribute warmth or cooling through the house via ducts or pipes. It usually uses more energy as it often reaches the whole house, whether individual rooms are occupied or not. By contrast, space (room) heating or cooling targets the one room—or several rooms in an open plan area—that are in use. For the best results, design the system so that:
- The areas to be heated or cooled can be controlled, including zoning to allow for shutting off heating or cooling to unoccupied areas.
- The output heating (or cooling) capacity of air heaters, boilers or heat pumps matches your heating and cooling needs. This will reduce the size and upfront costs of your system as well as running costs.
- The system uses the most efficient energy source and technology for your climate and circumstances.
Installers should be able to provide expert advice to best meet your needs.
Warm air is circulated throughout your house via ceiling or under-floor ducts, providing convective heat. A gas heater or a reverse cycle air conditioner (heat pump) can be the heat source.
For effective and efficient heating and cooling:
- As ducted heating systems heat most of the home, it's important to choose an energy efficient model. Gas ducted heaters carry Energy Rating Labels (not monitored by government) to help consumers compare the energy efficiency of different models. The labels show a rating from 1 to 6 stars. The more stars the more efficient the heater and the lower the running costs will be.
- Only some reverse-cycle air conditioners carry the Energy Rating Label. Single-phase ducted reverse-cycle air conditioners have star ratings to help you choose but for three-phase ducted reverse-cycle air conditioners the rating is voluntary. In this case, talk to your retailer or check the product specification sheet and look for more efficient models (those with a higher Coefficient of Performance).
- Consider having a zoned system installed. This will allow you to limit heating to 2 or 3 zones when whole-of-house heating isn't required, saving energy and money.
- Ensure ducts are well insulated. Ask your installer the R-value of the ductwork and ensure it's sufficient for your climate.
- If you're also using the system for cooling, you will need to ensure the size of ductwork is correct for your system. For example, ducted evaporative coolers will need to use separate and a much larger diameter ductwork.
- Install adjustable outlets for controlling air flow, and ensure that air from the outlet vents is able to make its way back to the central system.
- Consider floor outlets to deliver heat to where it's most needed. While floor outlets are often better than ceiling outlets for heating, well-designed ceiling outlets can also be an effective option depending on your circumstances.
- Note that systems that use a reverse cycle air conditioner can also provide cool air, making them useable throughout the year. You can also incorporate a refrigerative air conditioner into your gas ducted system to provide gas heating in winter and electric cooling in summer.
- Ensure you clean your air filter regularly.
- Ducted systems should be designed and installed by accredited experts.
Hydronic or boiler systems circulate hot water or coolant through radiators or pipes in the floor, providing a mix of convective and radiant heat.
A benefit of hydronic heating compared to ducted gas heating is that radiators or pipes in unused rooms can be closed off at a central point. This allows you to send heat only to where it's needed and avoids heat loss along the pipes. Ask your supplier about zoning and ensure that the zoning system means it turns off at the central point, not at the end of the pipe or the room outlet.
Hydronic systems are usually gas but can be heated by a solar, a heat pump or a wood fired system. They are an adaptable option—for example systems using solar can be designed to use gas or wood heating as a back-up.
Ensure that the water circulation pipes are well insulated to reduce heat losses in the pipework. It is also advisable to insert wall cavity insulation behind any radiator panels to prevent heat loss through the walls.
In-slab floor heating
Concrete floors can be used to store heat from electric cables or hydronic pipes set into the slab during house construction or renovation.
- Consider solar with gas heater back-up to reduce your energy costs. Electric in-slab heating generally has the highest greenhouse gas emissions of any heating system and high running costs.
- In-slab systems are unsuitable for houses where heating is needed only occasionally as they store heat in the concrete slab and are slow to warm and cool due to the high thermal mass of the slab.
- You should obtain expert advice to design your system and before making decisions on which type is best for you.
Natural gas and LPG (liquefied petroleum gas) produce 25 to 30% of the amount of greenhouse gases produced by standard electric heaters. See options for ducted and central gas heating.
- Gas space (or room) heaters can be either radiant or convection (or a combination of both), fixed or portable, flued or unflued heaters.
- Gas space heaters are typically used to heat the main living areas.
- You have the choice of choosing a flued or unflued model. Be aware that due to health and safety issues, unflued gas heaters have a range of requirements—for example in some states they can only be used with LPG gas and in situations where adequate fixed heating is also installed in the home. The potential to cause indoor air pollution in your home that may affect your health means that ventilation is always required. See the NSW Health Factsheet—Unflued gas heaters for further information and ensure you find out the requirements in your state or territory.
- For all gas space heaters it is recommended that the heater is serviced by a licenced gas fitter at least every 2 years. Where heaters are installed in a chimney it is recommended that the carbon monoxide emissions from the heaters are checked. Energy Safe Victoria has further information on heating your home safely with gas.
- Fixed gas wall units and floor consoles usually contain fans to circulate hot air and can provide convective or radiant heat—or a mix of both—depending on what kind you install.
- Gas space heaters carry Energy Rating Labels (not monitored by government) to allow consumers to compare the energy efficiency of different models of the same type of heater. The labels show a rating from 1 to 6 stars. The more stars the more energy efficient the heater will be and the less it will cost you in energy bills.
- For flued gas heaters, models with a "balanced flue" are generally the most efficient type of flued gas heater. As exhaust gases are removed through the internal pipe their heat is used to warm the incoming combustion air as it comes in through the outer pipe.
Decorative gas appliances
Decorative gas appliances are purchased for their appearance and the 'atmosphere' of warmth they create. They're also selected for their heating function in some of the warmer states.
- There are a variety of decorative appliance models, ranging from purely decorative to models which can supply some space heating function.
- They are designed to be inserted into existing fireplaces or as stand-alone products.
- The gas consumption of decorative appliances varies widely, from around 20 to 60mJ per hour. This is much higher than unflued gas space heaters which consume 8 to 25mJ per hour.
- Given their high energy consumption and generally poor heat output, they are a poor choice as a primary source of heating and could result in high energy bills and inferior comfort. Decorative gas heaters are not required to carry Energy Rating Labels.
- If you purchase a decorative gas heater to use in addition to ducted or other gas heating, avoid using it for long periods and only use for its intended decorative purpose.
Portable gas heaters
An unflued portable gas heater can be a cost-effective choice for larger living areas in some locations and climates. They are not recommended as the main form of heating in colder climates as they produce a lot of water vapour and can lead to condensation problems.
- They can operate using LPG and in some states also on natural gas and are often used in rural areas as an alternative to electric or wood fire heating. In most states you will only be able to install an unflued gas heater if you have adequate fixed ventilation in place to maintain good air quality, which can significantly reduce energy efficiency of your heater. Indoor air quality issues make unflued gas heaters unsuitable for smaller rooms and they are not allowed to be used in bedrooms.
- If you're considering this type of heating look for models which burn more cleanly, produce lower combustion emissions and require less ventilation. An efficient externally-flued heater is usually a better option but may not always be possible, particularly if you're renting.
- Unflued gas heaters can also create problems with condensation problems in other cooler areas of the house which could lead to mould growth.
- Check with your local council or state government as the use of unflued heaters is restricted in some states.
There is a variety of fixed and portable electric heaters available with different levels of efficiency.
- Reverse-cycle air conditioners (heat pumps) are the most energy efficient—using 33% of the power consumption and producing fewer greenhouse gas emissions compared to conventional electric heaters. They have the added advantage of being able to heat as well as cool and are available as window units or split systems generally mounted on the wall.
- Energy rating labels allow you to compare the energy efficiency of different reverse-cycle air conditioners and choose the most efficient model you can afford to save money on running costs. The more stars the more energy efficient and the less it will cost you in power bills.
- Split systems are usually quieter and more efficient as the compressor is installed outside the house with one or more outlets located inside the house. They are more expensive than window units to install. However, a unit with an inverter could give energy savings of 10 to 33% by adjusting supply as the need for hot warm or cool air changes. If you're installing a multiple split system you will need to ensure the correct size unit to supply a number of rooms.
- Electric portable heaters can be a less expensive option to buy but as they run on expensive peak electricity tariff the running costs can quickly add up to more than the purchase price over the life of the product. Choose heaters with a thermostat and timer to help reduce energy use and save on your power bills.
- Electric column and flat panel heaters provide a mix of convective and radiant heat that can provide background heating in well-insulated, draught-free rooms but are often slow to heat the room. Models with fans can help to distribute heat—or you can improve efficiency by operating with a ceiling fan on at low speed.
- Radiant electric heaters, such as bar heaters provide almost instant heat to the body and do not heat the air. They can create a small "zone of comfort" and may help when sitting in large or poorly insulated rooms. They should be turned off when you leave the room.
- Radiant lamp heaters (heat lamps) specially designed for the bathroom can be a good option to provide heat quickly where you need it on a cold winter's day. Used for short period as you dry and dress they use a lot less energy (up to 20 times less) than staying in the shower to get warm. This is because they can be turned on to provide instant warmth for the few minutes when you need them. An additional timer can also be installed to turn them off automatically after a selected time to avoid wasting energy in situations where they are accidentally left on.
- Fan heaters heat the air and provide convective heat. Larger upright models which release their heat close to the floor are generally more effective. They can warm the air around you or smaller rooms quickly but can be expensive to run. Some have thermostats to help reduce energy use.
- Convection heaters heat the air, which then rises naturally—this means that they will tend to heat the room from the ceiling down. They are not recommended for rooms with high ceilings or poor insulation levels or where there is a high ventilation rate.
Wood heaters are used in many Australian homes however they aren't the most energy-efficient option. They can't be turned off when a suitable temperature is reached and are often supplemented by other forms of heating to warm the rest of the home.
An open fireplace is highly inefficient with up to 90% of the heat being lost up the chimney. Slow combustion heaters are the more efficient option producing less pollution than a pot-belly stove or open fire because the fire is sealed in an air tight box and air controls allow wood to burn more slowly. Newer models have been designed to promote secondary combustion, making more heat available from the same quantity of wood. If you have an older model wood heater you may wish to consider upgrading to a newer model slow combustion heater to improve your heating and reduce air pollution. A heat shifter could be used in conjunction with a wood heater, to get better distribution of the heat around the home. As with any ducted heating system you need to allow a return air path for the air back to the heater.
How efficiently you operate your wood heater can have a significant effect. A poorly managed wood heater produces large amounts of greenhouse gas and particulate emissions. Air pollution from the smoke from wood heaters, wood fires and stoves in combination with the greenhouse gases from transporting firewood to urban areas also have a harmful impact on the environment. Wood is a renewable energy source only if it is harvested sustainably.
Before getting a wood heater, it's worthwhile thinking through your heating needs including whether there is a more energy efficient option, such as gas, available where you live.
If you have an existing wood heater or are considering purchasing one there are a range of steps you can take to avoid or minimise the impacts:
- check with your council or local government to find out if smoke and particle emissions from wood heaters are a potential health concern in your area and what regulations apply
- choose a low-emission heater such as a newer model slow combustion heater that promotes secondary combustion; not an open an inefficient fireplace
- wood pellet heaters which burn recycled sawdust are an effective option and have very low greenhouse gas emissions
- where possible, source firewood from suppliers who subscribe to the voluntary Code of Practice for Firewood Merchants certified by the Firewood Association of Australia (FAA)
- avoid taking timber from native forests and keep in mind that even dead wood provides essential habitat for animals and plants
- don't burn treated timbers as they may give off toxic fumes.
Heat shifters move air from heated areas of the house to unheated areas via ducting and a fan.
- Heat shifters can be useful to provide backup heating for rooms that don't require constant heat. They are an inexpensive option to install and run.
- You can use heat shifters to redistribute warm air from the ceiling back down to floor level, or from upstairs to downstairs, or to move heat from a living area to rooms requiring low level heating such as bedrooms.
- Heat shifters can transfer heat up to about 12m. They can either be used to move residual heat from a heated room to another room once the heating is switched off. Or to move excess heat while the heating is still on.
- When installing you need to ensure a return path back to the heat source.
Once you've taken advantage of any relevant passive cooling options, the next step is to choose appropriate cooling for your situation.
You'll need to take into account your local climate to decide how often you'll need cooling throughout the year. Other factors include the size of the area to be cooled, and whether you'll need to cool the air itself or if creating a cool breeze will be enough. Considering energy efficiency alongside comfort will help you to keep running costs down while achieving the temperature you require. Do your research so you get the best option for your circumstances.
To handle a hot summer, the three main options include:
- fans, which are the cheapest option and often sufficient—they can be an effective and low cost cooling option on warm summer nights
- evaporative coolers, which are particularly good in low-humidity areas
- air conditioners.
For evaporative coolers and air conditioners, look for models with inverter driven fan motors, as these use much less power than standard models.
Ceiling fans are an effective and economical way to help keep you and your household cool during summer. To get the most from this option ensure you:
- Choose the most efficient fan motor available to save on energy use. You can do this by comparing the power consumption and air flow rate of different units. An efficient fan producing 140 cubic metres of airflow a minute typically has a power of 75w.
- Use your fan as your first cooling option, switching to higher energy using air conditioner when it becomes too warm and uncomfortable. You can also use your fan to make cooling from your air conditioner more effective. After cooling the room with your air conditioner you can switch it off and turn on the fan to circulate the conditioned air, reducing the amount of energy you need to cool your home.
- Use your ceiling fan to help distribute warm air through a room during winter. If your fan has a reverse rotation function, ensure it's on the correct rotation for the season to push the air in the right direction for heating or cooling.
- Portable fans can also be a good option particularly if you're renting. Sitting a bowl of water in front of the fan also helps to distribute moisture and has a cooling effect.
Evaporative coolers work by blowing air over a film of water on a filter or sponge, cooling the sponge and the air. They can be a very effective choice in many areas of southern and inland Australia, but are less effective on humid days and if you live in a humid climate. Moderately cheap to buy and run, evaporative coolers use around half of the energy consumed by an air conditioner of similar capacity—and far less for some models.
- Portable and ducted models are available.
- Newer whole-house ducted systems can be fitted with electronic thermostats and timers. The option to run some units off a solar electricity panel makes them an attractive energy saving option.
- 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.
- You'll need to consider the water use from an evaporative cooling system—this can range from 4l an hour for portable systems to 25l an hour for central systems. Check that your system will comply with any water restrictions in place in your area.
- When in use you'll need to leave some doors and windows open to allow the hot air to escape from the house.
- To get the best out of your system carry out regular maintenance to keep the filter clean, and close off the vents in winter to reduce heat loss.
Reverse-cycle air conditioning or heat pumps
Reverse-cycle or heat pump air conditioners can both heat and cool your home and use less energy than other types of air conditioners to do so. They're also available in cooling only models.
- Room reverse-cycle air conditioners are required to carry an Energy Rating Label. Compare the energy efficiency of different air conditioners and choose the most efficient model you can afford to save money on running costs. The more stars the more energy efficient and the less it will cost you in power bills. Models with inverters are generally the most efficient with energy savings of up to 30% as compared to standard units.
- Keep in mind that if your air conditioner is not installed correctly or maintained properly, it won't operate efficiently, costing you more in energy bills and creating a negative impact on the environment.
- Clean the filters on your cooling system regularly to ensure that it runs efficiently—follow the manufacturer's instructions.
- Turn off when leaving the room for a period of time or use the timer to make sure that you are only cooling your room when and as much as you require. See the free consumer guides on the Australian Refrigeration Council website for information on how to choose, install and maintain your air conditioner.
Portable air conditioners
Portable air conditioners (sometimes called spot coolers) are not as efficient as other cooling options but are popular due to their lower purchase price and ease to install. They can also be an option for people in rental accommodation. Running costs can quickly add up over a hot summer resulting in higher energy bills. They are noisier and can also require higher maintenance than a fixed air conditioner. Portable air conditioners are not fully portable as they usually come with tube that feeds out through a window to remove the warm air. To save energy and greenhouse gases, look for a unit that comes with fan-only or evaporative cooler options.
The size and type of air conditioner best suited to a room or your home will vary greatly based on a number of factors including:
- local climate
- room and house size
- ceiling height
- insulation levels
- area of windows and their orientation.
There are a number of online tools available to assist you. Size Calculator is an online calculator that can help you work out the capacity of the air conditioner required for the area you want to heat or cool. This can be a good way of getting an initial estimation of the size of the unit required. However, it's still best to consult with an industry expert or experienced installer for a final decision on the right size and type of air conditioner.
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Did you know?
An air conditioner with an inverter could reduce energy use by 10 to 30% by adjusting supply as the need for warm or cool air changes.
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