Home Innovations Display Centre

Alternative Heating & Cooling

What are your options for heating & cooling your home?

Building technology has advanced in leaps and bounds over the last 20 years and along with it so has the Heating & Cooling technology. We've outlined most of the options below for you to then make the right choice for your home.

Energy choices

Gas heaters and efficient reverse cycle heat pumps produce only one third the amount of greenhouse gas emissions of standard electric heaters.

Gas heaters and reverse cycle heat pumps have energy labels to help you choose the most efficient model. It should be noted that there are indoor air quality issues surrounding the use of unflued gas heaters. Wood can be an excellent fuel because it is a renewable energy source, if sustainably harvested. However, air pollution from wood fires and the transport of firewood to urban areas are environmentally detrimental.

About 20 per cent of homes use wood for heating, but the wood is often obtained from unsustainable sources. Use only sustainably harvested wood to avoid habitat destruction and rare species extinction. Do not use treated timbers that may give off toxic pollutants when burned. Burn wood only in high efficiency, low emission heaters.

CENTRAL HEATING

Central heating can often heat a whole house, whether individual rooms are occupied or not. Space heating heats the one or two rooms that are in use.

Ducted Air

Hot air is circulated through roof or underfloor ducts, providing convective heat. Gas or a reverse cycle heat pump can be the heat source. Design the system so that the extent of the area heated can be controlled or zoned with indiviual thermostats in each zone. This allows you to shut off heating to unoccupied areas to save energy and help reduce emmisions.

Hydronic Systems

Hot water is circulated through radiator panels in rooms, providing a mix of convective and radiant heat.

Hydronic systems are usually gas fired but can be heated by a wood fired heater, solar systems or heat pump. Solar systems can use gas or wood heating as a back-up. Hydronic systems have the advantage of adaptability of energy sources as energy markets change. Each panel or room should have its own control. Low water content systems are best as they reduce energy use and it is very important that the water circulation pipes are well insulated.

Exterior walls behind panels must also be insulated to prevent heat loss to the outside. Use wall cavity insulation, or a layer of installed reflective foil on the internal wall behind the panel.

In-slab floor heating

Concrete floors can be used to store heat from off-peak electric cables or hydronic pipes set into the slab. These are insulated during building construction or renovation.

The best system for minimising greenhouse gas emissions is hydronic pipes using:

Solar with gas back-up.
Efficient slow combustion wood heater with a wetback.
Geothermal or water-body heat pumps.
In-slab systems provide a combination of radiant, convective and conductive heat.

The table below assumes well designed and efficiently operated systems. Running costs and greenhouse gas emissions are general and you should obtain expert advice before making decisions on which type is best for you.

SPACE HEATING

Electric heaters

These devices heat a smaller area - one or perhaps two rooms. There is a wide range available.

Electric portable heaters

Electric portable heaters can be cheap to buy but are expensive to run and sometimes ineffective. They include the following:

 - Radiant heaters, such as bar heaters, are good for bathrooms as they provide almost instant heat direct to your body and do not directly heat air. Less warm air is lost when an exhaust fan is used compared to other heater types. No thermostat is fitted so a timer or switch should be used. Turn off radiant heaters when leaving the room for any length of time.
 - Fan heaters heat the air and provide convective heat. Larger upright models are more effective. They can warm smaller rooms quickly. Some have thermostats to help reduce energy use.
 - Convector heaters heat the air, which then rises naturally. They are not recommended for rooms with high ceilings or poor insulation levels or where there is a high ventilation rate.
 - Oil filled column heaters provide a mix of convective and radiant heat but are slow to respond. Some have thermostats, timers and fans. They are more suitable for larger rooms with high ceilings.
 - Electric systems may produce high greenhouse gas emissions - up to six times as much as an efficient gas central heating system.

Electric fixed heaters

Reverse cycle heat pumps provide convective heat and are the most energy efficient electric heater. Wall panel convectors use peak electricity and are expensive to run.

Off-peak electric storage heaters provide a mix of radiant and convective heat. They use bricks to store heat produced overnight using off-peak electricity. Unless carefully controlled they can lead to overheating in periods of milder weather.

Gas heaters

Gas portable heaters
Unflued portables can provide either convective or radiant heat and run on natural gas or LPG.

Adequate ventilation is needed to maintain good air quality, which can significantly reduce efficiency. An efficient externally flued heater is usually preferable but may not always be an option, particularly for tenants. In these cases, units are available which burn cleaner, producing lower combustion emissions, requiring less ventilation.

Gas portable heaters

Unflued portables can provide either convective or radiant heat and run on natural gas or LPG.

Adequate ventilation is needed to maintain good air quality, which can significantly reduce efficiency. An efficient externally flued heater is usually preferable but may not always be an option, particularly for tenants. In these cases, units are available which burn cleaner, producing lower combustion emissions, requiring less ventilation.

Unflued gas heaters often create condensation problems – usually at the opposite (coolest) end of the house. Care is needed to ensure they don’t lead to mould growth.

The use of unflued heaters is restricted in some states.

Gas fixed heaters

Wall units and floor consoles can provide convective and/or radiant heat. They usually contain fans to circulate hot air. Most are flued, requiring less ventilation and producing fewer condensation problems.

In low humid climates, humidity trays may be required to maintain room humidity levels. These need to be topped up regularly.

Gas pot-belly stoves and fireplace inserts provide mostly radiant heat. High mass structures nearby can store and convert this to convective heat.

Wood and other solid fuels

Open fireplaces

Open fireplaces provide radiant heat, but are highly inefficient, with up to 90 per cent of the heat energy going up the chimney. Large amounts of cold air are drawn into the room to replace air lost up the chimney. They are the least efficient of all wood heating methods and produce the highest levels of air pollution. Open fires are better at producing ambience than heat.

They provide a combination of convective and radiant heat.

Slow combustion inserts are up to 60 per cent efficient if they are installed correctly by sealing the chimney at ceiling level and providing vents back into the room to reclaim heat from the flue and case. If the wall behind the fireplace is external it should be insulated. Non-airtight potbelly stoves provide mainly radiant heat and are only about 40 per cent efficient. Slow combustion stoves and heaters provide convective and radiant heat and can be up to 70 per cent efficient. They are most suitable for large spaces that need heating for long periods. They can take a long time to heat up and cool down. Many can be fitted with a wetback to heat water.

COOLING

 Mechanical cooling devices

 -Points to consider when choosing cooling systems:
 -Does the air require cooling or will creating a cooling breeze be enough? 
 -How big an area needs to be cooled? A single living area is often sufficient to survive a few days of summer heat wave in many climates. 
 -How often and for how long is cooling needed?
 -Is space cooling or a whole house ducted system required? Whole house systems are more expensive to buy and generally cost more to run.

There are many variables to consider and expert advice should be sought before proceeding with the design or purchase of a mechanical cooling system.

Fans

The three major methods of mechanical cooling are fans, evaporative coolers and air conditioners. Fans should be the first choice for mechanical cooling. With good design and insulation, fans can often provide adequate cooling for acclimatised residents in all Australian climates. They save money and the environment.

Fans are the cheapest to run and have the least greenhouse impact. Fans cost little to buy and run. They circulate air but do not reduce temperature or humidity. Portable table and floor fans or fixed ceiling and wall models are available. Fans are useful in combination with an air cooling system as the extra air movement provides comfort at higher thermostat settings.

Evaporative coolers

Your second choice for mechanical cooling should be evaporative coolers. Evaporative coolers work best in low humidity as the air has greater potential to absorb water vapour. They are significantly less effective in climates with high humidity. They will cool the air to just above the ‘wet bulb’ temperature. You can check with your local bureau of meteorology to see if the ‘wet bulb’ temperature is at a comfortable level for you in summer.

Operating costs can be low as only the fan uses energy. Evaporation provides the cooling energy. However, many units have inefficient fans that consume more energy than necessary. Evaporative coolers use water on the cooling medium. You should check with your council to see if there are ant restrictions on using water for evaporative cooling.

Purchase costs are moderate.

Portable units have to be topped up with water regularly, about four litres per hour. For central systems water use can be 25L or more per hour on hot, dry days and this needs to be considered in water restricted situations. Make sure the bleed-off rate isn’t excessive – ask the installer to set it to the recommended minimum.

Refrigerated coolers (air conditioners)

If thermal comfort cannot be achieved with passive design, fans or evaporative cooling, air conditioning should then be considered. Air conditioning can provide comfort in any climate.

For efficient air conditioning, the house or room should be sealed and highly insulated with bulk and reflective insulation. Windows must also be shaded from the summer sun. Purchase costs are higher than evaporative coolers.

Efficiency varies between units and models. Systems using inverter technology can show energy savings of up to 30 per cent vs standard units, however, are more expensive. Always choose the most efficient model for your application. Air conditioners are available as portable, wall, window, split and ducted systems.

Operating tips

Shade outdoor components from direct sun. Some units are noisy in operation. Split systems (where the compressor is outside) are quieter inside but consider your neighbours when locating external components.
Reverse cycle models can also be used for heating. Units that use electric heating elements cost more to run and produce more greenhouse gases.

Types of Air Conditioners

Portable split units

Portable split units consist of separate indoor and outdoor components connected by a flexible hose that is passed through a partially opened window or door. They plug into a standard power outlet. They are generally not as efficient as other types of air conditioners, but are suitable for small rooms up to about 20m². Always check the energy rating label.

Through wall/window units

Through wall/window units are placed in an existing external window or a hole made in an external wall. Smaller units can use a standard power outlet, but larger ones may need special wiring. They are generally less efficient than fixed split systems and suitable for single rooms up to about 50m².

Fixed split systems

Fixed split systems are generally the most efficient domestic air conditioners. The indoor wall or floor mounted unit can be up to 15m from the outdoor compressor. Multi-split systems have more than one indoor unit running off the outdoor compressor.

Ducted units

Ducted units are used to cool large areas or an entire house. Systems should be zoned to cool only those areas occupied and to allow different conditioning in living and sleeping areas.

Alternative heat exchangers

Reverse cycle air conditioners, in both cooling and heating modes, mostly use an air to air heat exchanger, like a refrigerator. This dissipates heat extracted from the room to the outside when cooling or from the outside air into the room when heating.

Do not leave heating and cooling appliances on overnight or when you are out, although slow combustion stoves can be left on in very cold weather. If you must have the house comfortable when you arrive home, ensure you have a timer and turn your system on about 15 minutes prior to your return.

Practical Tips for Heating & Cooling 

Maintain your heater. Keep reflectors shiny and free of dust. Clean air filters regularly. Service all heaters and coolers according to the manufacturer’s instructions. Pay special attention to air filters. Close windows and doors in areas where a heater or air conditioner is on unless ventilation is required for un-flued gas appliances. Close drapes or blinds, especially in the evening when you are heating.

Dress appropriately for the weather. Putting on a sweater is better than turning the heater up. Maintain your heater. Keep reflectors shiny and free of dust. Clean air filters regularly. Service all heaters and coolers according to the manufacturer’s instructions.

Pay special attention to air filters. Close windows and doors in areas where a heater or air conditioner is on unless ventilation is required for un-flued gas appliances. Close drapes or blinds, especially in the evening when you are heating.

HIDC Exhibitor(s) who specialise in this area;

EnviroGroup

Heat - On Systems

HRV Australia

Jetmaster (Vic) P/L

Precision Heating & Cooling

Speedheat & Coldbuster