Article by Danielle King, Green Moves Australiareverse-cycleac

Where ever you live there will undoubtedly be times you need to find ways to cool down or warm up in your home. Most of us are familiar with the various types of systems available, but it’s always good to have something that does both. It saves space, can be slightly cheaper overall and reduces maintenance.

This article takes a look at the ‘dual duty’ systems, those that both heat and cool a home. There are a few to choose from and what is right for you will depend entirely on your situation, budget and personal preference.

However there are key things that apply to everything in this space, they are:

• Consider where you need the heating/cooling and only condition that area
• Investigate what type is best for your situation and climate
• Think about how often are you likely to use it?
• If it’s a ducted system, ensure ducting is well insulated, joints well sealed, zoning is appropriate and it has self-closing dampers.
• Get the most efficient model you can – reach for the stars

Note we don’t include the ‘add on’ systems because having a gas heater with an electric ‘add on’ for cooling isn’t one system, it’s two!

Here’s what’s available in Australia.

Reverse Cycle Heating and Cooling (often called Heat Pump or Inverter systems)

Reverse Cycle Air-Conditioners are effectively a refrigerated air conditioner with a valve that enables it to switch between operating as an air conditioner or a heater through reversing the flow of the refrigerant. They can be particularly energy efficient.

Most heating or cooling systems have a coefficient of performance (COP value) of 1:1, that is for every 1 kW of energy in, you get 1 kW of energy out.

Inverter/Heat Pumps are able to do much better. Many have a co-efficient of performance of 4 or 5 kW of output to every 1 kW of energy. Most are around the 4.5 kW output to 1 kW of energy input, so a COP value of 4.5:1 – which is very efficient.

These units come in various sizes from those that are suitable for single rooms through to whole of house systems. Some heat pump systems can also provide hot water.

Geothermal Heating and Cooling (and hot water if necessary

Geothermal (often called ground source heat pumps) systems utilise the ground temperatures to provide heat, cooling, and hot water. It works by pumping water (or sometimes air) through a system of pipes which could be open or closed loop, or vertical and horizontal. For heating the water absorbs the heat from the surrounding warm earth. For cooling the earth absorbs the heat cooling the water. Heat pumps are attached to circulate and extract the heat/cool direct it into the home.

Geothermal is a highly efficient, well proven and environmentally sound method for providing heating, cooling and in some systems also hot water, to a home.

Geothermal systems are gaining popularity in Australia, and are well used internationally. Installation costs can be high but running costs are minimal.

Solar Powered Heating and Cooling (and hot water if necessary)

CSIRO has invented a new solar air-conditioning system for Australian homes. This technology will help to reduce Australia’s emissions, reduce your energy bills and reduce our demand for electricity and gas. It is an innovative three-in-one technology that provides hot water, cooling and heating.

It works by using heat from the sun and employs both desiccant and evaporative cooling technologies.

Solar heat is first collected and stored as hot water, which can be used directly in the house. A portion of the hot water is diverted into the solar air-conditioning unit, which is used to either heat or cool the air coming into the building.

This technology is not yet commercially available and is currently being tested at the Hunter TAFE Campus in NSW. The blog notes that availability is still some time off but we look forward to it being commercially available!

Information on this system was obtained from the CSIRO website – See for more information.


We continue to keep an eye out for efficient systems, particularly those that are powered by renewable energy. If you have any questions on these, or other heating and cooling options, visit the experts at the Build & Renovating Expo for some free and unbiased advice and guidance.

We look forward to seeing you there.


The CSIRO has invented a new three in one solar air conditioning system that provides hot water, cooling and heating. It works by using heat from the sun and employs both desiccant and evaporative cooling technologies.

See how the technology can work in the home in the short video below;