How can we improve Choice's Air conditioner energy saving tips?

I believe that Choice’s Air conditioner energy saving tips ( can be improved by:
(1) Amending the quote “For the best efficiency, aim to set your unit around 8°C cooler than the outside temperature” to “For the best COOLING efficiency, aim to set your unit NO MORE THAN 8°C cooler than the outside temperature.”
(2) Including advice to ensure that in a cold climate the cool/warm air outlet is installed near floor level, and in a hot climate it is installed at or above head level. That will give the best temperature distribution, because hot air rises and cold air falls.
The heating/cooling unit of my split system reverse cycle air-conditioner was installed near the ceiling (as per the manufacturer’s instructions for Canberra’s cold climate!). The result was that we got cold feet, because the temperature at foot level was four degrees lower than the temperature at head level. After spending thousands of dollars on an air-conditioner, we had to buy a ceiling fan to fix the problem.
It would be a simple matter for Choice’s air-conditioner tests to include temperature measurements at head height and at foot height.
This issue is discussed at
How else can the air-conditioner energy-saving tips be improved?


The head or indoor units installed towards the ceiling are not intended to be installed near floor level. The Choice member reviews indicate for the type of AC whether they are a “high wall mount” or a “floor mount” etc.

There are reviews of 13 floor mount units. They are purposefully designed to be slimmer and duct air accordingly.

The compromise with the type and location of indoor unit may be greatest where there are high summer cooling and winter warming demands.

Whether a floor mounted unit is better suited to the needs of those living in the inland corner of the SE. Can how a room is furnished negate any benefits by blocking air flow across a large room?

Choice has also previously addressed the specific benefits and savings of using a ceiling fan

Possibly @ChrisBarnes could further edit the current lead in information for the Air Conditioner reviews and buying guide. IE to better highlight some of the other key considerations for AC installations intended for predominantly winter heating.

Is it likely measuring in a test set up any difference in air temperature layering between reviewed models will show a meaningful difference between similar products? Looking across the full depth of the Choice member and unrestricted content may provide a satisfactory answer.

If adding to an existing home, renovating or building a new home, the best solutions for home heating and cooling will differ. Installing AC in existing homes is often a compromise. The energy saving tips are most relevant for installs in existing homes, vs a newer high energy efficiency designed home.


Asking @ChrisBarnes to edit the buying guide is an excellent suggestion. A ceiling fans can indeed cut the running cost of a poorly-designed heater. Choice could conduct tests on split systems, to see which models are designed well enough to provide good temperature distribution without a ceiling fan.
You can negate the benefits of a floor-mounted indoor unit by, for example, putting a sofa directly in front of it. However, it would be much easier to move the sofa than to move the indoor unit.

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In the Grand Designs Mac-Mansion of my partners dreams. Our homes have been more modest. In our youth sitting on the floor in a bean bag was easily accepted. Perhaps if we’d kept up the Yoga classes? :wink:

It’s true there are Aussie homes with ballroom scaled living areas and free-form design. A reasonable assumption is those who can afford such luxury are less concerned with the daily cost of the home and more with absolute comfort.

It’s arguable that they would all fail. How meaningful is any result given variations in room size, shape and layout? Is the assumption the effectiveness of air circulation defines a poorly designed split system?

It’s not IMO a useful test or a useful comparison. In one scenario there is the high relative efficiency of a ceiling fan (m3 per Whr) of air moved. The alternative is the several times worse efficiency of the higher pressure barrel fans drawing air through the air pathways and heat exchange coils of a split system.

The large swept area of a ceiling fan circulates a large air volume at low velocity creating effective mixing. A split system wall or floor unit offers only a higher velocity air stream. The addition of the swing air modes to the better quality split systems is evidence of the limitations of the system design common to all similar products.

It’s likely we will disagree that the use of ceiling fans to improve room comfort is a symptom of poor Split System AC design. Heat pump sourced hydronic heating with underfloor and wall mounted radiators are another alternative that offers a more perfect solution.


The location of the air outlet will only affect the area close to the unit hence the use of a fan will help, (it is more noticeable when heating due to the hot air rising to the ceiling while we are in the lower portion of the rooms).

In the choice article they state ceiling fans are good for circulating cold air, true but most ceiling fans have a reverse function for circulating warm air which works better than pedestal fans due to the slower movement of air not creating breezes and the ceiling fan will affect a larger area.

Energy saving tips could include:
keeping doors and windows closed, eliminate draughts where possible ie door seals
close blinds and curtains (or roller shutters) to reduce losses through glass (unless double glazed windows are installed). Consider installing heavier curtains for more insulation.
On cold days, sun shining through glass will help heating hence open blinds and curtains when the sun is passing through glass.
Ceiling insulation and in more extreme climates underfloor insulation for non slab houses.
In summer keeping sun off windows by the use of external shades makes a significant difference, curtains still help as glass will conduct heat.
Roof ventilators help reduce the heat in roof cavities reducing the cooling needed in summer and also reducing the impact on ducted air conditioners, ie the ducts and the AC inside unit are normally installed in the roof space.
Some roof ventilators can be turned off for winter to keep more heat in the roof space.

An interesting benefit of roof mounted solar panels is they reduce the heat within the roof space as they provide shade to the portion of the roof getting the most sun, ie cooler house in summer

Monitor outside temp and humidity via the BOM website or other means and open up the house when the outside conditions are favourable, ie a cool southerly in summer can cool faster and cheaper than an air conditioner.


Noted the reference to humidity. Personal comfort is greatly influenced by the indoor humidity. The safety of the indoor environment is also a factor with differences in temperature and humidity between inside and outside air. These can add to health risks if not understood and managed.

The design, insulation, moisture protection and age of housing will find many Aussie homes deficient. RC air conditioning systems do not solve all home comfort needs without attention to other defects.

“Engineer’s” comments indicate that heater manufacturers overstate the size of rooms that they can heat.
On the other hand, heaters would be much more effective if their heating outlets were located closer to the floor and they had fans that could more effectively push warm air across the room.
Manufacturers could offer “all seasons” air conditioners that circulated cool air from their top vents in summer, and circulated warm air from their bottom vents in winter.

A take on efficient use of A/C to complement Choice advice.

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YIKES! at 27º I am dying. I turn on the a/c when the inside temp is only 22, and thats where my units are set. I struggle with self regulation of temperature and I cannot cope with temps over 30º … add humidity and I am a puddle. I’d rther have bigger bills than die in discomfort.


A temperature by itself is guidance but most homes have temperature gradients from the heat/AC to the thermostat. Our house has large and plentiful single glazed environmentally hostile 1990s aluminium frame windows; in winter our hydronic thermostat is set to 23.5 and it is cool where we sit near the walls but overall works for a comfy home. In summer the splits get set from 24~26C when used, depending on outside temps. We do not use the split for heating because the cycling nature in heat mode doesn’t work well for the floor plan.

The setting for any particular building is as much subject to the building itself as to the advice.

+1 for those of us fortunate enough to have the choice.

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yes temperature and humidity can be a very complex subject ie the National Maritine Museum installed special air conditioning to protect old items on display.
To simplify it for home owners it is recommended to maintain relative humidity between 30 and 60%, levels easily maintained by most air conditioners (except Actron see my post in spot a shonky Nov 2022)
So if your happy with the outside temperature and the outside humidity is between 30-60% open up and let fresh air in.

However as the house walls and roof space may still be hot it is possible for the inside temperature to go higher than outside if there is not enough airflow, if that happens close up and put the AC back on.

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It isn’t really a choice, I live on the age pension with no other income. I go without other things at bill payng time.

And aren’t they horrible. I tried to get them replaced earlier iin my time here but not one tradie was interested in taking on the job.


Yes. And from 2017

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In regard to the single glazed aluminium framed windows heavy curtains may be something worth considering,


Although either can be fairly expensive excepting for small-to-average sized standard dimensioned windows where one can buy ready made products.


Adding a second layer of glazing is far from a complete waste of money. Aluminium frames typically occupy only a very small proportion of the window area. It’s easy to apply an insulating layer to the inside and/or outside of the metal frame.

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That is is, for a cost. But from what I understand it does not work like ‘proper’ double glazing or does it? The aluminium frames conduct heat/cold unlike the insulated properties of the modern plasticised frames. Using my single glazed aluminium windows as an example they have horrifically poor ‘insulating’ properties.

Applying the second glaze might be easy on some windows, or prohibit being able to open them on others (without removing the faux doubler glaze panel). As I posted

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There are two issues here: the insulation value of the frame, and the insulation value of the glazing. It shouldn’t cost much to put a layer of insulating form, or an insulating wooden batten, between the frame and the new glazing. A second layer of ordinary glazing will roughly halve the heat loss from the window. That’s not as good as top quality double glazing, but it’s better than nothing.

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That is essentially what businesses would do for the 30-40 year payback I mentioned, allowing for opening windows and a professional finish… roughly $2,500-4,000 per each of my windows and double for sliding doors.

It seemed over the top then, and now but those price points seem to prevail, at least where I live.

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Already have those, got rid of the venetians when I moved in, I’ve always known the value of curtains, mother taught me well.