Recently I’ve been living next to someone who I’m convinced sets their air conditioner to about 20C (70F). I’ve heard it turn on when I have been very comfortable both inside and outside. At the same time I reckon that they probably have their heater set not much below that, so they always stay right at the same temperature year round.
The recommended temperature to set your air conditioner to is 25C (77F). This is the best setting to balance the economy of running your air conditioner and setting it to a comfortable temperature.
Some people find 25C to be too warm to set the air conditioner to. If that’s the case for you then running a fan is an economical solution to help augment cooling provided by the air conditioner. My personal preference is to run the fans on high with the air conditioner set to 25C rather than setting the air conditioner any cooler then that.
I have a few friends who really crank down their air conditioner at night because the like to be cold when they sleep. To help us sleep at night in the summer we leave the air conditioner at 25C, set the fan to high and remove the duvet from our duvet cover, so we just sleep with the duvet cover. This helps us to sleep at a comfortable temperature, without increasing the costs to cool the house.
What temperature do you have your air conditioner set to and what do you do to make your air conditioner cool your house more effectively?
19 responses so far ↓
Nathan K // Aug 14, 2009 at 8:53 am
See thats just wrong on all levels. The reccomended temp for AC is 23-24 degrees. Also you running your fan is crazy. A fan actually uses more power than the current inverter AC split systems, so you are doubling your power usage, way to go!
Bill Hutchison // Aug 15, 2009 at 3:25 am
Thanks for the feedback Nathan.
The recommended temperature according to the Australia Government Energy Rating Web-site is 23-26°C. According to Origin Energy you can save up to 10% off your energy costs for every 1 degree that you increase the temperature inside your room.
The average ceiling fan uses about the same amount of power as a 60 watt light bulb and costs only a few cents per hour to run. Origin Energy recommends using fans over air conditioners to help reduce your costs of cooling.
I would like to see where you get your stats that a fan uses more power than running an modern AC. I can’t find anything to back that up, but I can find lots of sites that show using an air conditioner uses at least 10 times as much power as a fan, including the Australia Government Energy Rating Site.
For example:
John Parry // Aug 21, 2009 at 9:42 pm
25°C. Are you serious? I would wake up in a puddle of sweat if our air conditioner was set at that temperature! I set ours at 17°C overnight, but when lounging around in our house at night, the lounge is set to 23°C. Any hotter is uncomfortable.
Having said that, I was in Brisbane when it was about 22°C outside and had to argue with some retards on the table next to us about turning off the overhead heater.
Bill Hutchison // Aug 23, 2009 at 7:57 am
17°C overnight eh? I can’t imagine the electricity bill …
The most we ever had to pay in the hottest of months in Townsville (tropics, high temperature and high humidity) was $100 per month.
Keith // Sep 22, 2009 at 3:58 pm
Interesting topic. There is another factor, is your house insulated. If not the AC is working against the heat load in the roof which can be considerable. At 25 degrees in a properly insulated house I expect the temp would be quite comfortable.
I find that the “dry” setting alone is often sufficient to provide comfort in a properly insulated building.
Bill Hutchison // Nov 5, 2009 at 4:26 pm
Sorry I missed your comment somehow Keith.
We have a reflective paint on the roof that keeps the temperature transfer down considerably upstairs (on the hottest day I can be on the roof barefoot).
The bedrooms are downstairs so are well insulated from above and there is some insulation in the exterior walls.
I find 25C is very a comfortable temperature with the fan on, and I grew up in Calgary, Canada, where 25C was considered a hot summer day!
Steven Barker // Nov 20, 2009 at 1:35 pm
I found this posting quite interesting and just had to respond since i used to work in the refrigeration industry. Well lets look at things. For starters since power companys have been promoting the a/c set temp at 25c they have had minimul brown outs on their ageing grids so thats a plus for their bottom line. But do your research properly. The human body operates comfortably and with the least amout of stress at temperatures between 19 to 22 degrees celcius. (medical archive). Go to a power companys hi rise building and ask them what their a/c is set at. It will be controlled by and enviromental control system which will be set at 22c and 50 % humidity. Bit controdictive dont you think ! All hi rise, shopping centres and public places are set at 22c becuse thats what they are designed to operate at. The higher the set point temperature the less moisture that is removed from the air and the more ubcomfortable the air quality is. Humidity is always the killer so the more time the a/c compressor is running the more moisture is removed from the air = more comfort. Why run another cooling appliance in conjunction with an air conditioner expecially a ceiling fan ? Air conditioners are designed to creat their own air draft for balanced cooling and dehumidification, putting a fan on throws the air conditioners air flow out of wack plus the fan has a motor which generates heat. Makes no sense to me why you would. I have 2 8.5 kw inverter Mitsubishi Electric Splits for lounge,dining,kitchen and rumpus and 4 3.5kw inverter Mitsubishi Electric Splits for the office and 3 bedrooms, all are set at 22c and cost me bugger all to run. Use the air conditioner as it was intended and it will do its job properly without using fans. Just 1 other note most if not all car climate control systems have their factory preset temperature at 22c wonder why ? 25c to hot to humid. 22c all the way.
Steven Barker // Nov 20, 2009 at 1:41 pm
one other note removing that batteries from your a/c remote and re installing them will give you the factory preset temperature in each mode that the company who made the product thinks is the best comfort temperature for each mode. The Mitsibishi preset is 21c so thats close enough for me. not 25c
Joy Naley // Dec 16, 2009 at 1:45 pm
Just wondering if anyone has any ideas on whether the air conditioner should be left on all the time or turned off at some point. We already have all the unused rooms closed off. So is it more economical to leave it on or to turn it off and just use the fans at night? There is lots of information about the temperature, but does it use more energy to cool a room or keep it continually maintained?
Evan // Dec 24, 2009 at 3:16 pm
I think what also needs to be taken into consideration is whether someone is setting the AC at a low temperature to cool a larger/adjacent room, or just a small room (i.e. bedroom). I find that in my bedroom where the bed’s directly under the AC, 24 degrees can get a bit cool, especially when the fins are oscillating and blowing cold air directly onto me at times. I’ve since set it to 25, and don’t feel uncomfortable at all now!
Needless to say, if I’m cooling the kitchen/dining room, with perhaps some sunlight reflecting into the curtains off the patio, setting it a little cooler (say 22 degrees) may be necessary.
Andrew Middleton // Jan 18, 2010 at 1:53 pm
I dont know what all you guys are complaining about, saying 25 is too hot. thats just pathetic haha. i ususally set my air con to 27, which is sometimes too cold. you obviously dont get very hot weather where you are.
Bill Hutchison // Jan 24, 2010 at 4:21 pm
It’s what you get used to isn’t it Andrew. If I were to go from mid 30s with high humidity come into a house set for 21C or 22C it would feel absolutely freezing. Even 25 feels cold at first, but pleasant after a couple of minutes, or when the sweat isn’t there any more.
I also think that the home is a lot different than an office. At home we can dress for the weather a lot better than at work. Somehow I don’t think that it would be acceptable to go in shorts, t-shirt and without socks to most work places or offices, whereas doing that at home makes a lot of sense.
Francois Viljoen // Feb 8, 2010 at 8:10 pm
I think all you need is acclimatization.
I hate running an aircon. Everyway I look at it it is a waste of energy.
I lived in Nigeria for two years where the weather was tropical and very hot (>=30C and 90% humidity during the day and rarely dropping below 25C at night).
Your body adapts. By the end of my stay, I never ran the aircon anymore. I would sometimes run the fan at night, but never the aircon. I was totally comfortable.
The downside is, now that I’m back in my home country, I find that I find aircons annoyingly cold everywhere I go and I’m always carrying around a bunch of jerseys and jackets and beanies.
Air Conditioner // Apr 30, 2010 at 6:17 pm
I think that 20C is good just make sure that you just do it 5 to 10 hours and not exceeding to atleast minimize the effects of climate change.
katie // Jun 10, 2010 at 11:34 pm
hi bill!
i came across your article, after arguing in my office about what i considered too cold and they thought was outrageously warm. im canadian too! (although from niagara region in ontario) and im working in an office in budapest. apparently what i consider a beautiful day here, they consider rather cool. to cut it short, i set the office ac for 26.5 C since its only june and beautiful outside. once the temp hits 40, which it usually does in august, then we’ll see. thanks for the info in any case.
-katie
katie´s last blog ..effortless concentration
Greg // Jul 16, 2010 at 3:32 pm
All of your comments seem to relate to settings for summer.
What about winter? Our office seems to be around 26C which is way too warm in Sydney.
Bill Hutchison // Jul 16, 2010 at 4:47 pm
That’s a good point Greg. I guess in North Queensland we never had to worry about it getting too cold, so we just turned our air conditioners off in the winter.
In Canada with our central heating we usually set it to about 20 for heating. I find that to be quite comfortable, especially since you will probably be dressing for the cold weather outside, and stepping into 26C would be a bit tough.
Emma // Aug 9, 2010 at 10:28 pm
Ha – you obviously don’t live in the Middle east. The average temperature here in summer is over 50 degrees c. (122f) with 100% humidity. if you don’t run your A/C below 22 everything goes mouldy from the humdity.
Kim // Aug 23, 2010 at 2:00 pm
Just stumbled on to this site!
Also being from Townsville, I can say that 25 in the middle of summer here feels really cool. Anything colder (23) would start requiring a jumper! Shopping centres and supermarkets are ALLLLWAYS too cold. Always! We rush because it is so cold in there!
But as for the acclimatising to the summer…. I’ve been here all my life (29 years) and I still run the aircon in summer because the humidity and heat is just way too much. I don’t see it as a waste of money or electricity, it is just one of those things about living in North Queensland. Obviously you evaluate it on a daily basis but it is often still really hot when you go to bed. The days are really hot and muggy, but you can always go swimming (as long as there is a shade cloth or it is like soup).
Usually the only ‘day’ we run the aircon is for Christmas Day!
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