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?
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!
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:
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.
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.
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.
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!
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.
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
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?
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.
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.
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.
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.
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.
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 =-.
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.
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.
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.
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!
A good rule of thumb is for air conditioning to be set to only 10C below the outside temperature. The dehumidifying effect of air conditioners on your home will mean that even at 25C or 26C inside, you will still feel cooler than if you were standing outside in 26C heat (ie because of lesser humidity). By the time you are going 10C BELOW the outside temperature, you will feel a substantial difference being inside. Run your air conditioner like that and you will find it pretty cost effective. Good rule of thumb – turn your air con UP on really hot days and you’ll still feel cool AND keep your ac bills low!
Are you sure it’s 23 celsius degrees
25 degress celcius to me, is the MINIMUM you should set it too! honestly! move to a colder climate if you cant handle that.
Where I am summer can reach to 40 degress so I firmly believe that 27 is ideal, 25 at a minimum.
People who set is lower at night- Honestly? You obviously arent campers either!!
Take off your woolly pyjamas, and ditch the doona.
Thank you for the advice but I think AC 23 is still better then AC 25
25 consumes just over 1kw on my inverter system, 23 does 3kw with the price of electricity I’m getting used to 25
Also 27 when it’s 40 outside is perfect
I definitely recommend 26 degrees celcius when it is 35 degrees + outside.
I think the main point is that it is relative. If the climate you are living in is NEVER likely to make it to 25 degrees celcius outdoors more than 1 or 2 days a year, then of course you will find the idea of setting AC to 26 degrees a bit excessive.
You might even question why you would have air conditioning installed at all!
But for those living in climates where a 3rd of the year or more will be + 29 degrees and up, the higher setting on your AC really will pay dividends, and maintain your home as a much cooler and less humid environment than outside.
Can someone in the know please tell me how to combat high humidity in the home. It is Jan 2011 with all this rain and humidity here in Melbourne the tiled floor in the home and the painted garage floors have taken on a film of dampness and Im worried about it being a slipping hazard let alone any other damage that all this damness can cause. Obviuosly running my evaporative AC system would increase the problem, any solutions would be appreciated.
Yeah people, keep turning your aircon to lower and lower temperatures, every degree colder you make your little indoor home bubble just helps pollute our entire planet even more.
Man up! Deal with whatever temperature you live at, unless you want your grandkids to be living in a world where the outdoor environment is too noxious for them to ever step outside.
Taken from http://www.originenergy.com.au/
Brisbane
30°C, Hazy
Keep your air conditioner at 24°C for ideal comfort levels and efficient running costs.
Pingback: Combat High Humidity with a Dehumidifier | Renovate Australia
This is interesting, there are so many factors though. I must say, you should be able to adapt more to your country’s weather and then work from there. I’m one of the ones that is used to the temp and get cold in buildings thus, but I deal with it because I know most people don’t struggle with it as much as I do. (I wish I could handle the cold like you Canadians!)
Women get cold quicker than men, which is our biggest problem. The ladies are cold and the men get hot, but its an open office so we need to agree somehow. It would be interesting to see the difference in preference between women and men.
Humidity would play a big part in this too, I assume. What would be the correct humidity? I live in JHB South Africa and apparently its dry here (though I just checked a weather forecast for today and it said 59% humidity, don’t know if thats very dry?). The cold a\c can dry it out more, I find sometimes too much, and then people start getting sick and that spreads because of the aircon too. Is there a specific percentage that is best for the average person maybe?
I live in Perth where it has been a bit warm lately, we’re having runs of high 30s (c) and pretty humid – however our work aircon is set to 19 degrees!!! It is rediculous- if it were winter we would be turning it UP to 25 degrees so why have it so much lower in summer? in the middle of summer we are all wearing jumpers and have blankets at work. I keep trying to change it up to 24 but it always gets changed back down again. I’m sick of freezing my arse off in the middle of summer!
I agree with you on that one Rachel! And its aweful to walk out of the building and be hit with the heat wave. When you go somewhere after work, you’re always dressed too warm! I don’t see why 25 deg is ok in winter but not in summer…
This is an interesting thread, which prompts me to contribute my two cents. However, to save time, I will be directly lifting some material from other sources, especially wikipedia.
Human metabolism always produces heat but at the same time the body needs to maintain a constant temperature of 98.6 degree F. Therefore, to dissipate the extra heat, the surrounding temperature needs to be lower but how much lower depends upon the metabolic rate of each individual because every person has a different metabolic rate, and these rates can fluctuate when a person is performing certain activities, or under certain environmental conditions. Therefore, even people who are in the same room can feel significant temperature differences due to their own metabolic rates, which makes it very hard to find an optimal temperature for everyone in a given location. Food and drink habits, body shape, height, weight, etc will affect the thermal comfort. Generally this temperature is in the range of 20-26 degree C.
Humidity is another factor which determines how the perspiration from the body evaporates and causes a cooling effect. If the surrounding environment is very humid the evaporative cooling effect will be less and hence one feels hotter. Remember how the evaporation of water from body makes it feel cooler when one comes out of the swimming pool. This also reminds me of the favorite school question as to why the water in earthen pots (porous) is found to be cooler than in metal containers (non-porous). The human body has sensors that are fairly efficient in sensing heat and cold, but they are not very effective in detecting relative humidity. Relative humidity creates the perception of an extremely dry or extremely damp indoor environment. This can then play a part in the perceived temperature and their thermal comfort. The recommended level of indoor humidity is in the range of 30-60%.
Many other factors including air velocity, clothing insulation, gender differences, thermal sensitivity and adjustment mechanisms of individuals, etc also play a part in thermal comfort.
Thus you must set air-con to the temperature you feel most comfortable with. The temperature value itself is not that important because the temperature sensor of the air-con might be far away from you or you may be closer to a source of heat/cold (window/door/kitchen/etc). In an office environment (or a public place) you do not have much control though. If you feel cold then just wear warm clothing and if you feel hot then just strip. The latter will increase the body temperature of others and they will themselves rush to set the air-con to a lower temperature to dissipate their heat at a faster rate in order to maintain their body temperature at 98.6 degree F.
Personally I prefer to set the air-con to a degree or two more than thermal comfort during summer and a degree or two less during winter (just opposite of what others do to make up for inadequate thermal shielding of the building) in order to achieve reduced thermal shock while leaving the building and reduced mental shock while receiving the electricity bill.
I live in Aurora, Ontario. My front room window
is on the west side. My room temp. reads 8I what should I set my air coditioner at?
If you live in the tropics or 60% + humidity with temps around 25 to 30 degrees use a whole house dehumidifier which is much much better than using an A/C.
Aircons are not very good at removing moister from the air.
Dehumidifiers are cheaper to run and give you better air quality and much more comfortable house.
And if you use your Aircon with your dehumidifier it will have to do a lot less work
i got alot of tips from people regarding what temp to run my air co thanks
Are some people actually being serious in saying that 25 degrees Celsius is too hot???
LOL. I live very close to the equator (Malaysia) where the humidity is just insane. And a lot of the people here love to freeze their butts off setting the AC at 17-22 celcius. I find that to be crazy cold, I would normally set it at 27-29 celcius and it’s comfortable for me. I prefer a little heat. As long as it doesn’t make me sweat. Or maybe it’s just because I’m skinny.
What should be the difference between 5 Star Split AC 1.5T Grill temp and AC Display Temp.
If display shows 18degrees centigrade what should be grill temp. Also what is the lowest Grill temp possible.
This may seem a dumb question but ……just moved from queensland australia to south island new zealand. In australia used air-con on cool setting, usually around 20-24degrees depending on weather, summertime only. Here in new zealand we have a split cycle, so can be used on cool or heat settings. It is winter so average 11degress celcius top temp during day, 0degrees or below at night. Do we have to set air con to heat setting (we have been at between 18-25dgrees celcius)? my Q is can we set to cool setting say 24degrees celcius? Would this still heat our house if it were only 10degrees without using the air con? would this be cheaper than using the heat setting?
/
Nice read. I never set my air con lower than 28C and my normal setting for the aircon is 30C in the mid summers of Japan. Japan has a dreadful summer, strong sunlight, high humidity average of 65% and not much wind. Imagine sitting under the a 30C AC is a bit cool in mid summer(I normally sit in front of a PC and dont move much so its cool)
Aircon and fan is a good combination. Since circulating air passing through your skin brings away moisture. However, if you set your AC at a cooler temp, once the room temp reach the point you feel cool enough, u can switch off the fan and let the AC maintain the temp.
Why institutions set 22C is because of the volume of air which the AC need to cool down. In the end, their aim still roughly to be around 25C. To cool down an inner building which receives heat from outside, and people inside which emit heat like a 100W light bulb, machines etc. You would need a lower setting. Try taking a thermometer into a big building with 22C setting, it will never be 22 but higher. Thats how my lab’s situation is.
Bill, this was a really interesting article. I had no idea that 77 degrees is the best temperature to have the air conditioner set at. My husband and I just moved into a new house and we have been thinking about what temperature we should set the air conditioner for. After reading this I think we are going to set it to 77 degrees! I will have to show this to my husband and see what he thinks.
Emily Smith | http://www.floridaradonmoldandairconditioningllc.com/products.html
My. Manager at my apartment says for me to not  go any,lower than 72  My question is why and when I do it get hot in my apartment start to sweat
My apartment manager says for me to leave thermostat 72 but I don’t want to. But if I do move it to 68 it stats getting hot WHY is that for some reason she want it set THER is it CAUSE its malfunctioning. Pleas hel answer this
Interesting article and comments.
I have gas heating only, no cooling.
Each person is unique, so stating a ‘set’ temperature is a bit strange.
Some people hate the cold, some hate the heat.
I have had Chronic Fatigue Syndrome since 2000 (approx.) and it has changed my inner thermostat, so that if 22C is the normal comfort level
(in normal clothing), I need 25-26C.
Sleeping is different. If the temperature is too hot (24C or above) it affects my sleep badly.
If the temperature is too cold (18C or below) ditto, with muscle/joint pain.
I live in Melbourne, Australia, so for me, it’s not the ideal place. The default temperature for 6 months of the year is 10C min. to 20C max.
Even in summer there are days at the above temperature.
Winter is cold (8C min, to 15C max.).
Summer often has ‘heatwaves’ e.g. 4-8 days at 30C-35C.
I am with Bill (poster) on setting the temperature at 26C, but that is because I am a very cold person.
If you are a heathy person with a good metabolism, 26C might be too hot.
If you are a warm person, 26C will be too hot.
It all depends on the person.
If I lived in Far North Queensand, I would set the A/C to probaby 26C or 27C
during the day, and to 22C or 23C for sleeping.
That would be my dream setting… : )
I set mine at 18 degrees for sleeping. Anything over 18 and I can’t sleep well.
25 can’t possibly be a good temperature for sleeping. That is the temperature where you don’t need any bedding. Studies seem to show the ideal sleeping temperature to be 16-19 degrees. Air conditioning lowers the humidity a bit more than normal so I think 20-22 is probably fine.
As for cost, the cost of air conditioning is dependent on the difference between the current temperature and the temperature of the air conditioning unit. It the temperature in the room is 17 and you put the air conditioning on 16, it only has to lower the temperature by a single degree.
Everybody is different. I like 25C during the day and just a fan on low speed at night.
I can’t stand AC at night. It makes my mouth dry, sore throat, and I end up with cold/flu symptoms the next day.
I have a window A/C with built in temperature setting’s. I like it cold wen I sleep! what temp should I set the a/c to achieve that coldness?
A well-detailed article about air conditioning, thanks for sharing this information.