With bills and prices skyrocketing lately due to the situation of the world economy, my wife is freaking out that we will be unable to pay our bills in the near future. She’s becoming a little crazy with some of the things we have to do in order to save money. But it’s practically summer already here in Okinawa and temperatures inside our house can get uncomfortably warm. I don’t mind it myself, but I worry for our 1-year-old girl who gets cranky when temperatures are too hot for her. I also worry for my wife who is currently working in a 28 degree office room in our house.
I put on the air conditioner in our daughter’s room to make it comfortable for her, but my wife got mad at me and brought up the bills again. She also mentioned how hot it is in her office already and how she’s slaving away in there for our family. I turned off our daughter’s A/C and told my wife that it’s off so she can use her office’s A/C.
She then responds with: “I don’t want to keep switching on and off the A/Cs. The very act of starting them up and shutting them down takes up more electricity, so it’s a waste of money.”
That didn’t sound very accurate to me, so I tried to look up whether the actual start up and stopping of A/C wall units actually takes up that much extra electricity, but could not find anything online.
Anyone else know more about this? Any sources to show that a significant amount of electricity is used up in the process? TIA
Update:
I do not keep the A/C on 24/7. My family rarely ever turns it on. I only turn it on for my daughter when she’s in her room playing or napping and when it gets to 26 degrees Celsius or higher. She can’t nap and gets cranky when it’s too hot.
Also, the majority of our electric bill does not come from our A/C units since we almost never use them.
13 comments
first google result for your question: https://enechange.jp/articles/aircon-cooling
(of course, they’re also trying to sell you something, but they do explain what and why)
Your daughter is 1 right? So I’m sure she’s pretty much only in her room during the night and during the day I assume she would be in the living room or whatever playing right? I think it would definitely save money to turn off the aircon during the day when nobody is in there.. compared to keeping it on 24/7.
I’m skeptical on that point because of a simple formula:
on = using electricity
off = not using electricity
The answer to this question doesn’t matter. You have much bigger problems at hand in your relationship with your wife, and you should probably pay more attention to that than the wholly unimportant detail of whether or not it actually costs more to turn an aircon on/off.
Heating and cooling is not like a car, where once in motion, to maintain the speed, you just have to overcome wheel friction and wind resistance, so that highway driving 55 mph gives you better MPG than stop and go 30 MPH in the city.
To maintain a temperature, your air con must add energy to the room equal to the rate of energy being lost through the walls to the outside.
Per Newton’s law of cooling, the rate energy is lost through the walls is proportional to the temperature difference between inside and outside. I.E. a 28C room will lose energy at a faster rate when the outside is 10C compared to when the outside is 20C. Corollary, maintain a room at 28C when outside is 10C will require more power than when the outside is 20C.
Therefore it is always more economical to shut an aircon OFF.
I did an experiment in the middle of summer a few years ago.
For July, I turned the A/C off and on each time I left and entered the house.
For August, I left it on 24/7, set at 29c when not at home, and 24c when I was there.
August’s electricity bill was cheaper than July’s by quite a bit.
This was for a 2LDK concrete/steel apartment on the top floor of the building.
It’s cheaper to leave it on all the time. Constantly on means that it is just maintaining the temperature what ever you set it at. Basically just idling along. Whereas if you turn it off and then back on a few hours later the AC is constantly fighting against the heat and humidity. It goes to max to get to your desired temperature every time you turn it on.
Get a usuage meter and connect it to it to get your specific case data.
It’s true – modern air conditions have what’s called Variable frequency drives allowing compressions to ramp up and down accordingly to demand.
The purpose is to draw smaller current at lower load demands for accurate cooling as well to run more electrically efficient.
When you start and stop your air conditioner / heat pump repeatedly it initiates higher current draw than it would just to leave it running. Now the machine will turn on an off automatically but quite often it will also run at a very low maintainable speed for the purpose of drawing less current for when the demand rises.The purpose of the machine is to maintain a desired spaces temp by removing moisture from the space.
A similar concept like “wasting fuel” would be to imagine turning on your and off your car at every red light – the amount of gas you’d waste would be foolish. So utilizing VFD compression allows for better electrical efficiency through run times. Keep in mind this theory is based on correct installation practices and if your unit was sized correctly based on the target heat load
Resource: I am a Canadian Red Seal Refrigeration Mechanic by trade.
If you are looking for legitimate engineering kw/hr usage refer to the installation manual and in the back there will be charts referring to electrical efficiency, sizing, air flow balancing, piping recommendations – all kinds of good stuff. I’m sure you could also resource the manufacturer spec based on the model/ serial on the side of the unit on their website.
I know you’re going to say “that’s not what I asked”, but you can get pretty strong airflow by turning on your ventilator 換気 and then only opening the vents but not the windows. In my experience, this results in a lot of cool air shooting through the vents (to go up through the ventilator) thereby rushing through the house and offering a nice breeze.
I presume running the ventilator costs a lot less than running A/C. Just a thought.
Ah yeah working at home with a 1 year old and a husband who doesn’t earn enough to pay the flipping bills haha I’d be cranky af too.
28 is fine come on…
Starting the aircon use power yes, I’m not sure what else you expect
In the hotter months, I heard it is actually cheaper to just leave it on all day. In winter, this is not the case. I just leave ours on “dry” most days during the summer to prevent mold and keep out roaches (that don’t like cold/dry)
What I heard is AC tends to use more energy when turning on rather than continuously using it.
For example, when turned on , it consumes 200% energy, whereas it consumes about 30-40% when running.m continuously.
So in general, it is cheaper to run ac continuously rather than turning on and turning off again and repeating it. Also ac usage cost in winter are higher than cost in summer.