What Temperature Should I Set My House At?

Recently, I posted a question on Instagram asking what topics you would like to hear about on our blog. I received some really good feedback and lots of interesting subjects to discuss. One of the questions that was posed was: “By how much should we turn down the thermostat at night or when we leave the house for energy save.”

I know what you’re thinking: “Wow, great subject Avril. Could this blog BE any more boring??” Well, to be honest yes, you should read my other blogs. “Interesting” isn’t exactly the word I would use to describe them. But let’s be real, we’re talking about HVAC (H-what?? Don’t worry, there’s a blog coming about that super exciting subject too!!) Where was I? Oh yes, we’re talking about HVAC here so everything is pretty technical, aka, boring. But hopefully this can at least be informative and help some of you to understand things about this extremely FUN and ENTERTAINING subject. So let’s hope you’re not here to be entertained and Ooed and Awed (is that how you spell that?), but hopefully you’re just here to learn something that can possibly save you money. And as bored as you are reading this, I’m sure I grabbed your attention at “saving money.” Who doesn’t want that? So now, back to the subject at hand: By how much should we turn down the thermostat at night or when we leave the house?”

Before I answer this I’d like to give you a little rundown about my history. What makes me qualified to answer this question for you? Before Nathan and I got married, I used to work as a draftsman (or draftswoman? Is that a thing?) for a company that specialized in designing energy saving systems for both residential and commercial buildings. Things like solar panels, geothermal wells, heat pumps, etc. The goal of this company was to find the best way to heat and cool buildings while having the least negative impact on the environment. During their extensive studies, they did take this subject into consideration. I drew lots of plans of buildings with “Occupied Mode” “Unoccupied Mode” and “Semi-occupied Mode” because all those situations would require different temperatures. Fast forward to a few years later and I ended up marrying someone who worked directly in the HVAC field, actually working on and installing some of the very same items I spent all that time drawing! (And no, it wasn’t HVAC that brought us together, but it sure did help me to understand Nathan when he was talking about work.)

So now that I’ve brought you up to speed, between the research that the previous company I worked for did, and from Nathan’s years of experience in the field, I feel pretty confident in the answer I’m about to give you.

The general consensus seems to be that when you go out or while you’re sleeping, you should adjust your thermostat by 2-3℃. What?? Only 2 degrees? We were shocked too the first time we heard that. But when you think about it, it’s easier for your machine to maintain a certain temperature than it is for it to heat up an entire house, or to cool off an entire house. For example, let’s say in the winter your home is set to 21℃. Then, just before you leave, you set it to 14℃. Ok, so after you leave, your system has it nice and easy, just letting the temperature slowly drop. But if it’s really cold outside, or your house isn’t very well insulated, it might reach that temperature pretty quickly while you’re gone, and then, not only will you come home to an uncomfortably cold house, but when you set it back to 21℃, your system has to bring the whole house back up by 7 degrees. That could take a while (again depending on the outside temperature and the level of insulation in your walls and around your windows) and then by the time it finally gets back up to a comfortable temperature, you’ll just be dropping it back down for the night. So your machine had to work really hard to warm up all the air in your home and all the items in your home too (just think of how cold your tile floor would be if your home was set to 14!) So although you saved energy at the beginning of the day while your heating system didn’t have to heat very much, you lost all those savings when it had to run non stop to get your home back up to 21℃.

On the other hand, if your house is normally at 21℃ but when you go out you set it to 19℃, it saves a bit of energy by heating it to a slightly lower temperature, but then when you get home and put it back up to 21℃, it’s not hard for it to bring everything back up to that temperature.

So whether you are manually adjusting the temperature or you use a programmed thermostat, 2℃ is a pretty safe fluctuation. But like most things, there are different situations, different means of heating your home, different schedules etc that could affect this. For example, if you have a chalet up north that you only use from time to time, that would be a different situation. This 2 degree recommendation is for homes that are used regularly, so it’s always best to ask a trained technician what’s best for your particular situation.

I hope these guidelines can be of some use to you and that they kept you at least mildly interested in the subject. Feel free to leave comments below if you have anything to add!