Will I save energy if I sleep with the windows open?

Will I save energy if I sleep with the windows open?

Opinions differ when it comes to the question of whether I will save energy if I sleep with the windows open in the summer, or whether it is better to keep them closed at night and run the air conditioner.
It’s clear that the less the air conditioner runs, the more you save on energy costs. But in certain circumstances, the math doesn’t add up so easily. We’ve taken a closer look at the subject for you.

Sleep with open windows

When does it make sense to run the air conditioner overnight?

First of all, of course, it depends on the climatic circumstances. In places where it is hot and humid, the heat may not be noticeably reduced overnight. If that’s the case, you’re usually better off leaving the air conditioner running and maintaining a certain temperature. Of course, one has a great advantage if the house is reasonably insulated. This can save immense electricity costs.
In the case where it remains humid at night, it makes sense to keep the windows closed. On the one hand, so that it does not get too hot, but above all it should be avoided that the moisture gets into the house. Because this automatically makes it feel warmer and it makes the air conditioner have to work harder to keep the house cool.
The math is simple: you can save 20-30% on energy costs by turning off the air conditioner overnight. But in humid, very hot areas, it’s harder for the air conditioner to cool the house back down during the day, resulting in an additional 20% consumption throughout the day, according to studies.

When does it make sense to turn off the air conditioner during nighttime?

When the nights are milder, or when temperatures drop below 70 degrees at night, sleeping with the windows open can have a positive impact on your energy bills. But it always comes back to the key word “insulation.” For example, if the attic isn’t well insulated and ventilated, it can create immensely high temperatures there that can’t drop noticeably even overnight, and that heat in turn can affect the rest of the house, possibly causing temperatures in the house to rise significantly again when the air conditioner is turned off.
But this is also a problem that can be solved. For example, by sensibly installing ventilation in the attic. And, of course, through insulation.

When does it make sense to sleep with the windows open?

So, to sum up, depending on the outside temperature, sleeping with the windows open and the air conditioner off can mean significant savings in energy costs. But the conditions of outdoor temperature and the nature of the house should not be ignored. If temperatures don’t consistently stay in the 80s, turning off the air conditioner and opening the windows overnight is usually the more cost-effective way to sleep comfortably.
You can also program your thermostat to turn off the air conditioner around midnight, when it’s cooler outside, and turn it back on early in the morning.

Alternatively, you can use a fan at night (make sure you use a newer, more energy-efficient model, or the energy savings will be less). If you don’t have a ceiling fan, but one that you can position flexibly, it makes sense to place it in such a way that it distributes the cool air from outside into the room.