Should You Turn off Your AC and Open Windows at Night?

Every year, rising summer energy bills prompt homeowners here in Bountiful, UT to try some age-old tricks to cut their cooling costs. They assume that cooler nighttime temperatures in the summer mean that they can save some energy by turning off the AC and opening their home’s windows overnight. It’s an idea that has tremendous staying power, with some homeowners swearing that it works while others disagree. Here’s a definitive answer to the question of whether you should turn off your AC and open windows at night to lower your energy bills. In addition, we’ll discuss a few money-saving tips that can help you lower your summertime cooling costs.

WHAT HAPPENS WHEN YOU OPEN YOUR WINDOWS AT NIGHT

On its face, the idea of opening windows and turning off your AC seems like it would obviously save you energy. By opening up your home’s windows, you can take advantage of lower nighttime temperatures and allow natural airflow to keep your home cool. And guess what? Doing so can help you stay comfortable in your home at night without using your air conditioning. Based on that, this is a tactic that seems like a no-brainer.

The problem is that doing this works against your home’s air conditioning efficiency. The reason for this is simple. Let’s assume that you, like many people, keep your thermostat set to about 67 degrees at night. At the peak of the summer here in Bountiful, that’s the exact average nighttime temperature. So, if you open your windows at night, it may not seem to have a noticeable impact on your comfort.

The trouble is that the outside temperature doesn’t stay at a comfortable 67 degrees all night. On most days, the outdoor temperature is likely closer to 80 when you settle in for the night. And, by the time you wake up, the temperature will be around 75 degrees. So, there’s only about an hour or two when you can actually take advantage of the cool outside temperatures you’re counting on.

As a result, your home’s indoor temperature will likely reach at least 75 degrees by the time you wake up and close the windows. And while you may not have noticed the extra few degrees of heat, it will have a meaningful impact on your energy bills, and not in the way you might think.

TEMPERATURE SHIFTS AND AC EFFICIENCY

The reality is that air conditioning systems do a far more efficient job of maintaining your home’s temperature than they do at altering it. So, although you saved some energy by turning off your AC overnight, the opposite happens in the morning. When you turn your AC back on, it will use up all of the energy you saved — and maybe more — to bring the indoor temperature back down to where you want it.

So, in the end, all you manage to do by opening your windows at night is to delay some energy use until the following morning. Plus, you will be asking your AC to try and correct your indoor temperature exactly at the moment the daytime heat starts to build.

High humidity can make the tradeoff even worse since humid air requires a great deal more energy to cool. By opening your windows and letting moist air inside, you’re guaranteeing that your AC has a harder time the following day. It’s estimated that on humid days, you’ll suffer a 3% energy increase for every degree lower you set your thermostat. So, on humid days, opening up your windows at night will drive up your overall cooling costs instead of lowering them.

And if you happen to rely on a time-of-use energy plan, the energy savings are even lower. It means you’ll turn off your AC overnight while energy rates are at their lowest. Then, you’ll ask your AC to re-cool your home during peak rate periods. This can have a catastrophic effect on your bottom line if you aren’t careful.

HOW CAN YOU SAVE MONEY ON COOLING COSTS?

The truth is that there are only a handful of ways to cut your home’s cooling costs meaningfully. One is by raising your thermostat a bit. According to the US Department of Energy, setting your thermostat at 78 degrees offers the greatest energy savings during the summer months. However, you don’t need to go to that extreme to save some cash. You’ll see meaningful savings for every degree you increase your thermostat. Your best bet is to change your home’s temperature one degree at a time until you discover a setting you can live with. If you’ve already gotten used to the warmer temperatures from leaving your windows open at night, you should already have some idea of where to start.

Plus, you could install a smart thermostat to give your home’s AC an inexpensive efficiency upgrade. On average, the addition of a smart thermostat will help you save around 8% on your annual energy costs. However, some higher-end models can save you more than that, with some users reporting savings upwards of 15%. A smart thermostat accomplishes this by learning your comfort patterns and automating your HVAC to serve them perfectly. It will also make more efficient use of your AC’s fan to offer additional cooling without engaging your AC’s compressor, saving you money. Best of all, a smart thermostat accomplishes all of that without forcing you to sacrifice any comfort.

Another tactic you can use to save energy is to install ceiling fans. They won’t change the actual air temperature in your home, but they will help you to feel cooler than you otherwise would. In fact, having a ceiling fan running allows you to raise your thermostat by up to 4 degrees without noticing any comfort difference. And since fans consume far less electricity than your AC, this translates into plenty of savings.

However, your best option to save money on cooling costs is to upgrade your home’s HVAC to a more efficient model. If your AC is approaching 20 years old, even a minimally-efficient new system could save you up to 30% on your cooling costs. Plus, it will keep you even more comfortable through improved airflow and more effective operation.

YOUR HVAC SAVINGS EXPERTS

With over 20 years of HVAC experience on our team, Blue Best Plumbing, Heating, Air, Generators is your HVAC savings expert in Bountiful. We offer complete HVAC services, including installation, repair, and maintenance. Plus, we offer the latest HVAC technology, including heat pumps and ductless mini-split systems. We’re also a Better Business Bureau accredited business with an A+ rating and the 2023 Best of State Award winner! We even offer financing on approved credit and a handy SEER calculator so you can see how much money you’d save with a new air conditioner. So, if you need help finding ways to save money on your Bountiful home’s cooling costs, or have any other HVAC questions or concerns, call the experts at Blue Best Plumbing, Heating, Air, Generators today!