Air conditioning is often a major expense but also necessary to ensure your home stays comfortable in the summer. Some people try to save on air conditioning costs by opening windows at night or early morning. While open windows can help keep you cool in certain situations, you should never have any windows open while your air conditioning is still running. There are also many situations where you’re better off keeping your AC on at night instead of opening your windows. Let’s dive deeper and decide if opening your windows when running your air conditioner is okay.
What Happens if You Run the AC With Windows Open?
Some people think it’s okay to open the windows in one or more rooms while their AC is running as long as the doors to those rooms are shut. The truth is that running your air conditioning while any windows in your home are open is always a bad idea. For starters, much of the conditioned air that your AC system blows out of the vents will escape through the open windows. This is especially the case in rooms with a supply vent near a window, which is quite common.
Another issue is that open windows allow lots of humid air inside your house. Air conditioning works by actively removing heat from inside the home. That means you’re defeating the purpose of turning your air conditioning on if you have open windows, allowing heat back inside. The blower in a central AC system also essentially creates a draft that will enable it to pull air in through the return vents and ductwork. That means instead of the hot outdoor air flowing inside, the blower can actively pull hot air into your house. This effect is lessened if the door to the room with the open windows is closed. The issue is that closed doors make an AC system less effective since they interfere with air circulation in the home.
If you even have a few windows open during the hotter parts of the day, you’ll make your home hotter and cause the temperature to rise much faster than it usually would. Which means your air conditioning will have to cycle on more frequently. The system will also use more electricity since it will take longer to cool your house fully every time it comes on. If you have the windows open any time when it’s much hotter outside than your desired indoor temperature, your AC likely won’t ever be able to keep up. Put differently, it will likely run continuously until the outdoor temperature cools off much later in the evening.
Is It Better To Sleep With Windows Open or Leave the AC On?
It is sometimes acceptable to open the windows in the evening once the temperature outside is close or lower than what your thermostat is set to. However, you still want to shut off your AC when you open the windows so that it doesn’t just waste energy.
The issue with opening the windows in your home in Missouri is that our summers are often extremely humid, and open windows will allow lots of moisture inside. This means you may still feel hot and uncomfortable since humid air affects how your body senses temperature and how hot you feel.
The heat index measures how hot air feels based on the relative humidity. Let’s say your AC is running, and your home is 75 degrees and not all that humid, but you then open your windows and shut the AC off. Even if the air temperature outside is also 75 degrees, the moisture in the air coming into your house through the windows can eventually make your house humid enough to start feeling nearly 10 degrees hotter.
The other issue with opening your windows when it’s humid out is that moisture soaks into carpets, walls, and furniture. That results in your air conditioning running longer once you switch it back the following day since it will need to remove moisture from the air before it can effectively start cooling. In many cases, this will increase the energy an AC system uses compared to if you just left it on at night and had all the windows shut. This is why, in a humid climate, experts say you should always leave the AC running, and the windows closed at night other than on nights when it’s much less humid outside.
If you’re having trouble keeping your home cool, RW Heating, Air, Plumbing & Electrical is here to help. We’ve been providing quality air conditioning and heating, as well as plumbing and electrical services, in the Hernando area since 1999, and our team is ready to handle your HVAC installation, maintenance, and repair needs expertly. Contact us today to set up a consultation or schedule a service call.
