Five ways to lower the temp and the A/C bill
I always liked the idea of keeping fresh air flowing through the house, but I’ve found it easier said than done. On a humid summer afternoon, opening a window doesn’t make the room fresh — it just makes it hot! But for anyone who’s stepped into a stuffy old room, it’s clear that never opening windows makes the air stale and unpleasant. While air conditioning does keep the temperature down, it might not always keep fresh air circulating in and out of the house. Plus, constantly turning on the A/C weighs down the electric bill. Here’s what I’ve learned about strategically opening windows to keep the home cool and aired.
Why air out the home?
There’s something about the sound of a breeze and the scent of fresh air that makes us feel relaxed and refreshed. So it’s only natural that bringing a dose of that air inside helps create a homey environment. Of course, we’re not going for a completely natural state that would make sitting in the living room feel like camping. Think of airing as “filtering” the outdoor air in and through the home to strike a balance between fresh and cozy. In the summer, window airing also helps cut costs by lowering air conditioning use, so it’s a habit that can help everyone at home breathe more easily (pun intended!).
1. Step outside.
The best times to let air circulate through the house is when it’s cool and dry outside. In most areas, that’s not all the time! So it’s helpful to check the weather before ventilating. Whether it’s taking a walk, stepping onto the back patio, or even just checking the weather app, knowing what the outdoor atmosphere is like will help determine when is a good time to open (and close) the windows.
Generally speaking, the morning and evening are the best times to ventilate with windows. Cheryl Mendelson’s Home Comforts offers a good summary of this point: “Proper ventilation can also help cool your home, but only when the air is cooler outside than inside. The Department of Energy recommends that you ventilate in the cool of the morning and evening, and shut windows and employ shade devices in the heat of the afternoon.”
If you need numbers to guide you, indoor temperatures are best kept between 65 and 74 degrees Fahrenheit, with humidity levels between 40 and 50 percent.* To help you measure and regulate these factors, consider buying a hygrometer (which tells you the temperature and humidity levels in a room) and a dehumidifier or humidifier as needed.
2. Create the “chimney effect.”
When it comes to cooling a home, wind is a great ally. With windows open, wind can help blow air through the home, keeping the internal atmosphere both cool and fresh.
How should I set the thermostat?
*In 2019, a Department of Energy report surfaced recommending a 78°F thermostat setting during the summer. That high temp sparked controversy. Following the recommendation could help save energy, but it might not be the right plan for your home. It is possible to cool a home with little or no air conditioning, but when you’re melting in the living room, don’t be afraid to crank up the A/C.
To make this happen, open windows strategically so that wind can pass through easily. First, take note of the direction of the wind (with a glance at the weather vane, flag pole, or trees in the yard). Next, go downstairs and open windows on the side of the house where the wind is coming from. (That is, if the wind is blowing from east to west, open windows on the east side of the house). Then go upstairs, keeping doors open as you go, and open windows on the opposite side of the house (the higher up these windows, the better).
This window setup creates a “chimney” or “stack” effect because the wind comes in through the lower windows, travels up through the house with the heat, and escapes through the upper windows. You can read more about the chimney effect in this Department of Energy article.
3. Work the fans.
Fresh air is moving air. On a windless day, the chimney effect can still work if you help the air along with fans. Ceiling fans are excellent because they keep air moving throughout an entire room without taking up floor space. Window fans are great too because they pull air from outside and propel into the house — or, if turned around, they suck the warm air out of a room and expel it outside.
To keep hot air moving out of the home, use fans especially in rooms that generate heat, such as the kitchen, bathrooms, and laundry room. Exhaust fans in these locations are ideal not just for coolness but also safety, since moisture and chemical fumes can collect and make the air harmful to breathe.
4. Create shade.
In my living room, there is a big, beautiful bay window that offers an expansive view of the front yard and street. They let in lots of natural light (which I love), but that also brings a lot of natural heat, which in the spring and summer is not so pleasant. To keep that heat at bay, I have sheer pull-down shades along the bay window and blinds on several other windows throughout the house.
These kinds of shades are nice because they absorb a lot of heat without removing the light completely. Leave the shades up in the cool of the morning and evening, and lower them as the temperature and sunlight rises throughout the day. Try using table or standing lamps instead of overhead lights, which generate a lot of heat. (I find lamplight gentler and more inviting than bright ceiling lights anyway.)
If you want to get really committed to natural cooling, planting shade trees near the house can work really well. Mendelson recommends choosing deciduous trees such as oak, maple, and sycamore.
Homemaker Hack: Blinds
I have a love-hate relationship with Venetian blinds. They are very good at directing and blocking sunlight in varying degrees, but they also aren’t pretty. I’ve struck a truce with them by letting them stay on the windows and hanging curtains over them. The curtains add color and decoration as well as the ability to block out more light when needed.
These large, beautiful trees acts like huge umbrellas, and according to Home Comforts, they can bring internal temperatures down as much as 9°. As a bonus, when they shed their leaves in the fall, sunlight can penetrate your home more easily and help heat it naturally as well!
5. Move heat sources outside.
Whether natural ventilation or air conditioning is cooling our homes at a given time, generating heat inside works against those systems and makes them less productive. For example, using a hot oven on a hot day forces the A/C to work extra hard, uses up a lot of energy, and causes the energy bill to surge. In the warmer months, I like to think about the rooms that tend to generate the most heat and consider whether I can find an alternate approach. Here are a few ideas:
- Use the outdoor grill for cooking (this is also a healthy option, since it tends to require less grease than stove cooking).
- Use an Instant Pot (I’m a HUGE fan) rather than the oven.
- Make cool side or main dishes, such as salad or fresh produce.
- Sit under an umbrella and eat outdoors (so that you can give the A/C a break and enjoy the fresh air).
- On a nice day, air dry some or all of the laundry to reduce dryer use.
- Take short or cool showers.
Putting it all together
With all this information in mind, I’ve come up with a general pattern of window use during the summer at home. It goes something like this:
- Early morning: Wake up and go for a walk. If the weather is cool and dry, open the windows with a chimney effect when back home. Turn on fans.
- Late morning: Take note of the temperature. If necessary, close windows and shades.
- Afternoon: Turn on air conditioning (and turn off when leaving the house).
- Evening: Check the forecast for the night. If moderately cool and dry, turn off the air conditioning and recreate the chimney effect. Go to sleep.
The pattern changes depending on the weather patterns in a given week or month, but I find it helpful to have a default framework.
To execute whatever plan you create, a programmable thermostat is super handy because it will automatically adjust the temperature according to your daily schedule (although you will have to remember to shut the windows when necessary!).
At the end of the day, the most important goal of airing out the house is making everyone inside feel comfortable and loved. Whatever strategy gets that job done (especially if it’s cost efficient) is a winner!
What if I have allergies?
For those of us with pollen sensitivities, the spring and summer might not be a good time to let fresh air in. Mayo Clinic recommends keeping windows closed during pollen season. Otherwise (and depending on your sensitivity level), try installing fine mesh screens in the windows and removing plants in and around the house. Also make sure that the house has a good air filtration system with HEPA filters, and switch them out regularly.
More Resources
“Spring and summer energy saving tips,” The U.S. Department of Energy (Energy Saver)
“The Air of Your Castle,” Cheryl Mendelson (Home Comforts)
“Tips to keep your house cool on a budget,” Home Climates
