At 4 p.m. on a scorching afternoon this week, the thermometer on our bookshelf read 81 degrees and the bedroom AC was humming like it had opinions. I was working at the little desk by the window, Olive was flattened on the bathroom tile, and I was doing the math I do every August: how cold can we keep this place before the electric bill starts to sting?
Our apartment is all-electric, a third-floor walk-up in a brick building that soaks up heat all day and gives it back all night. We have two window units, one in the bedroom and one in the living room, and no central air. Our summer bill averages around $85, but last August it hit $112, our highest summer month so far. This year I wanted to stay out of triple digits, so here's what we've been doing.
Cool the room you're in, not the whole apartment
The single biggest change was simply not running both units at once. During the day I work from the living room, so that unit runs and the bedroom door stays shut with its AC off. Around 9 p.m. we switch: bedroom unit on, living room off. Two units fighting the heat in 640 square feet sounds reasonable until you see the bill.
We also stopped setting the units to their coldest setting and walking away. Most window units don't cool faster on the lowest number; they just run longer. Ours sit at 74 during the day and 72 for sleeping, and we use the fan setting on low when it's merely warm instead of miserable.
Small fixes that made the units work less
- Cleaning the filters every two weeks. The filters slide out the front. I rinse them in the bathtub, let them dry on a towel, and put them back. It takes five minutes and the air coming out is noticeably colder afterward.
- Sealing the gaps. The accordion side panels never fit our old windows well. A strip of foam weatherstripping along the top sash and a rolled towel at one corner closed the gaps without any screws in the window frame, so nothing to explain to the landlord at move-out.
- Blackout curtains on the west side. Our tiny balcony faces west, and the afternoon sun through that door used to turn the living room into an oven by 3 p.m. Thermal curtains on a tension rod cut that noticeably.
- A box fan in the hallway. It pushes cool air from the living room toward the kitchen, which otherwise stays several degrees warmer.
Cooking and chores around the heat
Our galley kitchen has no window and no real ventilation, so turning on the oven in July means heating the apartment and then paying the AC to cool it back down. In the hottest weeks we lean on no-cook dinners, the toaster oven, and a lot of things that happen in one pot on the stove after the sun goes down.
Laundry already happens in the basement, which helps; the dryer heat stays down there. But the dishwasher, the hair dryer and the oven all wait until evening when we can. I don't think any one of these is huge on its own. Together they're the difference between the AC cycling off now and then and running flat out all afternoon.
What didn't help much
I bought a cheap smart plug last summer, thinking I'd schedule the bedroom unit to come on an hour before bed. It works, but our unit restarts in its default mode every time power cuts off, which means the schedule turns on the fan, not the cooling. I gave up and just walk over and press the button.
I also tried running the living room unit all day at 78 to "save money," and the apartment never really cooled down; by evening the walls were warm and the unit had to work twice as hard. A moderate setting while we're home and fully off while we're out worked better for us.
Keeping an eye on the bill
We split utilities the same way we split rent, by income, so a high bill isn't a disaster for either of us. Still, I check the usage graph on our provider's website about once a week in summer. If a week jumps, it's almost always a heat wave plus one of us forgetting to switch units off at night.
So far this summer we've stayed under $100 each month, and Olive has stayed on the tile, which is how I know the system is mostly working.
