Landscape view westward on the north bank of the Columbia River at sunset. The 205 bridge is on the horizon. On the shore to the right a woman looks out onto the water, where a few hundred feet distant a group of people are swimming

Heat Dome

Published 2021-06-28

No one asked but here’s my system for keeping a house cool in hot weather with minimal A/C. It is a heavy adaptation of the system my mother used when I was growing up in Nebraska (“Where Wyoming Meets Iowa”). As a kid in western Nebraska (“Wyoming hot”) we had no A/C at all and then we moved to Lincoln (“Iowa hot”) where we still often ran the A/C only during the day. Jenny and the kids call this The System and they make fun of me for it. But it works

The gist of The System is treating cool air like a school of farmed fish. When the outside air is cooler than the inside air, you encourage it inside. When it gets warmer outside than inside, you seal up the house to keep it from escaping.

I also tried to add some shade around the house — a difficult task as we have a lot of southern and western exposure, directly onto concrete. This year I put up some triangular sun shades over those parts of the yard, to some success. I don’t take the shade thinking as far as my mother does, with mylar curtains, but we do have blackout cell shades on most of our windows, which helps a lot. Also new insulation and fancy new windows that reflect more infrared light when the sun is high (i.e. in the summer).

Importantly: We also have A/C in half the house — the part we sleep in.

The System works really well when we don’t have a Heat Dome sitting over us. The Pacific Northwest has surprisingly dry summers so even when it hits 100° (usually a rare event) it still cools to the 60s or even 50s at night. So in non-heat-dome hot weather the usual routine is:

  1. early evening: open the windows in the non-A/C part of the house
  2. set up fans directing air in
  3. set an alarm for the time of night when the outside temp is likely to drop below wherever we set the A/C (usually around midnight to 2am)
  4. retreat to the A/C for bedtime
  5. when the alarm goes off: open all the windows and direct air in and upward
  6. In the morning: gradually close the windows facing toward the sun, by 9am or so the house is closed up

When the Heat Dome first capped Portland on Wednesday or Thursday, this system still mostly worked! I could keep the non-A/C part of the house to within a degree or two of the A/C part. But the nighttime temps failed to drop below any reasonable A/C temperature. So The System looked more like:

  1. set an alarm for the time of night when the outside temp is likely to drop below the inside temp
  2. when the alarm goes off: open all the windows in the non-A/C part of the house & direct air in
  3. set another alarm for very early when the outside temp exceeds the inside temp
  4. when that alarm goes off: close all the windows & shut the house up for the day

As the Heat Dome thing wears on (projected high today: 114°F), at the very coolest hours (around 5 or 6 am) the temperatures are still in the 80s. Instead of having windows open all night bringing the interior down to the 60s or 70s, I open them for an hour or two and bring it down one or two degrees. Right now the non-A/C part of the house is 85°F

Other than The System our strategies are familiar:

  • Wednesday we went to a beach on the Columbia. The System as usual.
  • Thursday was mostly just The System, plus we spent a little time in the Willamette. The girls went to Oaks Park. It was hot, but just kind of Regular Portland Hot. Had to modify the System a little, as above, but kept the house to about 77°F
  • I don’t remember Friday. I worked all day, in my office (on the southwest corner of the house.) Probably not any warmer than 78°F in the house
  • Saturday was all rivers, all day. We spent the morning in the Willamette and the evening at the Columbia. The spot we have there (on the Washington side, behind some private property), has several springs and seeps at the shoreline. The water was so cold my teeth were chattering!. Fully modified system, house about 80°F at the coolest
  • Sunday we managed to get an hour at the neighborhood pool. This is tricky because of COVID + staff shortages. I had to buy the whole family tickets on Friday to swim for one hour on Sunday. It was nice to finally get back into the pool after two years away! During the night with some effort I cooled the house to 83°F. The A/C is struggling — it was about 79°F in that part of the house, regardless of where we set the thermostat.
  • Today I’m working again, this time from our bedroom in the A/C. It’s about 79 or 80 in that part of the house, with the compressor running full-tilt. The non-A/C part of the house is about 85 or 86°.

The forecast today says we’ll finally have some sea breezes blowing in around sunset. I’ll believe it when I see it.