Night Flushing keeps workspace cool

It's been really hot here this past week. I was fairly diligent in opening and closing the windows in the studio. And this few minutes of attention morning and night mad a huge difference in the comfort level in the space during the unbearable heat, reaching 98 degrees on Thursday. Yet the indoor temperature never exceeded 77 deg.


I've had some temperature sensors being monitored by a computer running in the shed behind the studio. I've not done much with the data, occasionally saving it to a spreadsheet and plotting it. This week two of the sensors provided an interesting view of how the building responds to these long hot days with full sun and a little management of heat gain and loss.

We live in an environment where the diurnal temperature swing is nearly always significant. Probably the Puget Sound offers that. We are just east of Lake Washington. Maybe that's a factor.

So with a day/night swing of over 30 deg, the opportunity to cool without using electricity (not to mention the capital cost of air conditioning) is available for the asking. It just takes a few minutes of opening windows at night, and closing them in the mornings.

The design of the studio contributes to this ability to use night temperatures to stay cool. There was very little wind this week, so the high and low windows take advantage of the chimney effect, moving the warmer air at the ceiling out the upper windows and pulling the cooler night air in through the low windows.

The roof is a scissor truss, with lots of cross ventilation and roof vents near the ridge, above a well insulated ceiling. This keeps the heat gain through the ceiling under control.

The porch roof provides some shading on the south side, reducing the heat gain through the south wall somewhat.

The clematis on the east side of the building reduces the gain on that side. The west side is unprotected from hot west sun. The cedar tree that shaded it was cut down for a slash and burn project next door. But at least the glazing is limited on the west.

Ideally, there would a way to get air in from low on the north side, but the shed is attached, so there are no openings there.

This building has a somewhat more elaborate heating system that makes for a comfortable winter work environment, but that's for a winter posting. I need to get some code between all these sensors and the circulation pump to complete that story.