I’ve been going to the meetings of the ASHRAE residential ventilation committee (SSPC 62.2, to be specific) for the past few years. As a matter of fact, I’m writing this article from my room in Houston, the site of the summer meeting. It’s always interesting to go to these things because the attendees are people who have a broad range of knowledge and experience in best practices for buildings, the latest research results, and some even have practical experience.
And then I look around the building we’re meeting in. It’s a rare meeting when there’s not some kind of problem with the ventilation or heating and cooling. In Orlando a couple of years ago, the room was small, crowded, and stuffy. I wish I’d had a carbon dioxide monitor because I’m sure it must have been at least two thousand parts per million. (Experts recommend that it stay below one thousand ppm. At least one study found that high levels of CO2 may affect cognitive function.)
And then there was Las Vegas last year. There aren’t many places — at least not in North America — where you can smoke indoors but Caesar’s Palace in Las Vegas is one them. They don’t let you smoke in the meeting rooms, but still, you can’t walk through the building without accidentally smoking a cigarette or two.
This summer, the conference is in Houston, just a few miles from where I was born. It’s the land of humidity, as you know all too well if you’ve been here in the summer (which usually lasts about six months). And that gets us to the photo at the top of this article.
Kimberly Llewellyn (with Mitsubishi Electric), standing next to the grille in that photo, called me over to check it out. I put my hand in front of it and felt warm air. But the air was more than just warm. It felt wet. It was sticky. Our guess is that the ventilation system for this hotel brings in unconditioned air straight from outdoors.
One potential problem with dumping unconditioned air right into a building are comfort. That area was noticeably different from the rest of the space. One person said the women’s restroom, which is right there near the grille, was about 20° F warmer than the other areas. It might also explain why the rooms were so cold. They had to turn down the thermostat in an attempt to control the humidity.
Another potential problem is that the outdoor air may not have done much ventilation. With the exhaust fans running in that restroom, much of the air may have gotten pulled right out.
And then of course, there’s the possibility that introducing a lot of humid air in one area could start an unintentional biology experiment through accidental dehumidification.
Meanwhile, back in the residential ventilation committee meeting, people discussed superposition, block schedules, and filtration efficiency. Oh, and hyperbolic cotangents. It was quite a meeting.
Photo by Nikki Krueger of Therma-Stor, used with permission.
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