|
|
|
|
|
|
by pchwalek
1570 days ago
|
|
|
I would disagree with new houses not considering ventilation. There are set building standards (ASHRAE 62.1, 62.2, and ISO standards) that have been around for a while that specify how ventilated spaces should be for given use cases. There’s a more recent trend to evolve these standards to take into consideration non-hazardous levels of particulate matter and gases that still show cognitive impairment—-I’m currently exploring this topic area for my PhD work. What we’re seeing, though, are tighter building envelopes so that the structure is thermally efficient. However, with a tighter envelope, active/natural ventilation systems becomes even more important than in older structures where there is some rate of natural air exchange with the exterior through building cracks and terrible (by todays standards) windows. There are companies coming up that are looking at “Personal Comfort Systems” and there is a fair amount of active research in this area (ex., https://cbe.berkeley.edu/research/personal-comfort-system/). It’s an interesting space since you have essentially two knobs to play with: (1) a persons actual heat exchange with the environment and (2) a persons perceived heat exchange. |
|
|
If you're lucky and live in an older house of the correct design from just before A/C, (most of the oldest two-story single family homes in Berkeley, FWIW) you might notice that some of the internal walls stay well below room temperature during the summer.
The buildings typically have pier and beam foundations, and the cooling walls have passive draft ways that pull cool air over the ground under the house and up against those walls. This is great in the summer, but not so much in the winter. I don't know how they use convection to pull cold air up, or how they prevent moldy foundation dirt air from permeating the house. I've heard there are some pretty clever designs, but (of course) they're hidden behind walls.
Anyway, our modern house is one story, and has an intentionally-uninsulated concrete slab on grade foundation, so we get a similar effect. (Passive solar heat keeps it toasty in the winter.)
We usually have our windows open, but we also over-insulated the walls (for noise and efficiency), and have a tight building envelope, so the heating/cooling bill is tiny.
(Edit: I bet they vented the walls into the attic and under the floor. That'd create a strong updraft in the summer (out the attic vents), but (if the attic is well insulated against the rest of the house) not in the winter.