Out of sight out of mind

Ya know how if you have junk food in the house… you eat it? So best to not buy it in the first place? Well, we’re going to try the same thing with our house in two aspects — no exterior venting of our (electric) stove. And no clothes dryer (we’ll see how that works out! We’ll probably have our old one, just not plugged in, and we’ll sell it if all works out…). Health first obviously. Saving energy is a distant second…. so first and foremost this has to make sense from a health stand point. No internal combustion in the kitchen (electric range), so no need to vent out carbon monoxide (CO) from combustion. And clothes drying… no health issues there, except that we obviously need to keep humidity levels in check.

Well so the problem with both of these types of holes/vents in a house in the first place is that there would need to be an equal amount of make-up air coming IN to the house from another source, and since our house is quite tight, that might be kinda tough to get it via leakage as in most houses. (Our house tested at just above Passivhaus tightness levels, and this was the first blower door test before drywall… so we will be even a little tighter probably.) And the basic point that you are venting out conditioned air, and bringing in cold (or hot in summer) air in exchange. So that’s a waste.

On the other hand… it’s also a bit of a waste to be cooking with electricity (vs propane or natural gas) as it takes 3 times the amount of fossil fuels at the power plant. But I believe I’ve done the calculations, and given the fairly low efficiency of gas ranges, the numbers don’t work out to be quite so bad. And some money savings, since no need for “dual fuel” to get an electric oven out of the deal.

Anyway, back to clothes drying. Our clothes already come out of our washer almost dry actually (front loader) so hanging them on a drying rack, even right in the house, should dry them out rather quickly. If need be, a space dehumidifier can help with moisture levels. Or we will stop being lazy and hang clothes outside. Imagine that! See this building science article on latent vs sensible loads. Basically the issue of “how do you dehumidify when you don’t need cooling?” BSI-028: Energy Flow Across Enclosures especially “Photograph 6: Hotel Room Fix—The through-wall unit controls the temperature (the “sensible” system). The dehumidifier controls the humidity (the “latent” system).”

Others will say that this (0.6 ACH) is excessive tightness, and something more like (2.0 ACH) is still plenty tight but would alleviate issues with make-up air. And maybe at that level an “exhaust only” ventilation system would work with no need for a HRV or ERV. Maybe. I think there are smart people on both sides of this issue. Let’s check back in 10 years and see what people think? My current thinking is KISS — keep it simple stupid — so if there is a way to do this with less complicated and more local methods (less complicated HVAC equipment, cellulose-only insulation instead of spray foam) etc, then that’s a more sustainable gameplan ultimately. Better for the environment and the local economy. Another way to put it is I’d rather spend money on people doing work than on expensive equipment. That said, I also prefer negawatts to megawatts. So let’s aim for both of these… local and negawatts!

Good night.

[Update: I should have explained one thing better… There IS a range hood with some fancy grease filters, but it does recirculate. And there IS also an exhaust duct for the HRV in the kitchen. And an operable window right behind the range. We are basically following the approach used in Passivhaus construction to use a recirculating hood and a HRV exhaust duct nearby but not directly connected. We’ll see how it goes. We can always add an outside vented range hood but thought it would be good to at least try this since it apparently works fine for 1000s of passivhauses in Europe.]


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