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Back in September we started a series here debating vented vs. sealed crawl space vents. You can catch up on that here.
We also talked about how dirt crawl spaces are super energy wasters.
Let’s get back to the debate, talking about venting a crawl space on a cool or winter day since that is what we are experiencing now.
If the RH of air goes up when we cool it, it goes down when we heat it. So if we vent our crawl spaces in the winter and bring in 35-degree air with 60% RH, and we warm that air in our 62-degree crawl space, the RH goes to 3%. With this dry air we can begin to dry our crawl space. Of course, the dry cold air mixes with the crawl space air and cools the crawl space, and we have water evaporating from the earth into the crawl space air, so we never achieve 3% RH in our crawl space- but materials dry out and there is no condensation.
Hey, we’re drying our crawl space with vents now! This is great, right? Well, if you like high energy bills, cold floors, and cold drafts, then this is for you!
When we hit spring time, we will circle back and debate what venting crawl spaces does on a spring day.
Parts of this post are excerpted from Crawl Space Science.