Radiant slab floor over basement – insulation question
Hi all. This is a new construction build. I have a radiant system installed in a 4″ thick concrete floor suspended over a non-walkout ICF basement. The basement is not living space and I prefer to keep it on the cool side (root cellar/fermentation).
I’ve read plenty on insulating the ceiling of the basement to prevent overheating in the winter and that makes perfect sense to me, but at the same time, I feel like I am going to lose out on the ability to cool the house above in the summertime.
My thoughts are to insulate at the bottom of the 22″ metal trusses – thus leaving 22″ of space below the floor that will be heated by the radiant floor above in the winter, but then build some type of contraption that allows me to circulate the cool basement air into this 22″ space during the warm summer months. Am I crazy or does this seem reasonable?
Additional info:
720 sq ft basement – 1 large room
6″ ICF basement wall – 10’8″ tall (22″ of this is occupied by the trusses)
No doors/windows in basement
located in South Carolina
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Replies
Just out of curiosity, did you install insulation under the basement radiant heat slab?
>"I’ve read plenty on insulating the ceiling of the basement to prevent overheating in the winter and that makes perfect sense to me, but at the same time, I feel like I am going to lose out on the ability to cool the house above in the summertime."
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>"Am I crazy or does this seem reasonable?"
I'm coming down on the side of "crazy"- it's an unfounded fear. The amount of "free" sensible cooling you get from the ground with 720 square feet of uninsulated slab as the earth-coupling heat exchanger is de minimis, especially in SC where the subsoil temps are in the mid-60s F:
https://www.builditsolar.com/Projects/Cooling/US-ground-temps.gif
With a 65F basement slab and 75F at the floor of the first floor slab (high 78-80F air conditioned first floor) you're getting only about 1/4-ton of sensible cooling from 720 square feet of basement floor slab, best-case. If the space upstairs is kept cooler it's even less.
将辐射的地板绝缘放在板坯的底部，并尽可能使地下室变得气密。
史蒂夫，
There is no radiant system in the basement slab. It's on the main floor. The deck pan is corrugated, so there is no insulation under the concrete.
达娜，
This is the kind of answer that I'm looking for, but can you tell me where you are getting your numbers from? The soil temp under the basement floor (12' below grade) has got to be a lot cooler than 65F - even in the summer. Also, I'd love to understand how you are able to determine that it would be equal to about 1/4 ton of AC.
谢谢，
Russ