Optimum R-Value for Slab Insulation
jordan_harder
| Posted in Green Building Techniques on
How much slab insulation, would like some cooling effect..
I am designing a house for my family in Spokane WA. Cold dry climate 5b, but it is quite hot in summers. We are putting the bedrooms on the ground floor and the living above. We like bedrooms cooler, like around 60 degrees. Wondering if there is a way to determine optimum R value of slab insulation. Not a huge delta T between ground temp and desired room temp, and some cooling effect would be welcome in the summer, but I don’t want to be a major thermal drain on the whole house in the heating season.
Thanks!
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Replies
Any level of sub-slab insulation is going to pretty much negate the earth from becoming a heat sink in your climate zone, so you'll only have the "thermal mass" of the concrete itself to help even out daily temperature swings. I would insulate to at least code-minimum levels, make the enclosure airtight and use efficient cooling equipment for predictable results.
If you really want to use the earth as a heat sink, don't insulate below the slab at all, just be aware that on an annual basis you will use more energy than if you had insulated below the slab.
Ok, Thanks Michael!