Has anyone ever vented a lifted foundation’s air cavity into a house or attic to create an earth tube or solar chimney?
I have a house in San Antonio Texas that is going to be lifted onto piers because of expansive soil. The house will have two tunnels entrances that connect to each other in addition to the 4 to 6 inches of regular air space between the soil and the slab created by the lift. My house has a vented attic and the house has a heat pump conditioning system.
Would it be a good idea to have the cavity space created by the house being lifted onto piers act as source of cool air that can use natural heat convection to cool my attic or possibly cool my house? The only issue I can see is slightly higher humidity from the soil being a problem. This is why I am mainly thinking of only having the air vent into the attic since it is also uses heat convection to cool the attic space.
I would plan on using one or several 4-8 inch pipes to get the air into the attic and have 1 or 2 inlet pipes to let air under the foundation where they foundation company made the tunnel entrances.
I figure this would be a cheap and efficient way to keep a vented attic cool in the hot Texas summers.
Thanks!
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Replies
Scott,
By lifting the house, you are basically creating a crawl space foundation. There are several ways to detail your new crawl space. For more information on the topic, see this article: "Crawl Spaces vs. Skirts."
Your plan doesn't sound anything like the installation of an earth tube. (For more on earth tubes, see "All About Earth Tubes.")
In general, the quality of crawl space air isn't very high, so I don't recommend your plan. In terms of cooling potential, you should know that the volume of air in a crawl space is tiny compared to the volume of air needed for cooling a house -- the physics contradict the idea that useful cooling is possible simply by introducing crawl space air into a hot house.
In a place as humid in summer as San Antonio the latent cooling load of using earth-cooled outdoor air for sensible cooling is pretty high- in most cases not worth the effort. See:
https://weatherspark.com/m/7137/7/Average-Weather-in-July-in-San-Antonio-Texas-United-States#Sections-Humidity