This is a short collection of some
thoughts, questions, and comments on using sandbed thermal storage in homes.
These articles listed in this section... are the only ones I've been able to find -- if you know of others, please let me know.These homes use a concrete slab with a compacted sand bed under the slab for the storage of solar heat. The sand bed typically extends under all of the house and is typically about 2 ft thick. The sand bed and slab provide a large mass for storing heat. The sand bed outer edges and bottom are insulated to prevent heat loss to the outside. Heat is delivered to the house directly from the slab/sand bed into the living area.
The claims made for the system are that compared to a system that stores heat in a water tank, it can 1) collect heat more efficiently, 2) store more heat at a lower cost, 3) be cheaper to build, 4) and deliver a higher solar fraction with the same collector area that an system using water storage.
The system certainly has some simple and appealing features, but I can't help but wonder what its like to live right on top of the thermal storage and have your living space coupled directly to it. It seems like there is always going to be a compromise between wanting a fair amount of temperature swing in the storage (to store more heat), and a desire to keep the storage temperature within a fairly narrow range for occupant comfort. It also seems like the heat loss area outward and downward is large compared to water storage. It would be really nice to see actual data on real homes that use this system to address both the performance and comfort issues.
The limited feedback I have received from people living in sandbed storage homes has been uniformly good -- the owners I've heard from like them and feel that they are a good way to go.
It would be oh so nice to instrument one (or more) of these homes and get a better understanding of the performance. I''d be happy to loan data logging equipment to anyone who is in a position to do this.
This page describes a method that was tried by the MN Ag Extension to heat soil in high tunnel greenhouses. It seems to me that it might have some potential for being used as a way to heat sandbed storage for shops, or barns, or houses. The system could be implemented for a fraction of the cost of solar water heating collector methods, and I don't see an reason it would not work as well?
Any thoughts on this?
If you know of any other material on sand bed heat storage homes, please let me know.
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Gary May 21, 2008, March 3, 2012