Light-weight thermal mass option for passive solar?
Hi, I am trying to design a single 40′ long high cube storage container to be converted into a living space. It will be completely off-grid, insulated very well with closed cell insulation. I want to take advantage of as much passive solar heating as I can. The container will have great un-obstructed southern exposure. I want to keep construction weight down as much as I can.
I am wondering if I could have a recess in the floor. Would be roughly 4″ deep, maybe 2 1/2′ wide, and long enough to cover the kitchen, dining and living space (maybe 10′-15′, or wherever I have window space to heat it). The recess would be then filled with 3″-4″ rocks, and covered with a piece of glass.
Would be an effective thermal mass to collect energy? I dont know if the glass over the rocks would be detrimental to the energy transfer, or if the rocks are even a good mass? My idea is that I could take the rocks out to keep weight down, for ease of future transportation. Also could be very appealing to look at.
Other things to consider:
-could also fill in gaps between rocks with water?
-if container is on piers what r value would you suggest for floor insulation? (closed cell spray foam)
-walls will have around an R-35 (closed cell foam), ceiling will have around R-60 (closed cell foam)
-windows will be a quality triple pane window with high SHGC
Please let me know your thoughts, any help would be appreciated
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