My home has acid stained concrete floors through out. Its a very effective heat sink. So, between the 66,000 lbs of concrete and the ~8000 lbs of drywall, I don't think the mass of my 4'x8'x1' masonry hearth, the 8'x12' stone mantle wall, or the 440 lbs of soapstone (1800 lbs total?) even make a drop in the bucket. A quick run of the #'s show 1.3 million btu's stored in the slab. I used to live in a wood floored crawl space house, heated up-cooled down much faster. I much prefer the heat sink effect. Opinions?