.I'm not familiar with it. Since most heat is lost through the ceiling, as heat rises, that is where we started. I'm skeptical about retrofitting foundations as being effective for much of anything. If you technical information about it, I'd be interested in seeing it. Thank you.
I had a white paper somewhere that I will try to find, but here is a quick link: Frost-Protected Shallow Foundations - Fine Homebuilding While convection heat losses are significant, conductive losses through the slab can be quite substantial once your roof is properly insulated and your walls are tight.
If your home started as a barn and the slab is not insulated then it can make a big difference. Beyond the absolute heat loss, the perception of cold reduces significatly if you have any tile or concrete floors in the home. If you have an non-contact IR thermometer, see what your floor temperature is relative to the space temperature— that should give you an idea if it is worthwhile. More than about 5 degrees below your indoor temperature and you should see some improvements.
If you have already put a floating floor above the slab on grade with insulation then the benefits would be minor.