I had been using BEopt, putting together a 3600 sf residence, slab-on-grade, and the results were consistently at least plausible. BEopt also is spot on modeling our existing residence, confirming our unfortunate experience in it. Then I switched to OpenStudio, beginning with Sketchup in order to obtain heat loads also for each area of the house. It hasn't been easy, but the results make sense and are generally consistent with all previous BEopt results. The results are also consistent with results from a famous hydronic person's load calculation software. So far, so good. Recently I brought in the BCM measure, AedgOfficeHvacRadiantDoas. It's not residential construction, but it seems to work. With considerable effort the work has been continuing. I'm especially interested in how radiant results differ from furnace and boiler results, both in BEopt and OpenStudio. Trying to make sure that results for radiant heat at least make some sense, I modeled two inches of XPS on top of the internal source construction slab, expecting that the results would be as ridiculous as the idea itself. Unfortunately the result was all but the same as results from the bare slab with the source half way into the 4" concrete. Obviously something is amiss here, but I'm not seeing it. Any ideas?