Anyone managed to work out a comparison between carpet + underlay and hardwood flooring + underlay? I have some numbers but no idea if they are correct. Thermal conductivity (k) of good typical carpet + underlay = .05 (W/mK). Hardwood typically 0.17. Fibre or foam underlay 0.05. Translating to R values (thickness in m / k) gives R value of say 0.3 for 15mm carpet+ underlay, 0.1 for 18mm hardwood, 0.12 for 6mm hardwood underlay. So carpet + underlay at 0.3 is slightly better than hardwood + underlay at 0.22. I have avoided using American figures available on the web as these are imperial and confused the hell out of me until I realised. This might be a bit technical but I think it's important and there doesn't seem to be a real answer on the web, just carpet companies saying that carpets are much better and wood flooring companies telling the same story! We all know wood flooring feels much colder underfoot but with a good underlay it could be just as efficient? 
