In equal thickness PVCx by a long shot almost 3 times better R value. The issue is most do not use komacel in 3/4, but melamine often is. 3/4 melamine is about R 2. Expanded pvc sheet (PVCx) at 1/4 is R 1.2. If you were planning on using 3/8 as many do it would be very close with melamine slightly better. I personally don't think there is enough of a difference in insulate value to make up for the monumental advantages PVCx has over melamine. (general health / air quality, Fire resistance, weight, moisture resistance, and strength to weight) PVCx is better in every way, melamine is cheap. If you are going to all the time and effort building a rack why use low quality materials?
FYI UTH do not add huge amounts to the heat of air. The balance of heating ambient air with just UTH is difficult at best. Luckily you only need a few degrees... I would suggest that more than 6º for the air is difficult with out major modifications.
Reply With Quote