RE: Relative thermal properties (November 14, 2008, 06:42:51 PM)

I have a CD with the BFRC prgram on it, but I simply can't be bothered to gather the obscure data needed to fill all the boxes. These estimation programs were supposed to replace the hot box method, which really needs months of painstaking work to build tables from different samples. I suspect your technique would require a grid to sample many points from which your calculation would produce an average. The relative proportion of frame/glass is a hellish complication, which is why I use the BRE calculator. I might suspect its accuracy (I think it's pessimistic) but it does deal with the frame issues.I have found several sites offering hand-held laser/IR gauges for under £30 with claimed accuracy of 2%. Should be good enough for my purposes. I think I will build a box around a redundant doorway in my workshop and use it this winter to run my own experiments. Steady-state temperature measurements with a small lightbulb in the box should produce useful data over a few months. I am only interested in the fundamental (probably gross) difference between a Low E sealed unit and a solid or insulated wood panel using the same glazing method. Should be interesting.

Part of correspondence with Philip Rougier of Fenestration Associates: Follow the whole thing in The windowman forum http://www.double-glazing-web.info/