I'm adding a sunroom to my 1950 era home and want to use energy efficient windows--LOTS of 'em. When I built my last home, in Florida, using double paned windows , gradual, insidious fogging ruined 2 windows, which had to be replaced after 3or4 years. I don't want this problem in a kitchen-sunroom comprising floor to ceiling windows! Contractors seem to assume that double paned is the way to go. Anyone know of a type or brand of high efficiency windows that are NOT double paned or perhaps with a warranty that actually covers replacement costs?

Carol (location: outside Philadelphia)