Apparently, Florian lists a lot more glass factors now than when you got your glass, Ursula. I don't see any number than relates to your HRR of 4.7, but these are the numbers that fit the two glass types I am using. Many these numbers are basically percentages compared to what a standard, 1/8" pane of clear glass would transmit.
Roof glass (double the cost of the wall glass) Side (wall) glass
Shading coefficient - 27% (allows 27% of the solar gain compared to single pane glass) 40%
Relative heat gain - 32 (BTU per hour) 81
Visible light transmission - 47% (I assume this is like having a 50% shade cloth?) 69% (30% shade cloth equivalent?)
UV light transmission - 10% 14%
Inside glass temperature in winter - 57F (when the outside temp. is 0F and inside temp. is 70F) 57F
Inside dew point - -8F (the outside temp. that will cause condensation when inside temp. is 70F) -8F (based on the inside relative humidity being 60%)
Winter U-value - .25 (heat transfer through the glass due to differences in outside/inside temp.) .25 (the lower the better....single-pane glass is 1)
Winter R-value - 4.0 (resistance to heat loss, based on single-pane glass being 1) 4.0 (the higher the better....4X better than single-pane)
Many of the numbers mean little to me. I need to be an engineer.
What is the (practical) difference between Winter U and Winter R-values? Basically all this means is that the glass is extremely well-insulated, having clear tempered over clear tempered safety glass which is dual sealed.
