Please help me understand Variable Transmittance
Hi everyone. We're looking to purchase Andersen's A-series DH windows. The regular LowE4 has a VT of .52 and meets the .3 U-factor and SHGC for the tax credit.
Unfortunately, the LowE4 doesn't meet in the 200/400 series gliding windows and the picture windows we're looking at for another room. I'd have to go with the SmartSun to get the credit on these windows.
My question is: Is VT the ONLY measure that drives the way the window looks when you look through it? i.e. how tinted it looks? For example, would a lowE4 window with 0.52 VT look the same as a SmartSun glass with 0.52 VT?
In general, how is VT measured and why does it change with window size? I imagine it would be a measure of light per unit area. So why, for example, would a DH have a 0.51 VT but a glider or picture window with the same glass option be 0.48 VT (assuming no grilles in all cases)?
Sorry for all of the questions - Thanks.