Please Help With Energy Efficiency Comparison
How significant a difference are the following specs when comparing windows (especially energy efficiency wise)? A dollars & cents estimate would be very helpful. We are in central NC with majority of windows facing either due north or due south with approx 1/2 under porch.
U-Value: 0.35 vs 0.29
SHGC: 0.25 vs. 0.28
VLT: 0.47 vs. 0.48
Thanks for any insight you can provide!