My wife wondered if the difference in size would be "significant" to us. A perfect question for her Excel Math expert. Here's how we figure it out. The following drawings are done to scale using the actual dimensions I measured off the windows:
I calculated the square inches of the entire window, then subtracted the space occupied by the pillars. Each pillar was quite thin on Version 1 (1 inch x 36) with the original steel window framing, but quite fat (3x31 or 3x33) on Versions 2 and 3 with aluminum framing.
Because the newest windows have thinner frames around the perimeter, there's more glass area in Version 3. The gain is 227 square inches, or about 1.6 square feet. Is that significant?
Take a look at the small window below. It's 17.5 x 13.0 inches in size, or 227.5 square inches. That's how much extra glass area we gained in the Version 3 kitchen window.
Now that we can see there is more glass, does that mean more light comes in? Maybe. It depends on the Visible Transmittance (VT) factor of the window.
VT is an optical property that indicates the amount of visible light coming through the window; it is expressed as a number between 0 and 1. The higher the VT, the more light is transmitted. That sounds like a chance to use some more math. Next time.