U-Factor and SHGC recomendations for Denver area

[mitvel]

We need to replace the windows on south side of the house in Denver. It's getting very hot in summer but the sun helps a lot in winter. We talked with several local installers but we need help to decide what kind of glass to select based on efficiency parameters.

I understand that we need good U-Factor to keep the heat inside but we confused what SHGC value will work the best. Going low will keep sun from heating the house in winter but high is bad for summer. My coworker installed very high efficient windows several years ago and he complains that the rooms are getting very cold in winter but it works very well in summer time.

Most of the options we got have SHGC from 0.19 to 0.34 and U-Factor from 0.20 to 0.44
Can somebody please advise what numbers we need to look for in our situation?

[Windows on Washington]

Unless the home is set up to take advantage of the passive solar heating, go with the lower SHGC glass. Better yet, go with triple pane.

[mitvel]

Thanks, Windows on Washington.
We just thought that, because we have a good heating effect with our old builder grade windows, we can get it somehow with new windows too.

We was considering a triple pane but two installers (reputable based on the reviews) said that it does not make sense to install a triple pane in Colorado. The efficiency parameters are very close.
Still, we are thinking about installing triple pane but we are concerned that all the options we got have a very low VT like 0.34-0.38. We would like to have more light in the room. The double pane with good SHGC has VT around 0.46-0.48. Is it going to be a big difference?

[Windows on Washington]

What window are you putting in that has a VT of 0.46 in a Double Pane?

Are there grids in these windows? The window that we most often use has a VT of 0.55 in a double pane without grids.

10 points will be noticeable to the eye.

[mitvel]

One of the option is Zen Lotus/Imperial Elite with double-pane Low-E VT 0.48 or Solar Low-E VT 0.46. Zen says that the will do Lotus with triple-pane (VT 0.36/0.34) only but we are still talking with them because their brochure allows to get it with double pane glass. And I am not sure that we want to downgrade to Nirvana only to get double-pane.

Another option is Sunrise Vanguard. It has double pane option only with glass S2210x with VT 0.48. Actually, I just saw that Vanguard has vary low Condensation Resistance - 44. Is it too low?

[Windows on Washington]

44 is kind of low if you live in a cold climate. Must be a surface 4 low-e which is a no-go in a cold climate.

I would be looking at one of the Sunrise triple pane windows. The Zen models are older designs and usually installed as part of a franchisee model that doesn't necessarily have a background in actual window installation.

[mitvel]

Thanks, I will try to find another reputable Sunrise installer in Denver area because this one does double-pane only. I will be grateful if somebody can suggest one.

About Zen windows, I have read somewhere that the Imperial Elite line is quite new and it's a replacement for the Imperial LS which is almost the same as their top Elements line. Is it correct?

Next week I will also talk with Simonton installer. Is it considered a step down in comparing with Imperial/Vanguard?

[Windows on Washington]

The Elite does look like the LS. And yes, the Simonton is NOT a performance competitive equivalent to the Sunrise or the Soft Lite window.

[mitvel]

We just got another quote from distributor of Anlin Catalina windows. The windows look comparable to Zen Nirvana or Simonton Daylightmax with better warranty but I could not find the DP rating for Catalina.

Anlin provides the performance class/grade LC30 or R20. I failed to find the information how to interpret these values.
Can somebody explain what does it means and how we can compare it with DP values for other manufacturers?