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SHGC - does it only matter with direct sunshine on window?

Posted by fromhollywood (My Page) on
Mon, Oct 12, 09 at 15:03

I'm in the process of making some double pane insulated glass units as storm windows. Oberon has really helped me understand these glass/window concepts but I'm still a bit confused about SHGC.

I trying to pick glass that will have a high SHGC number to get the benefit of passive solar heat (I'm in the Northwest where summer temps rarely get very hot but winter nights are routinely in the 20's F). Half of my windows though never get any direct sun hitting them during the year. Would it be better on those shaded windows to forget a high SHGC and get a low SHGC number instead?

Thanks very much for any ideas you could share.


Follow-Up Postings:

RE: SHGC - does it only matter with direct sunshine on window?

If the windows are largely shaded, throw the SHGC component out of of the equation and stuff the best U-Factor window that you can in there. Look for a two surface low-e or triple pane. If you don't like the idea of less light, I would look for a window with Low-e on surface 3.

RE: SHGC - does it only matter with direct sunshine on window?

Hi WindowsonWashington,

Thanks for the tips. I'm doing the double-pane storms since I want to save the historic windows.

I'm also replacing some cheap aluminum single-pane windows with some new ones. I find most of the big window companies don't give much in terms of technical details. Is there someplace where you can find out exactly what the specs are for the glass in a company's windows? I've been looking at Jeld-Wen vinyl windows and can see their performance specs but I'd like to know exactly what each piece of glass is and it's coating.


RE: SHGC - does it only matter with direct sunshine on window?

Cardinal and PPG publish U-factors and SHGC for their glass on their websites.

Here is a link that might be useful: PPG Site

Re: SHGC - -does it only matter with direct sunshine on window?

Here's the Cardinal Glass link

Here is a link that might be useful: Cardinal Glass

RE: SHGC - does it only matter with direct sunshine on window?

Skydawggy, Thanks for the links to Cardinal and PPG.

Do most of the big window companies like Jeld-Wen use glass from one of these two manufacturers? I seem to remember hearing that there are really only a few glass manufacturers in North America but I've never confirmed that.

How do you get out of the window manufacturers exactly what type of Cardinal or PPG or other manufacturer of glass is being used in a specific window? For instance, Jeld-Wen seems to have just a few glass choices when you look at their link called "Performance Ratings". I called their customer service but they didn't have an answer for me.

This is the only thing on their website that I can find that says anything technical about the glass and it's not too specific. They list "Clear", "Low-E 272", "Low-E 366" as the only choices but they don't say who makes the glass or what type of coating is used.

RE: SHGC - does it only matter with direct sunshine on window?

LoE 272 and LoE 366 are Cardinal glass. PPG uses Solarban 60 and Solarban 70 as comparable glass. I would just simply ask the Jeld Wen dealer what glass they use. I'd tell you but I really don't have any dealings wih Jeld Wen.

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