Low E Glass & Solar Gain??

[Chuck_Surette]

I can't remember where I read/heard it - are Low E Bad/Good for Solar Gain??

Low transmissivity to me seems like it would be bad for overall Gain.

[John Raabe]

For maximum solar transmittance into the house or collector you would not want the glazing to be low-E coated.

It can get a bit more complex in passive solar houses where the light is converted into stored heat and then re-radiated back out the same window at night. Then the low-E is helpful.

If you have a solar energy organization in your climate area they would have more specific recommendations based on your application and what type of glass would be best.

[Chuck_Surette]

Thanks John,

I thought I had heard that somewhere.

Flipping through The Passive Solar House by James Kachadorian & couldn't remember/find anything on window coatings....

He does mention putting thermo-shutters on the inside of the largest south facing glass - to prevent loss of heat.

[Bart_Cubbins]

Expanding on what John said, the low-E coating can either be applied to the outside glass to keep heat out or it can be applied to the inside glass to keep heat in.

For best solar gain, look for windows with a high solar heat gain coefficient (SHGC). A window with low visual transmittance may also have a low SHGC but not necessarily. Most of the energy in sunlight is not in the visible light portion anyway, so you can partly block the visible light and still get most of the heat. For example, the right mix of glass and coatings will let you gather most of the solar energy while still cutting out glare.

Hope that helps.

[Chuck_Surette]

It does help - thanks Bart.

I'm on the right path now.

Found the following link also- Giving ranges to shop for by your areas climate range:

http://www.accentwindows.com/efficientwindows/selection2.shtml

[GaryGary]

Hi,
This is also a very good window site:
http://www.efficientwindows.org/index.cfm

Try the Window Selection Tool

[jraabe]

I added these good links to the Referral page. Thanks guys!