Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a west facing window. How can I get max light while avoid any heat coming from it?

share|improve this question

To reduce heat gain from the sun, you need a window with a good "low e" rating (also called low emissivity). You can get similar results on an existing window by adding a film that reflects IR.

You also want multi-layer windows to block heat transmission (a lower U value is better, it's the inverse measurement of an R value you see on insulation). And finally, you should make sure that the window has good weather stripping to block any drafts, causing a direct heat loss/gain to your home.

Here's an article that describes this in more detail.

share|improve this answer

You may want to try an after market installation of some of the newer low E films before replacing a window with factory applied coating.

You have 2 competing factors that cannot both be optimized: Visual transmittance (VT) and Solar heat gain coefficient (SHGC)

Two measures of a film’s energy performance are visible transmittance (VT) and solar heat gain coefficient (SHGC), which range from a unitless measurement that is between zero and 1. A higher VT value indicates greater amount of visible light passing through the film, while a lower SHGC means more solar radiation is rejected by the film. Mid-range products with VT and SHGC values around 0.5 are “ideal for northern climates,”


Films where VT greatly exceeds the SHGC are suitable for hot climates

Excerpted from Eco building pulse article

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.