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I'm going to put some mirror polarized window film both for privacy and because I get a lot of sun (and thus heat) and I was wondering if a gold or copper color film would reflect more of less light/heat than the 'classic' silver film, or if its the opposite.

Any info on this?

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Each manufacturer publishes ratings for their products. You’ll want to compare:

  1. Visible light reflected
  2. Visible light transmitted (that’s transmitted from exterior to interior)
  3. Total solar energy rejected (this will be a %)
  4. Solar heat gain coefficient
  5. U value
  6. Solar heat rejected (this will be a %)

Comparing these ratings will tell you their performance, and thus which is “better”.

Also, you can get a rating of visible light to solar heat gain. It’s a ratio you may want to consider. One type of film may block a significant amount of solar gain, but will make your room “dark”.

  • So color has zero influence whatsoever? I been thinking copper or gold would also make it harder to see the inside of the room from outside thus more privacy, what do you think? – Ghost Oct 5 at 3:51
  • @Ghost Oh, color is a factor and will be reflected in each of the 6 items listed above. However, it’s not advisable to say silver has more light transmission than gold. You must compare all items. – Lee Sam Oct 5 at 4:33
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The transmission is mostly what you care about for heating.

In a cooling environment, you can reflect 90% of sunlight, and the room will still be bright. Sunlight is thousands of times brighter than room lighting.

It gets trickier if you are in a net heating environment, but you have hot summers. Now you have to strike a balance between too much incoming light in summer with high heat bills in winter.

One good compromise is to let the light in, with a normal window, but have a canopy that can extend far enough to block the sun most of the time. This you adjust for time of year. You likely will still want solar heating on March 22 (spring equinox) but not want it on September 22 (fall equinox -- same solar path)

You may also be able to find films that have variable reflectivity depending on the angle of incidence.

  • Nah I never get harsh winters here, not even below 0°C temps – Ghost Oct 5 at 3:50

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