I'm curious if tests have been conducted to evaluate the energy efficiency gains and resultant savings produced by insulating window films like these 3M Window Insulator Kits. (There are also films that are adhered directly to window glass that block UV and such; I'm specifically talking about the kind you tape on to the window frame to seal leaks and create an extra pocket of air.) The bottom of that page states:

Using a 3M window insulator kit can save up to $18 per window this heating season. Values based on averages from the northern half of the United States. Actual energy savings are subject to change and will vary depending on furnace and window type, average indoor/outdoor temperature, length of heating season and other factors. Savings based on energy costs as of August 2011.

I'm curious if tests have been conducted to verify these claims. Perhaps the best and most practical/useful way to go about the question is:

For the average house (# of windows, type, size, heating costs, etc.) in the northern US, is the cost of the window film (ideally more) regained in energy savings?

Let's assume that the kit costs $15 and insulates 5 windows (but 8 windows should be treated like two kits ($30), not $15 kit/5 windows per kit x 8 windows = $24).

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    Anecdotally: I've used such kits and found them effective, but not as effective or aesthetically pleasing as insulating window shades, which of course are much more expensive but have a longer life. – Larry OBrien Nov 20 '11 at 18:41
  • I've used them against single-pane windows, and they did help reduce the cold somewhat during winter seasons, but they were also inconvenient and a nuisance to install (I wasn't using the 3M brand), plus with condensation the corners would "un-stick" sometimes (and need to be re-stuck with tape or thumb tacks). They're definitely nowhere near as effective as just replacing with double-paned windows (with a factory-sealed vacuum between the two panes), but I'd be willing to use them again as a temporary measure. – Randolf Richardson Nov 20 '11 at 22:33
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    @RandolfRichardson I use them with single panes as well. Part of asking is that I've tried tracking my energy costs during the past three winters. First winter was film only, next winter I added 12" of insulation to our attic and used film. I didn't see the savings I expected. Our windows are super leaky -- the film sure makes a difference with how it feels to sit near one and must help with energy, but it's been hard to prove. Thus, after just applying it for the 3rd time, I wondered if a 3rd party has conducted a cost/benefit analysis. – Hendy Nov 21 '11 at 1:25
  • @Hendy your "study" is useless as the conditions under which you tested aren't identical for both situations. – jwenting Nov 21 '11 at 13:14
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    @jwenting It is the intonation-sterile internet, but your comment comes across as a bit of an insult. Did I convey that I attempted peer-review journal quality research above? Isn't this the point of asking if a non "useless" (your word) study has been conducted (which is what this question does)? – Hendy Nov 21 '11 at 17:21

Here is a link I found where some kids did a test


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    Thank you for that answer. Could you please provide a brief summary of the study and its results in your answer, so that people can get a general idea about it here? – P_S Nov 20 '14 at 16:02
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    Welcome to Skeptics! Without wanting to disrespect the noble efforts to teach children science, the quality of science done in science fairs tends to be very low - some have been debunked here. This isn't a reliable source. Furthermore, the experiment does not address the question of whether the film pays for itself. – Oddthinking Nov 20 '14 at 23:56

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