Window Film over sealed window - worth it?

I am sure everyone in this thread has seen that shrink-wrap window film you can put over old windows to save energy. We have old windows in our house and have used this the past few years with great perceived results.

However, this year, I decided to totally caulk two of our very old wodden sliders shut, because next spring they are going to be replaced anyway. So everyone is aware - these are VERY old windows - single pain wooden sliders. They do have a storm window on the outside as well but this adds little R value.

So, my question is this. Since I already totally caulked the windows shut, do you think it is worthwhile to also apply the window film over these windows? The primary purpose of this film is just to stop drafts, of which there should be none.

But my theory is applying it properly would also create another dead-air zone between the film, which should increase the R value beyond the single pane of glass. But, this isn't low-e argon or anything - I am unsure if it is worthwhile doing this.

Opinions? It would cost about $1.50 worth of film to apply per window I gather, so maybe $3.00

I would, as you stated, for the dead-air zone theory. C'mon...$3.00?

Windows lose heat thru 3 ways :

1) drafts/leaks
2) conducting
3) radiation

#1 isn't in the equation any more. And there isn't anything you can do about #2. So, adding another layer of film will simply reduce heat loss thru #3 radiation.

But just keep in mind that radiation works both ways. During the day time, sunshine will bring heat in (assuming that window gets sun). But, at night, heat radiates outward.

Originally Posted by IronMac

I would, as you stated, for the dead-air zone theory. C'mon...$3.00?

It's not the cost really. The film is a PITA since we have cats, and also makes the window look more ugly. If it isn't going to do anything I don't want to bother.

Originally Posted by brunes

It's not the cost really. The film is a PITA since we have cats, and also makes the window look more ugly. If it isn't going to do anything I don't want to bother.

Not to mention the time it takes to do this.

My mother has us seal the windows, and then keeps the thermostat at 54F all winter...

If you've sealed them up good you've probably already managed to seal out a lot of the cold. Adding a thin layer of plastic now would probably be a waste of time, and doesn't look very nice. Just get some updated windows for next year.

For a north facing window it might be ok. Most people use films for privacy more than energy savings though. I'm using a nice patterned light diffuser film, and you can make out shadows and large forms through it, but can't see anything distinctive.

What I prefer to do is to get a cheap roll of black electricians tape (usually 2 or 3 rolls for a buck at the dollar store) and run it around the windows (especially the south windows) It seals all the drafts out, and gets fairly warm in the sun to, which I'm sure heats up the metal frame so that it does not feel so cold in the winter. About 5 cents worth of tape will do, and the rest can be used as electricians tape for other projects, or reapplication next winter.

its definitely worth it, consider the space between the glass and plastic as a dead air space the same as in a dual pane window with the attendant savings

Originally Posted by blackhawk

its definitely worth it, consider the space between the glass and plastic as a dead air space the same as in a dual pane window with the attendant savings

+1

another thing you can do is take a candle and hold it near the window frame on the inside of the house. you will probably see the flame move which indicates something is going on. add the shrink wrap and repeat the exercise. it should be reduced and or eliminated.