energy film for windows....

I put some film on my west facing windows and it made a dramatic difference in solar gain in the summer. I assume that since it reduces radiant gain in the summer it would reduce radiant loss in the winter as well.

I think I used this:

http://www.homedepot.com/Decor-Wind...splay?langId=-1&storeId=10051&catalogId=10053

I wouldn't expect it to make any difference in winter, only for solar heat gain in the summer. Even the manufacturer (in the link provided) doesn't claim any improvement at holding heat in. And you know if it made ANY difference at all they'd be playing it up.

If your south facing windows are shaded from the summer sun but let in the winter sun the covering would actually hurt the widow performance because you don't get the solar heat gain in winter.

My mom had a couple windows that cooked her dining room in summer so she installed a similar film over them and it seemed to help.

Since you're asking about insulation though I'm assuming you want to keep in warmer it winter rather than cooler in summer. Sealing up air leaks (around windows, doors, etc) and installing attic insulation (depending on what's there now) will be your biggest bang for buck.

Having loose blown cellulose put into the attic is fairly cheap and easy.

Alan

i don't think that stuff will help at all in the winter. For winter time use the window kits that are sold in the weatherization section. The type you tape on and put the hair dryer to it. Works very well. Very good ROI.

And it's almost that time of year to peel the stuff off! Whoopie!!

pyper said:

I put some film on my west facing windows and it made a dramatic difference in solar gain in the summer. I assume that since it reduces radiant gain in the summer it would reduce radiant loss in the winter as well.
I think I used this: http://www.homedepot.com/Decor-Wind...splay?langId=-1&storeId=10051&catalogId=10053

Click to expand...

Agree with Alan and FlyingCow. These types of stick-on films can help in the summer by blocking the near-infrared radiation part of the solar spectrum from entering the room. By contrast, the room temperature radiation trying to exit the room through the window glass is centered around the medium infrared range, where window glass has almost zero transmittance to start with.

The window kits mentioned by FlyingCow (that trap a substantial layer of air between the plastic and the glass) are indeed much more effective since they can easily double the R-value of a window.

Not everyone likes the looks of these plastic membranes, though, nor the fact that it tends to make it difficult to open/close windows and may get in the way of curtains and blinds

A less drastic approach to improve the R-value of a window or glass door is to preserve/enhance the natural layer of stagnant air found on the inside of all ceilings, walls, doors and windows. The thermal insulating properties of these air layers can easily get up to an R value of 1, which is not insignificant considering that most single pane windows have R-values in the 1-2 range with double panes reaching 2-3.

On a large smooth window pane only a relatively thin layer will be able to stay stagnant, whereas on a window divided in smaller boxes, e.g. French door style, thicker layers should be able to remain stable. Horizontal blinds should further promote stagnancy (by counteracting natural convection flows), as should drapes (especially when closed, of course).

By contrast, any arrangements that disturb the stagnant air layer, i.e. room fans partially aimed at the window or electric baseboard heaters underneath the window, will reduce the R-value, thus increasing heat losses.

Henk