Which way does the insulation go?

[mpire]

Ok, so I have some 2" foam board with a foil side and a white side.

I am trying to stop the relentless Florida Sun coming through the window, so I am putting the foam between the single pane window and the blinds.

Does the foil go towards the sun or towards the inside of the house?

 

[brentm]

I'd put the foil towards the sun to reflect the energy rather than absorb it.

 

[dfiler2]

Yes, foil towards the sun, and if you really want to see a difference, put the insulation on the outside.

 

[mpire]

I'd put the foil towards the sun to reflect the energy rather than absorb it.

That's what I thought. There is still a bit of an air space between the glass and the foil so hopefully it will help.

Yes, foil towards the sun, and if you really want to see a difference, put the insulation on the outside.

I can't put anything on the outside. The dreaded HOA would lose their minds!

Although, I have been trying to get them to let me put an awning over the window to block direct sunlight.

I have aluminum lined cellular shades in the windows now, and it gets so hot that it has warped and bubbled my tint on the East facing windows. I have to replace it every couple years.

 

[Junkman]

There is an insulated glass that is so effective in blocking the sun, that I have seen it demonstrated using a infrared heat lamp on one side, and the other side of the glass is ice cold. Don't know the name of it, but it is sold with replacement windows. I have the opposite problem. I want the sun to warm the home, but in New England, that only happens in the summer, when you don't want it to happen....

 

[brentm]

You might consider reflective interior film treatment for the windows. We did this in our daughters room that has two windows and faces the heat of the sun. It the Gila cling tint (non-adhesive) I purchased at Home Depot. From the outside, it looks flawless. Inside, you can see a few flaws, but it's not embarrassing. But it does a good job of reflecting the sun's rays and keeping her room cooler during the day.

Combine that with your insulation and you'd probably have a decent solution to the Florida sun. I wish I could fight the Florida sun We're a little unseasonably cold up here in Washington.

 

[mpire]

You might consider reflective interior film treatment for the windows. We did this in our daughters room that has two windows and faces the heat of the sun. It the Gila cling tint (non-adhesive) I purchased at Home Depot. From the outside, it looks flawless. Inside, you can see a few flaws, but it's not embarrassing. But it does a good job of reflecting the sun's rays and keeping her room cooler during the day.

Combine that with your insulation and you'd probably have a decent solution to the Florida sun. I wish I could fight the Florida sun We're a little unseasonably cold up here in Washington.

I already have the windows tinted. The windows gets so hot the tint bubbles and warps.

 

[Racer_X]

You might consider solar window shades.:

http://www.idahocanvas.com/id227.htm

The Duplex silver/silver reflects the most light/heat.

http://www.idahocanvas.com/id153.htm

 

[James-W]

Could you use aluminum foil on the outside of the window stuck on with double sided tape?

 

[mpire]

Could you use aluminum foil on the outside of the window stuck on with double sided tape?

Yeah, like the HOA would ever let that happen.

 

[Falcon67]

Could you use aluminum foil on the outside of the window stuck on with double sided tape?

That'll put you on the drug task force list too.

 

[mpire]

That'll put you on the drug task force list too.

Really? You think so?

What benefit does it give to the drug dealers?

 

[787B]

I can't put anything on the outside. The dreaded HOA would lose their minds!

The HOA busybodies are probably going to lose their minds with reflective foil on the inside too if it's visible from outside.

To work the best you want the foil side right up against the window so there is no room for air that can get heated by the sun.

Still your best option is a heat-reflective tint. If your current tint is bubbling and peeling it's **** tint and/or **** installation. Quality tint properly installed won't do that. I lived in Brevard County for a decade and tinted a truck with quality 3M tint. It got SUPER hot inside in the Summer, but the tint never bubbled, peeled, or faded.

 

[mpire]

Well, its probably not the best tint in the world, just what they sell at home depot.

Gila Heat Control is the brand.

I doubled up the tint on those windows so you really can't see the foil clearly. It helps that the foil doesn't have writing on it.

The tint is only bubbling on the west facing windows. It is fine everywhere else in the house. The west facing windows have aluminum lined blackout cellular shades that are always closed, so I assume it gets pretty hot.

 

[rlitman]

I'd put the foil towards the sun to reflect the energy rather than absorb it.

You would think so, but this is actually exactly the wrong advice.

If you leave a mirror or shiny piece of metal out in the sun, you will notice that it gets quite hot. With enough sun, it will get too hot to hold. A white piece of plastic however will hardly get warm at all. So what's the reason behind this? Reflecting the heat is only part of the issue, and in this case, is not all that important.

What is important is emissivity. In the case of the foil vs foam surface, the foil has a low emissivity, and the foam has high emissivity.

Emissivity is a measure of how much heat a material radiates as it gets hot. In the case of the foil, the answer is not that much. So while that hypothetical mirror above may reflect 97% of the heat that is radiated onto it, that small 3% proportion of absorbed heat is largely not re-radiated back out until the surface gets quite hot. In the case of the white plastic, maybe only 90% of the heat radiated onto it is reflected, but that 10% that is absorbed is also easily re-radiated back out.

By placing the foil on the INSIDE, even when the foam gets hot, very little infrared energy will be radiated back inside the house. That's what the foil surface is there to help with.

 

[mpire]

Well, That stinks. I guess I will have to re-do it.

 

[mpire]

Do you think I would get the same benefit if I put aluminum foil on the inside of the foam?