Do Thermal/Blackout Drapes Actually Work?

ViRGE

Elite Member, Moderator Emeritus
Oct 9, 1999
31,516
167
106
Fellow light-intolerant denizens of ATOT, I need your advice: do thermal drapes actually work to keep out the heat from the sun during the summer months?

I have a home office with an east-facing window, and while I have standard white slat blinds, I find that the room still heats up very quickly in the summer months. And combined with the equipment in the room I pretty much have to bust out the A/C fairly early in the year. This year I want to do something about the problem.

I'm considering thermal drapes, however I can't seem to find any good advice. The top articles on Google are more along the lines of "yes, they're great (compared to nothing)" which isn't helpful in my situation. The blinds already block out most of the sunlight, but they still seem to let a lot of the heat through.

So I ask you: is throwing thermal drapes behind the blinds an effective means of keeping out more daylight heating, or is this a fool's errand? Really I want to find a solution that's moderately effective without having to replace the blinds entirely (or place something in front of them), since it's a street-facing window and any such change wouldn't match the rest of the house. But I'm worried that I've lost this battle the moment the sun hits those white vinyl slats.
 

Imp

Lifer
Feb 8, 2000
18,828
184
106
I don't really understand how they would work for summer weather...

A window with a special treatment would, theoretically, reflect light (e.g. UV, visible, and infrared) back outdoors before it gets inside.

But a thermal drape/curtain is on the inside. If the curtain is inside, the light has already gotten inside, and therefore the heat is inside. Doesn't it essentially just transfer the heat from a floor/wall to the curtain? I guess if it heats the curtain, the curtain would emit/radiate a portion of the heat back out the window?

During the winter, I think it would act as a layer of insulation so that the warm indoors can't emit heat out the window as easily, and it'd probably help with heat conductivity in the air and convection by blocking off a window.
 

Red Squirrel

No Lifer
May 24, 2003
69,680
13,317
126
www.betteroff.ca
White is the best thing as it's the most reflective, you won't get any better than that without going with foil or something reflective. Basically you want to bounce the energy out, not just stop it from getting further into the room, because it will just get absorbed and still radiate around over time. The white will bounce some of it out but also absorb some. A darker colour will absorb more.

Foil would look kinda ghetto though.
 

Elixer

Lifer
May 7, 2002
10,371
762
126
They kinda work, but, the window area isn't air tight with the drapes, there is a pretty big gap between them, so, heat still radiates into the room.
I use solar shield tinting that you put on the glass itself, and, that does a better job IMO.
Issue there is, you have to decide how dark you go, with the darker material being better in terms of not letting as much heat through, but, you lose light, and, since you mentioned you don't want to go this route, then, you could some awnings?
If that isn't an option either, are your windows triple pane? Some of those also help keep the temp more stable from outside to inside.
 

Blue_Max

Diamond Member
Jul 7, 2011
4,223
153
106
Heat entering via window must be both reflected AND sealed to contain the remainder generated by the glass itself. That gets expensive but I suppose cheaper than A/C in the long run.

I've gone the simplest route of a blackout blind for the bedroom to sleep better - keeps out a portion of the heat, but not what's generated by sun hitting the rest of the poorly-insulated house. In my case, excessive blinds won't help a great deal for heat - only light.
 

Carson Dyle

Diamond Member
Jul 2, 2012
8,173
524
126
Consider moving whatever equipment can be moved out of your office. It always amazes me to see people with racks of servers, switches, firewalls, routers and other gear in a room in which they spend 8 to 12 hours a day. Most of that stuff can live life in a basement utility room or some other unused space. You just need an ethernet drop or two to the room.
 

ViRGE

Elite Member, Moderator Emeritus
Oct 9, 1999
31,516
167
106
What you want is something like this if you're looking for an extra layer to keep some heat out.

http://www.amazon.com/Gila-LES361-C...ie=UTF8&qid=1459308379&sr=8-1&keywords=LES361

Did this with thermal curtains for sliding door (ie no blinds) that was west facing getting all the afternoon sun heating up living room, think combo of the two in that situation helped quite a bit.
Holy cow, why have I never heard of this stuff before?! A semi-reflective window film; that looks perfect. Thanks Olivas!:D

I use solar shield tinting that you put on the glass itself, and, that does a better job IMO.
Issue there is, you have to decide how dark you go, with the darker material being better in terms of not letting as much heat through, but, you lose light, and, since you mentioned you don't want to go this route, then, you could some awnings?
I'm not so much worried about losing light (I'm already a pasty white nerd) as much as I am looking tacky. I never realized they made slightly reflective film until now; all I had ever heard about was highly reflective foils and the like.
 
Last edited:

piasabird

Lifer
Feb 6, 2002
17,168
60
91
If sunlight comes into the room, it heats up the floor and increases temperatures. Even a blind might help.

I got some window world windows installed they have optical coatings on the glass and argon between the panes and it definitely cuts down on the amount of light that comes in from outside. Just some dark drapes will help or maybe some blinds.

You could just paint your widows or put some aluminum foil up against them. I have seen that done in Alaska (Land of Midnight Sun). You could just hang blankets up on the windows.
 

piasabird

Lifer
Feb 6, 2002
17,168
60
91
Be careful putting Film on windows. It can cause water droplets to form that can cause mold and rotting wood. Looks promising. They make it in rolls that can be pulled down like blinds. I have seen it in store fronts or at some restaurants with lots of windows.
 

thesmokingman

Platinum Member
May 6, 2010
2,302
231
106
Fellow light-intolerant denizens of ATOT, I need your advice: do thermal drapes actually work to keep out the heat from the sun during the summer months?

I have a home office with an east-facing window, and while I have standard white slat blinds, I find that the room still heats up very quickly in the summer months. And combined with the equipment in the room I pretty much have to bust out the A/C fairly early in the year. This year I want to do something about the problem.

I'm considering thermal drapes, however I can't seem to find any good advice. The top articles on Google are more along the lines of "yes, they're great (compared to nothing)" which isn't helpful in my situation. The blinds already block out most of the sunlight, but they still seem to let a lot of the heat through.

So I ask you: is throwing thermal drapes behind the blinds an effective means of keeping out more daylight heating, or is this a fool's errand? Really I want to find a solution that's moderately effective without having to replace the blinds entirely (or place something in front of them), since it's a street-facing window and any such change wouldn't match the rest of the house. But I'm worried that I've lost this battle the moment the sun hits those white vinyl slats.


Black out drapes work decently for the vampire in me. For blocking heat, not so much. For heat you might try the cellular shades, like the triple cell kind. I use the aluminized black out shades btw.
 

shortylickens

No Lifer
Jul 15, 2003
80,287
17,080
136
Yes. I got some from JC Penny a long time ago. They are awesome. A little expensive, I think my mom sent me over there when they had a sale going.

I cant even see my tactical light thru them. Highly recommended for daytime sleeping.
 

DaveSimmons

Elite Member
Aug 12, 2001
40,730
670
126
I have blackout shades in my apartment but they are designed for blocking light not heat.

I use them to block light from the windows when watching a movie before dark, for sleeping late, and for blocking the glare from coming in to my home office. I'd expect white shades to work better for reflecting heat.
 

John Connor

Lifer
Nov 30, 2012
22,757
617
121
Hmm, I smell an opportunity. Maye you could line the window with these and power an air conditioner?

A solar cell could work too.
 

Miramonti

Lifer
Aug 26, 2000
28,651
100
91
Yes, had some and loved them. I didn't run a scientific test on the temp differences tho, but they were very thick.