Introduction: Heat Blocking Curtains

Picture of Heat Blocking Curtains

Summer is nearing/here, and it's getting hotter in my house. To save electricity with our super expensive A/C, I constructed reflective curtains to block sunlight from warming our house. Think auto windshield. This is super simple and kind of obvious, but it works well.

Step 1: Materials:

2-3 Emergency blankets/foam reflective pads/ windshield blockers*
Roll of 2" wide tape (I used aluminum tape)
Bag of Grommets and crimper
Bag of curtain hangers

*I don't know about in the US - I've had these before in my camp pack as "emergency blankets" for protecting you in the event of shock or if you have to sleep somewhere in the cold. The emergency blankets don't have any backing on them, so maybe you might want to glue some foam/paper/cloth to the back. Super 77 tack is perfect for this.

I'm currently in Japan, and in the 100Yen shops (great places for makers - come to Japan just to stock up for supplies) they have these mats that are meant to be used as picnic mats.

Step 2: Constructing the Curtain

Picture of Constructing the Curtain

Fold top edge of the curtain over and staple in several locations to hold it in place. This will give more "meat" for the grommet to grip when you crimp it.

Then decide where the curtain will fold and crimp a small grommet into the fold as shown. The grommet should be able to punch thru this - I've crimped grommets thru fabric and it usually cuts a little hole for you. If not, an X-acto blade should clean it up nicely.

- small tip, I made it so that the folds end up rubbing against the window - this makes it slightly annoying to push open the curtain completely; two hands are needed. See if you can fix my mistake on your design. (-:

Step 3: Add Extra Lengths If Necessary

Picture of Add Extra Lengths If Necessary

Our windows are bigger than the curtains - I cut up another blanket and turned it into an extender by taping it on.

I taped it in the front using aluminum tape (doesn't make much of a difference, but it looked better on the shiny side) and used normal packing tape to secure the back.

Step 4: Tips and Suggestions

Secure one end to the anchor point so you can slide this easily from one side to the next.

You can make two curtains, one for each side, but I found that this one curtain is easily hideable behind one of the decorative curtains.

Whole project cost:
$4 for blankets
$1 for grommets
$1 for tape

~$6 total

I think this will save a lot off of our summer electricity bill since I can't feel the heat from this window anymore. The wall next to it heating up is another issue, but I don't see how to really fix that.


Deedles (author)2017-05-29

Yesterday the sun was very hot and heating up my cabin to unbearable from heat from the NW windows. I had two windshield sun reflectors from Dollar Tree I was going to use for my cars but in a bit of desperation to relieve the heat situation in cabin I used them to cover one of my windows. Amazing difference. These also already have the foam backing on them. A little more time pondering how to make them look more like window coverings for a house to improve their appearance is what needs done now. Maybe a lace sheer or lace table cloth to cover them? Something cheap and attractive. Will also reverse the car shades for the cold winter months to keep heat inside. Great Instructable! It's been on here for years and still getting comments!

csmith2 (author)2016-11-14

Thank you so much for this idea. My apartment gets the morning sun and it also gets really hot in the summer and my portable air conditioner can't seem to keep up with the heat. This is going help so much in my living room & bedroom. I put a thick painters canvas drop cloth over the window that helps a little but your idea is going to save the day!!

BtheBike (author)2016-05-07

i did this a few years ago with mylar stapled to regular curtains . Yes , hella ghettoish . No gf tho so ... .Alas it was too loud when turning on the baseboard heaters just the convection would make then rustle . Plus I had to press them against the wall to allow the baseboard heat to rise inside apartment instead of between curtain and cold window .
Want to now make horizontally pleated double bubblewrap foil blinds next .

Kris T. (author)2013-05-22

I'm thinking of turning the bed of my truck into a "mini camper," so I think this would be a superb idea for covering up the topper's windows during the summer (they could even be reversed to keep warmth in during the winter!). Many thanks for the idea!

tinker234 (author)2012-03-12

i wonder if a mirror finsh tow way glass film and it can reflect off heat as weel

scidoom (author)2010-08-14

idk how if this will work for heat but it works well for cold a good idea as tacky as it may be is to put saran wrap infront of the windo not tuching

all_thumbs (author)2010-08-01

Draping some emergency blankets across the windows with clothes pins or office tape, brings quick and cheap relief. I have used it for years. The downside is that all women hate it. No big wonder, there were never any women the Apollo lunar lander.

AZroadrunner (author)2010-07-12

Can paint your glass with insulating nano paint. Expensive, but think of the energy savings! One drawback, it does distort viewing, best for frosted glass. Can also use the nano paint on interior/exterior walls. Exterior plastic film on glass won't work here--frequent sandstorms scratch glass, much less plastic. Have to use a variety of sun-insulating methods in combination; i.e., thermo-curtains, nano-paint, etc.

nf119 (author)2008-06-17

sweet! i would love to make my house all shiny cept community laws keep me from doing so. i can't sun dry my clothes or install solar panels! basically i can't do anything "green" cept if no one can sees it.

I think now (as of 2010) you can fight those community issues and win. Especially due to the fact that everyone is going green. They used to have a no laundry drying line law in my area, but they can't enforce it anymore due to more and more people saving the earth and telling the "neighbourhood anal retentive committee" (you know who they are... they go around measuring everyone's lawn height) where exactly they can stick it!

sideways (author)nf1192008-06-18

Can you put on tinted window film? There's removable types so it can be taken down if you need more light in a cold winter climate. That's what I've done on my west-facing windows, and it makes a big difference in how hot the rooms get in the afternoon.

nf119 (author)sideways2008-06-18

it's probably allowed. is it easy to install?

sideways (author)nf1192008-06-18

yep. Spray clean window with soapy water, put the film on, and use the squegee to work the bubbles out to the edges. I got mine at a big-box home improvement store, it came in a nice little kit with a small spray bottle and squegee included. I think it was in the section near the curtains & blinds. The box might say "RV window film" but I ignored that. Glass is glass.

iq_abyss (author)nf1192008-06-18

I hate covenaces...

Tolstoi78 (author)2008-06-19

I think this would be best if you were able to put the blanket or some type of shutter on the outside of your window, as the less light you let reach the window, the less heat you're going to have inside. The same can be done with UV windshield protectors, because once the light makes it's way through, the heat's already inside. But if you get one of those large accordion ones with straps, you can avoid a whole lot of heat altogether.

laernmoer (author)Tolstoi782009-07-10

If you put something outside, you have to make it weatherproof. In my case, from the 3rd floor, it's a bit difficult to attach something to the outside.

adambeazley (author)2008-08-12

You know you could just as easily go with a window energy film, they are pretty cheap and will block quite a bit of the radiant heat, while still allowing the natural light to come in.

laernmoer (author)adambeazley2009-07-10

I was living in the apartment, so I didn't want to spend a lot of money on something that I eventually had to throw away - this was the cheap way. Besides, the windows were textured, so the film wouldn't attach to the glass.

laernmoer (author)2009-03-07

That might work, good luck with that! Again, i just used trial and error to see if it would work. Thanks for the comment

JodiLynn (author)2008-08-27


linuxnewbie (author)2008-06-19

Easy way to get the shiny film for the blankets- Look for "survival blankets" or "space blankets" sold for about a dollar in military surplus and camping stores. They're just sheets of this shiny coated mylar. Another source for this stuff is potato chip bags. Just cut them flat and tape together. By the by, I just use the mylar shiny sheets. I use low-tack tape directly on the windows in summer at the same time that I take down the shrink wrap double glazing for the winter.

Xellers (author)2008-06-17

I did something similar to this right before I read your instructable. I just used a few surplus reflective blankets and used clips to hold them on dowels that I hung onto my windows (I don't have big windows like you). Great instructable though!

James (pseudo-geek) (author)2008-06-17

this is brilliant. I will do this when I move away from my parents in a year.

chaveza94 (author)2008-06-16

this reminds me of something we just did in our house which was put somehting like that material over our insulation, well we didnt the "Energy Doctors" did. And i would really like to makea recommendation for these guys because it is a great investment and plus you get a gvmnt tax refund for installing this. here is their website.

fayrho (author)2008-06-13

Thank you for this idea. I live in Oklahoma, and have been looking for an inexpensive way to reduce the heat in an east-facing room. I'm going to try this-or some version of it.

Rane84 (author)2007-07-25

You know, there is a radiant barrier fabric that blocks 95% of the heat, which is probably a higher percent than an average space blanket. It's also softer and better looking. You can buy for about the same price as any other fabric. A company called Mechoshade Systems will probably use them as heat-resistant black-out curtains. Take a look.


laernmoer (author)Rane842007-07-25

Thanks, Temptrol might be a good idea - again, I was going for cheap, easy. Got a link for a place that actually sells the stuff, rather than the manufacturer's site? I'd be willing to try this stuff out if you could find me a japanese vendor.

rupamagic (author)laernmoer2008-02-09

you can mail order it here for $12.99/yard. It's 59" wide, which is great.

More expensive than the original design, but I haven't been able to find those space blankets or car sunshades at my local dollar stores.

Bad Link.

Oh, bummer, it was working when I posted it! It looks like they may have let their web hosting lapse or perhaps they really are under construction. Sorry I don't have any other suggestions besides google. Good luck!

DIY-Guy (author)laernmoer2008-02-22
(You mentioned you wanted to buy?)

The key ingredient for these "heat shield" curtain designs is something called a RADIANT BARRIER. Good radiant barrier shielding will block 97% of the heat and reflect it back to where it came from. Add a little layer of air bubbles or foam and it becomes extremely effective at keeping heat out, or keeping heat in if you live in a cold climate. Some people in the Northwest just put a layer over the inside of their bedroom windows during the winter to bounce the house-heat back into the house.

Rane84 (author)laernmoer2007-07-25

They aren't just the manufacturer, they sell it too. Unfortunately, I think it's only sold in the US, so you'd have to pay for shipping to Japan.

naqoyqatsi (author)2006-07-05

Living in Holland at the moment with a heatwave going on for about a week (30++ degrees cent.) and humidity rising to absurd levels this realy looks like a valid solution to our heat-problem. Got the normal sun-shade down all day and the curtains closed but still we tend to dehidrate within minutes after comming in. Poor cats... Anyway, about the winter application for this instructable... If you can get some sort of double sided stuff (aluminiumfoil) you can actually sew it onto normal curtains. No need to take them off as the hot summer tuns into a cold winter (-:

deepbluejazz (author)naqoyqatsi2008-05-24

This is a fantastic tip = thank you!

bigredcanuck (author)2007-06-13

Well I know wallyworld sells the reflective mylar emergancy blankets in the sporting goods dept for around 2 bux apeice. They are pretty big ones too.

ElMarko (author)2006-07-16

Several things 1) It looks like you uset that thin polyethylene foam usually used to wrap stuff for shipping on the back. What kind of store sells it? 2) I considered using black neoprene on the back so I could turn them around in winter but had to give it up. That stuff is expensive and for some reason my cats love to chew on neoprene. It's the only synthetic foam they'll eat. 3) I tested the IR opacity of the blanket with my Palm Zire and TV remote and it doesn't seem all that efficient.

laernmoer (author)ElMarko2007-05-14

1) the reflective material is from a 100 yen shop here. I don't remember where I've seen similar things in the US. This is used for preventing heat from running through your floor to your subfloor. They have electric mats that are used to warm your house. 2)I went for "cheap as possible" 3)I don't know the IR opacity here, it seems pretty good with my curtains.

radiorental (author)2006-06-19

this is a really good idea although I suspect you might not notice much difference in the average temp in your house. I run a simple fan in our room at night. I know it uses less electricity than an ac unit but not sure how much. One very 'cool' trick is to have a)have the fan point at the bed, near the bed b)a spray bottle near to hand c)squirt water in the direction of the fan It will blow back in the form of a cool mist that is very refreshing. I know the residents on the island of Corsica in the mediterranean keep a cotton sheet in a bucket of water beside their bed. They wring it out and sleep under that till it dries... rinse and repeat. I've tried this and it works really well on the very hot nights.

iv done this as well works great till your bottle runs dry/your fan shorts out XD i like this idea alot iv been trying to think of ways of keeping my house cool and this is by far the best one yet. one little thing, it may be summer in japan, but in the states its gettin cold and wintery..... this conversations making me really thirsty

laernmoer (author)radiorental2006-06-19

The idea behind keeping the light out is to make sure that the sun doesn't heat up the interior surfaces of our apt. We are in Japan, and the issue with using water to cool yourself is that the humidity here can sometimes get up to 70% with near 40's (C) temps. Water is something you really don't want to have around you when it's humid. I come from Southern California, which is hot and dry, so I know that the evaporative technique is great (-: used to use it on my T-shirts to keep from dying in college.

Trans_Am (author)2006-07-30

-15C? pah! We get -35 to +35! This may defeat the purpose, but having good insulating windows helps. Also, if you have an underground basement, shut all the AC vents down there, so that the AC blows the cold to where it's needed, upstairs.

fourthjinn (author)2006-06-20

Hey, brilliant idea. I also live in a country where we suffer from high heat coupled with high humidty. However, in winter, we suffer from freezing cold (30ish in summer, -15ish in winter). I think that these curtains would be awesome in winter in order to maximize passive solar heating of the house. Simply let the sun shine in through the window during the day, and close close the blinds at night (with reflective side facing inwards) to conserve the heat produced by the sun and your heating system (electric, gas, etc).

TossManual (author)fourthjinn2006-06-30

This is exactly how I lived in Atlanta. I turned off the heat and never used it during my years there. It helped that I was sandwiched between two floors (so I received the benefit of my downstairs neighbor's heat and upstairs insulation), but the insulating curtain was a major factor. I had a South-facing window, so my curtain was up against the window frame (grommets, if I remember correctly) to seal very well. During the Summer, I would set the AC to go on one hour before I got home and it would be wonderful by the time I did. Doesn't work if you have a loved one at home during the day, I suppose...

jayKayEss (author)2006-06-29

This is a fantastic idea! I live in NYC, where it's hot and muggy pretty much 24/7 during the Summer. I'm trying to be green and live w/out A/C this year, but so far it's been hellish. I'm going to try for during the day while I'm at work. I suspect the emergency blankets would work really well spray-mounted to bamboo roll shades.

laernmoer (author)jayKayEss2006-06-29

good idea - that might actually make the interior surface look a little more aesthetically pleasing.. wish I'd thought of that. oh well.

Cristian Lavaque (author)2006-06-20

I understand that an awning is even more efficient than curtains to prevent interior heating by sun.

I only wish the architects of our apt thought the same way.

Chicken Buddha (author)2006-06-28

For the outside walls, we bought some bamboo screening that you can get at just about any large home center. I think it was about $15 for a roll that was 8'x8'. We tacked it directly to the overhang, but it could just as easily be tacked to the outside wall. It worked wonders!

meddler (author)2006-06-26

I don't know how this would work in a humid climate, but in idaho it's fairly low, i took a 5 gallon plastic bucket with a broken bottom and sawed the bottom off with a jig saw. then i froze a gallon milk jug full of water and set it laying down on a towel in the bucket(that was laying on it's side)i aimed it at thew bed and put a small fan behind the jug and turned it on. My wife says it works great, which is who i did it for.

trebuchet03 (author)2006-06-19

I'm also in a hot excessively humid climate... Yes, running a fan is much cheaper than your a/c (compressors require rridiculous amounts of energy to operate)... Spending the time to seal up your house works well too ;) You can also use peel/stick plastic tinting (never tried, but a friend did). Cooking outdoors helps too... less heat inside the house. I always wondered why refrigerators did not have a vent to outside. Why cool air inside your icebox just to heat your house and then eventually cool that again?

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