A Homemade Solar Window Heater

A sash window in Paddington, City of Westminst...

Image via Wikipedia

You can turn any window in your house into a homemade solar window heater. It is recommended that you use a window that’s facing south.  You could use an east or west facing window, but it won’t be as effective as a southern-facing one (assuming that you live in the Northern Hemisphere).

You’ll also need:

  • a piece of corrugated cardboard
  • black paint
  • a paintbrush
  • a knife or scissors
  1. The first step is to cut the cardboard to the size of your window. The corrugated cardboard must cover both top and bottom panes of the window. Be sure that the corrugation runs vertically, with the holes at the top and the bottom.
  2. Once you’ve cut it into size, paint the corrugated cardboard black. Be sure that you don’t get paint inside the corrugation holes. These are needed for proper air flow, once you put the cardboard in place. Let it dry before handling it again.
  3. Now take out the window screen. This will give your homemade solar window heater more space, and at the same time increase the amount of solar energy it can absorb, and will therefore increase its effectiveness.
  4. Once the paint dries, slide the black cardboard into the window, with the black side facing the outside. The cardboard should be between any storm windows and the inside glass panes. In this way, it will be protected from rain and dew.
  5. The bottom of the corrugated cardboard must be raised above the window sill. The distance should just be enough to allow air to flow into the corrugation holes. You can use anything to prop up the cardboard, as long as it doesn’t block the holes.
  6. Now that the cardboard is in place, open the window panes on the top and bottom – about one inch is fine. This opening will allow the air to flow in the bottom, go through the slots of the cardboard (where the air is heated) and then exit out at the top of the window and come back into the room. When the sun is out, open the windows, but remember to close them at night or else you’ll be letting cool air in.

If you think that the cardboard makes your room ugly, you can easily take the homemade solar window heater out and store it nearby. You can also decorate the cardboard with something attractive to make it look better.  If someone is in serious need of saving on energy bills while keeping a room warm, this might be the most cost-effective solution for them, in which case the aesthetics of the matter will not be their top priority.

This simple yet effective homemade solar window heater might be the solution you’re looking for. It can help provide the heat you need, without causing you to spend more money on energy.

By | 2017-03-10T05:10:28-08:00 July 18th, 2009|Alternative Energy|

About the Author:

Grace is a writer for Living Clean, LLC.


  1. Matt September 20, 2011 at 4:12 am

    these instructions are a little unclear.
    Does anyone have any graphics or photos to share to explain the process step by step fro my dummy self?
    Many thanks.

  2. Romy @ Natural Gas Heaters December 11, 2009 at 3:09 am

    i also live in a house that is a little hard to keep warm during winter, because of the large rooms. I wonder if this is practical for big rooms, and large windows…does it do its job?

    If we think about it, it should do great with large windows, as it has more heat coming in…no?

    I would like to try it, but I didn’t quite understand how to put it in practice, maybe some drawings would come in handy..

    Anyway thanks for the info..


  3. Chloe Maclaren Triumph August 26, 2009 at 9:15 pm

    Sounds like a great and easy way of saving on energy bills, but dont know if i could put up with the ugly looking window…i know you could try to decorate it nicely, but i just dont think it would help.

  4. JG August 16, 2009 at 4:23 am

    I cant wait to try this in the winter. I live in an old home that gets pretty chilly in the winter, this look great, Thanks.

  5. David@Wedding Photographer Nottingham August 6, 2009 at 10:30 pm

    I think you are right Andrew. I’ve visited a few countries outside of England and they don’t seem to put up with the cold indoors like we do, except for the Welsh; they don’t seem to mind either. I lived in Wales for a few years. Still, good sales for hot water bottles and cosy toes slippers here 🙂

    I think some of it may be to do with how border-line we are, regarding temperatures. We don’t really hit the coldest temperatures or the biggest floods. We have occasional freezes and occasional floods. As a result, it’s not economically viable to prepare for the worst, as it only happens a few times a year. So we don’t invest in snow ploughs, sufficient gritting machines, adequate heating, insulation or tire chains. The cost of these things would be very high. Instead we are incapacitated for a few days a year and during the colder months, lots of our old people, who cannot afford insulation or heating, die.
    When you see the maths, it’s hard to dispute the political decisions made but you are glad if your grandparents have a private pension and don’t have to choose between heating and food. The British disease is bronchitis. I do sometimes wonder if I could potentially live longer in Gibraltar. What do you think?

  6. Andrew August 6, 2009 at 1:26 pm

    That’s amazing. Probably it’s a better choice for those rooms with several windows. I’ve heard that people in England never use enough heating (or at least a lot less then I’m used to), so if I ever move there, I’ll might have to use this..

  7. David@Wedding Photographer Nottingham July 20, 2009 at 10:08 pm

    That’s pretty clever. I take it this is using windows that have secondary glazing with a traditional window to the outside? Am I understanding that correctly? Also, out of interest, why does the corrugation need to run vertically?

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