11 Cheap Ways to Block Heat from Windows or Doors

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Published: Last Updated on
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While there are plenty of cheap ways to block heat from windows and doors, some are certainly more attractive than others. But if looks aren’t important, you can block heat almost for free.

In this article, we’ll look at the best way to block heat from windows and doors along with plenty of DIY options.

Understanding Heat Transfer

Sunlight (and, by extension, heat) feels hotter through glass because of its properties. Glass isn’t a great conductor of heat, but is an amazing conductor of light – that’s why we use it.

Light passes through the glass and turns into heat energy. This then can’t escape, meaning it sits in the air around your glass windows and doors. It’s why heat feels hotter in front of a window than elsewhere.

So, the main reason why heat enters through windows is because of direct exposure to the sun, but also to hot air. If you’ve got a balcony or veranda, the floor material can make a big difference, too.

In sunny areas, we often choose flooring based on its reflective properties. After all, the last thing we want is a hot floor when walking on it. But it has to reflect this heat somewhere, such as into your home.

Shiny and light-colored floors reflect heat the most, while dull and dark floors absorb it. Wood is a decent absorber of heat, but varnished or painted wood will generally reflect it. Similarly, tiles reflect heat, whereas natural stone often absorbs it.

The bottom line is that your outdoor area could be a big contributor to the heat entering through your windows or doors. We’ll offer some suggestions below to combat this, and you can also check out our dedicated article on ways to cool down your outdoor space.

11 Cheap Ways to Block Heat from Windows or Doors

1. Blackout blinds

Arguably the best way to block heat from windows is with blackout blinds. They’re designed to block up to 100% of light, which also blocks heat. Of course, this does mean sitting in the dark, but it’s a small sacrifice if your home is too hot.

2. Aluminum foil

If looks are not at all important and you want to spend almost nothing, covering your windows with aluminum foil is the next best option. Foil reflects heat, which is generally why we use it in cooking. This also makes it ideal for covering your windows.

It’s also one of the quickest and most convenient options since it’s very likely that you already have some on hand, so it’s a great hack if you want something done ASAP.

Again, it’ll block out light, and does look awful. Think about your neighbors, too, as shiny foil could blind them or make a nearby building much hotter thanks to all the light it reflects.

3. Shade sail/awning

As mentioned, your outdoor area could be making your heat problem worse. So, one of the best cheap ways to block heat from windows is to use a shade sail. You could buy one or make it yourself. We have a guide on DIY balcony shades, so check that out if a DIY project is more your style.

Adding an outdoor awning is another option. Awnings will be pricier than most other options on this list, though.

4. Bubble wrap

Bubble wrap is a surprisingly good heat insulator. The little air pockets trap heat and stop it from transferring through the material. Again, it won’t look the best, but it can reduce heat transfer by up to 50%.

The advantage over aluminum foil is that it’ll let in light, too. Also, you can get it for free, and it’ll insulate in the winter. Overall, it’s perhaps the best way to block heat from windows for free.

5. Cellular blinds

Cellular blinds basically have small pockets (cells) of air in the middle. Like bubble wrap, these insulate and so reduce heat transfer. In fact, cellular shades can reduce heat transfer by up to 60%.

6. Hanging blankets

If you’re looking for an immediate and short-term solution, hang some blankets over your windows and doors. Quilted fabric will be the best option because it has several layers, which trap heat. Securing it in place is the only issue, but you could use anything from a curtain rail to tapes or hooks.

7. Window film

If aluminum foil really isn’t for you, consider using reflective window film. It does the same job but will still let some light in while blocking up to 80% of the sun’s glare. You can also get tinted or frosted window films, which let in light but aren’t the best way to block heat from windows.

8. Get a rug

Putting a rug on your balcony can help reduce reflection from the floor. The color doesn’t really matter, as fabric isn’t as reflective as materials like stone or tiles. Of course, if you want it to remain cool, choose a lighter color.

9. Use plants

Plants are almost perfect for blocking heat from your windows. After all, they absorb it for energy, so it’s the best of both worlds. The EPA states that plants can reduce temperatures by up to 9F. You’ll want something fairly tall, but this could also act as a natural privacy screen.

10. Set up an umbrella

Much like setting up a shade on your balcony, an umbrella is one of the better cheap ways to block heat from windows. Unlike a shade, you can take it down when it’s not needed, although that does mean finding somewhere to store it.

11. Shut the curtains

This is a bit of a no-brainer, but it’s one of the best cheap ways to block heat from windows. Simply shut the curtains. They prevent light and heat from entering the room, instead trapping it near the windows. Blackout curtains work best, although any kind of insulated curtains will be fine.

If you’re after an inexpensive solution, check in thrift stores for velvet drapes. They’re usually lined, meaning they’re very thick.

Final Thoughts on Blocking Heat from Windows or Doors

The best way to block heat from windows or doors is to use either a reflective or insulating material. If you want the cheapest option, it’ll be aluminum foil or bubble wrap.

Of course, neither looks great on your windows, so consider splashing out on something more exotic like window film or new blinds. It might seem like a bit of an investment, but it should save you some good money on your AC bill.