I put curtains on my wall and it made all the difference (keeping cool in hot conditions)

When I was a kid, there were several people who were from the 19th Century.  The one thing they all had in common is that most rooms had curtains on the wall.  This seemed so silly to me, something medieval perhaps.  Curtains are for windows and maybe 10 inches either side.  Not for walls.

But now I wonder if they were on to something.  Time to experiment.  

Well, I have a problem with one bedroom in the house.  The room is West-South-West facing and, if it has any insulation at all, it's unlikely to be above an r4 given when it was built.  The windows and hidden wood in the wall around them were upgraded to modern standards, but the wall was not. The sun gets fully on this wall from about 3pm to sunset (10-ish) and the room is easily 90-100F (35-40C) by the end of the day.  It's even worse on those rare occasions when the world outside gets over 30C during the day!  

We've tried a lot of different things.  The potted Yuzu trees have done a lot to help as too has hanging a bamboo shade from the eves outside.  honeycomb blinds on the window shut just before the sun hits, then open again after sunset.  All help get it to the temperatures I listed above.  Without this, I don't know how hot it could get.

It's also one of those walls that radiates cold back into the house in winter.  Insulation is so important.

But what do we do if we can't open up the wall and stuff it full of the insulation that should be there?  

When we replaced the curtains for the window, I got extra ones.  The math didn't math well, so it was cheaper to get four panels of blackout curtains too big than to get two the right size for the window.  I put the rod up high next to the celling so the curtains wouldn't cover the heater.  And went wall to wall.  The entire wall, except the heater (and the space around it for safety) is now covered by blackout curtains.  They aren't even fancy heat stopping ones.  Just light weight and light stopping.  

It's shocking what a difference this has made.

The room very seldom gets to 80F at the hottest and stays closer to 72F (sorry, inside temperature is still mostly F in Canada - something like 20 to 26C maybe) .  Even if I forget to close the curtains over the window during the heat of the day, they block so much heat coming in through the walls that it makes a significant difference.

I had imagined they would be useful in the winter, but I didn't believe they would do so much good in the summer.  Maybe they knew something useful back in the 1880s when wall curtains were all the rage?

I have this drafty rental's windows covered with blankets in winter, I keep them in place over the summer  too, pull them on scalding hot days. Anything that blocks the cold coming in the windows blocks the heat coming in them too.
We also have quilts hung "decoratively" in this place, yeah, that's it, just decorative. No... it keeps the cold walls warmer.

R Ransom: Time to weave a classic tapestry! That's WHY they made them. Castle walls are COLD.

My sons room is small and the only one that doesn't get shade in our 100 year old poorly insulated house. Il have to try this out and see if there's much of a difference in there. I have him sleep downstairs in the summer cause I worry about the heat otherwise.

I'm really encouraged to read this because I have a similar problem in the front room of our house. The southwest corner wall is either terribly hot or cold to touch depending on the season. Like R, I question whether there is insulation in that corner. I've been wondering if a fabric covering would help. it seems like I need to try this! Covering the large window with a quilt + thermal curtain liner + mylar reflective blanket has helped a lot, but I still need to tackle that corner.

r ransom wrote:When I was a kid, there were several people who were from the 19th Century.  The one thing they all had in common is that most rooms had curtains on the wall.  This seemed so silly to me, something medieval perhaps.  Curtains are for windows and maybe 10 inches either side.  Not for walls.

But now I wonder if they were on to something.  Time to experiment.  

Well, I have a problem with one bedroom in the house.  The room is West-South-West facing and, if it has any insulation at all, it's unlikely to be above an r4 given when it was built.  The windows and hidden wood in the wall around them were upgraded to modern standards, but the wall was not. The sun gets fully on this wall from about 3pm to sunset (10-ish) and the room is easily 90-100F (35-40C) by the end of the day.  It's even worse on those rare occasions when the world outside gets over 30C during the day!  

We've tried a lot of different things.  The potted Yuzu trees have done a lot to help as too has hanging a bamboo shade from the eves outside.  honeycomb blinds on the window shut just before the sun hits, then open again after sunset.  All help get it to the temperatures I listed above.  Without this, I don't know how hot it could get.

It's also one of those walls that radiates cold back into the house in winter.  Insulation is so important.

But what do we do if we can't open up the wall and stuff it full of the insulation that should be there?  

When we replaced the curtains for the window, I got extra ones.  The math didn't math well, so it was cheaper to get four panels of blackout curtains too big than to get two the right size for the window.  I put the rod up high next to the celling so the curtains wouldn't cover the heater.  And went wall to wall.  The entire wall, except the heater (and the space around it for safety) is now covered by blackout curtains.  They aren't even fancy heat stopping ones.  Just light weight and light stopping.  

It's shocking what a difference this has made.

The room very seldom gets to 80F at the hottest and stays closer to 72F (sorry, inside temperature is still mostly F in Canada - something like 20 to 26C maybe) .  Even if I forget to close the curtains over the window during the heat of the day, they block so much heat coming in through the walls that it makes a significant difference.

I had imagined they would be useful in the winter, but I didn't believe they would do so much good in the summer.  Maybe they knew something useful back in the 1880s when wall curtains were all the rage?

That's a really interesting observation. I always thought wall-to-wall curtains were mostly decorative in older homes, but your results make a lot of sense. It sounds like they're adding an extra insulating layer that helps slow down heat transfer. With older houses where opening the walls isn't practical, this seems like a surprisingly simple solution. I'd be curious to hear how well it works once winter arrives too.

The longer I use this, the cooler the room seems to get.  I think it was storing a lot of heat in that room.

As mentioned, it was cheaper to get 4 panels instead of two needed for the window. I didn't attach them together yet, and found that having 3 panels on one side, a gap where the window opens, then the last panel covering the wall works best.  So far.  Many more experiments to do.

I've been putting tight mesh shade cloths and tarps on the outside of our uninsulated exterior walls and it helps a lot! Anything that can prevent the direct sun from hitting the house is a win for me during hot days. The key to preventing house heating during summer is preventing light from hitting the house/entering windows (the other is not having a hot black roof). For cold days blankets and quilts are also in the windows but I have to be careful to check the window/quilt gap space for mold because condensation can hang out in there. My dream is to have shaded porch/greenhouse areas around the entire house and a white/reflective roof but those are long term plans. Photo (not mine, from www.sevendaysvt.com) for inspiration:

Leigh Tate wrote:I'm really encouraged to read this because I have a similar problem in the front room of our house. The southwest corner wall is either terribly hot or cold to touch depending on the season. Like R, I question whether there is insulation in that corner. I've been wondering if a fabric covering would help.

Indeed!! I also have one of these walls. It gives us more trouble during the winter, when it gets covered in condensation during the night (and then molds).
I wonder if putting a curtain over this wall would minimize the condensation (less direct 'shock' between the cold wall and our humid warm breath at night). Right now we're in a warm snap but the cold is coming back on Wednesday, I might have to experiment.

Tereza Okava wrote:Indeed!! I also have one of these walls. It gives us more trouble during the winter, when it gets covered in condensation during the night (and then molds).
I wonder if putting a curtain over this wall would minimize the condensation (less direct 'shock' between the cold wall and our humid warm breath at night). Right now we're in a warm snap but the cold is coming back on Wednesday, I might have to experiment.

I suspect that having a curtain would make the condensation issue worse unfortunately - In winter the curtain would keep the warmth of the room away from the wall, but not the humidity in the air, so the wall would be cooler so you'll probably get more condensation. Added to that there would be less ventilation, so the wall would dry out even less It's complicated. You probably need the curtain (insulation) on the outside of the wall to keep the whole wall warmer, or a vapour proof barrier in the curtain and really sealing that around so the air can't get to the cold surface at all (difficult to achieve in practice).
The curtain would make your room warmer though! Maybe if you had the curtain up at night and open in the day to let it dry out again, like with window curtains, it might be OK?

Nancy Reading wrote:I suspect that having a curtain would make the condensation issue worse unfortunately - ....
The curtain would make your room warmer though! Maybe if you had the curtain up at night and open in the day to let it dry out again, like with window curtains, it might be OK?

Oh boo. We already put in unholy amounts of effort with this room in the winter (dehumidifier/fans and window drying every single day). Too bad it's the room we sleep in (under lots of covers) and it's kind of necessary!! Unfortunately the outside of that wall is in someone else's yard, so there's not a heck of a lot I can do about it.

Interesting. If it only got to 80 inside, what was the outdoor temperature? Apology if I missed that.

Cara Cee wrote:Interesting. If it only got to 80 inside, what was the outdoor temperature? Apology if I missed that.

It's usually less than 30C in the summer.

But even at 25C, the room gets over 80 or 90F (inside temp still has F in much of canada) depending on how long the heathas been around.  

We had a few 35C days this week.  The room stayed about the same temperature,  maybe as much as 75 on the day when it was over 37c.  It would normally be well over 100f with that outside temperature pre-drapes.

These flimsy drapes are making such a huge difference.

But also, I suspect the modern windows have an r value of something like 9 vs the r value of 4 the wall has.  The energy audits focused on windows, but it was the wall all along causing the problem.

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Curtains on beds have been a thing....     Sorta a tent in wide cold rooms.

Wow, so at only 77F it gets that hot inside? Is it a concrete house?
Anyway, I'm sorry  about the heat, but glad the curtains worked!

Good tech indeed. I'm lucky enough to have great insulation, but oversized textiles still make a huge difference around doors/windows.

I clamp old sheets or drop cloths to the fascia outside the east and west windows during unusually hot weeks.

I also have some harbor freight magnet strips above all doors that open directly into the main spaces of the house, and some pretty factory-made quilts that I've sewn metal washers into one hem of. So putting up the door-cover in extreme weather is as simple as throwing the metal edge of the quilt in the general direction of the magnet.

For the walls themselves though, I was raised to recognize full bookshelves as the best form of insulation from a "how good is it to have this around" perspective. So the first intervention I'll reach for will always be a bookcase and more books, and then curtains can go over those if they have to