You ever reach way back into your brain and uncover something from the not-too-distant past that seems weirdly obvious yet isn’t popular anymore? That’s right, I’m talking about window awnings! You used to see these everywhere, especially on those cute brick ranches kitty corner to the house where you grew up - I’m sure that’s a universal experience. But lately, they’ve fallen out of fashion. And I would like to make the case that we should get them back. Quick programming note, I’m not gonna be recommending any specific kind of awning or product line or anything like that. I am not here to sell you anything ...YouTube ads notwithstanding... though I do like spreading ideas.
And awnings are one of those ideas that our ancestors figured out but as far as I can tell we just decided we’re too cool for these days. Which is ironic because window awnings keep you cool. That’s their point! Or at least, a central point. See, we like windows. [WIndows XP error sound] Maybe not that kind, but that kind is pretty universally liked. They let in natural light and allow us to look outside and see things.
But windows are also great big holes in walls which we only plugged with thin sheets of glass. While they have gotten surprisingly good over the years at keeping heat energy from moving through them, they’re still nowhere near as good as the thick walls which surround them. And, here’s the important bit to this video, they become a major source of heat gain when the sun shines through them. Ever heard of the greenhouse effect? That doesn’t just happen in greenhouses, it happens any time the sun’s energy makes it through a transparent window and into an enclosed space. Like your house. Once sunlight makes its way into your home, it lands on the stuff inside like flooring, furniture, et cetera.
That stuff absorbs the sun’s light energy which is then re-radiated into your home as heat energy. This heat gain from solar irradiance, in the context of buildings, is called insolation. Not insulation - but insolation.
Don’t look at me, I just work here. Thanks to recent innovations in coatings on the glass, a lot of this energy is reflected away and kept out of your home. But, fun fact, the sun is extremely powerful so even with really fancy windows there’s a lot of energy getting inside that ultimately becomes heat. Don’t take my word for it, just ask a cat.
In the winter months this warmth can be a pretty nice benefit, but in the summer months - it sucks. And our ancestors knew this. They figured out that if you designed a structure so that the windows couldn’t be in direct sunlight, then there would be no greenhouse effect and the interior of that structure would stay much cooler.
Those grand covered porches you see on fancy old houses throughout much of the Southern US weren’t just for enjoying the breeze, they kept the windows entirely shaded. In fact they kept pretty much the entire structure shaded. And it wasn’t just plantation houses - the galleries attached to historic French Quarter buildings also help keep the buildings cool.
Notice how the building is in direct sunlight here but almost the entire structure (other than the roof) is in shade. Of course, those examples have multiple purposes. I can’t earnestly say that shading windows was “the point” of a covered porch. It also created a pleasant outdoor space and protected windows and doors from the elements, allowing you to leave them open in a rainstorm. But we did recognize the value of that coverage. So much so that in the not-too-distant past, there were popular products for your home which provided the shade and cover of an opulent wraparound porch but with minimal materials and easy installation.
What products, you ask? Awnings! It appears these really came into vogue in the 1920’s. This 1927 article in Building Age and National Builder comes out swinging: “A Beautiful home which is devoid of awnings resembles a well dressed man without a necktie. The awnings give that finishing touch, just the last point to complete the proper taste.”
Seems like the author really likes awnings! But why? It’s all about keeping comfortable! “An awning on the porch permits the use of the porch when the hot afternoon sun is shining. They will keep the porch shady and pleasant, and this also reduces the temperature of the rooms adjoining the porch.” And here’s my favorite part: “The fact that the awning excludes the sun from the window glass is quite an important asset in reducing the temperature of the room, and in preventing the fading of wall paper and carpet.”
Sure seems like awnings are the cat’s meow! In 1925, Hal and Helen Davis wrote in Better Homes and Gardens “Awnings - they have such possibilities, such delightful possibilities, that foolish indeed is a house to go without them, if they can be afforded.” That’s right, we just got called fools by the Davis family! Honestly this article is a useful tool for understanding how they were spreading. It even breaks down the differences in awning configurations by locale and the pros and cons of various types. This used to be a big deal! And they were a selling point for your home - real estate firms are beginning to learn the value! Plus they’re just a fun accent piece. I mean, who wouldn’t want to flaunt their unusually picturesque nature with a cool set of Arabian Awnings? The spears really sell it. But hundred year old magazine articles are one thing and the real world is another.
How big were awnings really? Well, if you dingle around on the ol’ Streetview and visit practically any old Chicago neighborhood, you’ll find plenty of houses which still have exterior window awnings providing that overhang for shade, especially on South and West-facing windows. You can see in this image how effective they are: this side of the house is being hit with direct sunlight, but the awning is almost entirely shading the window below it. Thanks to that awning, the old front room is staying much cooler than it would without it. Many of these products also allowed you to leave windows open in the rain - at least if they were installed correctly and you had the right kind of window. They offered a lot of benefits! Yet despite remaining extant in various styles, the functional purpose of window awnings seems to have almost entirely left the public consciousness.
Why’d this happen? I’m gonna say it’s a mix of two factors: air conditioning and fashion. The advent of mechanical air conditioning diminished the importance of the passive tricks we used to rely on to keep cool. As more and more people started hooking up energy-consuming air conditioners to the power grid (boy I hope it can keep up with all that… sorry wrong topic). As more and more people got air conditioning, suddenly the temperature in their home was controllable.
And so long as those air conditioners were powerful enough to overcome the heat gain of solar irradiance, the awnings that previously helped keep us cool in a heatwave didn’t seem necessary any longer. And, technically, they weren’t. So, fast forward a decade or two, and new homes are getting built without them. No need for awnings when we can pump the heat right out! That meant that all the older homes with awnings started to look dated. And if there’s one sin in the fashion world, it’s looking dated.
As you can tell I take this very seriously. Beyond fashion, though, awnings on a home may very well have been a sign that the home didn’t have air conditioning, and I’ll bet many a realtor in the 1960’s suggested taking them down. "No one wants a house with awnings," they’d say, "those are for old fuddy duddies. And poor people."
And now, other than that one infomercial, awnings are largely forgotten. But dang it, I think it’s time for us to consider bringing them back. For one, I actually think window awnings are pretty cute.
Maybe not the aluminum ones that you still run across sometimes, though hey - they sure proved their longevity. But there are so many different styles of awning out there, plus many more to be discovered. And like those 1920’s people, I think window awnings offer a real way to put a personal touch on a home. And what’s cooler than a way to express yourself that also literally keeps you cool? There’s a lot to like about them! Heat waves would be a lot more manageable with window awnings keeping the sun’s heat outside your home, and day to day they save money on electricity bills.
How much money? Well, unfortunately, that’s not the easiest thing to answer. It's annoyingly hard to get an idea of how much heat energy is actually coming through a window when the sun shines through it. It depends on so many factors: your location on the planet, the direction the window faces, the time of the year, time of day, and of course the performance of the window itself all matter a lot.
Still, I wanted to give you some useful information so I reached out to someone who has access to modeling software which can predict the energy needs of a home. They took a typical house in Chicago and ran some numbers for heating and cooling demand while tweaking a few variables. There’s a lot of interesting stuff to cover here but what I want to highlight first is this: Doing nothing to the house but adding window overhangs reduced the annual cooling energy needed by 20%. That’s a big deal! But you’ll notice that other things had an impact, too. And if you notice even harder, you’ll see that those impacts were all double-edged.
In the past, I’ve mentioned Low-E windows. That’s kind of a catch-all term and doesn’t mean a whole awful lot on its own, but broadly it just means high-performance windows. And one of a window’s performance metrics is the solar heat gain coefficient. You can think of this as the percentage of the sun’s heat energy that makes it through the glass. There are windows on the market now with exceptionally low SHGCs: some windows don’t even let a quarter of the sun’s energy through, and those are great to have in warm climates where you rarely ever need to heat buildings. But they’re often not a great fit for us up North because over the course of a year we need more heat energy than we need cooling, and blocking the sun’s free heat doesn’t make much sense.
Notice that in our modeling, swapping out just the South facing windows to a lower SHGC dropped cooling demand a pretty similar amount to adding overhangs. But look what it did to the heating demand. It went up significantly because those windows are actually working against us in the winter. Our winters suck and some free heat from the sun is a very welcome thing. So there’s a tradeoff to changing the window’s thermal performance characteristics. And have you noticed what the lowest total annual power figure came from? Windows with high solar heat gain coefficients for free heating in the winter but which had overhangs to block sunlight in the summer.
That’s the beauty of awnings. We don’t have to make the choice between winter and summer performance when buying a window. We could use a window best-suited for winter heat gains and then in the summer just block the sun from hitting it with an awning. The reason why I’m making this video now is that, well, it occurred to me that there isn’t really a difference between a properly-installed window awning and some of the rather advanced home design techniques we see today.
Those with lots of money to spend when designing their new custom homes might get fancy and install different window types. One method I’ve talked about before is installing high heat-gain windows below an overhang so they provide that free heat in the winter but not in the summer. And then use low-heat-gain windows elsewhere in the house. That’s a cool idea but it’s a lot of work compared to slapping on an awning! And the best thing about slapping on an awning (besides how fun that is to say) is that it can be done cheaply and anywhere! Speaking of anywhere, here’s a clunky voiceover edit. I’m worried that I fixated too much on the scenario we face here and not enough on warm and hot climates.
Because even if you’ve got the best dang windows on the market with an SHGC of .2, five average-sized West-facing windows (I’m calling 3 by 5 feet average) are going to let in more than a kilowatt of heat for several hours every afternoon. That’s not far off from running a space heater on high, and when it’s 100 degrees outside that’s not the smartest move. For giggles I decided to look at some new homes getting built around Phoenix, Arizona and it’s frankly astonishing to me that in that climate there’s apparently no focus paid on window overhangs. Sure, back in the day we didn’t have the fancy glass we do now, but if window awnings were popular here in Chicago, where it’s really only hot 4… maybe 5 months of the year, it seems to me like there’s a lot of energy and money being wasted by not thinking of ways to keep windows in the shade.
Now, there's a couple of notes I want to add. Both myself and the person who helped me with the modeling here are a bit skeptical of some of the data it spat out. The impact of dark closed drapes when there’s already a 2.5 foot overhang seems really high, and the fact that those drapes by themselves are lowering cooling power more than the overhangs seems… impossible.
Drapes on the inside of a window don’t stop sunlight from passing through the window glass. At best, if they’re very reflective, they can push some of the sun's energy back out but having stood next to a West-facing window with a white roller shade, I can say from experience that that shade gets pretty stinking hot on summer afternoons. It is always better to keep the sun from coming through the glass in the first place, that way there is no greenhouse effect, so how this model is considering those factors seems a bit off. Really, if there’s one call to action I want to make here it would be that there needs to be more study on the effectiveness of window awnings. It’s quite strange how little information there is on this topic, and most of what I’ve found are claims from awning manufacturers so I’m not exactly taking them seriously.
But it does seem pretty obvious to me that if you can eliminate direct sunlight transmission through a window, then you’re effectively turning any window into a North-facing window no matter which side of your house it’s on. And that could make a dramatic difference in the warm parts of the year. Unless you’re in the Southern hemisphere in which case, strike that - reverse it. Now, it’s not like awnings don’t come with any drawbacks. Most obvious is that they make the interior of your home much darker during the day. If the awning is made of a translucent material you could still get plenty of filtered light coming through the window, but its entire purpose is to eliminate direct sunlight and if that’s something you or your cat appreciates, well a proper awning is going to eliminate it.
Although, I am quite curious about the potential effectiveness of a transparent awning made from glass with a really low solar heat gain coefficient. That might be a way to have the best of both worlds. And it would leave your view of the sky mostly unimpeded. Then there’s maintenance. The aluminum ones that still hang around were designed in response to the fiddle factor of fancy fabrics.
Those fabrics would fade with time and required periodic cleaning, and depending on the design of the support structure, removing the fabric from the awning could be a pain in the butt. A rigid awning made of aluminum mostly took care of these problems, and that’s most likely why they started spreading. Then again, materials science has improved dramatically since awnings went out of fashion, and some fabric awnings can be selectively deployed. A roller-awning can be retracted when you don’t need or want it, and don’t look now but throw some Wi-Fi and actuators into the mix and you’ve got yourself a Smart Awning that could deploy exactly as much as needed and stay retracted on cloudy days or in inclement weather.
The last main drawback to awnings that I can think of is pests. Through providing shelter for your window you’re also providing shelter for living creatures, and while I’d be pretty cool with a robin’s nest outside my window, a wasp nest is less cool. Then again, if the window is screened it’s not like that really matters all that much but I’ve dealt with my share of wasp nests and usually it’s best to not have to deal with them. But to be honest, all of those drawbacks seem pretty minor to me, and many of them aren’t even a thing all the time.
I can tell you that I would freaking love some awnings on my home - particularly on the West side. I’m still doing that thing where I only run the air conditioning in the overnight hours and one of the most interesting things that technique has revealed is the dramatic effect of the sun. On cloudy days, even though it might be quite hot outside, my home only heats up by 5 or 6 degrees Fahrenheit over the course of the day. But if it’s a sunny day at the same temperature, that just about doubles. Of course, not all of that is heat from the windows - the attic’s also getting stupid hot from the sun, and so are the walls.
So it’s not easy to isolate that variable. But I can say it is truly remarkable how quickly the rooms on the West side start to heat up once the sun reaches those windows. Awnings aren’t the only solution, of course. There’s been a whole bunch of Europeans just champing at the commenting bit to let you know all about those exterior roller shutters they’ve had over there for a while. Those are interesting, and they’re starting to be sold here, but I’m curious to know how hot those shutters get in the sun. When closed they seem to trap a bit of air between them and the window glass, so while I have no doubt they’re blocking the sun, it seems to me like the window will be getting quite warm as the shutters radiate their absorbed heat into that airspace.
I’d rather have an awning, then that heat isn’t trapped and I can still look outside! Then there are exterior blinds. I’m starting to see these spread, often on porches. They’re basically the same idea as Rolladen but usually fabric and not integrated into the window frame or anything. Again, those will absolutely do the job of blocking sunlight from hitting the window, but they also block the view when in use which awnings don’t, at least not the view out. If I seem gung-ho about awnings, well I am! I think they’re cool and have been tragically overlooked for the past half-century. Which brings me to one last thing. I live in a townhome which means if I wanted to install window awnings, I’d need to get the HOA involved.
And that’s not fun. So - circling back to that earlier call to action where I said we should do more research on them, if it turns out that window awnings actually could reduce a typical home’s cooling costs by 20%, then whaddya say we go ahead and neuter an HOA’s ability to forbid their installation? Or, if that sounds too extreme, at the very least force HOAs to offer an assortment of approved styles and colors. Something tells me we’re going to want to find more and different ways to keep cool as these heat domes keep happening, and if something as simple as a window awning is as useful as it seems to be, uhh we should probably encourage their use. Alright, well that’s it! If anyone out there is involved in evaluating building energy codes and all that fun stuff, please chime in with any info you might have on this topic. I really didn’t find anything specifically about awnings and how much they could reduce cooling costs, and from what I’ve heard there really isn’t much attention paid to the effects of window overhangs at all outside of hyper-nerd circles.
If window awnings were helpful before air conditioning, then surely they’re still helpful now. And given how a lot of new housing stock, even in places like Arizona, is getting built without window overhangs at all, either these new windows are miraculous marvels or we just kinda forgot the tricks of the past. Here’s to giving some of them another go. ♫ blisteringly smooth jazz ♫ …pretty universally liked. They let in natural light and allow us to look outside and see things! But… what was that? Probably nothing you heard but I stopped anyway. There’s gotta be two good takes in there.
I forgot how to tie a tie, I had to look it up! It’s been too long. Those grand covered porches you see on fancy… I am restarting this line. An awning on the porch permits the use of the porch when the hot afternoon sun is shining.
They will keep the porch shaft and pleasant, and this also reduces the temperature - I can skip the rest of this line because I already recorded the thing with the tie. That might be a way to have the best of both worlds. And it wood pfftehh…. [falls apart] [angry sigh] OK, so we gotta come up with some sort of pitch.
Oooh, pitch. Baseball! Awnings: like a baseball cap for your house! Or maybe.... AWWWWWW nings.
2024-07-16