Do You Really Need That Much Window Area?
August 26, 2023 10:08 AM Subscribe
Conduction, convection, and radiation through windows suck heat out of the house in winter and give it easy entry in summer. Cooling the heat caused by solar gain from a home's windows may be 50% of peak load. Limiting unwanted solar gains in summer, while keeping desired passive solar heating in winter can be a balancing act in some climates, but keep in mind solar impact on roof and wall temperature is lower in winter than summer due to shorter days and lower intensity sunlight.
Strategies to prevent unwanted solar gain? Interior curtains, exterior awnings and much more. Window awnings can reduce solar heat gain in the summer by up to 65% on south-facing windows and 77% on west-facing windows. Solar films can be exterior treatments or removable interior options.
Still in the construction phase? If you can orient your building along the east-west axis, it’s a lot easier to control the sun on the south, because it’s higher in the summer and lower in the winter. You can shade it when you want to and let it in when you want to. But the east and west faces of the building are a lot harder to control, because the sun is coming in laterally, and so it’s difficult to shade.
Strategies to prevent unwanted solar gain? Interior curtains, exterior awnings and much more. Window awnings can reduce solar heat gain in the summer by up to 65% on south-facing windows and 77% on west-facing windows. Solar films can be exterior treatments or removable interior options.
Still in the construction phase? If you can orient your building along the east-west axis, it’s a lot easier to control the sun on the south, because it’s higher in the summer and lower in the winter. You can shade it when you want to and let it in when you want to. But the east and west faces of the building are a lot harder to control, because the sun is coming in laterally, and so it’s difficult to shade.
Minor trick that’s done me a lot of good: summer vines planted in E or W wall window boxes. Shade outside the wall is better than inside, evapotranspiration is even more cooling, watching the dappled light is pleasant on a hot day, and it’s gone in the winter.
I’ve seen apartment buildings set up to do this for the whole wall many stories up but mostly with the system abandoned. If anyone has experience with one, working or failing, I’d love to hear about it.
If you manage the land outside a building there are longstanding techniques choosing trees of various leaf and shapes.
posted by clew at 11:11 AM on August 26, 2023 [8 favorites]
I’ve seen apartment buildings set up to do this for the whole wall many stories up but mostly with the system abandoned. If anyone has experience with one, working or failing, I’d love to hear about it.
If you manage the land outside a building there are longstanding techniques choosing trees of various leaf and shapes.
posted by clew at 11:11 AM on August 26, 2023 [8 favorites]
“Windows are just pretty holes in the wall.”
Sure, but ask the instructors if they lived underground with no daylight access at all... Humans need to protect themselves by living in some sort of box, but we're not freakin' moles.* I like having windows, both for the views and for cross-ventilation in cool-to-warm weather**. In a standalone house that's easier to do; unfortunately all I can afford these days is an apartment.
However, the main reason I chose this particular apartment is that it's specifically on not-the-top-floor northeast corner of the building. There's another building and a couple of trees on the east side that block a majority of direct morning sun (while still letting daylight in), and it's completely blocked off from southern and western sunlight. And it's got nice big - double-paned - north-facing windows in the living room and main bedroom. *And* a small covered deck on the north side, which gives me a place to use my electric smoker and a pleasant place to relax and read on nice days. Construction-wise the building could be more energy-efficient, but so far at least, where I live the weather doesn't get as extreme as it does in lots of other places. I mean, it's still a crappy apartment with plenty other issues, but I can appreciate that much about it.
* Well, most of us anyway.
**Granted, the percentage of days like that in a year is shrinking...
posted by Greg_Ace at 11:24 AM on August 26, 2023 [13 favorites]
Sure, but ask the instructors if they lived underground with no daylight access at all... Humans need to protect themselves by living in some sort of box, but we're not freakin' moles.* I like having windows, both for the views and for cross-ventilation in cool-to-warm weather**. In a standalone house that's easier to do; unfortunately all I can afford these days is an apartment.
However, the main reason I chose this particular apartment is that it's specifically on not-the-top-floor northeast corner of the building. There's another building and a couple of trees on the east side that block a majority of direct morning sun (while still letting daylight in), and it's completely blocked off from southern and western sunlight. And it's got nice big - double-paned - north-facing windows in the living room and main bedroom. *And* a small covered deck on the north side, which gives me a place to use my electric smoker and a pleasant place to relax and read on nice days. Construction-wise the building could be more energy-efficient, but so far at least, where I live the weather doesn't get as extreme as it does in lots of other places. I mean, it's still a crappy apartment with plenty other issues, but I can appreciate that much about it.
* Well, most of us anyway.
**Granted, the percentage of days like that in a year is shrinking...
posted by Greg_Ace at 11:24 AM on August 26, 2023 [13 favorites]
Growing up in India, summers meant fully open windows and ceiling fans at full blast. These aren't ornamental ceiling fans like you occasionally see in the US; Indian ceiling fans blast a lot of air and you have to use paperweights to keep papers from blowing off desks, etc. Yet they only consume about 70W per room, about a tenth of a window-mount air-conditioner unit.
The US is much more oriented towards air-conditioning, which (unless you are using a heat pump) is about 10x more energy-hogging than ceiling fans.
posted by splitpeasoup at 11:30 AM on August 26, 2023 [11 favorites]
The US is much more oriented towards air-conditioning, which (unless you are using a heat pump) is about 10x more energy-hogging than ceiling fans.
posted by splitpeasoup at 11:30 AM on August 26, 2023 [11 favorites]
My house faces west and is a prime candidate for awnings. Alas, the HOA, citing the covenants, does not allow awnings. We can’t tint our windows, either.
posted by Thorzdad at 11:41 AM on August 26, 2023 [5 favorites]
posted by Thorzdad at 11:41 AM on August 26, 2023 [5 favorites]
echoing Greg_Ace; we're not interested in living in a cave.
In the 30+ years we've owned our little house, we've replaced EVERY window and door. Modern double- and triple-glazed windows are much more efficient. We are also believers in ceiling fans; we have 5 of them in the house.
Our secret weapon is trees; our lot has trees to the southwest and west of it, so the back of our house is in shade on summer afternoons. And I give thanks daily that HOAs aren't a thing around here.
posted by Artful Codger at 11:48 AM on August 26, 2023 [10 favorites]
In the 30+ years we've owned our little house, we've replaced EVERY window and door. Modern double- and triple-glazed windows are much more efficient. We are also believers in ceiling fans; we have 5 of them in the house.
Our secret weapon is trees; our lot has trees to the southwest and west of it, so the back of our house is in shade on summer afternoons. And I give thanks daily that HOAs aren't a thing around here.
posted by Artful Codger at 11:48 AM on August 26, 2023 [10 favorites]
Looks like some of this is from a Southern Hemisphere perspective. If you feel like your North and South seem mixed up.
posted by ovvl at 11:54 AM on August 26, 2023 [2 favorites]
posted by ovvl at 11:54 AM on August 26, 2023 [2 favorites]
I will never forget the convenience of a shutter I saw in France that had a gap between it and the window, allowing the window to stay open while keeping the sun out. I wish that kind of thing were more common in the US.
We've planted a number of trees on the South and West sides of the house, but it's going to be a number of years until they provide enough shade to lower the energy bills. Even the quickest growing tree only grows so fast. But the roof will remain dark and heat absorbing for the foreseeable future unfortunately. I get the feeling whichever company gets the infrared reflecting paint to market at a low price first will make billions of dollars. Betting that the city of the future will be a high albedo cold island.
The naked person losing heat to window image from the first link is perfectly balanced between tasteful and silly, if only all heating and cooling pages could make their point so artfully!
posted by ockmockbock at 12:31 PM on August 26, 2023 [1 favorite]
We've planted a number of trees on the South and West sides of the house, but it's going to be a number of years until they provide enough shade to lower the energy bills. Even the quickest growing tree only grows so fast. But the roof will remain dark and heat absorbing for the foreseeable future unfortunately. I get the feeling whichever company gets the infrared reflecting paint to market at a low price first will make billions of dollars. Betting that the city of the future will be a high albedo cold island.
The naked person losing heat to window image from the first link is perfectly balanced between tasteful and silly, if only all heating and cooling pages could make their point so artfully!
posted by ockmockbock at 12:31 PM on August 26, 2023 [1 favorite]
The US is much more oriented towards air-conditioning, which (unless you are using a heat pump) is about 10x more energy-hogging than ceiling fans.
Typical US AC systems are heat pumps. However, they're usually only designed to cool interior spaces, dumping the heat to the exterior. More modern heat pumps can cool and heat. Yes, a heat pump in either mode will use significantly more power than a fan alone.
When I was a kid, we lived in the desert, and I often thought about somehow shading the roof to keep the house/attic/crawlspace from heating up and acting like a heat battery after dark. Neither me nor my family ever had the wherewithal to try such a scheme, and even if we did, it would have taken some significant engineering considering the typical high winds of the area, but I still think the idea is basically sound.
posted by 2N2222 at 12:46 PM on August 26, 2023 [6 favorites]
Typical US AC systems are heat pumps. However, they're usually only designed to cool interior spaces, dumping the heat to the exterior. More modern heat pumps can cool and heat. Yes, a heat pump in either mode will use significantly more power than a fan alone.
When I was a kid, we lived in the desert, and I often thought about somehow shading the roof to keep the house/attic/crawlspace from heating up and acting like a heat battery after dark. Neither me nor my family ever had the wherewithal to try such a scheme, and even if we did, it would have taken some significant engineering considering the typical high winds of the area, but I still think the idea is basically sound.
posted by 2N2222 at 12:46 PM on August 26, 2023 [6 favorites]
The US is much more oriented towards air-conditioning, which (unless you are using a heat pump) is about 10x more energy-hogging than ceiling fans.
Aside from using running water, aren’t all ACs heatpump of varying efficiency?
But yeah, it uses more power. Now you can have the keys to my car, but you’re not getting my windows, no way.
posted by WaterAndPixels at 12:51 PM on August 26, 2023 [1 favorite]
Aside from using running water, aren’t all ACs heatpump of varying efficiency?
But yeah, it uses more power. Now you can have the keys to my car, but you’re not getting my windows, no way.
posted by WaterAndPixels at 12:51 PM on August 26, 2023 [1 favorite]
We have heat pumps (which are becoming a de facto standard for heating in New Zealand, where I am). And solar panels. When it's high summer, I am powering the heat pumps for free to cool the house. Temperatures range from -2 or -3C lows in winter to 30C in summer so heat pumps are a good solution in these parts.
In pre heat pump days, I learned not to open the windows until after lunch... for some considerable time, it is cooler inside than outside, so don't let the hot air in!
If we were building from scratch or adapting to use more passive techniques I'd be investigating blinds and shutters for summer, to block the sun but allow air to move.
posted by i_am_joe's_spleen at 1:19 PM on August 26, 2023
In pre heat pump days, I learned not to open the windows until after lunch... for some considerable time, it is cooler inside than outside, so don't let the hot air in!
If we were building from scratch or adapting to use more passive techniques I'd be investigating blinds and shutters for summer, to block the sun but allow air to move.
posted by i_am_joe's_spleen at 1:19 PM on August 26, 2023
When I was a kid, we lived in the desert, and I often thought about somehow shading the roof to keep the house/attic/crawlspace from heating up and acting like a heat battery after dark. Neither me nor my family ever had the wherewithal to try such a scheme, and even if we did, it would have taken some significant engineering considering the typical high winds of the area, but I still think the idea is basically sound.
There have been a few people who have built houses under those open-sided pole barn structures that are used to shelter haybales and the like. It always seemed like a nice idea to me, assuming you lived out of town on the size of land where a pole barn looming over your house would look proportional.
posted by Dip Flash at 1:19 PM on August 26, 2023 [1 favorite]
There have been a few people who have built houses under those open-sided pole barn structures that are used to shelter haybales and the like. It always seemed like a nice idea to me, assuming you lived out of town on the size of land where a pole barn looming over your house would look proportional.
posted by Dip Flash at 1:19 PM on August 26, 2023 [1 favorite]
I often thought about somehow shading the roof to keep the house/attic/crawlspace from heating up and acting like a heat battery after dark.
Counterintuitive related design by Buckminster Fuller
posted by flabdablet at 1:24 PM on August 26, 2023 [20 favorites]
Counterintuitive related design by Buckminster Fuller
posted by flabdablet at 1:24 PM on August 26, 2023 [20 favorites]
I often thought about somehow shading the roof to keep the house/attic/crawlspace from heating up and acting like a heat battery after dark.
That reminds me of a house I lived in once, that had enough of a peak in the roof that someone (the builder? a previous owner?) had build a big-ass fan - maybe 4-5 feet across - in it, and a square bit in the hallway ceiling (the approximate middle of the house) with hinged louvers in it. When you turned on the fan, it pulled a massive amount of air in the open windows, through the house and the now-open louvers, and exhausted it outside. That helped keep the house and the attic crawlspace cooler...as long as the air outside wasn't hot enough to make it worse indoors even with a nice breeze. I wish more houses had that feature. Or at least proper ceiling fans like splitpeasoup describes.
posted by Greg_Ace at 1:32 PM on August 26, 2023 [5 favorites]
That reminds me of a house I lived in once, that had enough of a peak in the roof that someone (the builder? a previous owner?) had build a big-ass fan - maybe 4-5 feet across - in it, and a square bit in the hallway ceiling (the approximate middle of the house) with hinged louvers in it. When you turned on the fan, it pulled a massive amount of air in the open windows, through the house and the now-open louvers, and exhausted it outside. That helped keep the house and the attic crawlspace cooler...as long as the air outside wasn't hot enough to make it worse indoors even with a nice breeze. I wish more houses had that feature. Or at least proper ceiling fans like splitpeasoup describes.
posted by Greg_Ace at 1:32 PM on August 26, 2023 [5 favorites]
And solar panels. When it's high summer, I am powering the heat pumps for free to cool the house.
My next door neighbours have more than half their solar panels mounted on a west-facing roof pitch. At first I thought they'd done that purely because that happens to be the biggest rectangular piece of their roof, but in fact what it does is move peak production from their panels to roughly 3pm in summer, which is also about the time of peak cooling demand for their air conditioners. Smart people, my neighbours.
My own panels face north (southern hemisphere), so I just drop the thermostat and run the heat pumps hard a few hours before the afternoon outdoor temperature peaks, and keep the blinds closed. That keeps our interior completely comfortable as well, even though the temperature does vary more than next door's.
posted by flabdablet at 1:33 PM on August 26, 2023 [1 favorite]
My next door neighbours have more than half their solar panels mounted on a west-facing roof pitch. At first I thought they'd done that purely because that happens to be the biggest rectangular piece of their roof, but in fact what it does is move peak production from their panels to roughly 3pm in summer, which is also about the time of peak cooling demand for their air conditioners. Smart people, my neighbours.
My own panels face north (southern hemisphere), so I just drop the thermostat and run the heat pumps hard a few hours before the afternoon outdoor temperature peaks, and keep the blinds closed. That keeps our interior completely comfortable as well, even though the temperature does vary more than next door's.
posted by flabdablet at 1:33 PM on August 26, 2023 [1 favorite]
I know people who bought the incredibly sturdy shutters from Germany — Rolladen?— for other reasons but have been absolutely delighted with the not-heating effects. Also not-cooling in windy winters, as I understand it.
posted by clew at 1:34 PM on August 26, 2023
posted by clew at 1:34 PM on August 26, 2023
For what it's worth, I have west-facing French doors, and I'm very happy with the solar-powered solar shades I had installed over them. Been about five years now, and they really do help. There's still some heat gain through those doors, but it's only noticeable on days hot enough that the ambient temperature (rather than sunlight) is doing the heating.
My next roof (five or so years from now, probably) is going to be some form of solar-reflecting metal. Dark-colored asphalt roofs are ridiculous heat concentrators, and it really matters to the upstairs space where my home office and my rec space are.
posted by humbug at 1:34 PM on August 26, 2023 [1 favorite]
My next roof (five or so years from now, probably) is going to be some form of solar-reflecting metal. Dark-colored asphalt roofs are ridiculous heat concentrators, and it really matters to the upstairs space where my home office and my rec space are.
posted by humbug at 1:34 PM on August 26, 2023 [1 favorite]
Do You Really Need That Much Window Area?
Yes. Having lived in houses with hardly any windows, I now live in a house with tons of natural light and my mood is 1000% better.
posted by bondcliff at 1:36 PM on August 26, 2023 [13 favorites]
Yes. Having lived in houses with hardly any windows, I now live in a house with tons of natural light and my mood is 1000% better.
posted by bondcliff at 1:36 PM on August 26, 2023 [13 favorites]
To get an idea of how much heating your windows cause with direct sunlight shining in through them, use the rule of thumb that roughly a kilowatt of radiant power transits each square metre of near-ground-level area directly facing the sun. It will be less than that in high latitudes because of there being more air in between, but it's about right.
So if you've got a square metre of window directly facing the sun, and all the sunlight coming in through that window is absorbed by surfaces inside your house, then that's about a kilowatt's worth of heating power delivered to your interior. Yes, it will be a bit less than that unless your interior is completely black, but if you look at any picture of a house exterior in daylight you'll notice that the windows are the darkest-looking parts from outside; most of the light going in through the windows doesn't make it back out again.
Allowing direct sunlight in through two square metres of windows, then, is roughly equivalent to having one of these heaters running flat out, and lowering an interior or (better) exterior blockout covering over the window is equivalent to turning it off.
Arranging for your windows to face vegetation rather than the open sky will also make it much easier to cool your house in summer, just because so much of that incident kilowatt is going to be absorbed outside your house before the rest bounces in through the windows. Looking at vegetation is better for mood, too.
posted by flabdablet at 1:54 PM on August 26, 2023 [2 favorites]
So if you've got a square metre of window directly facing the sun, and all the sunlight coming in through that window is absorbed by surfaces inside your house, then that's about a kilowatt's worth of heating power delivered to your interior. Yes, it will be a bit less than that unless your interior is completely black, but if you look at any picture of a house exterior in daylight you'll notice that the windows are the darkest-looking parts from outside; most of the light going in through the windows doesn't make it back out again.
Allowing direct sunlight in through two square metres of windows, then, is roughly equivalent to having one of these heaters running flat out, and lowering an interior or (better) exterior blockout covering over the window is equivalent to turning it off.
Arranging for your windows to face vegetation rather than the open sky will also make it much easier to cool your house in summer, just because so much of that incident kilowatt is going to be absorbed outside your house before the rest bounces in through the windows. Looking at vegetation is better for mood, too.
posted by flabdablet at 1:54 PM on August 26, 2023 [2 favorites]
We’re in southern Arizona and our house is block, pretty much uninsulated, and it was built with single pane aluminum windows. The biggest window in the house is 6 feet by 4 feet, and it faces west. You can imagine what kind of problem that is in the summer. Even with two shade screens over it, and wood blinds that block out most of the rest of the light, it’s been brutal. In the winter you can feel cold air sheeting off of the window at night. Not too long back I found a video on YT of someone - in the same city no less - who replaced a window unblock and did a how-to video on it. There are four windows in that airspace, that big one, a 4 foot by 4 foot one, a 3 foot by 4 foot, and a 3 foot by 3 foot. Over the past few weeks, we’ve replaced all but the last one (we have the window, just haven’t gotten to that one yet) and I can’t overstate how much of a positive difference it has made. We have a temporary curtain over the big window right now while we find the blind we want for it, but even with nothing over it, with full sun in the hottest part of the day, almost no heat at all gets through now. We’re swamp cooled, so we’re kinda at the mercy of hoping there’s extremely low humidity and even then this past heat wave meant the best the cooler was gonna do was 85-90, so it still gets hot in the house, but it is not even remotely as bad as it was before.
posted by azpenguin at 2:01 PM on August 26, 2023 [3 favorites]
posted by azpenguin at 2:01 PM on August 26, 2023 [3 favorites]
When you turned on the fan, it pulled a massive amount of air in the open windows, through the house and the now-open louvers, and exhausted it outside.
My sisters and I dream of the ranch house we lived in for a few years with this set up. The eaves were massive and we could even have the windows open when it rained, and the attic fan gave us a nice breeze no matter what. The entire lot was heavily treed (oak, I think?), so long as it cooled off at night we could keep the house relatively cool most of the summer, even without AC. We didn't appreciate it at the time.
Our current house needs some more shade (working on it, yay for new trees!) And ideally we'll get a pergola or something for the patio to cut down on the sun hammering the sliding door in the evenings during the summer.
posted by ghost phoneme at 2:06 PM on August 26, 2023 [2 favorites]
My sisters and I dream of the ranch house we lived in for a few years with this set up. The eaves were massive and we could even have the windows open when it rained, and the attic fan gave us a nice breeze no matter what. The entire lot was heavily treed (oak, I think?), so long as it cooled off at night we could keep the house relatively cool most of the summer, even without AC. We didn't appreciate it at the time.
Our current house needs some more shade (working on it, yay for new trees!) And ideally we'll get a pergola or something for the patio to cut down on the sun hammering the sliding door in the evenings during the summer.
posted by ghost phoneme at 2:06 PM on August 26, 2023 [2 favorites]
That reminds me of a house I lived in once, that had enough of a peak in the roof that someone (the builder? a previous owner?) had build a big-ass fan - maybe 4-5 feet across - in it, and a square bit in the hallway ceiling (the approximate middle of the house) with hinged louvers in it. When you turned on the fan, it pulled a massive amount of air in the open windows, through the house and the now-open louvers, and exhausted it outside. That helped keep the house and the attic crawlspace cooler...as long as the air outside wasn't hot enough to make it worse indoors even with a nice breeze. I wish more houses had that feature. Or at least proper ceiling fans like splitpeasoup describes.
That's pretty common in places where simple air movement will do a lot of the cooling work - whole house fan
posted by LionIndex at 2:16 PM on August 26, 2023 [5 favorites]
That's pretty common in places where simple air movement will do a lot of the cooling work - whole house fan
posted by LionIndex at 2:16 PM on August 26, 2023 [5 favorites]
Have worked in multiple windowless basement offices (because us tech support folks are lesser people and don't deserve proper offices) and I cannot emphasize how horribly depressing it is or how much it screws up your metabolism - humans are engineered to be outside, or at least get some damn natural light. Sorry but I'm not giving up windows. Also energy-efficent windows are a thing, they are hardly "pretty holes in the wall".
posted by photo guy at 2:31 PM on August 26, 2023 [11 favorites]
posted by photo guy at 2:31 PM on August 26, 2023 [11 favorites]
With respect to whole house fans, I can recommend the products from QuietCool. They're not truly "quiet" -- it's more that they're not truly deafening like the older systems were. They work well, they're well-made, and the trick of putting the fan at the end of the flexible duct run makes them WAY easier to install.
posted by aramaic at 2:57 PM on August 26, 2023 [3 favorites]
posted by aramaic at 2:57 PM on August 26, 2023 [3 favorites]
I've been watching a lot of HGTV and other home improvement shows lately and thinking about how almost all of what's in style on those shows is terrible for efficiency - big open rooms with high peaked ceilings that are hard to heat and cool, huge windows, etc. Like the rich people who started the trend have the money for highly efficient materials and state of the art ventilation and a huge electric bill and then other houses ape the style bc it's trendy.
posted by subdee at 3:31 PM on August 26, 2023 [4 favorites]
posted by subdee at 3:31 PM on August 26, 2023 [4 favorites]
We have a lot of huge windows on the house but they're all shaded - either by the trees outside or the front or back porch, etc. I like that ivy trick though.
posted by subdee at 3:33 PM on August 26, 2023
posted by subdee at 3:33 PM on August 26, 2023
This is a WHOLE topic of which windows is just a small part. I recently built a house and windows were a large consideration where the standard designs assume you love huge windows in every room.
It starts with the block of land. For me the ideal block was in a dense estate, 16m x 31m deep and oriented along the north-south axis - the opposite of the typical advice, also repeated in the OP, which is to orient it along the east-west axis.
Yes, most summer sun comes in via east-west and winter sun comes in from the north (if you're in the southern hemisphere, flip it if you're in the north). So a building oriented along the east-west axis will ordinarily minimize summer sun and maximize winter sun.
However in a densely built block you want it the other way around. These narrow north-south oriented blocks ensure your neighbours maximize the width of their houses, so outside your east windows you have a 1 meter gap, then a 2 meter tall steel fence, then a 1 meter gap then your neighbour's house.
This allows you to have these large windows to let in natural light without being scorched by the direct sunlight in a 47°C summer day - every house is collectively shading each other from the summer sun. You can add a vine trellis and potted plants in that 1 meter half for visual interests.
The house is typically 14m x 26m on a 16m x 31m which gives you 7 meters in the north side as a backyard. This gives you a long enough approach that you're guaranteed unobstructed winter sun even up to the winter solstice. Also guarantees you can put in solar panels without any risk of being shaded by your neighbours. Put in large windows and triple stacker sliding doors to maximize the winter sun ingress, you can get sun reaching in about 8 meters deep.
On the south aspect, that only gets deep summer sun and is facing the street, that's where you put the double car garage, entry hallway. One room will be hit by direct summer sun but only for a few hours in the early morning or late evening so it's tolerable.
Bathrooms and showers don't need huge windows which you never leave uncovered anyway, that's just a loss of thermal efficiency for zero gain. I changed them to narrow but full width window slits across the top of the wall, so I could let natural light in and not need to have blinds installed maintained.
posted by xdvesper at 3:45 PM on August 26, 2023 [3 favorites]
It starts with the block of land. For me the ideal block was in a dense estate, 16m x 31m deep and oriented along the north-south axis - the opposite of the typical advice, also repeated in the OP, which is to orient it along the east-west axis.
Yes, most summer sun comes in via east-west and winter sun comes in from the north (if you're in the southern hemisphere, flip it if you're in the north). So a building oriented along the east-west axis will ordinarily minimize summer sun and maximize winter sun.
However in a densely built block you want it the other way around. These narrow north-south oriented blocks ensure your neighbours maximize the width of their houses, so outside your east windows you have a 1 meter gap, then a 2 meter tall steel fence, then a 1 meter gap then your neighbour's house.
This allows you to have these large windows to let in natural light without being scorched by the direct sunlight in a 47°C summer day - every house is collectively shading each other from the summer sun. You can add a vine trellis and potted plants in that 1 meter half for visual interests.
The house is typically 14m x 26m on a 16m x 31m which gives you 7 meters in the north side as a backyard. This gives you a long enough approach that you're guaranteed unobstructed winter sun even up to the winter solstice. Also guarantees you can put in solar panels without any risk of being shaded by your neighbours. Put in large windows and triple stacker sliding doors to maximize the winter sun ingress, you can get sun reaching in about 8 meters deep.
On the south aspect, that only gets deep summer sun and is facing the street, that's where you put the double car garage, entry hallway. One room will be hit by direct summer sun but only for a few hours in the early morning or late evening so it's tolerable.
Bathrooms and showers don't need huge windows which you never leave uncovered anyway, that's just a loss of thermal efficiency for zero gain. I changed them to narrow but full width window slits across the top of the wall, so I could let natural light in and not need to have blinds installed maintained.
posted by xdvesper at 3:45 PM on August 26, 2023 [3 favorites]
subdee, omg yes, those huge vaulted ceilings, whether in mcmansions or in the trendy multi-story loft apartment that is effectively one giant room soundwise.
And I both co-sign all the people who need natural light, I am one of them indoor all the time on Zoom people and need an apartment that has decent daylight, and also curse my past self for insisting on an apartment with lots of big windows. It's 10 degrees hotter than the outside temp in the summer and 20 degrees colder in the winter. I'm only exaggerating a little bit. I would prefer smaller windows and less being baked like a shrinky-dink all summer.
posted by spamandkimchi at 3:47 PM on August 26, 2023 [1 favorite]
And I both co-sign all the people who need natural light, I am one of them indoor all the time on Zoom people and need an apartment that has decent daylight, and also curse my past self for insisting on an apartment with lots of big windows. It's 10 degrees hotter than the outside temp in the summer and 20 degrees colder in the winter. I'm only exaggerating a little bit. I would prefer smaller windows and less being baked like a shrinky-dink all summer.
posted by spamandkimchi at 3:47 PM on August 26, 2023 [1 favorite]
We have mostly east-facing windows that go all the way up to the ceiling and I wake up in a panic at dawn to scurry around lowering windows (we use window fans at night to cool down the whole house), shuttering blinds, closing blackout curtains and most ridiculously putting up a giant reflective panel in the bedroom window before lying down and hoping that I can fall asleep and get another hour or two of sleep. It being the 46th parallel or so here, at the summer solstice that meant I was waking up at 5:15 am or so. I bought some interior solar film (spray water and apply!) to help cut down on the solar gain/unbearable daybreak.
(Shakes fist at my past self for insisting on lots of windows.)
posted by spamandkimchi at 3:54 PM on August 26, 2023
(Shakes fist at my past self for insisting on lots of windows.)
posted by spamandkimchi at 3:54 PM on August 26, 2023
@spamandkimchi right? It photographs well on TV but you can't feel the heat or cold through your TV set.
posted by subdee at 3:58 PM on August 26, 2023 [2 favorites]
posted by subdee at 3:58 PM on August 26, 2023 [2 favorites]
I often thought about somehow shading the roof to keep the house/attic/crawlspace from heating up and acting like a heat battery after dark.
Solar panels literally do this and turn the sun's energy into electricity.
The reality is that in a modern well insulated house, attic temperature doesn't really matter. Once you insulate the ceiling well enough to handle sub freezing temperatures, it also handles hot summers well enough, so there is usually no consideration given to cooling the attic.
Instead of shading the roof on the outside, it's typical here in modern construction to install insulation on the underside of the roof - called sarking. It's a foiled, heat rejecting semi permeable membrane that hangs an inch under the sloping roof that performs a triple role - it rejects radiant heat from the roof during hot days, it captures condensation from the underside of a cold roof at night in winter and channels it into your gutters, and it also serves as bushfire protection by stopping any embers from entering your roof space.
Most house losses during a fire are caused by embers entering the roof space via tiny gaps in the tiles. Tiles are not airtight and high winds with the air alive with burning embers will mean some inevitably end up inside the roof, particularly an old tile roof. Hence the single surviving house in Lahaina that had a modern steel roof.
posted by xdvesper at 4:02 PM on August 26, 2023 [4 favorites]
Solar panels literally do this and turn the sun's energy into electricity.
The reality is that in a modern well insulated house, attic temperature doesn't really matter. Once you insulate the ceiling well enough to handle sub freezing temperatures, it also handles hot summers well enough, so there is usually no consideration given to cooling the attic.
Instead of shading the roof on the outside, it's typical here in modern construction to install insulation on the underside of the roof - called sarking. It's a foiled, heat rejecting semi permeable membrane that hangs an inch under the sloping roof that performs a triple role - it rejects radiant heat from the roof during hot days, it captures condensation from the underside of a cold roof at night in winter and channels it into your gutters, and it also serves as bushfire protection by stopping any embers from entering your roof space.
Most house losses during a fire are caused by embers entering the roof space via tiny gaps in the tiles. Tiles are not airtight and high winds with the air alive with burning embers will mean some inevitably end up inside the roof, particularly an old tile roof. Hence the single surviving house in Lahaina that had a modern steel roof.
posted by xdvesper at 4:02 PM on August 26, 2023 [4 favorites]
A literally ancient approach is windows narrow but as tall as possible — they let light deep into the building. Roman public libraries, but it survives in library reading room designs even now.
posted by clew at 4:05 PM on August 26, 2023 [4 favorites]
posted by clew at 4:05 PM on August 26, 2023 [4 favorites]
We’re in southern Arizona and our house is block, pretty much uninsulated, and it was built with single pane aluminum windows.
Our first house had those same aluminum windows. I replaced them all with modern "low-E" windows that were much larger than the old windows, but even though they were larger they were vastly superior in terms of cold and heat. They also kept out noise much better.
posted by Dip Flash at 4:18 PM on August 26, 2023 [2 favorites]
Our first house had those same aluminum windows. I replaced them all with modern "low-E" windows that were much larger than the old windows, but even though they were larger they were vastly superior in terms of cold and heat. They also kept out noise much better.
posted by Dip Flash at 4:18 PM on August 26, 2023 [2 favorites]
Yes. Having lived in houses with hardly any windows, I now live in a house with tons of natural light and my mood is 1000% better.
I live in a home designed in the 1970, when they decided the answer was "no" and my house had 0 eastern windows and only 2 skinny western windows when I purchased it. It sucked. I've added like 6 windows in the past 15 years. Mine is actually one of the better ones- there are houses with zero windows on the north or south (front facing, depending on the side of the street) and they look horrible.
posted by The_Vegetables at 4:53 PM on August 26, 2023
Solar panels literally do this and turn the sun's energy into electricity.
The reality is that in a modern well insulated house, attic temperature doesn't really matter. Once you insulate the ceiling well enough to handle sub freezing temperatures, it also handles hot summers well enough, so there is usually no consideration given to cooling the attic.
Solar panels weren't really a thing when I was a kid. They were one of those "just around the corner" concepts for decades, before price per Watt came down into realistic territory. There used to be perhaps some kind of eco-fad using roof mounted solar water heaters back then. Are those still a thing? I haven't seen one in years. But yes, elevated PV panels very much do the shade job in addition to generate electricity.
The solar PV roofs on the other hand might contribute to the same problem as traditional roofs. Theoretically, good insulation should do the job. But in the real world in the deserts around here, I'd be giving you the side eye if you were trying to convince me. Considering how well trees perform can perform the function, I'd say whole house shade is still a good idea. Unfortunately, trees aren't easy or quick to do in the desert, either.
posted by 2N2222 at 6:03 PM on August 26, 2023 [1 favorite]
The reality is that in a modern well insulated house, attic temperature doesn't really matter. Once you insulate the ceiling well enough to handle sub freezing temperatures, it also handles hot summers well enough, so there is usually no consideration given to cooling the attic.
Solar panels weren't really a thing when I was a kid. They were one of those "just around the corner" concepts for decades, before price per Watt came down into realistic territory. There used to be perhaps some kind of eco-fad using roof mounted solar water heaters back then. Are those still a thing? I haven't seen one in years. But yes, elevated PV panels very much do the shade job in addition to generate electricity.
The solar PV roofs on the other hand might contribute to the same problem as traditional roofs. Theoretically, good insulation should do the job. But in the real world in the deserts around here, I'd be giving you the side eye if you were trying to convince me. Considering how well trees perform can perform the function, I'd say whole house shade is still a good idea. Unfortunately, trees aren't easy or quick to do in the desert, either.
posted by 2N2222 at 6:03 PM on August 26, 2023 [1 favorite]
I live in a home designed in the 1970, when they decided the answer was "no" and my house had 0 eastern windows and only 2 skinny western windows when I purchased it. It sucked. I've added like 6 windows in the past 15 years. Mine is actually one of the better ones- there are houses with zero windows on the north or south (front facing, depending on the side of the street) and they look horrible.
I see this a lot with new-ish construction, particularly from large builders, where there will be either zero windows on an entire side of a house, or just a couple of small windows. I'm guessing there are commercial reasons and it doesn't seem to hinder the sale of the houses, but it never looks ideal.
posted by Dip Flash at 6:39 PM on August 26, 2023
I see this a lot with new-ish construction, particularly from large builders, where there will be either zero windows on an entire side of a house, or just a couple of small windows. I'm guessing there are commercial reasons and it doesn't seem to hinder the sale of the houses, but it never looks ideal.
posted by Dip Flash at 6:39 PM on August 26, 2023
There used to be perhaps some kind of eco-fad using roof mounted solar water heaters back then. Are those still a thing?
Yes, it's also another one of those nuanced topics that can go on for several pages. Thermal solar hot water is about 3x more efficient than PV solar in producing hot water but come with several significant disadvantages and advantages which outweigh the pure efficiency considerations.
Main disadvantage is complexity, none of the solutions are what I would consider a robust solution for a homeowner. If you put the tank on the roof and use a thermosiphon with no moving parts, then you end up with a heavy tank on the roof which would require thousands of dollars of extra roof structure reinforcement during the build phase... negating any potential savings. Or you end up with a small tank with minimal insulation. If you use a regular ground mounted tank with a pump to move water between the panel and the tank, then the pump itself can fail mechanically, the temperature sensors can also fail. And the worst case is trying to install these panels where it gets below freezing at night - the water in the panels can freeze and burst your panels and pipes, leading to a sudden disaster of hot water coming out your roof at full mains pressure. In theory there are temperature sensors and pressure valves that prevent this but... will they still be good 10 years from now? How often do you do maintenance to check them? Also the heat losses through the glass panels are high and the system typically doesn't work much in winter - when you need it most.
Main advantage is that hot water basically serves as an extremely cheap battery. Normally if you want to store excess solar energy during the day, you get a $15,000 home battery installed, very pricy. Hot water can serve as "free" storage - your tank normally stores water at 60°C. During a hot summer day, these collectors can "supercharge" your tank up to 80°C. When you have a hot shower in the night, the tempering valve mixes mains water to output 50°C water into your hot water system, which slowly cools the tank but it won't drop below the 60°C threshold which would trigger the heating element to come on.
I have a thermal solar hot water system and if I get a string of hot days I notice the hot water heating element doesn't even come online for a week at a time, despite regular showers at night.
If you had a PV solar system, you would export the excess energy during the day (for practically nothing) then pay full grid price for a hot shower later that night.
You... could hook up your PV solar to a diverter that "supercharges" your hot water tank that achieves the same thing, basically you self-consume excess electricity instead of exporting it. But that's doing it at much lower efficiency, and you need to pay for an electrician and hardware install.
Generally the best but most expensive solution is to use PV solar and hook it up to a heat-pump hot water system, that achieves a 4:1 efficiency (uses 1kw of electricity to generates 4kw of heat) thus negating the efficiency advantage of the thermal solar hot water.
posted by xdvesper at 6:41 PM on August 26, 2023 [5 favorites]
Yes, it's also another one of those nuanced topics that can go on for several pages. Thermal solar hot water is about 3x more efficient than PV solar in producing hot water but come with several significant disadvantages and advantages which outweigh the pure efficiency considerations.
Main disadvantage is complexity, none of the solutions are what I would consider a robust solution for a homeowner. If you put the tank on the roof and use a thermosiphon with no moving parts, then you end up with a heavy tank on the roof which would require thousands of dollars of extra roof structure reinforcement during the build phase... negating any potential savings. Or you end up with a small tank with minimal insulation. If you use a regular ground mounted tank with a pump to move water between the panel and the tank, then the pump itself can fail mechanically, the temperature sensors can also fail. And the worst case is trying to install these panels where it gets below freezing at night - the water in the panels can freeze and burst your panels and pipes, leading to a sudden disaster of hot water coming out your roof at full mains pressure. In theory there are temperature sensors and pressure valves that prevent this but... will they still be good 10 years from now? How often do you do maintenance to check them? Also the heat losses through the glass panels are high and the system typically doesn't work much in winter - when you need it most.
Main advantage is that hot water basically serves as an extremely cheap battery. Normally if you want to store excess solar energy during the day, you get a $15,000 home battery installed, very pricy. Hot water can serve as "free" storage - your tank normally stores water at 60°C. During a hot summer day, these collectors can "supercharge" your tank up to 80°C. When you have a hot shower in the night, the tempering valve mixes mains water to output 50°C water into your hot water system, which slowly cools the tank but it won't drop below the 60°C threshold which would trigger the heating element to come on.
I have a thermal solar hot water system and if I get a string of hot days I notice the hot water heating element doesn't even come online for a week at a time, despite regular showers at night.
If you had a PV solar system, you would export the excess energy during the day (for practically nothing) then pay full grid price for a hot shower later that night.
You... could hook up your PV solar to a diverter that "supercharges" your hot water tank that achieves the same thing, basically you self-consume excess electricity instead of exporting it. But that's doing it at much lower efficiency, and you need to pay for an electrician and hardware install.
Generally the best but most expensive solution is to use PV solar and hook it up to a heat-pump hot water system, that achieves a 4:1 efficiency (uses 1kw of electricity to generates 4kw of heat) thus negating the efficiency advantage of the thermal solar hot water.
posted by xdvesper at 6:41 PM on August 26, 2023 [5 favorites]
I see this a lot with new-ish construction, particularly from large builders, where there will be either zero windows on an entire side of a house, or just a couple of small windows. I'm guessing there are commercial reasons and it doesn't seem to hinder the sale of the houses, but it never looks ideal.
I’ve noticed this too—they look really weird. No idea why they’re building them like this.
posted by MisantropicPainforest at 7:27 PM on August 26, 2023
I’ve noticed this too—they look really weird. No idea why they’re building them like this.
posted by MisantropicPainforest at 7:27 PM on August 26, 2023
Yes, it's also another one of those nuanced topics that can go on for several pages.
...in my area (South Bay), pretty much everyone that had solar-thermal has ripped them out and replaced with PV. The complexity of solar-thermal, even in an area that essentially never freezes, is such that nearly 100% of solar-friendly people just toss on another couple PV panels rather than deal with solar-thermal.
There's only one remaining solar-thermal system I'm aware of in my neighborhood, and it is entirely non-functional -- the grid is still up on the roof, but the panels themselves have been replaced by fiberglass sheets (just to occupy the space and keep birds out). It's amazing (as someone who once thought solar-thermal was pretty much a no-brainer, and is chagrined to have been so entirely wrong).
posted by aramaic at 7:30 PM on August 26, 2023 [2 favorites]
...in my area (South Bay), pretty much everyone that had solar-thermal has ripped them out and replaced with PV. The complexity of solar-thermal, even in an area that essentially never freezes, is such that nearly 100% of solar-friendly people just toss on another couple PV panels rather than deal with solar-thermal.
There's only one remaining solar-thermal system I'm aware of in my neighborhood, and it is entirely non-functional -- the grid is still up on the roof, but the panels themselves have been replaced by fiberglass sheets (just to occupy the space and keep birds out). It's amazing (as someone who once thought solar-thermal was pretty much a no-brainer, and is chagrined to have been so entirely wrong).
posted by aramaic at 7:30 PM on August 26, 2023 [2 favorites]
Aside from using running water, aren’t all ACs heatpump of varying efficiency?
Um...ACs don’t use running water. Neither do heatpumps.
posted by Thorzdad at 7:56 PM on August 26, 2023 [1 favorite]
Um...ACs don’t use running water. Neither do heatpumps.
posted by Thorzdad at 7:56 PM on August 26, 2023 [1 favorite]
In WA state, there’s some code limitations on the total window/wall ratio — you can go over but it requires at least interacting with the bureaucracy, maybe making up for it with triple glazing, etc.
So I would guess that the windowless walls are the least hassle for the developer to put in huge windows elsewhere on the house.
posted by clew at 8:19 PM on August 26, 2023 [5 favorites]
So I would guess that the windowless walls are the least hassle for the developer to put in huge windows elsewhere on the house.
posted by clew at 8:19 PM on August 26, 2023 [5 favorites]
clew is that what's going on with those weird side walls! #til "fenestration ratio", at most 0.3 in WA subject to further clauses.
posted by away for regrooving at 11:07 PM on August 26, 2023
posted by away for regrooving at 11:07 PM on August 26, 2023
"aren’t all ACs heatpump of varying efficiency"
So. Domestic air conditioning is an application (cooling of air). And you could consider different technologies to be air condition eg passive systems that pass air over a body of water, or generate a draught, as well as the refrigeration units that are usually called airconditioners.
Heat pumps use the same heat exchange tech as most air conditions BUT they can go in either direction, cooling the inside air and emitting heat, but also cooling outside air and emitting heat inside. In fact in my country people use them more for heating their houses than for cooling. I am sitting underneath one right now and it's blasting out 22C air while it's 8C outside and falling. They are danged efficient compared to any other kind of electric heating. I am not sure how they compare to a dedicated aircon unit for cooling efficiency.
The drawback is they aren't very efficient if the temperature goes too far below freezing, because the heat exchange unit outside tends to ice up and then you have to switch mode to defrost and it all gets silly. Mine are good down to about -5C, which is the lowest you would ever see in winter here. I believe -15C is the lowest anyone makes them for.
posted by i_am_joe's_spleen at 11:22 PM on August 26, 2023 [3 favorites]
So. Domestic air conditioning is an application (cooling of air). And you could consider different technologies to be air condition eg passive systems that pass air over a body of water, or generate a draught, as well as the refrigeration units that are usually called airconditioners.
Heat pumps use the same heat exchange tech as most air conditions BUT they can go in either direction, cooling the inside air and emitting heat, but also cooling outside air and emitting heat inside. In fact in my country people use them more for heating their houses than for cooling. I am sitting underneath one right now and it's blasting out 22C air while it's 8C outside and falling. They are danged efficient compared to any other kind of electric heating. I am not sure how they compare to a dedicated aircon unit for cooling efficiency.
The drawback is they aren't very efficient if the temperature goes too far below freezing, because the heat exchange unit outside tends to ice up and then you have to switch mode to defrost and it all gets silly. Mine are good down to about -5C, which is the lowest you would ever see in winter here. I believe -15C is the lowest anyone makes them for.
posted by i_am_joe's_spleen at 11:22 PM on August 26, 2023 [3 favorites]
Basically in terms of underlying tech "heat pump" and and "air conditioning" are the same, in other words, but the common names denote two different kinds of domestic device, dual purpose heating/cooling vs dedicated cooling.
posted by i_am_joe's_spleen at 11:23 PM on August 26, 2023 [1 favorite]
posted by i_am_joe's_spleen at 11:23 PM on August 26, 2023 [1 favorite]
Generally the best but most expensive solution is to use PV solar and hook it up to a heat-pump hot water system, that achieves a 4:1 efficiency (uses 1kw of electricity to generates 4kw of heat) thus negating the efficiency advantage of the thermal solar hot water.
I put an evacuated-tube thermal collector feeding a 315 litre ground-mounted electric-boosted hot water service on our place twenty years ago, and it's worked pretty well. Replaced a failed circulation pump about five years ago.
The storage tank was a vitreous enamel type and it's just now sprung a leak, so I'm in the process of organizing a replacement. I'm going to go for a Sanden heat pump unit that uses CO2 as a refrigerant rather than any of the common hydrofluorocarbons, claims a CoP of over 4.5 under all conditions and over 5.9 in warm conditions, and comes with a stainless steel 315 litre tank. It's all a bit gold plated Rolls Royce but over its expected service life I think it will probably pay for the difference between itself and a conventional resistive heater unit several times over.
I believe I can also hook my existing rooftop thermal collector into the new tank, though I probably won't. My current electricity retailer charges me a fixed monthly subscription cost and then supplies my electricity at the spot wholesale rate, and any time my rooftop collector is working well, so is solar PV everywhere which makes the spot price get very low. The new tank will probably last longer if it's not subjected to the rooftop collector's relatively extreme thermal cycling, which I suspect has cracked the enamel on the existing tank.
posted by flabdablet at 12:00 AM on August 27, 2023 [3 favorites]
I put an evacuated-tube thermal collector feeding a 315 litre ground-mounted electric-boosted hot water service on our place twenty years ago, and it's worked pretty well. Replaced a failed circulation pump about five years ago.
The storage tank was a vitreous enamel type and it's just now sprung a leak, so I'm in the process of organizing a replacement. I'm going to go for a Sanden heat pump unit that uses CO2 as a refrigerant rather than any of the common hydrofluorocarbons, claims a CoP of over 4.5 under all conditions and over 5.9 in warm conditions, and comes with a stainless steel 315 litre tank. It's all a bit gold plated Rolls Royce but over its expected service life I think it will probably pay for the difference between itself and a conventional resistive heater unit several times over.
I believe I can also hook my existing rooftop thermal collector into the new tank, though I probably won't. My current electricity retailer charges me a fixed monthly subscription cost and then supplies my electricity at the spot wholesale rate, and any time my rooftop collector is working well, so is solar PV everywhere which makes the spot price get very low. The new tank will probably last longer if it's not subjected to the rooftop collector's relatively extreme thermal cycling, which I suspect has cracked the enamel on the existing tank.
posted by flabdablet at 12:00 AM on August 27, 2023 [3 favorites]
Um...ACs don’t use running water. Neither do heatpumps
Some old ACs use city running water to cool the coils and pass air through them to extract the cold. Yep you read that right, it’s horrifying.
posted by WaterAndPixels at 5:31 AM on August 27, 2023
Some old ACs use city running water to cool the coils and pass air through them to extract the cold. Yep you read that right, it’s horrifying.
posted by WaterAndPixels at 5:31 AM on August 27, 2023
I was aware of water-cooled systems, but those systems are far beyond old. I haven’t seen one in a residence in well over 40 years, and that was during the removal of the water system and replacement with a contemporary ac setup.
posted by Thorzdad at 9:39 AM on August 27, 2023
posted by Thorzdad at 9:39 AM on August 27, 2023
There have been a few people who have built houses under those open-sided pole barn structures
I saw one of these recently and thought it was brilliant. It was at a house deep in the forest., though We're going to have to change our [homeowners associations'] attitudes about what makes a house attractive. Elevated roof/shades covered in solar panels is what our future needs.
posted by neuron at 10:04 AM on August 27, 2023
I saw one of these recently and thought it was brilliant. It was at a house deep in the forest., though We're going to have to change our [homeowners associations'] attitudes about what makes a house attractive. Elevated roof/shades covered in solar panels is what our future needs.
posted by neuron at 10:04 AM on August 27, 2023
This reminds me that New Orleans used to have these metal window awnings on all the 50's and 60's houses. Frames for the new energy efficient windows are a different size now, and we dropped the practice, but it was ubiquitous for a time
posted by eustatic at 1:22 PM on August 27, 2023
posted by eustatic at 1:22 PM on August 27, 2023
> Some old ACs use city running water to cool the coils and pass air through them to extract the cold. Yep you read that right, it’s horrifying.
I've literally never heard of that outside of a couple of jury rigged "air conditioners" on Youtube that use tap water or buckets of icewater as a source of cold water.
What you MIGHT be talking about is commerical air conditioning which in a lot of buildings does use water as the heat transfer medium but it's a closed loop to the chillers on the roof. It's a lot easier to plumb water for a 10-20 storey office tower and have local chill radiators feeding off that in the ceilings on each floor than passing pressurized coolant or using massive air ducts.
There's also the Deep Lake Water Cooling System that Toronto uses to cool several dozen large buildings downtown using water from the bottom of Lake Ontario. But that also does not use drinking water.
posted by barc0001 at 10:50 PM on August 27, 2023 [1 favorite]
I've literally never heard of that outside of a couple of jury rigged "air conditioners" on Youtube that use tap water or buckets of icewater as a source of cold water.
What you MIGHT be talking about is commerical air conditioning which in a lot of buildings does use water as the heat transfer medium but it's a closed loop to the chillers on the roof. It's a lot easier to plumb water for a 10-20 storey office tower and have local chill radiators feeding off that in the ceilings on each floor than passing pressurized coolant or using massive air ducts.
There's also the Deep Lake Water Cooling System that Toronto uses to cool several dozen large buildings downtown using water from the bottom of Lake Ontario. But that also does not use drinking water.
posted by barc0001 at 10:50 PM on August 27, 2023 [1 favorite]
This guy built a ground-sourced cooler without a heat pump, and says it works well for him.
posted by flabdablet at 8:11 AM on August 28, 2023
posted by flabdablet at 8:11 AM on August 28, 2023
Generally the best but most expensive solution is to use PV solar and hook it up to a heat-pump hot water system, that achieves a 4:1 efficiency (uses 1kw of electricity to generates 4kw of heat) thus negating the efficiency advantage of the thermal solar hot water.This is what we do now: we buy wind mains power so I feel less guilty about the winter use when our solar is producing the least electricity. There’s something really satisfying in the summer when a long hot shower has the water heater palpably cooling the house and our total monthly electric bill is like $5.
posted by adamsc at 8:54 AM on August 28, 2023 [1 favorite]
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