I built in an older style, with windows on every side, with a mind towards ventilation and light. Inexplicably most houses in the area, even $500k+ houses do not have these two things. My mom's condo has central air but the system is so feeble and the venting upstairs so poor that two bedrooms in the house remain stuffy anyways. It seems like light and natural ventilation are not even afterthoughts, but non-thoughts, and the designs all rely on electric light and forced air. Its amazing being in an expensive home where you need a light on in the kitchen at 8am. How do they decide what to build?
I built 9 foot ceilings on the first floor and 8.5 on the second. Then I placed the attic (3rd story) door centrally in the upstairs hallway. The result of the design is that airflow moves on the first floor in all directions, and upward, and on the second floor can move at least east-west (bathroom and hallway windows), and also north-south if bedroom doors are open. Finally, air flows upwards to the attic, which has windows north-south. So winds should suck air higher, and out.
If I close windows in the morning and open around 7pm, the result is that the house stays very cool, about(? only tested with temp gun a few times) 74 downstairs and 76 upstairs during these 90 degree days, and then gets cooler at night as I open windows again. So far, I've only bought one fan, though things might work better with more. Note I'm not an expert or an architect, I just included some design features that should be obvious to anyone who's lived in an old house for a summer.
This takes some manual control, but there are far fewer parts to maintain (this was a general design goal beyond AC), and summer electric bills are $50-60/month. With this design, there have been 3 icky-hot days so far this year, when there was no wind and the night did not get very cool.
So millage will vary.
Similarly with light, in winter by the time I get home its pitch black either way, so it wouldn't change a whole lot. And in summer the light from the windows doesn't play well with TV/monitors/etc.
Cats like the windows a lot though.
Leaving the windows open barely helps.
My grandmas flat, in Southern spain, did not have AC. But thanks to big walls and external blinds you could live comfortably even during 40+ C Summer days.
External blinds are a killer feature both for heat and cold insulation.
Agreed, but people also seem uninterested in simple techniques to work with what they've got. I live in MA, in an old house that doesn't have much in the way of modern energy efficiency but we get by without AC on all but the hottest days of the year by doing really simple things. Open windows at night. Close them in the morning. Pull the blinds down on windows that have sun exposure. You get the idea. The only serious retrofit we've done so far is have a contractor add cellulose insulation to the attic. On 90+ degree days the second floor will reach 80+ by the evening so then we turn on the AC if a window fan is unable to bring the temperature back down to something comfortable. In our climate AC should be the backup plan, not the primary cooling system.
I have explained the same things to my friends who come over to visit me. Some of them think I am crazy, others get it.
I have the benefit of a giant open loft, 2 story ceilings coming off the living room right into the master bedroom, with a giant ceiling fan sucking air in from outside and a large window open upstairs so the air has someplace to go.
If it gets to 90 it can be a bit uncomfortable, but the mid 80s is fine, it only gets a bit hot around 5pm or so.
I have friends who keep all their doors / windows open and use a fan throughout the entire day. Great job sucking the hot air into the house!
Although for older houses with lower ceiling that is pretty much the only way.
(edit) added link to youtube video
Doing this will even make your AC system work better if you have one, since you won’t have the extremely hot air in your attic heating your ceilings
A whole house fan is a very different story, but it’s only really useful in some climates.
In a well-built house, the roof and ceiling shouldn’t be a major source of summer heat gain.
What we really need is solar-powered AC. Ideally DC-driven air conditioning.
the first is the hardest to get done as most hvac companies resist, having the exhaust not be at the exact end of the the pipe. the pipe should end just beyond it.
the second is not having a return or sufficient returns in each room. if you are stuck with a central return then make sure doors are open if the room has no pass through vent to the hall with the central return; at most the master bedroom will have pass through vents to a hall so the door can remain closed.
the only omission from my current home is an attic fan but building codes precluded it at the time but I hear I can do it now if I want.
still I find even with central air a lot of comfort can be found by having a dehumidifier. down in the south it is not uncommon to wake to humidity higher than the temperature which makes it feel sticky and uncomfortable.
with regards to cooling needs and such, we simply have changed what we want and want we are willing to tolerate. its not a bad thing, we just have to find efficient ways to have it.
When it only gets down into the upper 80s (thats around 31C for those afflicted with metric) at night with humidity at 90% or higher, AC is mandatory.
When its up around 98 (37C) with high humidity during the day, not having AC can be a killer.
Really? In NH? How many days a year it even reaches 90?
Another interesting feature are houses that are built on brick pillars raised off the ground without a concrete slab. It’s amazing how even on a hot day they remain quite cool underneath and seem to cool off quicker at night. Many older wooden houses seem to be built this way.
I like to mentally toy with the idea of high rises or large apartment blocks having some kind of large retractable awnings on the sunny side of the buildings, or some kind of fake outside wall which can diffuse some of the suns light / heat.
Another downside is that when you do not have mechanical ventilation with heat recovery and your rooms are relatively well built (i.e. air tight) then you are left with bad air quality inside.
I think that best is to combine night cooling with mechanical ventilation with heat recovery.
As you noted, this used to be a fairly standard design for homes in some areas.
Perhaps a "whole house attic fan" could help on those marginal days?
The same thing happens here in Arizona; the proper way they should be building houses here would probably be a monolithic dome with most of the home set below grade - although caliche would make that difficult in some areas (and it would be expensive regardless). The next best thing would probably be rammed earth with 2-3 foot thick walls.
The biggest heat transmission problem in most construction isn't the walls, it's the windows. The amount of heat transmission you get via glass - even high-performance triple-pane glass - is significantly higher than heat transmission through the rest of the structure. Your walls are going to be R20+, your attic insulation will be R35+. Your best windows are going to be equivalent to R6 or so, with the median windows being significantly lower.
I think that the best combination is high thermal mass structure followed by the insulation inside. This way the heat is not easily transmitted to the inside and the thermal mass can cool off to the outside during the night.
Of course when the heat finally does get inside then it is trapped because the house will act like a thermos and only way of cooling would be the by circulation of cold air.
Problem of windows can be solved by outside blinds (or shutters but blinds are better) and IR reflective coating.
 I don't recall the other design details that made it so cool in temperature, but it was all analog/natural (i.e. no AC)
Many people do not have exterior walls on all sides. You must be generally aware, because your next sentence mentions a condo (in my case I have a townhouse).
You can design a house however you want, but without AC it's going to be hot and miserable here in Indiana when it's in the 80's or 90's with 80%+ humidity unless you have AC.
If you live somewhere that humidity is an issue - in some places that's in the winter (when you wouldn't use cooling AC) - get a whole house dehumidifier system. Ex: https://www.sylvane.com/whole-house-dehumidifiers.html -- Those will run and maintain the correct humidity regardless of AC.
Use the right tool for the right and you'll get the most efficient results.
They have compressors which can adjust speed, not just turn off/on like a single-stage AC compressor does. So there's a lot less worry about whether it's sized right because it basically "resizes" itself as necessary.
The two-stage type has off/low/high, so it can get a lot closer to the right size. The variable-speed type is essentially continuously adjustable, so it's like always having the perfectly-sized AC unit for whatever the weather happens to be like today.
Generally most modern forced air systems are designed to run more often (for heat and cool) / longer periods of time now.
On top of that you can get multi stage AC units. Mine will run at a lower setting for a longer period of time when the less efficient "full blast" stage is too much, but AC is still needed.
Both air conditioners and dehumidifiers are built on heat pumps. They both dehumidify in the same way: water condenses on a coil and drains away. But an AC unit pumps the extracted heat outside, and a dehumidifier pumps it back inside. When it's hot and humid, it wouldn't make sense to forgo the opportunity to pump heat outside.
A better solution is to get some variation of a two-stage air conditioner. Instead of a compressor that's either off or on, these have a compressor that can run at two speeds. Most of the time, it runs at the lower speed and behaves like an AC that is undersized, runs longer, and dehumidifies well. But when it gets really hot, it goes up to full speed so it can the temperature down. Compared to a single-stage AC, it costs more, but it's more energy-efficient and quieter and more comfortable because of smaller temperature swings.
These days they also variable-speed air conditioners that can adjust in tiny increments and run the compressor at almost any speed, so they are kind of the next generation beyond two-stage. They more or less run continuously, adjusting their power level instead of having an on/off duty cycle. It costs more than a two-stage, but it is even more efficient, quieter, and comfortable.
I have explored a dehumidifier for my Florida home, and after looking at the numbers, it just made more sense to tighten up the envelope and set the AC to 74. I have solar on the roof though, so the energy costs aren’t terribly high (vs possible mold remediation) for this approach. YMMV.
It operates a compressor that condenses a fluid with a boiling point below room temperature. As it condenses to a liquid, it generates a lot of heat. This heat is removed from the liquid. The liquid is then allowed to boil, which pulls heat from the environment.
In an air conditioner, the heat is radiated outside, and the cool air is vented inside. In a dehumidifier, the air is sucked in, blown over the cool radiator, which creates condensation which is collected, then blown over the hot radiator, and then blown back into the house.
So you might as well just use an AC and be more comfortable. There aren't any upsides to using a dehumidifier.
However, some of those other variables are not consistent across different designs. For example, they may use a different refrigerant that requires a different compressor. Centrifugal devices like fans and compressors use power in a non-linear fashion. Look up pychrometric chart and/or fan affinity laws for more detail
(Yes, I'm aware that such a set-up would be impractically noisy; it's just a thought experiment.)
An air conditioner has its heat pump capacity sized to cool a house, far in excess of what is needed merely to remove the humidity.
From my 96 year old grandfather: We planned to replace every piece of plaster in the wall in 10 years, and we kept hardwood floors because we could throw the rugs away and sand the floors down when the mold started to get bad.
That's wasteful and time intensive. No thanks.
Essential? You mean these climates were completely uninhabited before the invention of AC?
You can buy 15-20 bags of cellulose insulation and rent the blower machine from home depot, and you can do the whole attic in a few hours yourself. Including a rental van, that cost me around $600.
This alone made a noticeable difference in my house in Toronto (where it can easily get to 32°C/90°F in sun in the summer)
Any particular advice/pain points for re-insulating an attic with cellulose?
Also, because I live in Phoenix, we installed some ventilators on the roof to help exhaust hot air in the summer (in addition to the peak eave "vents" at the ends of the house). We wanted to do an exhaust fan, but there wasn't any way to get one into the attic. So far, the ventilators have worked fine.
If you've never done it or seen it done before, my only real advice is break up the cellulose into fluff before you put it into the blower machine, and put little bits gradually and slowly rather than stuffing it to the top. My wife thought she could shove a whole bag inside and have the mixing blade break it up, but it clogged the machine instead, and I had to waste a couple of hours unclogging the tube.
In terms of applying the insulation, you just want it to be thick, fluffy and somewhat even.
Other than that, just captain obvious stuff:
- you need two people (one in the attic and one feeding the blower machine)
- start from the edges towards the manhole
- use a respirator mask
- stay hydrated and take breaks if you need to (the attic is surprisingly hot)
So, to add to that: do it on a nice day in spring or fall.
You wouldn't get water from a leak, you'd get it from thin air via condensation. Ever had fog on your car window? That's water on the inside of your window, and not because the roof of your car has a hole in it that's letting water through. Water condenses out of the air.
Making sure condensation happens in the right places is one of the main jobs of well designed insulation. What you saw as shoddy work from a contractor may have been a standard insulation design that's intentionally skimpy on the internal insulation, because the condensation should happen in an outside layer.
By piling on insulation you may have moved that dew point to the inside of the house or past a layer of insulation meant to deal with it.
The rule of thumb is that you can't just add more to one layer of your overall insulation (which is everything from your outside weather layer to the paint on your inside wall) without considering the system as a whole.
Search for "hygrothermal analysis" or "dew point" in relation to outer wall insulation. You'll find resources like  and . The former has an example where more interior without corresponding changes to the exterior makes things worse.
I'm no expert on insulation, just a fellow home DIY-er. I've had enough experience with it to be very paranoid if I were in your shoes. It's worth bringing in a professional to evaluate this home improvement job of yours,
You may have created conditions for mold to thrive in your attic, or for water to seep into structural layers of your roof. By the time you notice those sorts of problems without having to open up a wall it's often too late.
I also did have someone come over to quote me on insulation work when I was planning it (since the mold thing was a concern). They said my setup was fine as far as mold risk was concerned, and that it was clear that the two layers that were there were insufficient.
If in doubt, you can always ask for a professional opinion before attempting any DYI.
This has very little to no help for existing homes unless you have a large budget to demo your existing home/yard/surrounding-infrastructure. For a perpetual renter such as myself (bay area lifestyle), this is useless information.
Where I live in the bay area - we live in a greenhouse of an in-law unit. Only solution to cool it without AC would be to tear it down and build something different. I can't even keep the top room below 80F on quite a few days with a window unit I installed. That unit is rated to do over 2x the size of the room too but it can't keep up. On days we know it'll be 95+, we leave the AC on all day. Otherwise, the heat soaks into the walls so much that we can't cool the house down after we get home and it'll still be 85+ in our bedroom past midnight. Opening windows has no effect since we can't get an effective cross-breeze.
I feel bad about it but I don't have much of an option if I want to be somewhat content. I get quite unbearable to be around if I am suffering in the heat.
If your in-law unit was built without permits (which seems likely since it's apparently below-standard for insulation), you can probably get out of your lease early if you wanted to.
Putting in more insulation doesn't require a full teardown, but it's not cheap if you had to, say, build false walls to add insulation.
I'm not able to afford such a thing. Most apartments/in-laws in my price range (<$2500/month) were remodeled no later than 1970.
Putting in insulation means you have to take down the dry wall (if it is even drywall - might not be). That's pretty extensive for most people.
It makes me wonder if people in hot climates that can't afford solar shouldn't just put white glossy panels a foot above their roof.
There are a lot of other obvious, non-exotic things we can do, like require a certain amount of tree coverage and reduce the spread of concrete surfaces. We could also use shade sails a ton more than we do (which are nice because they can be removed in the winter).
Above us, a mister was spraying water. None of the water was coming within 10 feet of the ground as it all instantly evaporated- Phoenix is a desert- but in doing so, the air was chilled. The cold air dropped, cooling this small area.
I cannot believe just how effective this means was. Now, granted, to do this they had to waste clean fresh water in the middle of a desert, which isn't great. But it does go to show the potential of some of these tricks. May not work in 99% humidity, mind you, but there are other tricks up the sleeve of the clever engineer.
It only works in dry climates, but it makes such a difference.
However, if there is some evaporation that can takes place (that is, the evap gradient is large enough to let it happen, but directly using that cooler air would make it uncomfortably humid), you can instead do what is called "evaporative chilling" (or something like that), where you run the water over a radiator, and the water evaporates, cooling the radiator (actually, removing the heat), and inside the radiator, you run coolant/water mix - that's your outdoor side. Inside you have another radiator, with a fan circulating air over it. It's something like an A/C system, with water/coolant as the "working fluid" and no compressor, just a pump. Think of it like a "dry evaporative cooler".
This kind of system does work - it's actually used for industrial A/C systems as some kind of "pre-chiller" or something, but it isn't something you can buy for a home that I know of - but you can build it. But like all evap systems, once the humidity gets too high, it stops working.
Another kind of system that can be used here in Arizona, but few do because it is ugly, big, and works only so well - are something called "solar chimneys".
The simplest is just a large 2-3 story structure painted mostly white at the bottom and mostly black toward the top; the idea is that the sun warms it, sucking air thru it and out the top - the bottom end is connected to the house, to make a "forced draft" through the house.
The better way is to make a similar "chimney" on the opposite side of the house and add cooling pads and a fan at the top (basically a large diy swamp cooler). Misting can also be used. So you evap cool the air, which falls, enters the house, then is sucked up and out the other side by the "hot" chimney.
Another "hot climate" design for cooling is something that used to be found all over the middle east:
Sometimes used in combination with:
As you can see, this is basically the ancient form of "solar chimneys" - if we instead used these in Arizona, coupled with either monolithic dome construction and/or rammed earth, and below-grade construction (to take advantage of earth insulation and cooling) - it'd be so much better for energy use here in Arizona.
HA! That's like a cool summer day - stay a while here in Phoenix, and you can easily experience 120+F days at times.
Nothing like it being 2am and 100+F degrees outside...
On the flipside - shorts at Christmas-time!
1. You don't need to cool "a house" - just the room you're in. If I do run the air conditioning for 20 minutes before bed, I'll block under my door to keep that cold air in.
2. If there's no reason for you to be in a hot house, then don't be. If I'm teleworking, I end up not just being cooler, but also happier, if I find a nice quiet spot somewhere else. I'm lucky enough that I have a free museum not far from me that has an indoor courtyard I can work at.
3. Air circulation and window fans that expel heat from the room can do a lot. Fan quality and fan placement is tremendously important for circulation.
4. At least the last two minutes of your shower should be cold.
5. Blinds should be closed during the day.
6. Drink lots of water, of course.
I think there's more I can probably do. For example, I've been meaning to research reflective blinds to see if they do more than normal blinds at keeping out heat. (Shutters aren't an option for my building.) Dehumidifiers are also something I want to look into.
I haven't personally found that bed sheets make much of a difference, outside the way too obvious things like I don't use my winter (flannel) sheets. But this might reflect that I only buy nice ones.
Most days we can leave the AC off. Temps will climb to about 75-76 by mid-afternoon, but rarely get too far above that.
The only part of the house that absolutely needs the AC is the upstairs converted attic. It was renovated in the 80s with no thought to air flow, and no way to get a cross breeze from the windows. So we have a mini-split we can run for that floor.
The house is going to feel warm if you're used to running AC 24/7, but 2 weeks in and 76 with a breeze feels fine.
I understand where you're coming from, the last place we lived was a more modern ranch house near Morningside, with bad layout for airflow and it was MISERABLE in the summer (routinely 90+ by 11am if the AC was off).
I'm just saying design matters a lot here, and makes a big difference. There's nothing special about Atlanta that makes that any less true.
My wife is almost 9 months pregnant and AC is mandatory!
I'm honestly shocked that's possible after living in the northern Virginia area for a summer. It was miserably hot/humid for the majority of the ~9 weeks I spent in the area.
It's easy because I live in an old 1920s apartment with thick brick walls, covered porches, and ceiling fans. The walls insulate most of the heat, the shade over the front and rear windows makes light less extreme, and the fans keep air moving which helps with humidity.
Buildings should be designed to fit their environment. My electricity bill would be much higher if I lived in a modern prefabricated cube with thin plywood walls and nothing hanging over the windows.
(Also I don't have kids.)
No, it isn't ideal, but I'm cheap and I don't mind using fans. And frankly, I don't like AC. I hate walking through a blast of 20 degree colder air whenever I pass a register.
I've found that having a big shade tree that blocks direct sunlight from the house helps a lot. (I know this since my shade tree died and was removed a year ago.) My house is natural brick and retains heat from sunlight for at least 8 hours, so any shade helps cool it a surprising amount.
I have earplugs, but prefer just not using the A/C.
I can confirm they work. It's much cooler in my small flat when they are closed for day, even though they are inside and a little warm. On a sunny day, my outer wall heats up to 60°C. Inside temperature can be 50°C with blinds open or 35°C with blinds closed. This was with outside temp 30°C and wall directly exposed to sun.
Even just from running fans, my electric bill in summer is much higher in months when I'm working from home frequently.
I wouldn't be surprised if I consume more energy cooling my house during a work-at-home day than I do commuting round-trip on the subway.
No, then the plants die, the occupants die a little by being in a prison.
Before AC buildings used to have awnings. They still should. New buildings should have functional overhangs. Often new buildings have an ornamental overhang that does nothing. Also window film can reflect heat so thats an option too
Wasnt there concern that sleeping with a closed door raised CO2 levels?
Note that even if you can't rebuild the house, there are still steps which can be taken like interior wall insulation, replacing windows, …
The maintenance issue could be remedied with better engineering. But the water issue will require lifestyle changes that include getting serious about recycling gray water and harvesting rainwater, both of which are basically illegal now in many parts of the West.
swelling of what, my I ask? (My guess would be the drywall or plaster of the home being cooled.)
His blog has occasional experiments with off-grid and low-power living.
I've seen through Islamic world and India buildings at least 500 years old that were constructed around constant air flow through buildings, having patterned stone mesh windows. It can be done with low tech approach.
The 2003 heatwave killed upwards of 70,000 people (in France, 8 consecutive days of 40°C [104 °F], in the Netherlands it reached 37.8°C) https://en.wikipedia.org/wiki/2003_European_heat_wave
It's that brutal. It's also something people used to do a lot of, especially if they were working outdoors.
I've seen house designs for the South which have an open central corridor. It catches and channels any wind and helps cools the rooms on either side.
I'm sure there are other tricks, but builders don't seem to know them any more, and architects build more with a view to looks than practicality.
Modern architecture - whether it's McMansion design, concrete box design, glass tower design, or suburban vernacular design - can be almost criminally stupid about environmental issues.
There are exceptions, especially in the occasional environmentally controlled low-energy office block.
The reality is that it's possible to manage heating and cooling far more intelligently and effectively in most kinds of buildings. But it's considered a fringe eco-hippy interest and not something most of the population needs to care about.
Here in Arizona, if we built things for cooling more like in the middle east (windcatchers/solar chimneys/qanats + thick walled rammed earth and/or monolithic domes), it would probably be more energy efficient.
But I can't imagine that style would go over well with our current (overall) political climate here...
Here in NY, with high humidity it can be upper 80s or low 90s outside but when you factor in the humidity you have no way to cool off. You can be laying down doing nothing but dripping in sweat. Combine that with being in an apartment that's on the upper floor with bad insulation and forget it. I imagine it's even worse in places like Florida.
It's also crazy how big of a difference there is between an upper floor that's poorly insulated vs a basement. You can expect a 15-20f degree difference.
(This was discussed recently on an HN thread, but I can't find it.)
It was interesting to see how they've built to adapt to their environment.
We had a north face hotel room and with the massively thick walls and double glazing (plus no direct sun) the room was just about bearable at night even without the AC (which was actually outputting much less cold air than the AC I had in a hotel in Manchester this year).
It was August, and very hot outside - well over 100F. Inside one of the apartments on the tour, someone was selling snowcones - a welcome relief. We went inside (had to duck under the doorway, as it was only 4-5 feet tall) and it was easily 20-30 cooler than the outside. The only thing we could figure was that being on top of the mesa, plus night temperatures, and the thick adobe construction, all acted as a thermal-mass barrier system or something. It was really amazing to experience. I honestly wish that kind of construction was more common here in the southwest.
Be interesting to see if that changes in a warming world, I hope so.
Curtains/blinds are not nearly as effective as external shutters or some kind of external blind.
I make my own frames with light coloured textile stretched across it that I attach over the sun-facing windows, which has a dramatic effect without completely blocking out light.
Our porch faces toward the west. We have a huge mesquite tree back there that shades the house during latter part of the day (plus our patio is covered), but in the later afternoon, sun will shine in as the sun sets, and heat the house up. So we strung aircraft cable with small turnbuckles and hung up colorful polyester fabric shower curtains (this was a recent change, originally we had used canvas dropcloths, which worked well too - but were difficult to keep clean). We can slide the curtains "closed" to block out the sun in the evening.
Between that, plus having double-glazed windows installed, extra insulation in the attic, roof ventilators, and the fact that our house is of concrete block construction (not stick frame) - while we still have to use AC, we find that we can keep it set higher most of the time, and during the early summer/spring and late summer/fall times - not at all (opening the windows at night and using fans to bring in cooler air - then closing things up in the morning before it gets too hot). It's noticeably reduced our bills, considering how old our house is (and we have two heat pump AC units on the roof - that has it's own interesting story, but not relevant here).
Even in Phoenix, the need for air conditioning can be reduced by designing houses well. As the article notes:
> Even in exposed, hot and arid climates, cooler temperatures are never too far away. In Jaipur, the capital of Rajasthan state in northern India, daytime temperatures regularly reach upwards of 40C in the summer months. But just a few metres below ground, the temperature of the earth in the region remains a much gentler 25C, even through the fiercest summer heat.
> But just a few metres below ground, the temperature of the earth in the region remains a much gentler 25C, even through the fiercest summer heat.
That can be a risky bit depending how it's used specifically e.g. london's underground was pretty much freezing when it first opened but the clays have a hard time shedding heat so these days the walls warm up the undeground.
This is talking about digging down a few metres and having a loosely covered courtyard in the space, very different.
> When much of central London’s Tube network opened in the early 1900s, temperatures in tunnels and at stations were recorded at around 14C.
> To understand how more of the Central line could be cooled down, just look at the Victoria line. In 2006, a similarly experimental groundwater cooling system was installed at Victoria station to lower temperatures in mid-platform areas. In 2011, TfL completed the installation of 13 ventilation shafts throughout the Victoria line, while the new fleet of trains running on the line allows TfL to operate a regenerative braking system, which returns power to the rails when a train brakes. And when a whopping 38 per cent of heat generation on the London Underground comes from trains braking, that’s a pretty big deal.
It's basically another example where sensible design can make a huge difference.
That's hardly likely in Phoenix.
> This allows air conditioning to be used very modestly, when it is necessary at all.
I'm not sure why every thread about energy efficiency improvements has people come in and do the "it's not a perfect solution for these edge cases" thing. Everyone knows that already, and it's totally beside the point.
Thick walls, passive roof cooling, maybe partly sunken... These things can work for a standalone house or certain types of commercial buildings but they're harder to work into bigger structures although evaporative cooling at least can be used.
That's enough for our old house to be net zero in the Southern California summer, A/C and everything.
Modern houses with actual insulation in the walls, and windows that don't turn the rooms into solar ovens, would fare an order of magnitude better than even my modest solar setup.
Furthermore, I would love to have water heating this way. Solar panels heating a water container in the winter, that is mixed into showers and even small pools on demand.
Any observant Jews here who don’t want to use water heating on Shabbat? This may be a great idea.
PS: Heating a house is the only application of Proof of Work Mining that I approve of. But even then, I would rather it be useful work like SETI or protein folding:
The hot air flowing from outside through your windows could be compressed making it cool.
I wonder if there are existing, not so ugly commercial products providing that. This could be a green alternative for air-conditioning.
Compressing air actually makes it hotter, but that's not what's happening. Forcing air through a smaller space makes it flow faster, which ironically makes it less dense -- and hence colder.
It's the same effect that people claim holds airplanes up. (But doesn't. That's mostly the angle of attack.)
This is especially important as the brick gets heat soaked and releases its heat well into the night.
An old farmer here claims that such a house is cold in summer and warm in winter. I once saw an architect on TV claim the same thing. But I was not able to find any explanation for this anywhere.
(It's a bit more complicated than that, but basically when you can't
I agree that they're great if ceiling height supports them.
The fingers of the next tall person to stretch his or her arms near your fan
It wouldn't work on all the suburban homes around us. The walls aren't insulated enough, there are so many windows that you'd never get them all covered.
I sincerely hope that my future places of work and residence will not regularly subject me to 85 degree interior temperatures on the assumption that I will "get used to it" -- which I strongly suspect actually means "live with it."
No, it means the human body acclimates to its environment. You really do get used it.
I'm curious if you went home to cooler temperatures, or if your whole summer was spent in warmth? I definitely have experienced harder times going back and forth vs. always being in the warm environments.
Conversely, I've noticed that when it first gets cold in NY, it's very biting and unpleasant, while late in the winter, the same temperature doesn't bother me at all and near freezing temps actually feel a little warm.
So I find that the timeframe for me at least is more than a week or two, but no more than about 3 months.
OTOH, I'm pretty enthusiastic about the exchange systems that circulate fluids to exchange heat with soil beneath home. That's a really reasonable approach.
- Insulated glazing
- Sunscreens in front of windows
- Wall and roof isolation
The nice thing about this is that these measures also keep you warm in the winter (lower energy bill), it's a double-edged sword.
I have cheap asphalt roof shingles (even so, $10K to replace them)- I did look into reflective shingles, but they were much more expensive, plus I had to consider resale value..
In the mid-Atlantic where I live now, night temps don't drop more than maybe 10 degrees below daytime highs of ~90F. So bringing in the evening air via an attic fan puts the house at no less than a toasty 80 (with 70% humidity) -- still uncomfortable.
Of course in older, not-well-sealed housing the venting poses the risk of drawing cooler air from the house to the attic, negating much (or all) of the benefit. So their efficacy is very situational.
Though old houses often have attic fans, they weren't there to cool attics. That was the purpose of widowed attic gables or breathing slats under wood shingled roofs. Attic fans are there to cool the house interior, especially the hottest rooms on uppermost floors. That's why the intake of an attic fan is the highest point inside the house and not the lowest point inside the attic. Even then attic fans aren't intended to run for more than perhaps 30 minutes a day after sundown -- just long enough to replace the hot air inside the home with cool air from outside.
To vent an attic, the ideal air flow is to intake cool dry outside air from along the attic soffet, pass it along the underside of the hot roof sheathing, and have it exit high where attic heat is at its peak. And do this passively without a powered fan if at all possible.
So yes, in Houston.
Humidity is as much the enemy here as heat. AC is how we mitigate that.
Of course, it also helps to live in a house that is out in the country or at least suburbs rather than a city apartment. A window AC unit or two also can help for things like cooling a bedroom for the hottest nights.
Obviously, Texas is a single place to people who don't live here, but be aware that at 269K square miles (686K sq km), it's fucking huge. It's almost 800 miles across (ie, the distance between Louisiana and New Mexico).
So there's LOTS of variety in climate. The dry climate you associate with movie-Texas does definitely exist, but mostly in the western half of the state, & especially as you move down towards the Mexican border.
Houston, however, sits on the Gulf Coast. (Houston proper isn't on the water, but the overall metro area includes Galveston, which is an island in the Gulf.) The Gulf Stream curves over us and keeps us warm and wet.
Not for nothing, but our annual rainfall is pretty insanely high (~49 inches).
Anyway, in a very humid place like this, swamp coolers that depend on evaporation are of limited utility.
Houston got the #3 spot. Only New Orleans and San Francisco are more humid.
(Another city on the list: El Paso, TX at #47.)
Also, barely above sealevel, so lots of techniques don't work.
Climate wise, it's a pretty uncomfortable place to live.