No A/C? No problem, if buildings copy networked tunnels of termite mounds
arstechnica.com
arstechnica.com
I'm slowly replicating these techniques plus some fans to help push hot air out, including a gabel fan in the attic. I started getting awnings, but not yet on every window, they definitely help. Started planting trees around the property and around the house to create shade. I did get two window ACs, one on 2 ND and one on the 3rd floor, to help when it gets to high 80's and above. I want to see how far I can take this. I'm definitely going with the approach of having more air flow vs. other passive techniques that lock in the air, e.g. closed attics.
But some homes were indeed designed with climate in mind. The broad rear side might face the south to be heated during winter. The whole house may be configured with one long hallway with windows or screen doors at either end to allow cross breeze. Windows on different floors may be designed to open part way to facilitate cross breeze. The fire place may be located deeper in the house near the bedroom, with subsequent rooms getting farther from the fire so in winter you can shut the doors and only heat your own room with the one fireplace.
An attic fan that can switch between blow and suck is essential to keep cool (and prevent mold using air flow). When it's cool in the early mornings, keep windows open to cool the house, then close them when the sun rises and close shutters. As the temps rise throughout the day, you crack a window upstairs and turn on a window fan (blowing inward) and one window downstairs (blowing outward) to create a downward breeze, or the reverse to pump heat up and out.
My ex hasn't owned an AC in 10 years. She just regulates the doors and windows and has window fans. House is 130 years old
Why would the AC attic need to suck air in? I never thought of that but will consider it now.
I think it's tempting to ascribe some lost ancestral knowledge to older house, but to be completely honnest a lot of them weren't designed with thermal considerations in mind (or rather, the thermal efficiency was accidently achieved by following some heuristics).
A lot of these older houses were simply badly insulated. They required a lot of wood or coal to keep warm during the winter or had the occupants wearing layers inside at all times but would cool down quite fast in the summer during the night, only to heat up again during the day.
Good, explicit thermal design appeared with mid-century houses. [0]
My second story in craftsman bungalow wasn’t finished until the 70s. And that is probably when the window AC was put in that makes it usable in summer. The first story has lots of windows for cross breeze and stays nice in summer.
Luckily it was fully equipped with fans and AC as it did not work at all out in the desert.
The future of energy-efficient cooling is not going to be one solution that fits all. There are going to be different solutions for each region. Summer weather can vary wildly even in the same place, so many solutions will end up using software to actively adjust its own mode of operation based on sensor readings, just like a modern HVAC system. You don't want your cooling apparatus getting all moldy when it rains unexpectedly.
I've seen mentions of whole house fans in the ArsTechnica comments and was intrigued as to whether that would be useful for my house. Here in the UK, our houses are designed to keep warm and don't have any A/C built in and that's becoming more of an issue as summers get hotter. However, I've discovered that OnlyFans is not the correct website to find whole house fans.
So if you can get away with it, sure, plant some trees. :)
It has a blueish tint though and really doesn't do much if it's the ambient temperature that's too high.
These houses are honestly quite pleasant to be in. The insulation has the side effect of being very good noise dampening as well. I was talking to the owners of one and they said they'd never used the backup electric heater. The one time things got a little cold they light a candle in their bedroom and everything was fine.
So I think in temperate climates, the answer is air tightness and thermal control, not whole house fans.
In the types of old houses described in your link, this type of thing was designed to be done by one or more open fires, which drew fresh air in through cracks and crevices and exhausted up the chimney.
Very thick insulation Heatpump Solar panels
Very energy efficient overall.
Except... In the summer it overheats. Once it heats up you cannot get it to cool down at all. Horrible.
My house is a bit older so doesn't have it, but new houses must have a heat recovery ventilator. Almost all of these have a 'summer bypass mode' which bypasses the heat exchanger, so effectively draws warm air out of the house. This is useful in the summer, as here although it can get to 30c+ in the day, at night it almost always drops to below 20c. The way our houses are built we have a lot of thermal mass, so if you can cool it down during the night, it will make it a lot more comfortable during hot days.
It's going to become a much bigger problem in the UK as we're struggling with having enough housing anyway and making them energy efficient is going to take a lot of money and work.
The (US) city I live in has streets built in the mid-1600s.
Considering the great fire of London and the Blitz, is your canard really accurate?
I own an old (1890's) terrace house in the UK. The only part that overheats is the modern loft-extension that I built 5 years ago. For the main part, it's like a cave; it retains heat in the winter, and remains cool in the summer.
It has single-leaf brick walls, which should be bad; but the frontage is quite narrow, which makes it pretty energy-efficient.
Same. Our downstairs is nice and cool during the summer (not so much when it was getting near 40 degrees last year), but our upstairs gets much more light and can get too warm.
It's a mid-terrace house, which means that the side walls abut onto the neighbours' houses. The side walls are much bigger than the front and back. So not much of the external walls are exposed to the external environment, which is why it behaves like a cave.
To be clear, it's not like a heat-pump; it just maintains a reasonable temperature.
Did Maxwell's demon perhaps live in a cave?
"They have no energy sources other than the sun and wind, and yet they circulate cool air through buildings and traditionally provided cold water and ice for the hot summer of the country's arid regions"
https://sci-hub.st/https://doi.org/10.1038/scientificamerica...
Will be interesting to see how it works out in practice...
[1]: https://www.fremtidensbygg.no/nydalens-mest-spektakulaere-by...
It would be interesting to see something like this work in e.g. Houston: https://weatherspark.com/s/9247/1/Average-Summer-Weather-in-...
I’m sure there are reasons it’s so common that I don’t know about, it’s not even close to an area of expertise for me. But moving from the US to Mexico I feel like concrete is the way to go vs drywall and wood framing. Sound insulation is so much better too.
I owned a brick ranch house in the US and had to have all the ductwork redone because it had accumulated mold. Cost me 3k. It just seems way more trouble than it’s worth.
That's a meme. There's a lot of variability between houses (and the shitty old houses don't tend to survive long), but insulation is one of the things that has unambiguously improved over time.
Matt Risinger has a good video on the "old houses were better" thing here, but his channel is full of great house-building content: https://www.youtube.com/watch?v=KBMMDY3LFAA
From what I have read, builds in the last 3 years have been horrendous due to supply and labor shortages. Maybe the sweet spot is to purchase something from before that era that is still new and get it thoroughly inspected.
I still appreciate the improved efficacy I get from individual units. But maybe I've just never lived in a properly that has good central AC. I will watch the video, thanks for the link.
Sounds similar to my parents', which was built in the 70s, in IL.
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Last summer I visited and ended up doing a bunch of deferred home maintenance on the place. One thing I discovered was that the central air return vents weren't installed correctly, after 50 years of them paying out the nose for unnecessarily high electricity bills every summer.
The construction technique used was clearly prioritizing low-cost and had the main return duct running the length of the house above the basement ceiling just opening up on top into the floor joists to reach rooms upstairs. The bays between the floor joists served as ducts branching out horizontally from above the main duct, and holes were cut in the upstairs subfloor where the stud bays in walls would serve as return ducts on the vertical axis.
When they hung the main duct they left a huge gap separating the thing from the joists, upwards of two inches wide towards the far end from the air handler which was also beneath the vertical branch for reaching the highest/largest (and hottest) return vent upstairs.
So despite having all these return circuits ostensibly present upstairs, the main return duct just pulled most of its air through this much closer and substantial gap drawing air from the lower level between the basement ceiling and the upper floor's joists.
Everyone had always assumed the cold downstairs was expected because Basement, and that the upstairs was just always hot in summer because of poor insulation and all the windows.
The way I identified the issue was by grabbing a long grocery store receipt and placing it across all the return vents while the AC was running (just get the blower on 100%). The receipt was nearly sucked through the basement return vent, and immediately fell off all of the upstairs return vents except the one directly above the air handler in the master bedroom. The one upstairs that worked doesn't depend on the long, leaky return duct. Then I fully blocked the obviously working return vents with cardboard, just to see if the non-working ones would start drawing enough to at least hold up the receipt - they didn't, zero change.
I was able to improve the situation with a can of expanding foam filling the gaps on the main return duct, through drop-ceiling access... If I visit again I'm ripping out the basement ceiling to fix it properly.
TL;DR:
If you've got a house w/central air that seems to not cool specific regions, get yourself a piece of thin paper like a shopping receipt and some cardboard and try some process of elimination to verify the return vents are all sucking air. Don't just focus on output vents blowing cold. You can do this preliminary check without any tools or creating a mess, fixing what you find might be a different story though.
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This dovetails with my other point, which is that masonry (not just as a facade) especially cement controls noise and seems to prevent needing all of these complex workarounds. I'd love to learn aside from "it's more efficient" (aka cheaper) the compelling reason for using wood vs cement.
It seems like it's just a foregone conclusion that of course we should be building houses with wood as the central element.
It's less expensive in many ways. Materials cost less, it's faster to build, it requires less skill to build, maintenance is less expensive, and changes are less expensive. Unreinforced masonry is a significant earthquake risk, which may a factor.
Wood meets the requirements and it's less expensive, so there you go. There's downsides of course, but modern building requirements are tough to meet with any construction type; drafty houses make for expensive HVAC, but tend not to accumulate moisture which leads to bad things.
https://www.bbc.com/future/article/20210810-the-ancient-pers...
We will likely see a massive expansion of air conditioning as more and more people come out of poverty and desire to be comfortable across the developing world.
We can’t conserve our way out of this crisis. We need abundant, zero carbon energy like wind, solar, and nuclear to support all the energy needs of humanity.
If we don’t have zero carbon energy people are not going to do without, they are going to burn fossil fuels. Take a look at Germany. Despite all their rhetoric about how much they care about climate change, they are burning coal which is the dirtiest of the fossil fuels.
Enough "passive cooling" articles. That's ventilation, just a part of HVAC. These articles makes it sound like the ancient Iran and the termites knew something an entire industry full of engineers doesn't.
Just about everyone has the intuitive understanding that some old buildings do a very good job maintaining comfort, and that modern buildings often fail to do the same or only keep up at enormous expense. It's perfectly understandable that, in the wave of globalization and cheap energy that swept much of the world for half a century, we lost the craftsmanship to create these structures well, then the knowledge to do so at all, and all the while we didn't care because electricity was so cheap. Now we're clawing back stuff we used to be able to do as a matter of course.
Central air is miserable to maintain. I want to maximize my comfort with ceiling fans and window units, or maybe ductless.
We've known about thermal mass, convection, venturi effect and other stuff for ages, and it's not going to help you be comfortable (another thing termites have no concept of) beyond a certain envelope.
> Architect Mick Pearce famously based his design in the 1990s on the cooling and heating principles used in the region’s termite mounds, which serve as fungus farms for the termites. Fungus is their primary food source. > > Conditions have to be just right for the fungus to flourish. So the termites must maintain a constant temperature of 87° F in an environment where the outdoor temperatures range from 35° F at night to 104° F during the day. Biologists have long suggested that they do this by constructing a series of heating and cooling vents throughout their mounds, which can be opened and closed during the day to keep the temperature inside constant.
Old buildings did not have: thermal insulation, ventilation with heat recovery, timed ventilation, etc. While new buildings won't even get a building permit without all that. There's a minimum required energy efficiency.
I have to ask: what is your experience with civil egineering?
So true.
I want to maximize my enjoyment of warm humid air while targeting 10% of the energy usage of those who fear it.