Basically the world I am designing gets really cold in the winter (coldest month of the year averages -75C in some inhabited areas). Because of this people dont really like to build small more isolated settlements and prefer to stay in cities. Over time these cities got huge, on average each city has a population of around 260 million human residents.

How would cold weather effect the overall height of buildings? Would they prefer to build shorter structures and expand outward more or go full coruscant and build massive skyscrapers?

Considerations: Some of these cities are built in hilly/mountainous regions so if expansion did occur it would have to be along the relatively narrow valleys. Every city is built near a body of water whether that be a reservoir that is refilled by melting snow each year or a river. Many of the cities on this planet are also built near areas of volcanic activity for heating during the winter, how could this be incorporated into the architecture?

  • $\begingroup$ In the summer, is the weather nice and pleasant? $\endgroup$
    – Alexander
    Apr 22, 2022 at 22:30
  • $\begingroup$ @Alexander Weather is pleasant during summer in the mid latitudes. The planet has almost no axial tilt and only gets seasons because of its eccentric orbit around its star. $\endgroup$
    – Boo Radley
    Apr 22, 2022 at 22:47
  • $\begingroup$ A 'city' of 260 million people may create its own warmer micro-climate. $\endgroup$ Apr 27, 2022 at 5:19

6 Answers 6


coldest month of the year averages -75C in some inhabited areas

The sublimation point of CO2 ice is -78°C. This implies that some of your settlements get dry ice snow, which will have interesting effects on your atmosphere. Assuming your settlements aren't in the coldest bits of your world (polar or mountainous ice caps) you're going to have some odd atmospheric effects, and probably layers of buried dry ice in ice caps. Melting of ice caps might trigger really exciting rapid global warming effects.

edit it also occurs to be that if enough CO2 precipitates out in the winter, then the later winter/early spring thaw might result in pools of deadly gas forming. CO2 is heavier than air after all, and on a calm day it may not mix quickly enough with the rest of the atmosphere. Living in a basement in such circumstances is probably hazardous. See also: Lake Nyos disaster.

That aside, you have to worry about ice formation on the roofs and sides of your buildings, and issues with cold embrittlement of tools and structural metals (note that steel becomes brittle at -73).

Some of these cities are built in hilly/mountainous regions so if expansion did occur it would have to be along the relatively narrow valleys

Be careful about construction in mountainous regions with big temperature swings. Lots of fun rockfalls and ice falls and avalanches to look forward to.

According to the wikipedia article on permafrost,

Permafrost is soil, rock or sediment that is frozen for more than two consecutive years. In areas not covered by ice, it exists beneath a layer of soil, rock or sediment, which freezes and thaws annually and is called the "active layer". In practice, this means that permafrost occurs at an mean annual temperature of −2 °C (28.4 °F) or below. Active layer thickness varies with the season, but is 0.3 to 4 meters thick

Your hilly areas, and valleys, are very likely to have a permafrost layer unless the winters are very short or the summers are lethally hot. Permafrost has a major impact on construction, because temperature fluctations in the upper layer cause ground to significantly soften in summer and then refreeze in winter with ice expansion capable of damaging foundations. Here's a building in Longyearben on Svalbard up above the arctic circle:

Hospital (Sykhus in norvegian) at Longyearbyen, Svalbard showing the characteristic piles for construction on the permafrost

Note that it is built on legs. Amongst other things, this helps prevent the heat of the building contributing to melt underneath it which could destabilize the foundations. In such conditions, no-one will be building sky scrapers!

(the linked settlements from the wikipedia article such as Yakutsk are probably relevant to your interests, as they are permafrost towns with record low temperatures approaching your average low temperatures)

That limits tall building construction to places where massive stable bedrock is accessible from the surface, avoiding the instability of the regular ground. Such construction is likely to be very expensive and require hefty bits of machinery to accomplish. This might well mean that the places where you could most commonly (and cheaply) build large settlements, nice wide open plains, are the places where you're least likely to find very tall buildings!

Assuming you still want your expensive cities on rock, "sky scrapers" seem likely to be much lower and broader and maybe even have sloping sides to mitigate excessive structural loading by ice and snow and to reduce the problem of ice breaking off the upper levels and falling onto things below around the building. Construction of tall buildings in hostile environments is challenging at the best of times, but maintenance of them is going to be worse... dealing with exterior damage on a very tall building in the winter is likely to be impossible!

Remember also that modern day super-tall sky scrapers are largely commercial buildings, with residential tower blocks being rather shorter, and both only really exist where land prices are high and minimizing the footprint of your building makes sound financial sense. Given how challenging the construction and maintenance is likely to be, and how unpleasant the winters will be, I can't help thinking that the skyscrapers will be further south in places where there isn't permafrost to deal with and the winters are less severe.

Additionally, you might consider that digging down below the permafrost level (where possible) might be a more sensible place to build. Ground temperatures are likely to be much warmer than surface temperatures, and there's substantially less risk from the weather. Underground cities might make a lot more sense than super-tall above ground ones, under the circumstances. (edit: at least in places where you don't get significant CO2 snow, at leas.t)

  • 1
    $\begingroup$ Thank you for the excellent answer. I hadn't even thought about the whole dry ice conundrum but it does make an interesting plot point, I will keep that in mind. $\endgroup$
    – Boo Radley
    Apr 23, 2022 at 16:06
  • $\begingroup$ Fears of "CO2 snow" are exaggerated (so no, there is no carbon dioxide snow in Antarctica). Solid CO2 would indeed sublimate at -78.5 C, but small amount of this gas available in the air won't freeze at that temperature. (Results: Lab experiment regarding CO2 "snow" in Antarctica at -113°F (-80.5°C) – not possible)[wattsupwiththat.com/2009/06/13/… $\endgroup$
    – Alexander
    Apr 24, 2022 at 3:58
  • $\begingroup$ @Alexander note the OP said average temperature, implying that it can get much lower, and potentially much lower over a much larger region, too. Also your link is broken. $\endgroup$ Apr 24, 2022 at 7:39
  • 1
    $\begingroup$ Sorry for the broken link, let's try it again: Results: Lab experiment regarding CO2 "snow" in Antarctica at -113°F (-80.5°C) – not possible. Indeed this can happen at a lower temperature - the question is how much lower. The temperature has to be below -130 C, at which no higher animals are able to survive. $\endgroup$
    – Alexander
    Apr 24, 2022 at 8:18
  • $\begingroup$ @Alexander that's more informative, thanks. I do think you'll get combined H20 and CO2 snow, though, and that "-75 average" does certainly have the potential to generate the dangerously low temperature needed. (probably the world wouldn't be inhabitable anyway, but that's a separate question, and presumably one that the OP has handwaved away) $\endgroup$ Apr 24, 2022 at 14:04

Mountain skyscrapers

The skyscrapers will be built in the mountains so only one side of the dwelling will be exposed to the outdoor conditions and the mountains will act as a barrier blocking most of the cold air. It will be easier to isolate and heat inside. It is similar to caves where they've been used as shelters in harsh weather conditions through the history. Here is a depiction of a mountain skyscraper:

enter image description here

As for utilizing volcanoes, the magma underground that drives volcanic eruptions can also provide heat or electricity generation from heat. Geothermal energy is derived from heat within the crust and we can harness more of this energy close to volcanoes.


Their cities will be more like anthills

Some skyscrapers may rise high, but general architectural trend would be "maximize internal volume".

I don't know if people of this world can be biologically the same as Earth' people, because -75 C is just too cold. One can go outside only very well bundled, with full face protection, and even then the air can be harmfully cold for lungs.

But assuming that those people are no better adapted to cold than our northern indigenous people, they would tend to stay indoors as much as possible during winters. Cities would tend to build covered galleries connecting buildings to each other, and those galleries would be much busier than open streets. Buildings would tend to be squat and small-windowed to preserve heat rather than lean and tall to let the most sunshine and air get into people's rooms.

Most likely people of these cities would live in Arcologies, which may get tall - but not necessarily. Main focus of arcology construction would be its reliability and self-sufficiency during long (very long for an eccentric orbit) winters. Large internal volume would allow for creation of indoor parks and recreation facilities.


Minus 75 is not that far off -40/-50 which is experienced in some parts of northern Canada, Europe and Russia.

It seems the cold is countered by sufficiently warm summers to melt the snow and presumably allow agriculture. This implies that large scale ground loop heat pumps would be very effective for temperature regulation.

  • District ground loop heat pumps.
  • Smaller/fewer windows. Or at least multi layer insulated windows.
  • Thicker outer walls with more insulation.
  • foundations designed to avoid issues with permafrost.
  • Mid-rise 5-15 stories to keep surface area lower. Think short thick as opposed to tall spindly
  • To maintain economic viability designers would need to ensure walkability of the cities.
  • Many covered walks/malls/galleries so that pedestrians can be sheltered while they go about their business.

Many of the covered walks could be heated to the -15+-5 cold enough to use ice as construction material, warm enough to be tolerable/comfortable. Not as expensive as heating to +20


They would probably be very much like Yakutsk, Russia:


House blocks (conserve heat) which are still not very thick (people want to have windows!) but may be fairly wide.

The Soviet city planning is not optimal - those wide streets attract winds.

You can expect a lot of Lego-like 9-story buildings connected by underground warm tunnels, perhaps even underground warm roads for public transit if not cars.


Winter coats.

ice cones

When the weather turns cold your buildings put on their winter coats. The nearby body of water is pumped onto the tops of buildings and freezes as it comes down the sides, sheathing the buildings in ice. Ice is an excellent insulator and keeps the buildings warm. When things thaw, the coats melt and run back down into the lake.

I considered more practical approaches, like long vertical undergrown sgafts insulate by earth and heated by the mantle below. Ice sheaths have the advantage of being awesome.

I think conical pyramids will need to be the underlying building shape. This will offer support to the overlying ice in a way a vertical wall cannot. Also, and importantly, the pyramidal shape will allow sledding. There are halfpipes between the cones so one can sled down the side of one and then up the next.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .