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Comment by mrweasel | Hacker News Reader

That is 13 degrees Celsius, that's pretty cold. Currently, due to the war in Ukraine and a reliance on Russian gas many Danish companies and government offices have been turning down the heat to 19 or 20 degrees Celsius. This has come with warning from engineers to not go much lower. In cold and wet climates, dropping below 19 degrees during the winter will damage building and allow mold to grow.

I can see 13 degrees not doing much harm in places arctic perhaps, but it is something to be aware of.

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> dropping below 19 degrees during the winter will damage building and allow mold to grow.

Can you provide a source ? This would mean that all unoccupied houses would be damaged, since they are just heated to avoid freezing (10 ?).

Just thinking out loud, I'd guess people living there would be an important factor since we produce quite a lot of water vapor, as do things like cooking etc. And when the house is cold, this has a tendency to condense on any surfaces. And humid porous surfaces (drywall) and even insulation will probably be a good substrate for mold.

Most insulation materials are engineered to reduce growth of mold. Drywall usually has an air gap on the cold side to let air circulate.

Drywall is very rare for non -internal walls across Europe, especially in cold countries like Denmark.

19c is basically a rule of thumb measurement.

Warm air can hold more moisture than cold air. Humans and their activities give off moisture. In winter humans maintain warmer than ambient temperatures. Therefore at some point the warm wet air is going to cool and reach its dew point.

Ideally you don't want this happening in the house, whether it does depends on the inside temp and the outside temp and humidity inside and out.

So there's a few knobs you can twiddle, temp being one.

https://sparenergi.dk/forbruger/spar-energi-i-dit-hus <- Danish Government Office for Energi (but in Danish).

They say 18 degrees, to avoid issue with moisture. It very much depends on how the home is built I'd assume, because holiday homes are normally kept colder, down to 5 degrees, during the winter.

Warning, annecdata: we turned down our heating signifcantly this winter, and both my roommate and me have gotten quite a bit of mold on and around our windows.

The thermostat is now back up to 19.5°C.

If you're able to invest in better windows (good double or even triple glazing), that will solve it. But just wiping down the window sill semi-regularly works well, even if it's an annoying chore.

With better windows the moisture may condense in other less visible places. Best to remove it with desiccator.

Sure, but there are insulation solutions that mostly prevent it. For example insulation foam layered between vapor permeable foil on the cold side and vapor inhibiting foil on the warm side.

But drywall (and other porous surfaces) are supposed to help regulate moisture, so if they never get an opportunity to dry because it's permanently cold and humid, yeah, that'll be a problem. Cracking a window at least 30 minutes per day (ideally on dry days) does wonders, though it won't help temperatures in winter.

Yep in theory it's all nice and easy, just put foils in and open the windows sometimes.

In practice... say, there is a dog that likes to gnaw on corners and thus punctures the vapor barrier. Happened to my own house's outside insulation. That's just one of many "unforeseen" ways how these foils and barriers stop working. I fully expect the polystyrene there to get moldy in 20 years or even less.

My insurance requires that my house be at least 16 degrees all year

How do they measure that?

Presumably your fridge and freezer is breaking that rule.

Edit: it's a genuine question. Is that the minimum temp anywhere in the house or the average? What about an attached garage?

One does not have to measure something to require it.

The insurance company does not want stupid actions by the owner causing property losses. If you have utilities shut off to the property for a month in freezing winter weather and all of the pipes freeze, they’ll be able to determine that you did not maintain 16 degrees.

Theres a wide gap between freezing and 16 degrees.

Which suggests this is more about mold etc. If they don't want to cover frozen pipes then fair enough, they should really state that because then it becomes unclear what the situation is in the case of a garage or if you have a pipe in the attic or cellar.

It's likely not about any one type of damage in particular and more about 16 c being a reasonable lower bound for indoor temperatures of a properly maintained property. Nobody from the insurance company is going around checking to see if people's houses are 15.5 degrees so they can cancel their policies. Provisions like this are just a slightly more objective way to say "don't neglect your damn property".

Now this also doesn't mean that frozen pipes aren't covered. It is possible to have pipes freeze while keeping normal indoor air temps. Not all pipes are in conditioned space.

>Nobody from the insurance company is going around checking to see if people's houses are 15.5 degrees so they can cancel their policies.

No of course they won't. That would be giving up good money. Instead when you make a claim they'll reject it on some basis around the property not being kept at 16c.

Of course, this is the point of outlining requirements within a contract.

To be honest I don't know.

> Presumably your fridge and freezer is [sic] breaking that rule.

You must be fun at parties.

>[sic]

touche

That's weird: in Denmark, I guess temperature would go above 19 degrees about 6 months a year. That means that buildings are built with the expectation of being warmed...

I think most buildings are build with an expectation of cold in the winter. Building for warmth would result in burst pipes during winter, when the temperature goes below freezing

I might be in for a surprise, but I don't think there has been a year where the temperature has been above 19 degrees for six months of the year. I'm curious if you have a source on that?

no source, was just guessing based on Denmark's position on the globe (and comparing to my own country)

I live in Edinburgh (Scotland) and we count _days_ over 19 degrees rather than months.

> That means that buildings are built with the expectation of being warmed...

That doesn't seem strange to me. At even lower temperatures, water pipes will burst, so you have to heat it at least a little in winter. Waste heat from humans might be enough to avoid freezing temperatures, but then humans also produce a lot of humidity, causing mold.

Can you source this? All of the advice from UK bodies says 15-16 rather than 19.

Usually the freeze dryed air there, kills any mold

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