[arethuza]

I suspect it very much depends what you are used to - I probably think of 15C as "comfortable" and 25C inside would be sweltering. Having said that I'm in Scotland - the other day we had heavy rain and it was 8C which is weather we could get at any time of the year!

[QuarterReptile]

Maybe I'm being dense and saying the same thing as you, but it's more about the difference from outside to inside. In the mid Atlantic of the US, 22C can be pretty pleasant, but in the South turning it below 26C is a much more pleasant setting. Meanwhile, spend time in Southern China and you'll be laughed at for going below 30C, because it makes you nearly unable to go outside. If I feel like the humidity outside is going to condense on me when I take the dog out, I'm cooling my house too aggressively.

Similarly, I don't heat above 15C in the winter. That way, getting dressed to go outside is less complex than suiting up for a space walk.

[arethuza]

I must admit that I don't know the difference in temperature from inside to outside - for half of the year (say May to October) we don't have heating on and we don't even have air conditioning (I don't know anyone who has air conditioning at home in Scotland).

The main difference I'd see between inside and outside is the lack of rain and wind in the former - temperature difference is secondary.

[_0w8t]

What closing do you use at 15C? After a few years in Norway I can be OK in a t-shirt at 18C. Anything below that still requires a jacket or sweater to stay comfortable.

[dEnigma]

Not OP, but here in Austria I wear t-shirts for most of the year. I even used to go out in just a shirt on warmer winter days with only light snowfall, but nowadays I really notice the cold when I do that. Everything above 10°C is very comfortable to me. Among my friends and relatives I am the exception of course. Most of them dress in more layers, some even in summer.

[arethuza]

Quite happy in a t-shirt at 15C - especially if doing something other than sitting at a PC!

[ownagefool]

Funny. I'm Scottish and I would find 15c utterly baltic, especially when inside.

[arethuza]

I suspect its because we used to live in a very old property that was very difficult to heat. So we got used to it!

Edit: I remember going to the halls at Uni for the first time and nearly dying of the heat - never lived anywhere that had central heating. Got used to and, of course, felt like I'd been exiled to Siberia when I went to my parents ramshackle large house for the Xmas break.

[NoGravitas]

Wow. I think of 15C as "comfortable if I'm outside doing stuff and wearing long sleeves", but inside, it's "put the heat on (to 18C) and put on a sweater". 25C inside is what we set the air conditioning to in the summer at night so it's easier to go to sleep, but in the day, 26.5 is fine. This is in the southeastern US, and I've converted all temperatures from how I normally think of them in F.

Also, my workplace keeps inside air conditioning much cooler than I would, around 20C, which is uncomfortably cold when I'm dressed for the summer weather (ranges from 27C to 38C).

[tjl]

In my department at my university, professors and staff usually end up bringing a sweater and leaving it in the office so they have it in the summer. It gets kind of cold in the offices.

I've set my apartment to 26C. I find that without the humidity (since the AC deals with that too), 26C is actually not too bad for the summer.

[snarfy]

After moving from Phoenix to the Seattle area, I've noticed the 'feels like' temperature is about 11C difference. 30C in Phoenix feels like 19C in Seattle.

[arethuza]

Humidity and/or wind?

I've noticed temperatures in Scotland on mountains feeling much colder than lower temperatures in the Alps.

[cafard]

Largely humidity.

In Denver, I could run for an hour in direct sunlight with the temperature about 30 C. In Washington, DC, that would have been suicidal.

[dionidium]

Yes, but DC is famous for its humidity, whereas Phoenix is known for its "dry heat."