17.9C is a tad low, but 23C is ridiculous. However I cannot understand why young people expect to be able to live in shorts and T-shirt year round in CH (or in the UK for that matter - at least in CH houses are somewhat better insulated- we had a 1920s house with single brick and the old metal Kritter leaded windows- very pretty ...but!). The regulations are spot on 20-21. Must say though I couldn't sleep at 20/21 - we have no heating in our bedroom and more or less always open the window at least a crack. A heated bedroom is a nightmare for me and I wake up in the middle of the night with a massive headache.

So, I sent another e-mail mentioning "Landesrecht" (http://www.admin.ch/ch/d/sr/220/index2.html#id-2-8-1) and success stories from http://www.mieterverband.ch/fileadmi...entscheide.pdf to the agency.
If I won't receive any reply within 1 day, I'll go the Mieterverband.

Thank you all for the answers, will keep you informed.

The problem with rooms which are "too cold" is that the humidity will condensate on the windows and lead to mold quickly.

A new, modern, MINERGIE-certified house will not get warmer than 21° C BTW (and maybe 23-24 in the bathroom).

because it's nice? I'm from a cold country, so if homes are cold too, those 9 months of winter would be really miserable. Actually, just looked it up, according to health regulations in my country, the school will be cancelled if it's less than 19C in classrooms. Way too cold to function properly.

The other option is to purchase an electric room-heater (InterDiscount or MediaMarkt for less than CHF 100) and place it where it is coldest. I purchased such a heater originally for our office when the heating failed again and again, then took it home, and over to the apartment of mum, where the heating failed repeatedly. Now, I have it in the room where I have my bed and which is the coldest room of the flat. Things are now back under control

No, to me it has to be at least 20°C . Alright, in the sleeping rooms in the home of Grandmum, where the living rooms downstairs got heated by a "Kachelofen" but the sleeping rooms upstairs only indirectly, we had heated sand-cushions in our beds (for example on Christmas or NewYear visits) to milder temperatures of between 13 and 16 degrees. It was surviveable, I admit. In the living rooms however, the temperature was between 20 and 24

Her contract states that she cannot use any extra heating appliances.

Anothe poster mentioned children being sent home from school when the temp dropped below 19C. I spent two years in a country where the apartments and the schools were heated to 25C. The school windows were all taped closed over winter, so no chance to open windows to lower the temp. I had one young student who used to strip to her singlet and tights each day to cool off. Outside the temp was -25C and I frequently wondered how healthy is was for us all to be going in and out where there was a 50C difference.

Before I left NZ, I was used to living in houses where we didn't turn on heaters or light the fires till the temp dropped to 10C inside - woolly jerseys were mandatory. I now shiver at the thought of going back to that .

Ours is Minergie certified (plate at the entrance) and I can confirm that it DOES go above 21. We have 23C (and nits not maximum yet) and we love it!

Hmm...this thread made me analyse my current situation. Had asked the concierge to check the temperatures a few weeks ago (as i felt a bit cold), and she had explained me the rule that the heating is lowered down at nights to save energy.
I requested her to get the temperature checked during the day, to which she said that everything was okay. I wasn't sure if there were any rules which I could have showed her, inspite of feeling cold (until reading this thread).

So today I have the room temperature with me at 18.4 C and the heating is at max. Its time to show her the facts!

Feel free to post your story afterwards, the thread is becoming useful not only for myself.

As for me, looks like I'm the only one who's suffering from cold. My neighbor's apartment is cool, but not sooo cool. For neighbor on the ground floor the temperature is too warm .

Also I discussed the case with swiss colleague. His resume is: Miterverband may help to decrease the rent/get this problem solved, but be ready that the agency may find the reason and kick you out.

As hot air rises, my apartment is always comfortable / warm even with our radiators set pretty low since we live on the top floor (attic apartment) so we get our neighbor's heat. I wake up sweating and have to go sit near'ish the slightly opened terrace door many nights.

I suspect this cycle is self-perpetuating though - I'm too hot and make it cooler, cool air sinks which makes my neighbors cold so they crank the heat.

While this could theoretically be so, IF they attempt this, I suspect they could face some problems if you bring it to the attention of the appropriate authority. I wouldn't worry about it too much... but if they're fussing over making your living actually comfortable for the little one, perhaps it wouldn't be a bad idea to keep an eye on options for the future, just in case. (If they're fussing about heat now AND make problems for you when you force them to fix it, they're not someone you should be entrusting your living to in the first place)

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The Joys of Opticianry

No idea if this helps but like a few others here we suffer from the opposite problem with the apartment being 21-26 with all the radiators off. This is after 3 years of concerted effort and the departure of one tenant who liked living in a sauna - it was 25-30 if we left the doors shut before. Even now we have to leave one veranda door cracked open which means that the humidifiers dont work very well and it is a real struggle at times to keep the humidity above 25%. Also a real pain as when it is -8 outside the draft is very cold.
When we investigated it turned out that the heating wasnt as straight forward as I had assumed (we have radiators in every room - all turned off).
It turned out that these were simply top up and the main source of the heating was underfloor with no temperature control apart from the water temperature. To make it worse this temperature control also regulates the hot water temperature so they wouldnt lower it below 60deg C due to the possibility of legonaires!.
Not sure how true this is as the temp is fairly constant with outside temps from minus 10 to plus 10 which would appear to contradict a supply temp regulated system but it is what a certified heating engineer has told us. Would appear to be a highly inefficient way of heating the building though.
Have been told that it will change when the boiler gets replaced to comply with new regs in a few years but until then it is t-shirts.

Is that true in the summer, as well?

To combat leginonella, you just have to heat to 60° once or twice a week.
A modern heating will do that automatically.
And yes, it's highly inefficient to have it at that temperature all the time.
But as long as the tenants pay...

No.
But in the summer, you just open the windows and no energy gets wasted.
;-)

Indeed, I had some success. I shared the facts with the concierge, she replied that they had not observed any issue last week but she'd send a service team to check.
In the next email she said that there is a problem for sure, and while it gets fixed they have installed an electric heater in the room as a stop gap measure

It does get lowered at nights even where we are.

We had no heating yesterday, and the temperature got down to around 17 degrees, which isn't too bad, but it depends what you're doing. I had a full afternoon of music teaching, and, while my students were okay as they just came inside for a short period of time, by the last lesson I was wearing my furry boots and a couple of jumpers. When you're just sitting in one place for stretches of time it does get pretty cold!

Oh my, what a complicated post. I'll try to get my head around this, as we seem to have the same issue: all the radiators are practically off and it's still very warm. It's great for me because I'm always cold anyway, but my husband tends to complain. Do you also have warm spots of floor even though technically there is no underfloor heating?

Kind of happy end It's now about 21 degrees in the apartment.
I have no idea what have they done, but now it's warm and comfortable.

Had to complain by e-mail, catch Hauswart and do the same. There was also another new tenant that also complained.