[Retric]

It’s a deep rabbit hole as condensation, humidity, etc also enter the picture. Efficiently lowering temperatures for sleeping further complicates things.

That said, heat loss is through exterior surfaces so you really want to avoid spot heating of poorly insulated exterior walls. Thus the design of baseboard heaters can make a larger impact than you’d think.

[looofooo0]

Baseboard heaters need very high temperatures. I would not recommend installing this anywhere. Having big Typ 33 heaters for temperatures below 45°C will greatly increase efficiency of your heating system. Otherwise, a split air con is also an efficient way of heating.

[sokoloff]

Baseboard heaters are often sized such that very high temps are needed (because that's what cheapest/lowest labor/least space used), but they don't have to be sized that way. In the attic bedroom, we have baseboards around the entire perimeter on two walls and same in the bath. I run the attic zone on the same water temp (outdoor reset controlled to be quite low) as the rest of the house (mostly large cast iron rads, one cast iron convector). Good insulation and air sealing in the attic means that the attic zone calls way less than the downstairs.

[looofooo0]

Which is not exactly efficient. 40C or less is desirable.

[sokoloff]

My return water temps are 115F (46C) on a P98 design heating day, and obviously cooler on warmer than design days. Cooler is always better, but "baseboards require 180F [82C] water because that's what's on the spec sheet" is a commonly-held but mistaken belief.

[looofooo0]

This is bad. Return water should be less 35 degree max. Actually 30 degree after the heat pump would be ideal: https://www.flow30.de/

[jillyboel]

[citation needed]