ᐅ Cooling with a heat pump through underfloor heating?

Your discussions about the installation options for air conditioning are certainly useful and helpful for others. Wouldn't it be better to continue them in one of the air conditioning threads?
This thread is actually quite good for learning about cooling in combination with underfloor heating and heat pumps. (Experience reports from air conditioning owners are only of limited help here)

Traumfaenger schrieb:

Maybe the technology has advanced compared to a few years ago. But I once worked in an office where, in winter, the women had to sit with an electric fan heater under their desks, while the men were too proud for that ;-) In short: it didn’t work at all. The architectural firm was also sued for these and other design errors, but later went bankrupt....

We have concrete core cooling, or thermal building component activation, in the load-bearing, freestanding columns in our office. Although I haven’t been there for 1.5 years, 22°C (72°F) in summer was fantastic.

Mycraft schrieb:

Yes, but only if there is an imbalance. If humid air is already coming in, then it can’t regulate anything. Humid air out -> through the humid enthalpy exchanger -> new humid air in. Result in summer -> humid air everywhere.

I’m not an expert, but shouldn’t there be a distinction between relative and absolute humidity here? The latter is the relevant factor for diffusion processes in the enthalpy heat exchanger. When I look at the absolute humidity for 30°C (86°F) and 24°C (75°F) at 70% relative humidity on an h-x diagram, there is definitely a difference. That’s why the warmer, more humid outside air transfers its moisture to the outgoing exhaust air. At least that’s my basic understanding. You can probably find detailed calculations for this in the pink forum and the green forum from Austria.

To summarize my understanding, there is ongoing debate about whether cooling through underfloor heating achieves a temperature difference of 2-3 degrees Celsius (4-5°F) or as much as 4 degrees Celsius (7°F), making it a cost-effective alternative to a true air conditioning system. Alternatively, only air conditioning cools effectively during hot summers and noticeably dehumidifies the air.

From the discussion, the apparent calculation is this: on a hot summer day with an outside temperature of 37°C (99°F), each degree Celsius of cooling costs about one thousand euros. Cooling via underfloor heating by 2-3 degrees costs around 2,000–3,000 euros (in one post even 4,000 euros), whereas air conditioning costs over 13,000–16,000 euros. If you are comfortable at an indoor temperature of 33–35°C (91–95°F), spending 2,000–3,000 euros might be acceptable. But if you prefer 21–24°C (70–75°F), you need to invest a five-figure amount to cool a single-family house properly. However, these are fundamentally two different things, both in terms of effectiveness and cost. Trying to compare them directly, in my opinion, does not make sense.

Traumfaenger schrieb:

Whoever feels comfortable at an indoor temperature of 33-35 degrees Celsius (91-95 degrees Fahrenheit),

Now don’t exaggerate!

Traumfaenger schrieb:

that’s nonsense

I agree…

driver55 schrieb:

Now don’t exaggerate!

What would you consider a realistic indoor temperature for a KfW 40/55 house after two weeks of a heatwave? 😉