ᐅ Cooling with a heat pump through underfloor heating?

Hello everyone,

we are building a KfW 40 house with a Viessmann Vitocal 200-S heat pump and an 8 kW photovoltaic system.
The heat pump is also capable of cooling. The upgrade would cost 1000 € (only the heating installer, thermostats extra).

Is it generally worthwhile to cool using the heat pump? Just because it can does not necessarily mean it is practical.
How fast does a room cool down? Underfloor heating systems are usually quite slow in response.

Or does it make more sense to invest in an air conditioning system and operate it with the photovoltaic system on hot days?

Thanks and best regards
Markus254

We have ceiling cooling in the office, which is much more comfortable compared to air conditioning. The cooling doesn't start instantly at the push of a button, but once it is running, it works really well. However, I’m not sure if floor cooling would be just as comfortable.

Opinions on this vary widely. Ceiling cooling is said to be significantly more efficient than floor cooling. Floor cooling would create a cold "pool" at floor level inside the room. Cold air naturally does not rise. Furthermore, it is said that the room temperature can be cooled by about 2°C to 3°C (4°F to 5°F). Of course, an air conditioning system is considerably more powerful.

Markus254 schrieb:

Or does it make more sense to invest in an air conditioner and run it with the photovoltaic system on hot days?

Definitely. Cooling with a heat pump is like a gentle breeze. Nice, but nothing more.

nordanney schrieb:

... a light breeze. Nice, but nothing more.

A light breeze can already be enough to keep the temperature "bearable" 😎

Certainly, an air conditioner is more powerful, but it is purely electric cooling.
A ground source heat pump, on the other hand, can sometimes achieve this without extra electricity, using PC (passive cooling).

I’m happy to share my experience if there is a hot late summer.

It's funny how everyone gets excited when a device is called a heat pump and is used for heating, but when the same device is called an air conditioner and is used for cooling, everyone thinks that's bad.