Air-to-air vs. air-to-water heat pump KFW55 house - cooling function important

Do not underestimate the heat generation in a new building.

The heat generation comes from the computers and people, not from the new building.

In summer you won't survive without air conditioning.

I wouldn't necessarily agree with that at first.
Even with underfloor cooling, a significant amount of heat can be carried away.

But yes, if you have two computers at 300W each, two people at 100W each, and then switches, servers, and so on, you quickly have to dissipate 1kW from a single room (and that without solar radiation and other heat transmission). That is quite a special requirement, especially if the room is relatively small and used for many hours at a time.

I always find it interesting that many say that air conditioning in winter for heating is very unpleasant, but in summer it suddenly should be comfortable to be blown on with cold air and deal with the noise?

I always find it interesting that many say that an air conditioner is very unpleasant for heating in winter, but in summer it is suddenly supposed to be pleasant to be blown with cold air and to have the noise?

The noise is an undeniable counterargument. Currently, I am still sitting in an old building, and the mobile air conditioner stands on the desk, practically 30 cm next to me, and that is already a bit annoying. However, not nearly as much as being terribly hot. They only blow on you if you stand directly in front of them. We can even solve that in our currently cramped apartment. The proper split units do not make nearly as much noise as the mobile ones (the thing that’s buzzing here right now), and you usually hang them over the door. It should then be adjustable so that it does not blow directly on you.

But yes, if you have two computers at 300W each, two people at 100W each, and then switch, server, and co, you quickly have to dissipate 1kW from one room alone (and that without solar radiation and other heat transmission). That is quite a special requirement if this room is also quite small and used for many hours at a stretch.

That’s true, but that’s just how we are – and judging by what the OP says, they are the same. That’s why my warning, since we already have experience with the scenario "intensive office use in a new building." We were very glad about the split unit in the room.

The heat generation comes from the computers and people and not from the new building.

That’s true, but the problem with the new building is that the heat cannot go anywhere without my intervention. In our current dwelling, I had no problems in the office in winter.

That's true, but the problem with the new building is that without my involvement, it can't go anywhere.

That's not true. You have walls, ceilings, screed; all of that absorbs heat. And air exchange with other rooms. Quite a lot happens there.

And what kind of machines do you actually work with? My work laptop has a 45W power supply, so it can't draw more than that. It can do everything I need for work, and it's fast enough as well. Heavy performance tests are better done on a server anyway.

My PowerPoint-pusher laptop also only has one of those 45W wall warts - my developers have workstation laptops whose power supplies are heavier than my laptop. And in the office, we have REALLY fast machines with three monitors attached. They draw quite a bit of power and turn it into heat. And the workstations cannot be reasonably relocated either. Sure, my switch is in the basement but that doesn’t make much of a difference.

I also have 3 external monitors (so 4 in total :D) in the office. It requires the expensive docking station from Dell with its own power supply, but it's really impressive what runs over such a small USB-C DisplayPort. We used to have workstations as well, but back then we were in the office every 5 days. When this home office thing suddenly came up, I didn't want that anymore. Honestly... Marketing and sales sell us as specialists for large amounts of data and we also have some customers with substantial data. But in practice, you usually test the code with datasets that you can manage. And for the big, hours-long tests, I don't even want that on my machine blocking something for me.

One more thing about underfloor cooling – how much the extra cost is depends on the system. We looked at 2 systems last week: - Viessmann - heat pump and ventilation system were 2 devices -> around 3k for the cooling - Stiebel Eltron - combo device (or rather cabinet ^^) - 500€; sounded like a "software update" was needed. Now we are back to the question – cheaper cooling or both separate (so that only one is replaced if something breaks; not the whole cabinet at once^^)