ᐅ KfW Energy Calculation with a Cooling Heat Pump

I'll join in here. We also considered using the mechanical ventilation system to cool the house in summer. We were recommended a system from Zehnder that includes an add-on for cooling. It’s called Comfocool, apparently. Has anyone had experience with this?

And does it make sense to pre-install the necessary piping for a split air conditioning system, so that air conditioning units can be added later with minimal effort or cost? Or is that unnecessary, and it’s better to install everything together? The technology might also change, and the piping could become outdated, right?

The cooling capacity of a mechanical ventilation system with heat recovery without proper cooling units is basically negligible. Any window that lets in even a little sunlight will immediately negate the limited effect. For effective cooling (or heating), the airflow volume of a standard mechanical ventilation system is far from sufficient. You only slightly reduce the intake air temperature and then distribute that small amount gently throughout the house. I would install a split system right away; otherwise, you’ll be starting again after your first summer in the house. For example, we planned a 3-zone split system for the bedroom, living area, and study. You can operate it excellently with solar power generated during peak sunlight hours when you might not otherwise need it. Cooling via the floor brings some improvement (though usually just cold feet), and a cooled ceiling is somewhat better. However, nothing replaces a unit that actively produces cooling rather than just slightly reducing heat.

freithelm schrieb:

which is supposed to cool as an additional feature. I believe it’s called Comfocool. Has anyone had experience with it?

It is a cooling coil using brine/water. However, it has limited effect because the maximum air volume for an entire single-family house is around 300-400 cubic meters (10,590-14,130 cubic feet), while active cooling typically requires about 800 cubic meters (28,250 cubic feet) per 30 square meters (320 square feet). You can do the math for the rest. The climate at the location is simply quite challenging, and controlled mechanical ventilation doesn’t achieve much in terms of cooling. But it does a very good job ventilating the house. Every system has its purpose, and usually fulfills its intended function well.

I would recommend planning for active cooling from the start and at least having the piping installed during construction. There’s no need to worry about the pipes becoming obsolete later. It’s just two copper pipes, a 5x1.5 NYM cable, and a condensate drain per indoor unit.

Mycraft schrieb:

I would consider active cooling right away and at least have the piping installed during construction. You don’t need to worry about them becoming obsolete. It’s just two copper pipes, a 5x1.5 NYM cable, and a condensate drain connection per indoor unit.

Two copper pipes per indoor unit, which then run to the location of the outdoor unit? The condensate drain must then be installed with a slope towards the nearest wastewater connection point?
We are also currently considering having the necessary preparations done. Although we’re quite used to the situation with our current top-floor apartment, you never know.

Yes, two pipes per unit from A to B plus NYM cable for power supply and control. With multisplit systems, you need to distinguish between different approaches: either all B units connected back to A, or from A to B to C to D, or from A to a distributor and then from there to the B units.

However, it is not wrong to install only from A to B (pre-installation), possibly multiple times. The costs remain approximately the same.

A = outside
B, C, D = inside

Condensate should then be drained with a slope, either directly outside through the wall/roof or into the next HT pipe (of course with a trap).

DaSch17 schrieb:

According to our heating engineer, that doesn't make sense.

Cooling is better done through controlled residential ventilation – but ideally with an air conditioning system.

That’s not entirely true. It does reduce the temperature by a few degrees. I know several people who can confirm this. Of course, it’s not comparable to an air conditioner. We are having a ground-source heat pump with cooling function from Bosch installed, along with a controlled residential ventilation system.