Integrate cooling into controlled residential ventilation or have air conditioning separate?

Hello everyone,

in our future house, the two children will have their rooms under the roof. From experience, I know that it gets extremely hot there in the summer.

Therefore, we want to integrate a possibility for active cooling into our house. We already had a conversation with a climate technician who sketched out an air conditioning system with a cooling capacity of about 13 kW based on the size relationships. The whole thing would cost about €15,000.

Now, Zehnder also has a cooling element (ComfoCool Q600 ST), which is significantly cheaper but only has a cooling capacity of 2.3 kW. The climate technician estimated that his system could cool down by up to 10°. The Zehnder system, however, has only about 20% of that capacity. Does it even help then? If with 20% cooling capacity it can only cool down by 2°, it’s pointless, isn’t it!?

[*]Does anyone of you have this unit in use?
[*]Should we rather install an air conditioning system in addition to the Controlled Residential Ventilation?

Honestly, I find it quite strange that the Controlled Residential Ventilation systems don’t come with proper cooling units. Until recently, I thought that practically all Controlled Residential Ventilation systems could also cool.

Thanks for your feedback,
junge_familie

Controlled residential ventilation has nothing to do with cooling. If cooling is needed, either a climate ceiling or air conditioning is used separately.

A good roof insulation and shading would help.

The cooling with the controlled residential ventilation is far too weak for real air conditioning. Maybe it can buffer a bit but nothing more. For it to work properly, you would need at least a 4-fold air exchange as well as a significantly higher cooling capacity (additional cooling unit).

How large are the rooms that are to be air-conditioned? Off the top of my head, I would say that the offer from your air conditioning technician is oversized. Max. €2,500 + installation. They are probably "normally" sized rooms. A multi-split set with two indoor units is enough.

As already mentioned, the most important thing is to keep the heat outside. Because the heat that does not come in, I also do not have to shovel out again.

Then you do a cooling load calculation. With this, you design your system.

I find the 13kW very high. If I have the values correctly in mind, we cool about 150m² of office space with 13kW.

The 13 kW is probably for the whole house. Just ask him about a system only for the two children's rooms

The mentioned cooling unit from Zehnder .... besides having far too little capacity, you can't cool selectively with a ventilation system. That means the supply air is centrally pre-cooled and supplied to all rooms. This doesn't bring much for the "hotspot" children's room in my opinion. It's not exactly cheap either and apparently only fits the Q600, which would be a considerable sizing for a single-family house

I would also not invest in either of the two alternatives. Better to have more bulk as insulation in the roof and provide shading (outside!) in the form of roller shutters.

We insulated our roof with regular mineral wool and the attic temperature never exceeded 23°C, even during this prolonged, warm summer. New houses no longer heat up that much if you provide proper shading. Once the heat is inside, for example due to improper ventilation, it is naturally not easy to get rid of it quickly.

Blown-in insulation is said to be even better against heat than mineral wool...