Air conditioning

My gut feeling about aircon is that you should consider visiting a place like Leroy Merlin and picking up their aircon brochure. If you choose to have the units professionally installed, they can connect you with a suitably qualified firm.

If you register with them, and you're not under immense time pressure to do the work, they'll write to you 3-4 times a year with up to 15% discount on everything in the store.  That'll save you up to €300 on 3 units. 

Measure the rooms and take the hit to buy (a) inverter units which do hot and cold and (b) which are quiet in operation.  If anyone has allergies to dust or pollen then select units with easily accessible filters. 

You know there are several other companies beside Leroy Merlin who install and maintain aircon. I just mentioned LM because I found their aircon brochure very helpful in choosing the units for me.

By the way,  I assume you are aware the external unit must not be visible from the street, unless it is replacing an existing one, and then only when there is no alternative location.  There are many people in the planning department who take their jobs very seriously!  It wouldn't be long before you got a "denunciation" and a big fine in the post.