

Ventilation systems are named a bit weird like that:
-System A is natural convection (like holes in the walls)
-system B is holes in the walls, and a motor brings fresh air in the building
-System C is only a centralised extraction (needs rosters in your windows so you have an air intake, so basically an energy-label-certified-hole in your brand new windows)
-System C+ is centralised extraction with a variable debit depending on CO2 and humidity detected (so it is less energy wasteful than the previous one)
-System D is a double flux system: one centralised unit with a heat exchanger built in. There are 2 circuits, one is fresh air and the other one is air extraction. the house is basically always a bit over-pressurised. It is possible to obtain also humidity regulation for the winter if needed (ex build-in humidifier or enthalpy exchange units). When testing for build quality in passive houses, they check that almost all air exchange goes only through the unit
-System E: System C+ with a heat exchanger connected to a centralised heat pump for the building. Never seen one outside of an expo room.
I wish ! But architects and building engineers you know. The building sector is filled with mysteries beyond logic. For example, I still don’t know why it’s such a hassle to have real HVAC in centralised ventilation systems in Europe. Or integrated solutions to move energy to other systems (like my water heat pump releases cold. Why am I out of warranty if I place a heat exchanger that cools my fridge heat exhaust on the air rejection?). Without floor heating air-water heat pumps aren’t super efficient, and retrofitting baseboards with water-heated ones for baseboards in a bitch to do.