The fundamentals of heating and cooling the air in a Passive House are not so different from a typical built home (adhering to the minimum requirements of code). Passive House HVAC is just taken to a much higher level, and as a result a Passive House built home can use 80 to 90% less energy than a home built to minimum code standards today.
The HVAC system, it's durability, the indoor air quality, and air distribution are all key improvements that you see in a Passive House build. The other stark difference from a typical build is that the size of the HVAC equipment needed for a Passive House is so much less than what a typical home would need. The heating and cooling unit for a Passive House is going to look more like what size unit you might see for a small apartment. It is that big of a difference and much of the efficiency to be gained with a Passive House comes with reduced demand for heating and cooling no matter what climate the house is in.
Another difference compared to a typical home is that there is an energy recovery ventilator (ERV) or A heat recovery ventilator (HRV) used with passive house, depending on the climate that you’re building in. In our climate (the mid south - we are in North Carolina), we will be using in the ERV.
The ERV essentially takes and conditions all of the fresh air that is being brought in to the home. It exchanges the heat or coolness that is in the air which is being exhausted and transfer is it to the outside air being brought in. It also will dehumidify that outside air being brought in if needed. So almost all of the energy that is in the air being exhausted is captured and put into the air being brought in. That is a HUGE part of gaining efficiency!
We are also going to be installing an air filtration system into the home we are currently building (it's actually ours), and this will be HEPA rated, as another way of ensuring we have the highest quality air in the home. It will not only have a HEPA filter, but also this will ensure that the majority of the air passes through that filtration. That is the key to success here.
Because we have a mechanical engineer involved, the airflow into each of the rooms is specifically designed to maximize the efficiency of the building and the comfort to the occupants. When combining all of the thermal insulation and energy efficiency of the home with a well designed HVAC system, Passive Houses are the most comfortable home to be in and live in.