A passive house doesn't require active heating or cooling systems to maintain a comfortable indoor temperature. Or at least the design greatly minimizes the use of HVAC.
It is a certified building standard organized by the Passivhaus Institut in Germany. That's an independent research institute. Passive House is the only internationally recognised performance-based energy standard for construction.
Passive House requirements are fairly simple. The criteria specify limits on space heating energy demand, space cooling energy demand, renewable primary energy demand, and airtightness. To meet the criteria, builders must optimize thermal insulation, the best window technology, ventilation heat recovery, and avoid thermal bridges.
Passive House Institute US is a non-profit organization in the United States. It trains and certifies professionals, and conducts research.