Combining efficient heat recovery with supplementary supply air heating
Passive houses have a continuous supply of fresh
air, optimized to ensure occupant comfort. The flow is regulated to deliver precisely the quantity required for excellent indoor air quality. A high performance heat exchanger is used to transfer the heat contained in the vented indoor air to the incoming fresh air. The two air flows are not mixed. On particularly cold days, the supply air can receive supplementary heating when required. Additional fresh air preheating in a subsoil heat exchanger is possible, which further reduces the need for supplementary air heating.

Electric efficiency means efficient appliances
Through fitting the Passive Houses with efficient household appliances, hot water connections for washing machines and dishwashers, airing cabinets and compact fluorescent lamps, electricity consumption is also slashed – by 50% compared to the average housing stock, without any loss of comfort or convenience. All building services are designed to operate with maximum efficiency. The ventilation system, for instance, is driven by highly efficient DC motors. High-efficiency appliances are often no more expensive than average ones. As a rule, they pay themselves back through electricity savings.

Meeting the remaining energy demand with renewables
Cost-optimized solar thermal systems can meet about 40–60% of the entire low-temperature heat demand of a Passive House. The low remaining energy demand moreover makes something possible which would otherwise be unaffordable, and for which available supply would not suffice:
 Over the annual balance, the remaining energy consumption (for space heating, domestic hot water and household electricity) is offset completely by renewable sources, making the Passive House fully primary-energy and climate neutral. This is being achieved in the CEPHEUS housing development in Hannover-Kronsberg.