1) Can a house really stay warm without a heating system?

- Passive houses that have been tested and are already occupied have conclusively proven: Even in our middle European climate, houses can be built with such low heating energy requirements that minimal additional heat added to incoming fresh air, is sufficient to keep the house warm and comfortable in winter. Measurements in passive home subdivisions have proven that energy requirements for heating can be accurately predicted, and that even with a great variety of occupants, calculated consumption agrees with average actual consumption.

2) Aren't passive houses too expensive?

- There are already companies that offer passive homes at prices comparable to standard construction. However, in general, the high quality of passive construction components tends to be reflected in higher costs. These costs have been computed for passive homes that have already been built: For an interior unit of a row house in Hannover-Kronsberg, having a living area of 100 m² (1076 ft²), around DM 15000 (€ 7669); for one unit of a double-house in Nürnberg, with a living area of 130 m² (1399 ft²), around DM 25700 (€ 13140). In the long run, annual energy savings between DM 1000 and DM 2000 (€ 511 and € 1023), coupled with tax advantages (German Eco-Supplement) and special interest rates offered under the passive house promotion program of the "Kreditanstalt für Wiederaufbau" (German Credit Institution for Reconstruction), make passive houses (in Germany) more economical than conventional construction.

3) Can you open windows in a passive house?

- Of course, occupants may open windows whenever they want; however, they won't have to. A passive house is continuously supplied with fresh air via the ventilating system. This has advantages: Unlike window ventilation, fine filters in the ventilating system keep out dirt and pollen. Air quality within the house is always excellent, even when occupants are away and/or windows are never opened. Of course, as with all houses, if windows are left open in winter for longer periods, the inside air temperature will decrease noticeably, and energy consumption for heating will increase.

4) People often express reservations about the need for a ventilation system: Are there problems with bacteria, noise and drafts?

- The ventilation system in a passive house is a fresh air supply system, not an air conditioning system that recirculates inside air. Bacteria growth is only a problem in recirculating air systems (and then, only if poorly maintained). Fan and valve noises are almost completely eliminated by sound control measures (e.g., vibration isolation mounts, low air speed, acoustic lining in ducts). Jet nozzles guide incoming air along the ceiling from where it uniformly diffuses throughout the room at velocities that are barely perceptible.

5) Isn't a passive house a complicated, high-tech house?

- No, a passive house is very user-friendly and the equipment is easy to operate. The ventilation system has fewer controls than a normal television. Passive house technology is so simple, there's no need to hire someone to perform annual air filter changes; you can do it yourself.