A Passive House is a very well-insulated, virtually air-tight building that is primarily heated by passive solar gain and by internal gains from people, electrical equipment, etc. Energy losses are minimized. Any remaining heat demand is provided by an extremely small source. Avoidance of heat gain through shading and window orientation also helps to limit any cooling load, which is similarly minimized. An energy recovery ventilator provides a constant, balanced fresh air supply. The result is an impressive system that not only saves up to 90% of space heating costs, but also provides a uniquely terrific indoor air quality.
A Passive House is a comprehensive system. "Passive" describes well this system's underlying receptivity and retention capacity. Working with natural resources, free solar energy is captured and applied efficiently, instead of relying predominantly on ‘active’ systems to bring a building to ‘zero’ energy. High performance triple-glazed windows, super-insulation, an airtight building shell, limitation of thermal bridging and balanced energy recovery ventilation make possible extraordinary reductions in energy use and carbon emission.
The Passive House concept is a comprehensive approach to cost-efficient, high quality, healthy and sustainable construction. The concept is easy to understand:
1. Contemporary construction is quite airtight; therefore the air replacement from infiltration is not sufficient. Ventilating by opening windows is not a convincing strategy either. Getting a sufficient volume of fresh air is not just a question of comfort, but a requirement for healthy living conditions. Therefore mechanical ventilation is the key technology for all new construction as well as refurbishment of existing buildings. Mechanical ventilation will work in all cold and all hot climates since in an airtight house, the heating and cooling energy required will be significantly less.
2. Even though mechanical ventilation systems raise initial investment costs, if designed efficiently they will reduce energy costs significantly, eventually paying off the initial cost. Ventilation units suitable for Passive Houses allow for an economic operation.
3. Now we explain the central "trick" of the Passive House concept: The fresh air needed is entering the room anyhow. If one could use this air to cover the heating load, without increasing the mass flow, without re-circulated air, without noise and without drafts - then the ventilation will pay off a second time.
4. This concept of "fresh air heating" is only possible in a building with superior thermal insulation, just like a Passive House. For experts: This is the defining requirement; the maximum heat load should be lower than 10 W/m², allowing the fresh air to carry the heat load.
Passive Houses require superior design and components with respect to:
• insulation
• design without thermal bridges
• air tightness
• ventilation with heat recovery
• comfort windows und
• innovative heating technology
To realize an optimal interaction of all components, an energy balance of the building has to be worked out.
