What is a Passive House?

 

A building constructed using passive house principles is 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 building 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.


 

European Performance Baseline (these metrics are teh basis for PHIUS current research that will yield standards specific to U.S. climate zones)

 

  1. Airtight building shell ≤ 0.6 ACH @ 50 pascal pressure, measured by blower-door test.

  2. Annual heat requirement ≤ 15 kWh/m2/year

(4.75 kBtu/sf/yr)

  1. Primary Energy ≤ 120 kWh/m2/year (38.1 kBtu/sf/yr)


In addition, the following are recommendations, varying with climate:

  1. Window u-value ≤ 0.8 W/m2/K  

  2. Ventilation system with heat recovery with ≥ 75%  

   efficiency with low electric consumption @  0.45 Wh/m3

  1. Thermal Bridge Free Construction ≤ 0.01 W/mK

  

 


Smith House residence built to Passive House standard in Urbana Illinois

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