Passive building comprises a set of design principles used to attain a quantifiable and rigorous level of energy efficiency within a specific quantifiable comfort level. “Maximize your gains, minimize your losses” summarize the approach. To that end, a passive building is designed and built in accordance with these five building-science principles:
- It employs continuous insulation through its entire envelope without any thermal bridging.
- The building envelope is extremely airtight, preventing infiltration of outside air and loss of conditioned air.
- It employes high-performance windows (typically triple-paned) and doors
- It uses some form of balanced heat- and moisture-recovery ventilation and uses a minimal space conditioning system.
- Solar gain is managed to exploit the sun's energy for heating purposes and to minimize it in cooling seasons.
Passive building principles can be applied to all building typologies--from single-family homes to apartment building to offices and skyscrapers.
Passive design strategy carefully models and balances a comprehensive set of factors including heat emissions from appliances and occupants--to keep the building at comfortable and consistent indoor temperatures throughout the heating and cooling seasons. As a result, passive buildings offer tremendous long -term benefis in addition to energy efficiency:
- Superinsulation and airtight construction provides unmatched comfort and even in extreme conditions.
- Continuous mechanical ventilation of fresh filtered air assures superb air quality.
- A comprehensive systems approach to modeling, design and construction produces extremely resilient buildings.
- Passive building is the best path to Net Zero and Net Positive buildings because it minimizes the load that renewables are required to provide.
The performance standard
Passive principles were pioneered in the 1970s by North American building scientists and builders with funding from the U.S. Department of Energy and the Canadian government. In the late 1980s the German Passivhaus Institut (PHI) built on that research and those principles, and developed a quantifiable performance standard that continues to work well in the Central European and similar climate zones.
In practice, the PHIUS Technical Committee and PHAUS members building projects have learned that a single standard for all North American climate zones is unworkable. In some climates, meeting the standard is cost prohibitive, in other milder zones it's possible to hit the European standard while leaving substantial cost-effective energy savings unrealized.
- Consequently, for the past year, the PHIUS Technical Committee has been working on adapting the performance metric to North Amercian climate zones, using the European metric as a baseline. The preliminary results are in, and the new standards will be implemented in early 2015.
- The standard adaptation presentation slides are available for download as a pdf.
- Regardless of the metric, the principles are the same, and the passive building community is working hard to make them the mainstream best design and construction practices.