Passivhaus Standards
Passivhaus: German for "Passive House"
Passivhaus — a set of performance standards that represent a 70-90% reduction in energy usage over standard residential construction.
The Concept
The basis of the Passive House concept is to reduce the heating/cooling loads sufficiently so that comfortable temperatures can be maintained through passive means — solar gain, waste heat from appliances and occupants, and a small back-up heating/cooling system. Even without a back-up system, temperatures in a Passive House will never drop below 50°F in winter or rise above 80°F in summer. By first conserving as much energy as possible, remaining electrical loads in a Passive House can then be met cost-effectively through renewable sources.
The Numbers
The performance requirements above all must be met in order to be officially certified as a Passive House by the Passive House Institute U.S. The performance recommendations are guidelines that aid in meeting the performance requirements.
Performance Comparison
Passive House performance far exceeds that of both average new and existing homes, Energy Star homes, and though not shown, even LEED homes. It clearly is the most stringent energy efficiency standard in the world. All energy efficienct houses share common benefits such as lower utility bills, increased comfort, and improved building durability. These benefits are maximized, however, in Passive Houses.
Cost-Effectiveness
The justification for striving to achieve Passive House performance is the cost-effectiveness of eliminating the conventional heating/cooling system (e.g. no furnace). This is only possible if all three of the energy efficiency improvements above are employed. Each individual improvement by itself falls short of achieving the necessary performance — the combined use of all three is the key.
Cost Comparison with Standard Residential Construction
The documented initial cost premium for a Passive House in Europe is about 5-10% higher than standard residential construction. The cost premium here in the U.S. is 10-15%. The higher U.S. cost premium is caused by the lack of widespread availability in this country (and hence higher costs) of windows/doors, heat-recovery ventilation, and back-up heating/cooling systems designed specifically for Passive Houses.
In spite of a higher initial cost premium, total costs of ownership (mortgage costs plus utility costs) are no greater for Passive Houses than for standard residential construction. Once the conventional heating/cooling system is eliminated, the remaining initial cost premium is balanced by extremely low utility bills. If you are considering a new home, it therefore costs no more to strive for the most dramatic energy efficiency improvements possible — those of Passive Houses. Planet Earth benefits, and you benefit also!
For more information on the three key energy efficiency improvements required for Passive House performance — airtight construction (with heat-recovery ventilation), super insulation (with elimination of thermal bridges), and high-performance windows — please see the following…
The articles entitled No Furnaces but Heat Aplenty in 'Passive Houses' [131 KB pdf, New York Times] and What is (a) Passive House? [136 KB pdf, Mother Earth News] offer a brief summary of Passive Houses. More detailed information can be found on Wikipedia, or at the websites of the Passivhaus Institut in Germany or the Passive House Institute U.S.