Passive building refers to a quantifiable energy performance goal, and the design methodology used to achieve that goal. Let’s start with the design priorities.
Conservation First – designers reduce the load on the heating and cooling systems by investing in passive measures in the building envelope.
Cost Effectiveness – the extra investment in conservation meets an economic feasibility test based on climate specific data and market conditions.
Look for other Efficiencies – further reduce the load on utilities and the building’s carbon footprint by using efficient mechanicals, lighting, appliances, etc.
Aim for Net Zero/Positive – assess the site, and if enough resources are available, add renewables (within a cost-effective framework) toward the zero or positive target.
The PHIUS + 2015 Performance Metric
The PHIUS+2015 metric was developed under a three-year research project funded by the U.S. Department of Energy (DOE)
Building America program, and conducted in partnership with Building Science Corporation (BSC)
Using the DOE’s BeOPT cost optimizer in combination with WUFI Passive Software, the PHIUS Technical Committee developed a method to generate climate specific standards that are both aggressive in terms of conversation, and cost-effective and practical for the project’s climate conditions.
Is the passive house approach only for houses?
No! The approach can be successfully applied to any type of building, including skyscrapers.
The term passive house is something of a misnomer — although plenty of single-family homes have been built to the passive house standard, the approach is increasingly being applied to multifamily apartment buildings and large scale commercial buildings as well. As a result, the term passive building is gradually coming into more common usage, as it’s a more accurate term than passive house.
Does it cost a lot more to build a passive building compared to a conventional equivalent?
Currently, a passive building typically costs about 5-10% more than a conventional building. In general, the larger the building the less of a cost difference there is. Also, as more large-scale window and door manufacturers bring high-performance products to market, economies of scale are expected to drive down costs.
What is it like to live in a passive house? Can you open the doors and windows?
Passive houses and buildings are extremely comfortable in all seasons. That’s because there are no drafts, temperature variance is extremely narrow (even near doors and windows), and active, balanced ventilation makes for superb indoor air quality. And yes, passive house owners open their doors and windows just as they would in a conventional home.
Passive buildings are super airtight – what about moisture and mold problems?
Passive buildings do require an extremely airtight building envelope. Combined with super-insulation, this approach dramatically reduces temperature variation, which also prevents condensation and mold issues. The constant, low-level ventilation also helps prevent moisture problems in addition to maintaining excellent air quality.
That being said, potential moisture issues must be carefully addressed at the design stage. That’s why it’s important to work with a Certified Passive House Consultant (CPHC®). CPHCs are trained to accurately model building performance and to identify and address potential moisture issues with a variety of techniques.
Do passive buildings all have to look the same?
Nope! Although many early passive homes used an austere European style, passive design does not dictate aesthetics. PHIUS has certified projects in dozens of styles ranging from Cape Cods to traditional Four Squares, contemporary multifamily projects, and more.