Passive House for Commercial Buildings
The Passive House Standard allows for extremely high levels of comfort as well as enormous energy savings – not only for residential buildings. The Passive House Standard has successfully been released in many different types of buildings including offices, hotels, factories and warehouses, administrative buildings, sport complexes, and schools. The holder of this certification is the PHIUS Certification Program, but, if your building does not qualify for certification, using the principles from Passive House design are highly efficient and beneficial for the longevity of the project. The Passive House movement originates from Europe, specifically Germany, but has transcended to be a leading high performance building design throughout the United States. The Passive House principles are guided by five factors:
- Thermal insulation
- High performance windows
- Ventilation heat recovery (ERV/HRV)
- Thermal bridge-free design
Benefits for Commercial Buildings
A large driver of the Passive House Certification or principles is a growing understanding that these principles are necessary to design buildings that will approach the low and net zero energy targets that are becoming more common. The benefits of Passive House design are similar regardless of project type: radically reduced energy consumption, a well-built and long-lasting building envelope, significantly smaller mechanical equipment, fresh indoor air, and significantly lower operating costs. The requirements of Passive House design are essentially the same regardless of project type and consist of four performance metrics:
- Maximum annual heating and cooling demand levels established based on the project site’s climate characteristics
- Peak heating and cooling loads similarly established based on the project site’s climate characteristics
- An airtight envelope with a maximum air infiltration rate of 0.05 cfm per square foot of envelope at a pressure differential of 50 Pascals.
- A total primary energy demand of 6,200 kWh/yr/person (note that this is primary energy demand meaning at the power source)
Exponential growth of all Passive House projects measured by total square footage. source: PHIUS.
For commercial projects and buildings larger than a typical house or small apartment building, a couple of the requirements are adjusted accordingly:
- For buildings five stories and above that use noncombustible construction, the airtight envelope requirement is relaxed to an air infiltration rate of 0.08 cfm per square foot of envelope at a pressure differential of 50 Pascals. Even with this increase, this air infiltration rate is significantly lower than current energy codes.
- For commercial buildings, the primary energy demand is based on square footage instead of the number of people in the building. The maximum total primary energy demand for commercial buildings is 38 kBTU/sf/yr. Like the residential standard, this is the primary energy demand at the power source.
Passive Solar Design (PH Principle)
Passive solar design integrates a combination of building features to reduce or even eliminate the need for mechanical cooling and heating and daytime artificial lighting. Designers and builders pay particular attention to the sun to minimize heating and cooling needs. The design does not need to be complex, but it does involve knowledge of solar geometry, window technology, and local climate. Given the proper building site, virtually any type of architecture can integrate passive solar design. Passive solar design strategies vary by building location and regional climate, but the basic techniques remain the same— maximize solar heat gain in winter and minimize it in summer. Specific solar design techniques that directly correlate and enhance Passive House design principles include:
- Using energy-efficient design strategies.
- Orient building with the long axis running east/west.
- Select, orient, and size glass to optimize winter heat gain and minimize summer heat gain for the specific climate. Consider selecting different glazings for different sides of the building (exposures).
- Size south-facing overhangs to shade windows in summer and allow solar gain in winter.
- Add thermal mass in walls or floors for heat storage.
- Use natural ventilation to reduce or eliminate cooling needs.
- Use daylight to provide natural lighting.
For a deeper dive into Passive Solar design, reference the resources below:
- Daylight in Existing Office Buildings: An Untapped Retrofit Resource
- Passive Solar Design from DOE
- Three Office Buildings Using Passive Heating and Cooling Design
- Sustainable Sources: Passive Solar Design
The Innovation Center, located in Basalt, Colorado is a 15,610 sf office building and state-of-the-art convening center, completed in December 2015. To advance the Passive House mission and propel the industry, RMI developed the Innovation Center to demonstrate how deep green buildings are designed, contracted, constructed, and occupied. A few highlights from this case study includes achieving net-zero energy, producing more energy on site annually than it consumes – one of only 200 buildings in the U.S. to achieve this distinction as of 2015, and uses 74% less energy than the average office building in this climate, as determined by ENERGY STAR.