Passive House certification is poised to expand to address buildings that produce some or all of their own energy.
The new “Passive House Plus” label offers certification that a building produces approximately as much energy as it consumes. The “Passive House Premium” standard certifies that a building produces more energy than it uses. The new standards offer a reliable means of determining net energy usage in accordance with the European Union’s new requirements.
The EU’s “Nearly Zero Energy Building” standard will be mandatory starting in 2021 for all new buildings. According to the EU’s Concerted Action Energy Performance of Buildings Directive, “there is significant potential for reducing consumption with cost-effective measures. With 40 per cent of our energy consumed in buildings, the EU has introduced legislation to ensure that they consume less energy.”
“A building that produces more energy than it consumes is not only possible, it is often very sensible,” said Dr. Wolfgang Feist, director of the Passive House Institute.
Because of seasonal differences in potential energy production, energy efficiency remains the foundation for the Passive House system.
“Photovoltaic systems typically yield very little energy in winter, which is exactly when the most energy for heating is used,” Feist said. “Therefore, the calculation only works when the energy demand itself is also very low.”
The new Passive House Plus and Passive House Premium standards also address a building's energy production compared to its potential production, based on its ratio of volume to ground area.
“A single family home built to the Passive House Standard can achieve an energy surplus relatively easily,” stressed Dr. Benjamin Krick, senior scientist at the Passive House Institute. “For an apartment building it is much more difficult, as such buildings have a far smaller roof area available per square meter of living space.”
The Passive House standard, one of the most rigorous energy efficiency standards for buildings in the world, has certified roughly 50,000 buildings in the last 20 years. Using a combination of advanced materials with specific and demanding construction techniques, buildings certified to the Passive House standard use only about 10 per cent as much energy for heating and cooling as a conventional building.
Certified Passive Houses must meet standards for air sealing, energy used for heating and cooling, and overall energy usage. The system requires high levels of insulation surrounding the living spaces, along with high-performance windows and doors. An active ventilation system ensures healthy indoor air quality while managing moisture levels in the nearly air-tight structures.
These changes often result in homes that need little supplemental heating, allowing for downsizing or even elimination of some heating and cooling equipment. That addresses one particular criticism that has dogged the Passive House standard for years: cost. Many critics claimed the standards were too rigorous, required very high-end materials, and did not make economic sense. They felt the extra costs required to meet the Passive House standard could not be recovered through lower energy costs during the reasonable lifespan of the building.
Recently, however, strong evidence of cost parity between certified Passive Houses and more conventional homes has emerged. Adam Cohen of Design/Build Structures in Roanoke, Virginia, completed the design and construction of a client’s certified Passive Home for about $14/square metre, right at the national average. The home was awarded the GreenBuilder Home of the Year Award for 2013 in the Best Mainstream Green category.