Passive House Institute unveils plus certification
A 16-unit apartment building (foreground) in Innsbruck, Austria, is the first of its kind to be certified under Passive House Plus, a new certification program combining efficiency standards with a renewable energy requirement. Photo courtesy of PHI
The Passive House Institute has certified a multi-unit residential complex with its first Passive House Plus designation, a new category that incorporates on-site renewable energy.
The Darmstadt, Germany-based organization this summer certified the complex in Innsbruck, Austria, along with a single-family home in Otigheim, Germany.
The new standard takes into account storage and transmission losses and balances energy demand and supply for renewable sources, Jessica Grove-Smith, a senior scientist at the Passive House Institute, told Architectural Record.
“The energy supply structure worldwide is transitioning from fossil fuels to renewable sources at an encouragingly rapid pace,” she said.
PHI built the first passive house structure in Germany 25 years ago, introducing a certification system for energy efficient buildings by introducing a rigorous performance-based standard.
The intent of Passive House Plus is to meet the European Union’s standards for Nearly Zero Energy Building (NZEB)—targets that all new buildings must meet by 2020.
This new certification system has some of the same requirements as the initial Passive House standard. For instance, both require a building with a super-insulated, airtight envelope that consumes less than 4.7 kbtu/sf/yr for heating and cooling and has fewer than 0.6 air changes per hour at 50 pascals of air pressure.
Passive House Plus has a much lower limit for primary source energy (the amount of energy a building consumes), capping it at 4.18 kWh/sf/yr, compared with 5.57 kWh/sf/yr for basic certification. In addition, to achieve Passive House Plus status, a building must generate at least 5.57 kWh/sf/yr renewable energy.
Innsbruck architect Vogl-Fernheim earned Passive House Plus certification for one 16-unit building at the Vögelebichl housing development (another 10-unit building at the complex has been certified under the classic system) by designing a super insulated envelope with R-51walls and an R-63 roof and installing a solar array that supplies about 8.9 kWh/sf/yr. For the house in Ötigheim, Lichtenau, Germany-based architect Sebastian Früh met the new standards by limiting primary source energy to 4.1 btu/sf/yr and installing a 680-square foot solar panel system on the south-facing roof.
Passive House Plus allows for other alternative energy sources, including wind and biomass. In cases when a site is not suitable for on-site generation, the rating system also permits new off-site renewable energy installations.
In addition to Passive House Plus, the Passive House Institute has also recently introduced Passive House Premium, which increases the amount of renewable energy required, essentially making the building a small power plant. Several projects are pursuing certification under this more stringent standard.
The Passive House Institute U.S. (PHIUS), which split with the original German organization in 2011, has its own program for encouraging net zero energy buildings — PHIUS+ — the outcome of a three-year study funded by the U.S. Department of Energy.
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