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Passive House (PHIUS) Concept & Standards

Written by Tessa Smith, The Artisans Group, for The Nisqually River Foundation

The Passive House (Passivhaus in German) concept was created in 1988 by Professor Bo Adamson and Doctor Wolfgang Feist, spurred on by their desire to positively affect climate change while decreasing reliance on a volatile energy market. Their research combined existing energy efficiency technologies and concepts making Passive Houses the most energy efficient building system in the world. Today Passive House certifications are administered by the Passive House Institute United States (PHIUS) in America and for other global regions by Passivhaus Institute in Germany.

Passive House designs can realize up to a 90% reduction in heating energy consumption, all without employing “active” technologies such as complex heating, photovoltaics or solar thermal water heating systems. The extremely rigorous Passive House standards are based instead on well tested energy efficient building techniques of conservation before alternative energy sources are considered. Concepts such as super insulation, mechanical ventilation, air sealing, and building orientation to take advantage of solar gains, are common in the green building industry. Yet, Passive House takes these rather simple concepts and goes one step further by accurately modeling these scenarios to achieve the most optimized building.

One of the primary components of the Passive House concept is mechanical ventilation. Current construction techniques result in nearly airtight structures. For this reason, Passive House uses mechanical ventilation, not only increasing occupant comfort but also to support healthy living. The initial expense of building a Passive House is often offset by the elimination of the independent heating systems, which is achieved through an integrated design approach utilizing the space conditioning or fresh air delivery system (such as a heat recovery ventilator) to serve for space heating as well. For example the cost for an efficient but expensive hydronic radiant heat system would no longer be necessary. This combined with super high-efficiency windows, innovative highly integrated technology and a building envelope without thermal bridges all interact to form an energy-balanced building.

Passive House standards are a pass-fail system. Noted earlier, PHIUS is the official certifier of Passive House in the United States. Although more than 15,000 Passive Homes have been certified around the world, only 8 have received the certification in America. These forerunners in American energy efficiency meet standards less than 1.4 KWh/(ft2yr) (or 4.75 kBTU/(ft²yr) ) for Specific Heat Demand (the energy required to heat and cool a house) and 11.1 KWh/(ft2yr) (or 38 kBTU/(ft²yr) for Specific Primary Energy Demand (energy required to heat, cool, provide domestic hot water and all electrical needs, appliances etc.), going far beyond other industry standards including LEED and Built Green, for the ultimate comfort, cost and eco-responsibility.

Reprinted with the permission of The Nisqually River Foundation