Passive House Pushes [& Seals] The Envelope

By Cordelia Pitman, Director of Preconstruction Services for Wright-Ryan Construction

Multifamily housing projects around the state have contributed to an improvement in construction activity post-recession. Hidden among the number of multifamily projects, two developments in particular are helping lead an emerging national trend in affordable housing – Passive House. The design standard offers a new path for project teams seeking out ways to build better while providing higher-quality, more affordable options for the communities they serve.

Two of the largest commercial Passive House developments in the U.S. are both affordable housing projects. One of those is Village Centre Apartments in Brewer, which added 48 units of much-needed workforce housing to the greater Bangor area in May, 2016. Another project of note in Maine is Bayside Anchor in Portland’s Bayside neighborhood, adding 45 units of mixed-income housing.

Both Bayside Anchor, developed by the Portland Housing Authority and Avesta Housing and designed by Kaplan Thompson Architects, and Village Centre, developed by Community Housing of Maine and designed by CWS Architects with sustainability consulting by Thornton Tomasetti, are built to Passive House Institute U.S. (PHIUS) standards, a rigorous design standard which results in ultra-efficient buildings that require little energy for space heating or cooling. Once the exclusive domain of custom home building in the U.S., technically adept developers, designers, and builders are seeing Passive House standards as a way to make affordable housing more affordable.

Achieving Passive House certification is all about results. The allowable air tightness limit for Bayside Anchor and Village Centre was 0.05 CFM50/ft2 – an aggressive target. Passive House buildings feature continuous insulation, ensure limited thermal bridging throughout the entire building envelope, and are incredibly airtight to prevent undesirable exchange of interior and exterior air. High performance windows and doors, balanced heat-recovery ventilation, and minimal space-conditioning systems are incorporated to maximize efficiency. Passive House projects also take advantage of solar heat gain, through strategic building siting, and internal heat gain to further reduce dependence on limited systems. Solar exposure is managed through glazing or shading to provide heating benefits in the winter and cooling benefits in the summer.

The application of Passive House design and construction principles means lower operating costs for building owners supporting the
long-term viability of properties.

Village Centre is estimated to be over 60 percent more energy efficient than a code building, with a targeted site energy use intensity of 22 kbtu/sf/yr. These are simply the results that can be achieved within the fixed budget (roughly $139/sq. ft.) defined by the project requirements as a publicly-funded development under the Maine State Housing Authority. Many cases demonstrate that Passive House buildings can offer energy savings from 75% up to 90% when compared with average new buildings or typical building stock.

The benefits for residents and other end-users, chiefly comfort and energy efficiency, are even more important. In many cases, the energy savings realized by building owners may be passed on to tenants, with individually metered units and segmented utility bills.

The lowest number often rules in the construction industry. It can be far too easy to lose sight of what’s most important – real value and the overall quality of life for the building occupants and end users. The Passive House standard holds up critical human elements of comfort and environment as its top priorities. The growing presence of Passive House work and the increasing knowledge-base in Maine will only serve to benefit our state and its residents as a whole.

Cordelia Pitman is Director of Preconstruction Services for Wright-Ryan Construction, a member of the Maine Real Estate & Development Association. For more info go to Wright-Ryan served as the Construction Manager for Village Centre and Bayside Anchor.

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