Black EPDM Roofing Helps Multifamily Buildings Achieve the Passive House Standard

Two years ago, the three low-rise apartment buildings at the intersection of Southern Avenue and Benning Road in Washington, D.C., stood derelict and abandoned, uninhabitable reminders of 1960s brick and block construction. Today, the buildings—now known as Weinberg Commons—represent a landmark effort to provide clean, secure and energy-efficient shelter to low-income families. For the scores of people—architects, energy consultants, contractors and experts in housing finance, to name a few—who helped repurpose Weinberg Commons and bring it back to life, this project represents an unparalleled achievement in retrofitting. For the families who now live here, it means a giant step toward a more secure future.

Thermal conductivity, air infiltration and exfiltration, and solar gain were important to the team working on Weinberg Commons

Thermal conductivity, air infiltration and exfiltration, and solar gain were important to the team working on Weinberg Commons.

One of the keys to that secure future will be very low or no energy bills. From the beginning, the team that oversaw the retrofitting of these buildings, each with almost 8,000 square feet of rentable space, was committed to ensuring that all three would show greatly reduced energy use and at least one would achieve Passive House (PH) certification.

The criteria to become a passive structure are rigorous and focus on three specific design elements to reduce energy. (The requirements and certification observed by the Weinberg Commons team are set by Chicago-based PHIUS, the Passive House Institute U.S.)

The first requirement is airtightness to ensure the building minimizes the amount of heated or cooled air it loses (0.6 air changes per hour at 50 Pascals of pressure).

Second, a Passive House cannot use more than 4.75 kBtu per square foot per year. This is specific heating energy demand (or cooling in cooling climates).

The third requirement caps the peak total amount of energy the heating and cooling system and appliances in the building can use per year, including domestic hot water, lighting and plug loads. It cannot exceed 38 kBtu per square foot per year.

three low-rise apartment buildings at the intersection of Southern Avenue and Benning Road in Washington, D.C., stood derelict and abandoned, uninhabitable reminders of 1960s brick and block construction.

Three low-rise apartment buildings at the intersection of Southern Avenue and Benning Road in Washington, D.C., stood derelict and abandoned, uninhabitable reminders of 1960s brick and block construction.

Michael Hindle, a Baltimore-based Certified Passive House Consultant who is current president of the Passive House Alliance U.S. Board of Managers, helped with the retrofit design of Weinberg Commons. (Passive House Alliance U.S. is a PHIUS program designed to advance passive building.) He points out these three pass/fail criteria are measures of success, not design principles to help a team achieve the energy savings that lead to PH certification. However, Hindle highlights five design principles have been identified as important guides in the design of Passive House projects:

  • Continuous insulation through the building’s entire envelope without any thermal bridging.
  • An extremely tight building envelope, preventing infiltration of outside air and loss of conditioned air.
  • High-performance windows and doors, typically triple-paned.
  • Balanced heat- and moisture-recovery ventilation and a minimal space-conditioning system.
  • Solar gain is optimized to exploit the sun’s energy for heating purposes and minimize it in cooling seasons.

Although only one building at Weinberg Commons has achieved PH certification, all three buildings were designed to the exact same specifications and technically could be PH certified as long as the rigorous airtightness threshold is met. Several factors influenced the decision, made at the outset of the project, to focus on just one building for PH certification. The design team’s perception was that airtightness would be the most challenging aspect for the contractor. Matt Fine, an architect with Zavos Architecture & Design, Frederick, Md., who led the project, explains: “The intention was to proceed with the first building, test its airtightness and improve on that scope of work for the next building. Repeat, refine and finally apply to the third sequential building.”

Fine points out the first two buildings actually achieved “super” airtightness results relative to any new-construction project built today but did not cross the 0.6 air changes per hour at 50 Pascals of pressure threshold of Passive House. Given the budget-conscious nature of the Weinberg Commons project, resealing and retesting of the first two buildings was not an option for the team, but lessons learned from these two buildings were applied to the retrofit of the third building. “In retrospect, all three buildings would have been able to meet the PH threshold with relatively little extra effort,” Fine says. “But the dynamics of construction sequencing, along with imposed schedules for occupancy, complicated our ability to be flexible with scope change once the contracts were executed and limited dollars were allocated.”

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Polyiso Insulation to Be Used in Innovative Apartment Complex for the Homeless

Polyiso roof insulation will be used in an innovative apartment building project that combines state-of-the-art environmental features with affordable rents for homeless families. The polyiso insulation, donated by the Polyisocyanurate Insulation Manufacturers Associations (PIMA), Hunter Panels and Atlas Roofing Co., will be used in the Transitional Housing Corp.’s Harry and Jeanette Weinberg Commons (Weinberg Commons).

The Washington, D.C., Weinberg Commons will reclaim three blighted buildings in Southeast D.C., using Passive House architectural principles that reduce the carbon footprint and the utility costs for low-income tenants.

When finished in mid-2015, the apartments will provide 36 low and moderate income families including 12 homeless or formerly homeless families with below-market rents, employment services and other support for youth and families. One-third of the units will be reserved for families with more intensive needs.

“Our goal is sustainability, not just in the environmental sense, but in an economic sense to keep these families in a stable, supportive situation,: said Polly Donaldson, executive director of the Transitional Housing Corporation, a D.C.-based nonprofit that functions as the co-developer, landlord and service provider on this project.

Generally considered the most stringent energy standard in the world, Passive House building is an innovative approach to net-zero building. Instead of relying on active energy reduction systems with high installation costs, Passive House buildings concentrate on energy use reduction. Passive House buildings work with natural systems to manage heat gain and loss, saving up to 90% of utility costs. In fact, the U.S. DOE recognizes the Passive House approach as the most efficient means of achieving net-zero building operations

“It is a privilege for our members to be part of a project that addresses both homelessness and sustainable housing,” said Jared Blum, President, PIMA. “Polyiso insulation is known for it high thermal performance and will be a key contributor for this net-zero building that is extremely insulated, heated by passive solar gains and requires ultra-low energy for space heating or cooling.”

The groundbreaking ceremony for Weinberg Commons was held in October and attended by Washington Mayor Vincent Gray.