At 5.2 miles long, the Grand Concourse, located in the Bronx, is considered one of the greatest boulevards in the New York borough. It contains one of the largest number of Art Deco buildings in the world and is home to a diverse population. The recently completed 425 Grand Concource development creates a strong visual and its location is significant as it’s a short walk from the Bronx Terminal Market, Yankee Stadium and the 149th Street Subway station which serves three important subway lines. The development is the largest Passive House (Phius-certified) project in North America to date.

Designed by Dattner Architects in collaboration with Trinity Financial, Inc., the 290-foot-tall building includes 277 units of affordable housing, a medical facility, supermarket, community support space and a new student services center for CUNY Hostos, the public community college. The project balances the critical need for affordable housing combined with the need for a high-quality, attractive development that promotes street and community activity in what is known as the Mott Haven neighborhood. Built to Phius Passive House standards, the building will consume up to 70% less energy than conventional housing projects. Tenants will pay less for their air conditioning in the summer because passive houses are very well insulated and they use highly efficient heating and cooling equipment. A passive house also minimizes the release of harmful, asthma-triggering combustion gasses both for tenants and the surrounding neighborhood by using filtered fresh air for ventilation, plus electricity for heating and cooling as well as for cooking.

Healthy + sustainable living

Located in one of the poorest congressional districts of the city, the area is known to have been affected by pervasive asthma in its population due to the high air pollution from heavy traffic and nearby solid waste transfer stations. One of the goals of the project and the impetus to build it as a passive building was to minimize the release of toxic compounds known to trigger asthma. The design also incorporates NYC Active Design Guidelines which encourages the design of building facilities that support space for physical activities. The building offers residents a wide variety of amenities including a recreation room, landscaped roof terrace, a lounge space, fitness room, laundry rooms and bike storage. The benchmark sustainable project provides a model for healthy living environments in a district with one of the worst childhood asthma rates in the country.

Climate management + window design

One of the challenges in building a passive house in New York City is its climate that is quite humid. Insulation, glazing, glazing exposure in a dense city environment and wall-to-window ratio, along with humidity management are very important. If you live in an area with high air pollution, unfiltered outside air is not really healthy. The current building code still allows fresh air to be provided through so-called trickle vents – holes in the window frame. When specifying windows, the team at Dattner Architects reached out to Starr Windows & Doors before selecting products.

Starr distributes two types of window systems appropriate for passive house projects in the United States; REHAU GENEO 4700 and REHAU EuroDesign 4500 uPVC. There were some considerations that the team at Starr took into account before recommending the REHAU EuroDesign 4500 uPVC. While GENEO 4700 is designated as a Certified Passive House Component by the Passive House Institute in Germany, this project was based on Phius+ 2018 Core certification which is geared toward U.S. building codes and U.S. climates.

While GENEO 4700 is extruded in Germany, EuroDesign 4500 is made in the Americas, with streamlined delivery and lower overall costs. Ultimately, Starr recommended the REHAU EuroDesign 4500 uPVC system with a white interior and a dark bronze Renolit Exofol exterior. Dattner Architects specified multi-lite units, consisting of fixed and operable windows, from the third floor up, while the lower floors use larger fixed and operable window units.

 “The high-performance REHAU EuroDesign 4500 uPVC windows were a key component in the environmental equity of the project; both for thermal performance and indoor air quality,” explained John Woelfling, principal, Dattner Architects. “The passive house strategy requires that the envelope limit the amount of uncontrolled air infiltrating or leaving the building. REHAU windows not only perform well when it comes to thermal transmission of heat but they have a very solid locking mechanism which results in a high-performance seal.” The project’s expansive windows provide abundant amounts of daylight into the apartments, while balancing the window-to-wall ratio that is crucial to achieving Passive House performance levels.

Passive House design standards

The design team was committed to creating a sustainable and energy-efficient building. The energy model met all of the Phius+ 2018 certification targets and exceeds the mandatory number of requirements for the Enterprise Green Communities (EGC) 2015 certification. The efficient energy recovery ventilation (ERV) system brings in continuous fresh air and removes stale air, while exchanging energy between the two streams to precondition the incoming fresh air. The building serves as a model for how to effectively employ Passive House strategies and efficient HVAC equipment to minimize energy use in high-rise buildings.

An additional benefit to the tenants at 425 Grand is that as a part of the development, an online “dashboard” was designed by Bright Power so tenants can review their current energy consumption and compare it with the average building readings – in live mode. The hope is that the takeaway will be a deeper understanding about energy use in their daily activities without actually feeling as though their building is anything different from what a building should be – a comfortable, quiet and healthy living environment.