Scalable, Efficient Retrofit Solutions Under Development
The New York State Energy Research and Development Authority (NYSERDA) recently awarded the first six Energiesprong-style retrofits. This announcement comes as an exciting new development to last year’s article in Passive House Buildings about New York State’s planned implementation of the burgeoning retrofit style that aims to create standardized, scalable, deep energy-efficient retrofit solutions.
NYSERDA has scheduled the design phase of these projects to last about six months, from technical solution concept development through schematic implementation plan. The finalized schematic implementation plan will include schematic architectural and mechanical designs, projected budget and schedule, a life cycle cost analysis, energy analysis, renewable-energy plan, regulatory-barrier analysis, and resiliency analysis. NYSERDA then plans to issue a solicitation to provide funding for developing and installing the designs.
Photo by Pericle Gheorghias
Multifamily Affordable Housing in Harlem
One of the New York City teams is led by The Levy Partnership (TLP), a leader in the energy efficiency consulting field. In addition to TLP, the core team includes building owner Joint Ownership Entity (JOE) NYC, award-winning architecture firm CTA Architects, P.C., ecologically minded mechanical engineers Peterson Engineering Group, international structural engineers MacLaren Engineering Group, and a construction firm experienced in Passive House design, M Square Builders. Solar One, Harvest Power, Sentient Buildings, Passive Dwellings, and Rocky Mountain Institute are also providing support. Together, they are working to bring an existing 20-year-old multifamily low-income building in Harlem to near net zero energy use. The team will also address improving indoor environmental quality and the resiliency of the building, all without displacing residents during construction.
The building owner, JOE NYC, a new entity for nonprofit-owned affordable housing assets in New York City, was founded by a group of prominent New York City Community Development Corporations in response to a set of challenges confronting New York City’s affordable housing stock and low- and moderate-income communities, and in particular the nonprofit community.
As JOE NYC Assistant Director of Asset Management Allison van Hee explains, “You can’t expect to maintain affordability without sustainability both in terms of the well-being of building occupants and the environment as a whole. As a result, the JOE is committed to pursuing the net zero energy goals of RetrofitNY and helping to achieve New York City and New York State climate goals.” RetrofitNY supports Governor Andrew M. Cuomo’s goal to reduce greenhouse gas emissions 40 percent by 2030.
Infill Site Typical of Urban Fabric
TLP and JOE chose an infill site that is representative of so much of New York City’s contemporary low-income urban fabric and the design challenges inherent in renovating it. The midblock building consists of one floor of community facility space and five stories of apartments. The façade is a minimally ornamented brick cavity wall with concrete masonry unit (CMU) backup masonry and a bearing-wall-and-concrete-plank structural system.
The team is currently looking at how to insulate the exposed walls, given the limitations of the site and the fact that the building is built flush to three of its four lot lines. Added to that, the original building plans included vertical shafts that the team intended to use to run ventilation ducts and piping to new heating and cooling systems. Unfortunately, the shafts don’t exist in the as-built conditions, so the group is busy working around these obstacles.
Thus far, the plan is to provide a significant amount of additional envelope insulation from the cellar to the roof. The exterior framed walls already have 3 inches of fiberglass batt insulation, and given the limited floor area, insulating more on the interior is not an option. The primary strategy is to use exterior insulation and finish system (EIFS) panels over the existing brick veneer and 8 inches of EPS underneath a new bituminous roof. The team is still grappling with code restrictions on expanding past the lot line toward the street, so different strategies may be implemented on the front and back sides of the building. Also in consideration as an alternative to EIFS is the use of large prefabricated panels inclusive of windows. Whichever approach is chosen, the renovations will include wholesale window replacement and air sealing.
A decommissioned trash chute and the existing corridor supply shaft may be repurposed to house ductwork going to each apartment. If these shafts are not usable, ventilation will likely be accomplished by running ductwork from rooftop ERVs down the building façade to apartments. Other options, such as cutting openings in the plank construction of the occupied apartments, were deemed too complex, costly, and disruptive to the residents. Existing exhaust shafts will be used to extract stale air from apartments and corridors. The ground floor and basement community spaces will have their own ERVs.
Eliminating Fossil Fuels
The project requirements include eliminating on-site fossil fuel usage, so the existing fossil-fueled space and water heating systems will be decommissioned and replaced with all-electric systems. Domestic water heating will likely utilize one or more air source heat pumps connected to the existing central recirculating system. These will in turn be outfitted with additional insulation and energy-saving controls.
The new systems also will provide space cooling, which will be a real amenity to the residents. The team is currently considering two options to assist with temperature control: a central variable refrigerant flow heat pump system with individual air handlers in each room and a hot/chilled water distribution system served by a roof-mounted heat pump.
A sizable PV array is planned for the roof level to defray the use of grid electricity, and energy-efficient appliances, lighting, and low-flow plumbing fixtures will reduce electricity usage in individual apartments. Part of the project’s larger vision is to provide replicable solutions throughout New York City’s multifamily housing stock, so all of the proposed systems are selected, and their implementation planned, with replicability in mind.
While the retrofit will include items directly benefiting residents, such as the new cooling system, improved ventilation, and new appliances, tenant engagement will be critical to the long-term success of the project and the replicability of the retrofit approach. For this reason, the project team is already planning a series of resident meetings to present preliminary plans and gather feedback on resident behavior and preferences. The team is dedicated and enthusiastic, and it looks forward to solving the challenges successfully, both technically and aesthetically.
Preliminary energy modeling has shown an approximately 90% decrease in site energy use based on the proposed solutions thus far, which include an extensive canopy-mounted full-roof PV array that would produce about 60,000 kWh per year. Because it is unlikely that a six-story building can achieve net zero with its limited roof area (four stories is generally considered the maximum for this goal), the building will seek to obtain the remaining 70,000 to 80,000 kWh from community solar.
In order to maximize collaboration, all the RetrofitNY teams are employing an integrative design process and have been provided a coach expert in this methodology by NYSERDA. By including M Square Builders on the TLP team, the design consultants have been able to make real-life decisions based upon its contractor’s experience. MacLaren Engineering Group will advise on the additional structural loads that can be imposed on the façade and roof so that CTA Architects has the parameters within which it needs to work to implement the solutions.
Collaboration really has been key, as this process includes a fair amount of brainstorming and creativity along with technical knowledge. “It’s fantastic having the full range of expertise in the room problem solving together,” says van Hee. “One of the values the JOE can provide its members is brokering early adoptions of new building techniques and technologies and providing better data on ongoing operations postbuild. NYC is on the precipice of a major shift in building standards. I’m convinced that our team is developing a model that will be the boilerplate for future resident-in-place affordable rehabs. The question for me is how quickly we can solve for the trickier aspects of implementation and standardize the solution.”
— Jordan Dentz and Christa Waring
Jordan Dentz is vice president of The Levy Partnership and Christa Waring is a principal with CTA Architects.