- THE MAGAZINE
At Community Environmental Center (CEC) in Long Island City, Queens, we have long held that New York City’s multifamily buildings are a marvelous place for solar hot water (SHW) systems. Our latest and largest installation is a 42-panel system on Wadsworth Terrace in Northern Manhattan”NYC’s largest solar thermal system to date for a multifamily building. It serves as an excellent illustration of the ways in which the complexities of an urban multifamily solar installation can be outweighed by the significant opportunity these projects present.
In early summer 2009, two adjacent buildings operated by Lemle & Wolff, Inc. were in the first stages of a gut renovation, a project that was funded under the NYC Department of Housing Preservation and Development’s Participation Loan Program. Around this time, Edmund Miller, one of the principals of Apartment Rehabilitation Corp., the general contractor on the job, attended a seminar on solar hot water systems, and he decided to give it a try. Reasoning that the timing seemed just right for the Wadsworth Terrace buildings, and that they got plenty of sun, Miller contacted CEC to ask about solar hot water for the project. CEC was already involved in the rehab project as energy efficiency consultant through the NYSERDA Multifamily Performance Program, and we were thrilled to offer a proposal.
Covering two adjacent buildings on the same lot with 83 affordable residential units and about 12,000 SF of roof space total, the project offered a prime concentration of high demand for hot water along with an unobstructed southern view from the roof – two critical criteria for a cost-effective SHW project. Like many pre-WWII buildings, both heat and domestic hot water are provided by one large steam boiler at Wadsworth Terrace. If one simply imagines firing up a huge steam boiler a few times each hour in the summer, just to provide hot water, it’s not surprising that this is a very inefficient way to provide hot water. The goal of the project was to install a solar hot water system that would preheat incoming potable water from the city main before it was fed into the existing boiler, where, if necessary, it would receive an extra boost of heat to bring it up to 130 degrees, before sending it out to the apartments. For any project to be viable, the system must pay for itself within its 25-year life, and with more than 40 percent fuel savings for domestic hot water heating anticipated, this installation, which cost approximately $170,000, should achieve a simple payback in less than 10 years.
To execute the project, CEC assembled a team that included Kingston, NY-based EarthKind Solar, a solar-products distributor with whom CEC has worked on previous installations. Nearly all the necessary construction trades were provided in-house, as CEC was able to draw upon the significant skill and experience of its weatherization crews (in addition to doing energy efficiency consulting and SHW installations, CEC is the largest low-income weatherization provider in NY State).
EarthKind Solar provided solar collectors and other system components as well as design services and technical support during the project. The design called for a total of 42 Phoenix Infinity 323 collectors, along with two packaged pump station/controller units, all provided by EarthKind. Additional panels would have resulted in more energy savings, but the usable roof area was restricted due to the building shape and because of restrictive fire codes that prohibited obstructions on a significant portion of the roof.
The Phoenix panels are designed and fabricated in Germany and are a new product to the United States. They are among the highest-performing flat-plate panels available and offer a considerable degree of flexibility in installation: the four-foot by seven-foot panels, at 80 lbs., are easy to maneuver; the modular mounting system has very few pieces; and the panels are connected by a flexible length of pipe to allow movement between the panels without compromising the fluid connections between them. The design also called for seven 200-gallon steel tanks manufactured by Bradford-White Co., to be installed in the basements to provide the hot-water storage needed for the SHW system.
Constructed in 1925, the five-story buildings have no elevator and are situated on a steep cliff, so that the buildings were effectively six-story walk-ups. The roof construction was typical for a building of this vintage: a wood roof deck supported by a network of wood members, installed on top of the rafters to give the deck its pitch for drainage. Figuring out how to provide a structure to distribute the load of the solar collectors across the wooden rafters, which were themselves between zero and 16 inches below the surface of the pitched roof deck, was lots of work for our project team. We settled on a wood support system that could be constructed and installed onsite--a job that called for over 700 feet of treated, heavy lumber and two and a half weeks to complete, all before the first panel could be mounted. We were fortunate to be doing this work during an extensive renovation of the building. With Apartment Rehabilitation’s roofing contractor onsite, gaining access to the rafters was relatively painless, as long as it didn’t rain. By late June, we had our final boom truck delivery, to lift the 42 panels to the Wadsworth Terrace roofs.
Installing the seven tanks, at 500 lb. each, was no simple task either. Our five-man team needed a whole day to get the tanks up and down narrow stairs, around corners and through doorways with just enough room for a finger on either side. There usually isn’t an easy way around this problem, so it’s something that must always be considered at the outset. For this project, un-insulated tanks were specified to keep the diameter small enough to fit, and insulation was added after installation.
We were also fortunate that the rehabilitation work included gutting the interior walls, enabling easier access to interior spaces where the copper pipe would run from the rooftop collectors to the new SHW storage tanks in the boiler room; however, on one building it was still necessary to route the pipes on the building exterior, because all available chases in that building had been previously eliminated. All together, we installed approximately 960 feet of pipe between the panel and tanks, and approximately 370 feet to connect the tanks to the boilers.
Despite the complexities of installing this system, we anticipate that the project will be highly cost effective for the owner. With lots of sunny roof space, a concentrated and consistent demand for hot water and the high cost of conventional energy, this building and other urban multifamily buildings are prime candidates for cost-effective SHW systems. Throughout the course of next year, CEC will monitor and verify the performance of the Wadsworth installation. In the meantime, there are literally hundreds of similar buildings in NYC where we feel, more than ever, that solar makes sense.
Project Team Members
Developer: Lemle & Wolff, 5925 Broadway, Bronx, NY 10463. www.lemlewolff.com
Solar Integrator: Community Environmental Center, 43-10 11th St., Long Island City, NY 11101. www.cecenter.org
Project Director: Larsen Plano, senior project manager, Green Building Services, CEC. firstname.lastname@example.org
System Design, Procurement, & Technical Assistance: EarthKind Solar, 500 Enterprise Drive, Kingston, NY 12401. www.earthkindsolar.com
Designer: Gerhard Klier, operations engineering manager, EarthKind Solar. Gerhard@earthkindsolar.com
General Contractor: Apartment Rehabilitation Corp., Edmund Miller, principal. email@example.com
Expediting: S&G Expediting Group, 760 67th St., Brooklyn, NY 11220.
Plumbing Contractor: Mercon Contracting Inc., 1616 Mermaid Ave, Brooklyn, NY 11224.