SUCCESS STORY: OCEANFRONT LIVING AND LEED GOLD
Boston’s Waterfront Place uses a high efficiency water source heat pump HVAC system with Taco’s single pipe LoadMatch® system. The system offers superior comfort and energy efficiency to a high end development on the waterfront in Boston. Because the system uses less pipe and materials, it has a much lower impact on the environment. In addition, it achieves lower installed costs by using less labor and materials and reduces maintenance cost by incorporating Taco’s no maintenance wet rotor LoadMatch® circulators.
This is a win-win for everyone, essentially a Value Engineered system with lower costs and lower impact on the environment, but without impact on comfort and operating efficiencies. In fact, the system provides better comfort and efficiency than air or refrigerant systems such as VAV or VRF.
This article, originally produced by Common Ground, highlights the innovative solutions to HVAC systems in today’s competitive environment.
Boston’s New Waterfront initiative has created an influx of business and new housing where sea meets land. The revitalized Seaport District in South Boston now sports a harbor walk that meanders through shops, fine restaurants, bocce ball courts and upscale neighborhoods.
One of the newest projects to break the skyline is Waterside Place. The aptly-named, 350,000 square-foot luxury apartment building is adjacent to the Boston Convention and Exhibition Center, and Seaport World Trade Center Complex. The lower two floors consist of retail space and a conference center, while the upper 17 floors are home to 236 apartments.
But it’s more than just an upscale apartment building. A tight building envelope compliments a unique, cutting-edge heat pump system to provide occupants with a carbon footprint smaller than the roomy apartments would suggest. Designers of the sleek high-rise are seeking LEED BD + C Gold.
Boston’s TRO Jung Brannen (TRO JB), an integrated planning, architecture and engineering firm, was sought out by the development group in 2011 for the genesis of the Waterside Place project. As LEED certification was a building goal from the beginning, TRO JB was tasked with designing the mechanical systems. Founded more than a century ago, the company has deep roots in the healthcare, research and commercial development sectors, among others.
Mechanical construction contractor J.C. Cannistraro took the bid on the project. With more than 400 employees, the company performs plumbing, HVAC, fire protection, service and maintenance for biotech, institutional and commercial properties throughout New England.
“From the very beginning, Waterside Place was to be – and is – an efficient, green, luxurious living space,” said TRO JB’s Director of HVAC Engineering and Associate Principal, Paul Kondrat, PE. “The challenge was doing it on a budget per square-foot that was lower than what typically accompanies most LEED projects.”
Water-Side System, Naturally
The apartments and common areas are conditioned via 425 water-source heat pumps, with a total cooling load of 600 tons, and a heating load of 5,600 MBH. In cooling mode, the heat pumps are served by a two-cell cooling tower for heat rejection. Three, 2 Million BTU modulating boilers are installed on the heating side. A single plate-and-frame heat exchanger in the penthouse mechanical room separates the open cooling tower water from the building’s central loop. A PEP centrifugal water separator installed on the condenser water loop removes most of the dirt that would otherwise make its way into the heat exchanger. The separator compliments a Dolphin non-chemical water treatment system selected for its “green footprint” and LEED points.
“In cooling mode, the heat pumps get entering water temp from the plate HX ranging from 87°F to 97°F,” said Jim Darragh, sales engineer at rep firm Emerson Swan, who offered product support during design, installation and startup. On the open side of the heat exchanger, the cooling tower takes water at 95°F EWT and sends 83°F LWT back to the cold side of the HX. In heating mode, water entering the heat pumps ranges from 75°F to 67°F.
Flow rates through either side of the exchanger are similar; roughly 1550 GPM in heating and cooling mode. Circulation is provided by a Taco TA Series horizontal split case pumps on the cooling tower side, and an FI Series end-suction pumps on the central loop.
But it’s the distribution of system fluid to the heat pumps that’s most unique.
A Twist on Proven Technology
To help keep the project within budget, TRO JB was asked to design the hydronic distribution around a one-pipe Taco LoadMatch system. C3 was the development project manager for Waterside Place since its inception. The Boston-based construction consulting firm is currently involved with numerous projects across the globe.
“We have a full department of engineers on staff, each with extensive experience in their fields,” said C3 experience with single-pipe hydronic systems that we were adamant about the use of LoadMatch at Waterside Place.”
LoadMatch is a unique blend of three technologies. Single-pipe distribution and primary-secondary pumping are proven technologies that – as part of a LoadMatch system – are enhanced by the use of maintenance-free, wet rotor circulators.
The primary distribution system is a single-pipe loop. The secondary distribution system is a relatively tiny, decoupled loop for each terminal unit – a heat pump in this case. Small, low-kW LoadMatch circulators provide the specified flow to each unit, eliminating the need for control valves and balancing valves on the heat pumps.
“Providing flow to water source heat pumps with individual circulators guarantees that each unit has the proper flow at all times and prevents heat pump lockouts typically experienced in improperly balanced two-pipe systems” said Jeff Pitcairn, Eastern President and CEO, James Kirby. “It’s based on our past
Regional Manager for Taco, Inc. Pitcairn used Taco’s revolutionary HSS Hydronic System Solution software to provide design assistance early in the project development stage.
The system is self-balancing, which reduces many start-up, commissioning, and operational problems because all zones are completely independent of each other and get their required amount of flow at all times.
In addition to the energy savings typical with hydronic systems, LoadMatch reduces head loss by eliminating many control and balancing valves, as well as some pipe. The result leads to a reduction in primary pump size by up to 50 percent, and total pump horsepower can be decreased by 30 percent, according to Greg Cunniff, P.E., application engineering manager for Taco, Inc.
The vertical heat pumps were ordered from the factory with the small LoadMatch circulators installed within the cabinets. Where a vertical configuration wasn’t feasible, several horizontal heat pumps were used. On these units, the circulators were installed on-site. All the secondary circulators are between 1.8 and 4.5 GPM, depending on the size of the heat pump.
Tight Budget Seeks an Aggressive Bid
After the project went out to bid in late 2011, one came back substantially lower than the others. J.C. Cannistraro’s bid was returned quickly, and with a number that the developer could appreciate.
“We had never installed a LoadMatch job before Waterside Place,” said Project Manager Paul Battaglia. But because two Cannistraro employees had attended training sessions about the system, familiarity with LoadMatch allowed the company to bid the job aggressively.
In July of 2010, Cannistraro’s Joe Mierzejewski, project manager, and Dario Corriea, coordinator, flew to Whitefish, Montana for a Taco Advanced Hydronics Training session. Among topics like chilled beam systems, self-sensing pumps and the company’s free design and analysis software, half a day was dedicated to the design of LoadMatch systems. Mierzejewski and Corriea were involved with the design process, and Battaglia took over on-site once the project began.
“The system had a few learning curves,” said Battaglia. “For instance, the individual circulators are so quiet that it’s often hard tell if they’re running or not. But ultimately, the system went in more quickly than a standard two-pipe system, so the labor and material savings added up for the developer.”
According to Battaglia, three, 7,500 CFM ERV units provide general building makeup air and bathroom exhaust.
The building officially opened in February, and reached 50 percent occupancy in early August. With all mechanical components working flawlessly in tandem as designed, comfort levels leave no room for improvement, and online reviews for Waterside Place at the corner of Congress and D Street – are Steller.
Article Courtsey of Taco