The Solaire at 20 River Terrace, New York City, is a showcase for how new technologies and thoughtful design can work together to create an efficient, earth-friendly building that is comfortable to live in. Dedicated in September 2003, the nation's first "green" residential building in lower Manhattan attracts tenants for its indoor air quality, natural light and stunning views of the Hudson River.

Being energy efficient is essential to being green. The 27-story Solaire by developer Albanese Organization of Garden City, New York, is specifically designed to consume 35 percent less energy than New York State Energy Code requirements. This goal is driven by local Battery Park City Authority (BPCA) Residential Environmental Guidelines, as well as state tax credits. In 2000, New York State introduced the nation's first green building tax credit. These incentives have helped the developer in their attempt to achieve a gold rating from the Leadership in Energy and Environmental Design (LEED) program, sponsored by the U.S. Green Building Council (USGBC).

The building achieved significant advances in energy efficiency through the use of a gas-fired absorption chiller from Daikin. "This central heating and cooling system is the major contributor to the building's estimated 60 percent savings in energy costs, and uses an ozone-safe water-based refrigerant rather than CFC and HCFC-based refrigerants," said Martin Dettling, vice president, Albanese Organization, Inc.

The building's other energy-efficient innovations include photovoltaic cells that convert sunlight to electricity, compact fluorescent lighting fixtures with daylight dimming and occupancy sensor controls, and highly efficient condensate domestic hot water heaters.

Typically, a building's heating, ventilating and air conditioning (HVAC) system is one of its biggest energy users, and engineers who designed the Solaire looked specifically for a system with the lowest possible Btu usage. Two 400-ton Daikin gas-fired absorption chillers send chilled (or heated) water to fan coil units located in each apartment.

"Through manufacturers' test data, we found that a gas-fired absorption chiller is more energy efficient than a conventional electric centrifugal chiller," said Marvin Lewin, lead engineer with Cosentini Associates. "The motor and compressor of a centrifugal chiller require substantial amounts of electricity; a chiller is often a building's primary electric load. When you factor in the energy required to produce electricity, the loss of Btu's along the electric line, and actual use at the building, it was evident that gas was simply more efficient. Gas produces energy directly at the source; in this case, the high temperature generator of the chiller."

Absorption Chillers: Using Heat To Cool

Advances in absorption technology have made gas-fired absorption chillers efficient solutions for residential complexes, commercial buildings, government facilities, college campuses, hospitals and other facilities requiring large centralized heating and cooling systems. Today's high efficiency, double-effect, direct-fired absorption chillers/ heaters from Daikin are twice as efficient as the more traditional single effect designs, and they can be applied in most building designs throughout the country. The double-effect chiller uses two high temperature generators, which can boost the Coefficient of Performance (COP: the cooling output divided by the energy input). The COP of a single-effect absorption chiller is about 0.6, while a doubleeffect chiller has a COP of 1.0.