Though they’re all part of greening Columbia’s Morningside campus, each new renovation has its own unique style. Knox Hall, on the corner of 122nd Street and Broadway, boasts four geothermal wells. These are Columbia's first geothermal wells, and perhaps the first active ones at any New York City institution of higher learning.
The wells are the stars of the gut renovation of Knox, formerly the site of stately faculty residences for adjacent Union Theological Seminary. Given its stately past, renovations placed priority on respecting Knox’s history and character, especially through reusing its architectural elements.
Columbia University took over Knox Hall in September 2005. Michael Iorii, associate director of Capital Projects Management, says a feasibility study then determined that academic rather than residential use would be more valuable to the University. The building has become the new home of the Departments of Sociology and Middle East and Asian Languages and Cultures (MEALAC), as well as the Middle East and South Asia Institutes and Institute of African Studies.
At the same time, “Helpern Architects reviewed, measured, and analyzed design options for the building systems, including mechanical and lighting,” Iorii says. “After the long review process, the University decided to go with the geothermal system – a first for Columbia and at the time, relatively new in New York City.”
A decision in favor of a conventional HVAC system would have required placing an air conditioning chiller on the roof. The chiller would have been unattractive, particularly so in a city block containing other buildings with landmark status. It would also have been a pollutant, and a large energy user.
“Studies confirmed by far the green benefits of geothermal, heads and tails above everything else,” Iorii says. “Reduction in energy use will be at least 22 percent and potentially higher, and without the chiller on the roof, there will be no carbon emissions, greenhouse gases or dust particles. The system will be very clean.”
Moreover, Iorii says the upfront costs of choosing geothermal will be repaid within six years because of the large energy reduction.
To a Knox passerby, the only signs of the new HVAC system are four simple manhole covers in the sidewalk along 122nd Street. Beneath each cover is an 1,800-foot hole that’s about 400 feet deeper than the Empire State Building is tall. Each hole, eight inches in circumference, is lined with a three-inch plastic pipe with a perforated bottom. Water comes into the holes from fractures in the granite bedrock. Known as standing column wells, Iorii says “they basically act like a big straw, sucking water in from the bottom into a closed loop system.”
The water is sucked into heat pumps with compressors that make cold or hot water to supply the building’s need for heating or cooling. When, for example, cold water is needed in summer, and the hot water produced by the mechanical equipment needs to go somewhere, a heat exchanger takes over. The exchanger – thin, veined pieces of titanium in a metal casing – transfers heat from the hot water to cool well water coming into the building that then circulates back into the well via another pipe. This process isolates each system from the other, which ensures that the building systems do not contaminate the ground beneath.
Margaret Castillo, a principal with Helpern Architects, has worked on the building since the beginning of its renovation. She describes “earth coupling” – use of water running through the earth as with the geothermal wells – as the most unusual feature of Knox. “From the preservation point of view, we don’t have chillers, we’ve kept the lead-coated copper roof, and retained the building profile and flues,” she says.
Energy efficiency from the wells has been reinforced by what Castillo describes as the “envelope efficient” building because of its massive stone walls that help retain warm or cool air.
Iorii also describes “smart decisions” made in other areas, especially energy-efficient windows. “We’ve got the tightest building we could get “because of them, he says. "There are six heat pumps in the basement. The systems was designed to run with four, but it’s actually running with just two – half what we were anticipating. This reduces electricity usage even more.”
Castillo points out that the building was designed with double-loaded corridors; nearly every room has windows and natural light, reducing the need for artificial light, which is monitored by timers and sensors. The double-hung windows have old-fashioned brass counterweights.
“I did lots of research marrying the new program to the existing building,” Castillo says, as she speaks about the effort to preserve and restore as many of the original architectural details as possible. Of the 11 massive oak fireplaces and mantels – all in the Arts and Crafts style, each one unique -- seven have been crated and tagged for future use in other areas on campus, while four have been reinstated strategically around the building.
Grueby tiles, also from the Arts and Crafts period, decorated the fireplaces and have either been restored with the fireplaces or removed for safe keeping. William Grueby, a Boston-area artisan at the turn of the 20th century, crafted the tiles using an opaque matte glaze and a unique shade of green, very often in leaf patterns.
“It was nice to find them, save and reinstall some,” Castillo says. “When you walk into the lobby, where the original terra cotta floor has been kept, you see what it used to look like. It’s important for students to see and appreciate history – the grace notes from the past.”
Iorii says an application has been filed for LEED certification of Knox.
The LEED system is described by the United States Green Building Council as “the nationally accepted benchmark for design, construction and operation of high performance green buildings.” Applicants employ design and construction, maintenance and operations standards consistent with LEED standards.