Cadets Go off the Grid

-- Building Design & Construction, 8/14/2009 12:00:00 AM

New rooftop PVs, an existing wind turbine (in background), and four co-gen microturbines (not shown) fuel the maritime academy.

The Building Team for the Massachusetts Maritime Academy could have taken the easy route: just build a new cadet residence hall on the only remaining open space on the landlocked 55-acre campus at Buzzards Bay, renovate the old dorms as well as possible, and don't even worry about saving energy.

Instead, the team—including PCA, Inc. (architects), Cambridge; R.W. Sullivan Engineering (MEP), Boston; Erland Construction (GC), Burlington; and Odeh Engineers (SE), North Providence, R.I —took the less-traveled path. They saved the green space by adding two floors—and 150 new beds—above two existing dorms, thus avoiding a “two-class” residence hierarchy for the Academy's 900 cadets: flashy new building vs. 40-year-old dorm.

Stacking new floors atop the 1960s complex while cadets were in residence was no trivial task. Core samples showed that the compressive strength of the concrete had more than doubled the original design requirements, providing enough strength to carry the interior load of two new floors.

The team then conducted delicate radar scans of the existing cast-in-place roof, peeling off small sections one piece at a time to locate the rebar and drilling down into the roof—making sure to avoid the rebar—to find the right placement for supports. This work had to be done in phased sections, since cadets were occupying the floors below. Shotcrete was used to reinforce the building during construction and bring it up to current seismic codes.

Building Team members conducted radar scans beneath a one-story connector building that was to be demolished and replaced with a six-story structure housing a new elevator. They uncovered power and telephone/data lines under the slab, and the whole construction schedule had to be reworked to reroute the lines.

The contractor, Erland Construction, came up with a way to avoid soldering all the pipes in the building, using a compression system called ProPress to seal the joints. The upfront cost was greater than soldering, but the process knocked two-thirds off the labor cost.

All well and good so far, but the owners, the Massachusetts Maritime Academy and the State College Building Authority, wanted more—at minimum, LEED certification. Many “low-hanging fruit” points were captured—daylighting, occupancy sensors, recycled content, sunshades, operable windows, C&D waste diversion, etc.—but it was in its energy systems that the project excelled.

Eighty-one kilowatts of photovoltaics were installed on the roof, with the Massachusetts Technology Collaborative paying one-third of the cost; the array has been operating at 108% of capacity. Four co-gen microturbines generate 260 kW of electricity (11% of campus needs) and 408 MBH to meet the hot-water needs of the whole campus. Combined with an existing wind turbine, the renewable systems are capable of offsetting 100% of the energy required for the project.

Ultimately, the $14.2 million, 36,000-sf addition was awarded the first LEED Gold rating to a public college residence in the Commonwealth. Since its completion in August 2007, four new energy-related courses based on the project have been added to the Academy's engineering curriculum.

“The combined technology—solar, microturbine, and wind turbine—has merit,” said Building Team Awards judge Anil Anuja, PE. “This is an engineering-heavy project, both mechanically and structurally.” —Robert Cassidy, Editor-in-Chief