The City Hall Annex in Cambridge, Mass., is an excellent model of how historic preservation and sustainable design can work together to simultaneously cut costs, lower carbon emissions and preserve historic buildings.
In 2005, following a one and a half-year renovation project in which 85 percent of all construction waste was recycled, the Annex earned a gold-level Leadership in Energy and Environmental Design (LEED) certificate from the U.S. Green Building Council, and a preservation award from the Massachusetts Historical Commission.
The Annex, at 344 Broadway, houses several city offices, including the Conservation Commission, the Cambridge Arts Council and the city’s department of traffic, parking and transportation. Thousands of people have visited it each year since its renovation.
Built in 1871 as a school, this red-brick building was renovated in 1899 after a fire destroyed its Mansard roof. The building was increased from two to four floors in height, and was crowned by new pediments rising from the central bay of each side, with a blind arcade running around the building just below the cornice line.
The 1899 renovations, which included tall windows and skylights, were praised because they filled the interior with natural daylight and ventilation.
But by the mid-20th century, when it was turned over to offices, the building was starting to deteriorate, and the pediments were taken down due to structural issues. Mold grew, and in February 1999, the building was evacuated.
The City of Cambridge did not give up on the building. Instead, it launched a green rehabilitation project in October 2002 that not only restored the building to use and to its former historic appearance, but also resulted in a 43-percent reduction in greenhouse gas emissions, according to the city’s Web site.
For these new renovations, the building’s historic shell (and embodied energy) was retained, and the parapets of the 1899 renovation were carefully re-built according to historic photographs, in keeping with the guidelines of the Mid-Cambridge Neighborhood Historic District Commission. Inside the shell, the interior of the building (measuring 33,216 square feet) was re-designed to create a more earth- and people-friendly environment.
Nearly all of the building’s offices have operable windows again, and 90 percent of the interior has access to natural light and ventilation. Skylights and interior transom and side lights provide natural light to most of the rest of the interior. The windows are new, but were chosen to match the appearance of the original windows, as requested by the local historic district commission.
A steel superstructure on the roof accommodates a large array of photovoltaic panels capable of producing 26.5 kW. In recognition of the local historic district commission’s requirements, these panels are not visible from the street – and therefore, they do not significantly affect the way passersby experience the building’s historical appearance.
The building also boasts good indoor air quality. Low volatile organic compound-emitting materials – including paints, carpets and wood paneling and products – were chosen for the new interior. Carbon dioxide sensors were installed, and major sources for indoor pollutants – such as copiers and printers – were segregated within the building.
Recycled materials (including steel, carpet and ceiling tiles) were also used, and more than half of all framing lumber was sourced from sustainable forests.
And, in place of a furnace or boiler, eight heat pumps located in the ground are used to heat and cool the building with the aid of earth’s geo-thermal energy.
Cambridge is to be commended for its dedication to preserving and reusing its historic City Hall Annex building – not once, but twice (in 1899 and in 2002) – in a manner that supports sustainable practices. By recycling the building and rehabbing it in an environmentally-friendly way, the city has made the best possible use of this historic resource, and has helped to retain a piece of its historic urban streetscape.