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Biomass Heating Facility

A large part of incorporating sustainability into architecture is setting goals, many of them tied to carbon neutrality and looking decades in the future – 2030 is probably the most popular target year

At The Hotchkiss School in Connecticut, 2020 is the year for achieving a carbon neutral campus, and an important element in fulfilling that goal is the Biomass Heating Facility, designed by Centerbrook Architects and Planners. The plant burns sustainably harvested wood chips from regional forests. More importantly it does this job under an undulating green roof that makes the utilitarian building beautiful and a symbol of the school's ambitious environmental goals.

What were the circumstances of receiving the commission for this project?

Centerbrook had an existing relationship with the client, having designed the Music Center at The

Hotchkiss School.

Please provide an overview of the project.

Viewed from the main campus of this independent preparatory school, down a hill and across a golf course, this peculiar looking building with its undulating green roof promises something special. Indeed, it houses a bio-mass heat plant that burns sustainably harvested woodchips to heat an entire boarding school (1.2 million square feet in 85 buildings) with over 600 inhabitants.The design meets two seemingly contradictory goals: creating an iconic presence for this seminal building while also merging into its natural setting, as befits its mission. Sited at the periphery of the School’s campus, the profile of this 16,500-square-foot building is capped by a rolling, vegetated roof that changes color, chameleon like, with each season.

Designated a carbon neutral fuel by the International Panel on Climate Change, the locally sourced woodchips are replacing some 150,000 gallons of imported fuel oil per year and cut emissions overall, most dramatically sulfur dioxide, by more than 90 percent. Waste ash is collected fo r use as fertilizer. The plant is an integral part of the school’s commitment to becoming a carbon-neutral campus by 2020. In addition to lowering emissions, the plant saved the school nearly $800,000 in fuel costs in its first year of operation.

Designed as a living classroom, the heat plant exposes students and visitors to ecologically sustainable technologies and materials. The mezzanine walkway overlooks and circumnavigates the wood burning boilers, wood chip bunker and conveyers, the stoker auger, the electrostatic precipitator, the ash auger, and an exhibit with computer terminals that explain the plant’s operation and track performance data.

Forest Stewardship Council wood or indigenous timber was used in the building’s construction. The building’s glue-laminated timber trusses embody less energy than reinforced concrete or steel and can be used for much longer spans and complex shapes. Outside, a nature path affords views of the green roof, which absorbs and filters rainwater runoff, a rain garden, bio-swales, and nearby wetlands.

The building received LEED Certification for features that include: renewable construction materials; water-conserving plumbing fixtures; use of local materials with a high recycled content; an abundance of daylight inside; and highly efficient mechanical systems, lighting, and exterior skin.

What are the main ideas and inspirations influencing the design of the building?

Rather than making a typically dreary home for infrastructure hidden away from the world, the architect’s concept was to design an elegant undulating building that would be present an alluring face to the campus while simultaneously fitting into a sloping bucolic landscape. Planted with sedums, the green room mimics its environs. Inside, the design supports the furnace but also serves the goal of making the building an ancillary classroom where students can learn real world lessons about sustainable practices.

To what extent did the clients and/or future users of the building influence the design and the outcome of the building?

Centerbrook held a series of interactive and inclusive workshops with a diverse group of the school’s stakeholders to determine everything from siting possibilities to the overall direction for the project.

How does the building relate to contemporary architectural trends, be it sustainability, technology, etc.?

Efficiently burning sustainably harvested woodchips from regional forests has enabled the school to drastically lower its greenhouse gas emissions, including sulfur dioxide and CO2. The LEED certified building embodies many sustainable approaches inside and out, among them the use of renewable wood building materials, such as glulam beams, from responsibly or FSC managed forests. The building’s green roof, connected to nearby bio-swales and retention ponds, absorbs and filters storm water before returning it to the ecosystem. By using local fuel, rather than foreign oil, the school also is contributing to a sustainable local economy. In terms of aesthetics the low, green and undulating profile of the building reflects the surrounding landscape in the foothills of the Berkshires.

How would you describe the architecture of Connecticut and how does the building relate to it?

Like most places, Connecticut boasts a wide diversity of architecture, from traditional and historic to modern design. The design of the Hotchkiss Biomass Facility with its clean, crisp lines and flowing profile comingles a contemporary sensibility with Yankee attention to function. It establishes a new visual presence on the school’s largely Georgian campus, while blending in with the surrounding bucolic landscape.

Biomass Exhibit ( Photo © : David Sundberg/Esto )


  • Lakeville, Salisbury, CT, USA
  • Centerbrook Architects and Planners