Concentration of CO2 in the Atmosphere

Renovated Peterborough Town Library Building is Heated and Cooled with Wood Chips


The rear section and basement of the Kyes-Sage House was converted into the boiler room for the new Peterborough Town Library. Pipes run from there, under the driveway and into library’s HVAC system. (Photos: Froling Energy)

Jim Van Valkenburgh

The town of Peterborough, New Hampshire just celebrated the opening of their newly renovated library. Work was completed in September after more than a year of demolition and construction. It is a stunning building with some interesting innovations.

Multiple goals were set for and accomplished by Ann Beha Architects of Boston. Among them were a well-lit, warm and welcoming building with separate spaces for adults and children, a 100-person meeting room that can be used after library hours, and a sunny outdoor patio to take advantage of the building’s setting, right beside the fast-flowing Contoocook River. The result is a lovely new building that is much more usable in the current era where libraries are places of information, group meetings and social connections.

The new library has a similar footprint to that of the old building which was mostly demolished. Only the classic 1890s library building on the corner of Main and Concord Streets was saved from the wrecking ball. This distinguished building was designed by Robert Morison, a nationally renowned mechanical engineer who was born and raised in Peterborough, but at the time had offices in Boston, New York and Chicago. Removal of the outdated 1957 and 1977 additions provided a blank slate for the architects to work with.

An old house that sits across the parking lot was and will remain the library’s used bookstore, but the rear portion was transformed into the library’s new boiler room. This is where an innovative dried wood chip boiler and absorption chiller were installed—key elements of a compelling innovation at the library. It is one that could be used in buildings across northern New England: the use of a wood pellet or wood chip boiler as the source of both heating and cooling.

Froling Energy’s blower truck delivering the first load of precision dry wood chips into the Peterborough Town Library’s silo behind Kyes-Sage House.

How do you cool with a boiler? A high efficiency Froling T4-150 dried wood chip boiler generates 190-degree Fahrenheit hot water and stores it in a 600-gallon buffer tank. When an area of the library needs heat, circulators pull hot water from the tank and send it through the pipes to where it is needed. When an area requires cooling, hot water from the buffer tank is circulated through a Yazaki 10-ton absorption chiller which outputs chilled water that is also pumped over to the library. Yes, it is true: the absorption cycle creates cool water from hot water like a heat pump but it uses water as the refrigerant. It doesn’t use any CFCs, so absorption is a very climate-friendly way to cool. (Get more info at

Four buried insulated pipes run under the driveway to the new library: two are supply and return pipes for heated water and another pair is for chilled water. These run to air handlers placed throughout the building for delivering heating or cooling, as needed.

The entire boiler and HVAC system was designed by Wilson Engineering and installed by Froling Energy. Partial funding for the absorption chiller was from a grant from the NH Department of Energy. The biomass boiler system is generating NH Class 1 Thermal RECs which reduces heating costs down to $6.25 per MMBTU. The absorption cooling system is 10% less costly to operate than the standard electrically powered chillers. A large solar array is now on the roof of the new addition, with a capacity of 71 kilowatts, installed by Revision Energy.

Residents of Peterborough are excited about their new library building. The innovations within it set a good example with its energy efficiency and use of renewables. At the last town meeting residents approved a resolution that set the goal to have 100% renewable electricity for all by 2030 and 100% renewable heating, cooling and transportation by 2050.

Jim Van Valkenburgh is the Vice President of Marketing at Froling Energy.

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