Over 10,000 calls are placed to University Operations Center each year from disgruntled students complaining about the temperature of their rooms, but very few students actually know how Harvard buildings, are heated, or in very rare cases, cooled.

Here, The Crimson brings you an exclusive, behind-the-scenes look of thermodynamics at Harvard.

According to Harry A. Hawkes, director of engineering and utilities, Harvard uses "district heating," which delivers steam from the Blackstone Station power plant in Cambridge through tunnels and buried lines to multiple buildings on campus.

The plant is located at the intersection of Memorial Drive, Western Avenue and Blackstone Street and is owned and operated by the Commonwealth Energy System (COM/Energy)

"Commonwealth Energy makes steam and we buy it from them," Hawkes says. "The steam travels in underground tunnels and across the river to serve different buildings at Harvard. There are about three-and-a-half miles of tunnels extending from the Blackstone power station along Memorial Drive and north to the Law School and through the Weeks Memorial foot bridge to the Business School."

Approximately 200 University buildings are currently heated with steam although only Radcliffe and the Quadrangle have their own boiler rooms, says Hawkes.

Steam is an older method of heating that Harvard has used since the 1920s, but the College is by no means the only institution to maintain this seasoned process. According to Morris A. Pierce, district energy historian and energy manager for the University of Rochester, a recent census by the Department of Energy found more than 30,000 district heating systems in the United States and thousands more worldwide.

"This method of heating is used in various parts of the country, but mostly in Europe," Hawkes says. Chief Engineer Paul A. Parziale adds, "Harvard is the plant's biggest customer. We're a small co-generating plant. We produce electricity and steam, [and] the steam mostly goes to Harvard."

The Logistics of Heating

A co-generation plant produces both heat and power from one thermodynamic process.

Hawkes says that the plant produces steam at high pressure, runs it though turbines to create electricity and then distributes the lower pressure steam to be used for heating.

The small plant has four boilers that operate at over 400 pounds per square inch steam pressure each.

To produce steam and electricity, the plant burns natural gas or number six fuel oil, which is a residual oil, according to Parziale. He adds that the emission stacks are monitored 24 hours a day "to ensure environmental safety."

Harvard buys the steam from COM/Energy at high pressure and converts it to lower pressure through regulating valves in the tunnels.

"We buy it at 100 pounds per square inch from the plant, but the pressure is under 12 pounds when it enters the building," Hawkes says.