Students who are hot under the collar about the temperature of their rooms can stop steaming: as of Columbus Day, Harvard's heat will be running on a computer-controlled thermostat. And until that date, a phone call to the "Hotline" can lead to those few keypresses that make the steam flow and fingers thaw.

Heat in the buildings is provided by three underground steam mains in a tunnel called the "Mill Street Header," which are activated by October 1 each year. A computerized valve system regulates the supply of steam to each building, and can be turned on or off from a terminal at the Facilities Maintenance Department. Until October 12, department members flip switches based on students' calls; after this date, a computer controls the heat automatically.

If the indoor temperature is at or below 68 degrees Farenheit, state and federal regulations require Harvard to heat the buildings. To monitor the temperature, the computer is connected to a network of temperature sensors called "space sensors" located both inside and outside Harvard's buildings.

When the system switches into automatic mode on Columbus Day, the computer calculates a composite temperature from space sensor readings and switches the steam valves accordingly. Facilities Maintenance estimates that 85 percent of the University is controlled by this system. The remaining buildings--mostly offices--run on their own thermostats.

Before October 12, though, the decision to heat each building is made automatically. Students who find they need to wear three layers inside their rooms can call Harvard's Heating "Hotline"