Open-Window Policy at Colorado College is a Breath of Fresh Air

NWF | November 14, 2008

At Colorado College, a private liberal arts institution in downtown Colorado Springs, academic study follows “the Block Plan.” Students pursue single subjects in full-time, three-week blocks, not multiple subjects in traditional 14-week semesters. The intensive scheduling promotes active student participation, the college says.

Active participation is also designed into the Russell T. Tutt Science Center, a LEED-certified building that opened in 2004. In fact, one particular feature harkens back to the college’s 19^th century origins-windows that people can open and close.

“We encourage people to open the windows,” said Jim Cain, manager of technical services at the college. Many days per year, Colorado’s climate is conducive to natural ventilation. While occupants of some modern buildings can only wish for fresh air, due to efficiency and energy concerns, students in the Tutt building can crank the casement-style windows wide open.

What makes it practical is a decidedly low-tech means of sensing open windows. The idea emerged with help from a security-systems vendor. A set of magnetic contacts (essentially a burglar-alarm sensor) is installed at each window. When it’s opened more than an inch or so, the HVAC system shuts down to avoid wasting energy.

So occupants are free to regulate their own comfort. They just can’t waste heating or cooling energy in the process, explained Stan Rovira, a staff technical project manager.

Two more modern buildings on campus now have the technology, but dorms and residence halls on the 134-year-old campus aren’t so well equipped. “Sometimes you’re walking around on campus in the middle of winter and you see windows wide open. It kills you to think the heat is running to keep up with it,” said Rovira.

A key aspect of the system is modern zone control, said campus architect Carl Brandenburg: “A basic problem in any air-conditioned building is that opening a window not only wastes energy. It throws the whole balance of the building off,” he said.

In the Tutt building, each of the eight classrooms and approximately 25 offices functions individually. An open window in one room affects only that room. Temperatures are controlled with heated and chilled water circulating from a central campus plant. Further climate control is done in the building with variable-speed fan drives blowing past coils of heated or cooled water.

The desire for fresh air in office buildings has long frustrated architects, said Brandenburg. In big high-rise buildings, it’s not practical because zone control isn’t sufficiently localized. Opening a window might throw off HVAC operation in a large portion of the building.

But one California high-rise building is operating effectively with opening windows. The San Francisco Federal Building, opened in 2007, is 70 percent naturally ventilated, according to a study by the Rocky Mountain Institute. The system saved $11 million in construction costs and is projected to cut HVAC costs by $500,000 per year.

“If natural ventilation is on the rise, no statistical evidence of it exists at the U.S. Green Building Council,” said Melissa Gallagher-Rogers, manager of government sectors. But anecdotes abound. In the offices of the Virginia-based Chesapeake Bay Foundation, people are urged by remote-controlled signs on the wall to open or close the windows.

Colorado College has considered using the sensor-equipped windows at the Tutt building to generate automatic email messages in response to changing weather. When outside temperatures drop, for example, security personnel could be instructed to close any open windows. Faculty members using the room could be copied via email as a means to encourage their active involvement. So far, no such policy has been implemented.

College campuses are often the proving grounds for ideas such as the Colorado system, said Gallagher-Rogers. They’re a great place to find out what’s possible.”