Controllability of Systems

Another aspect of comfort is the degree of control you have over your surroundings, particularly lighting, air flow and temperature. Underfloor air systems combined with task lighting tend to provide the highest levels of control, and there are even systems that take advantage of this fact to craft personal environments that allow users to control ambient noise levels, along with these three variables.

Buildings with operable windows can also provide user control, which heightens perceived comfort. Mechanical engineers tend to strongly dislike operable windows, because they make it difficult to control air pressures and require more zones on each floor. Of course, building HVAC systems need to be shut off in zones where the windows are open. In tall buildings, a strong wind can come in the upper-floor windows, so occupants must keep papers and other belongings from blowing around. In North America we are just beginning to see operable windows. In many European countries accustomed to letting nature provide the comfort, they are commonplace.

In 2002 I visited a new green building, the Telenor headquarters in Oslo, owned by Norway's state-owned telephone company. There employees work in 30-person task groups under one manager. When I asked who determines when to open the windows, the tour leader answered, "The manager." In the US I'd wager it would be easier and less contentious to have these decisions made impersonally by the building automation, instead of by a manager.

An early LEED Platinum-rated building, the Chesapeake Bay Foundation offices in Annapolis, Maryland, provided one way to solve this prob-

Johnson Controls Personal Environments allow user control of key comfort variables.

lem. When I visited this building in 2001, I was curious about the operable windows. I found that the designers had made the decision impersonal: whenever temperature and humidity conditions were favorable, a green light came on, and the 40 or so occupants rushed to the windows to open them. The Foundation was an environmental non profit, so you might think that they wanted to be more involved with the building and more in touch with the outdoors, but I don't think they are at all unique. A developer in Portland told me that a prime selling point for a new LEED-certified office space, leased to a major law firm, was that it had operable windows.

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