Despite a growing preoccupation among the general public with all things green and an industrywide awareness about the built environment's role in the depletion of natural resources, there is little available information about how buildings designed with sustainability in mind actually perform. Once the construction trailer is taken away, and the owner settles in, architects seldom systematically review a completed project to understand if it met its design objectives, if the occupants are comfortable and productive, or if it conserves energy and water.

One rarely used but potentially powerful tool for gathering such information is a postoccupancy evaluation, or POE. Though there is no standard definition of the process, a POE can consist of an analysis of resource consumption, an assessment of physical conditions such as lighting levels or acoustics, and an occupant survey or interview. A variety of other names are often used to refer to such a study, including environmental-design evaluation, building-in-use assessment, and facility- performance evaluation, but POE is the most common term.

No matter what term is used, advocates of the practice say that widespread adoption of such studies, and sharing of the resulting information, would help advance sustainable design because the evaluation can help identify strategies that work best, those that need refinement, and those that should not be repeated on future projects. Although designers might worry about the liability associated with an unsuccessful aspect of a project exposed during a POE, sources are reassuring: "Architects get nervous being held accountable," says Craig Zimring, an environmental psychologist and a professor in the College of Architecture, at the Georgia Institute of Technology, Atlanta. "However, I don't know of a single instance where a POE resulted in a lawsuit, but I know of many instances where a POE helped avoid one," he says.

At the Global Ecology Center, radiant slabs and air-to-air heat exchangers reduce the energy needed to condition ventilation in the largely daylit labs. Photo © Peter Aaron/Esto

In fact, the involvement with a project after its completion that is necessarily required for a POE can help enhance the rapport between architects and owners, sources point out. "The process strengthened our relationship with our clients," says Sandy Mendler, AIA, senior design principal in HOK's San Francisco office. The firm recently conducted POEs on several of its green buildings.

The spider graph shows the percentage of satisfied Global Ecology Center occupants. Graph courtesy Center for the Built Environment

One of the most important steps in the POE process is obtaining occupant feedback. Though their opinions about physical characteristics such as indoor air quality, privacy, and lighting are by nature subjective, they are nevertheless essential to understanding how well a building performs. "If we were only concerned about energy use, we could easily achieve 2030," says Max Richter, an intern architect in the Vancouver office of Stantec, referring to the 2030 Challenge, the goal for carbon-neutral buildings set out by Santa Fe, New Mexico architect Ed Mazria and adopted by several key industry organizations. However, occupants would likely be uncomfortable if lighting levels were lowered and thermostats adjusted, points out Richter, who is involved in a POE of one of the Stantec's projects.