Postoccupancy Evaluation

One of the key principles in sustainable design is to have a feedback loop, a process that helps organizations and individuals to learn from their decisions and to make better choices in the future. The key feedback loop in green building design is called post-occupancy evaluations (POE), in which someone goes back after a building has been completed to see if energy and water use are meeting projections, whether the indoor air quality is as predicted, whether the building operators are running the monitoring and control systems properly and so on. A key element in a POE is a survey of occupant comfort because so much of the resulting productivity gains expected from green buildings have to do with daylighting, lighting, ventilation quality and thermal comfort.

Developed in England, POEs have been slow to catch on in the US, primarily because no one has provided a budget for such work, and because most of the design and construction team has moved on to other projects. So it's left to the building operators and managers, many of whom might be under contract to the building owner, to make the building work.

In some ways the lack of interest in POEs represents a huge black eye for both architects and engineers. For architects, it indicates a lack of professional interest in how their designs actually work for the people in the building, beyond perhaps a few anecdotes. This may be because user groups are typically not well incorporated into the design process and have little input into important design decisions that affect the future occupancy of the building. Beyond commissioning the building at the end of construction, engineers seldom return to assess results. Perhaps it's because they are afraid of getting sued for buildings that don't perform as designed. If green buildings are to realize their full potential, there has to be money in every building budget to assess results and feedback to future designs.

A recent example of a successful POE was performed for Portland State University's (PSU) Stephen E. Epler Hall, a 130-unit dormitory that was awarded a LEED Silver designation in 2003. A master's degree candidate at PSU, Cathy Turner, did a POE for this project. The result evoked widespread interest in the Pacific Northwest in performing a similar assessment for other projects.123 If one thinks about it, there are hundreds of graduate students in various sustainability-oriented degree programs who would welcome the task of performing POEs on behalf of building owners and project design and construction teams. All that's needed is a little funding for their time and a solid connection to their degree programs.

A study by the Center for the Built Environment at the University of California, Berkeley, compared 21 LEED-certified and other green buildings with more than 160 conventional buildings. The responses to more than 33,000 questionnaires showed that green buildings had higher occupant satisfaction overall (statistically significant difference) and specifically higher satisfaction with indoor air quality (average satisfaction in

80th percentile of users surveyed) and thermal comfort (average satisfaction in the 90th percentile).124 This demonstrates the value of green building design properly executed to generate two key benefits: human health and worker productivity.

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