Post Occupancy Evaluation for Green Buildings

May 9, 2010

GreenHomeNYC volunteer Brian Rahm reports from an evening event organized by New York Academy of Sciences, about post-occupancy evaluation in green buildings.

On Thursday, April 15th, The New York Academy of Sciences (NYAS) hosted the third event in its four part series entitled “Green Building Solutions: What’s Working?” The series consists of presentations and updates from leading architects, building researchers, city and national policy makers, and developers. The third installment was a discussion on Post Occupancy Evaluation (POE) and served to highlight and explore the crucial and often problematic transition between building design and construction, and building occupancy, operation and management.

If there was a take home message from the evening, it was that building performance is as much a function of operation and occupancy behavior as it is a function of clever and sustainably savvy design. This is an important lesson for those who look to technology and green design as the answer for improving building performance both in terms of energy efficiency and reduced resource use. When buildings are not used as they were designed, or when design fails to properly consider the practical needs of operating staff and occupants, performance will suffer.

As a solution to the disconnect between designers and operators, the panelists suggested incentivizing design-side professionals to stay associated with the buildings they construct in order to help ensure that operators understand building systems and the conditions they were (and were not) designed to handle. On the other hand, it was suggested that operating staff and building managers be brought into projects prior to construction completion to better understand the building. All panelists agreed that it is difficult to generate sustained and meaningful dialogue between designers and operators given the practical delineations of each field. These problems are compounded when tenants and building owners do not share similar expectations about how a building should function, or when ownership changes hands. Continuous commissioning was also brought up as a possible solution, but again requires the support of building owners, operating staff, and tenants.

One of the more interesting themes of the evening was the concept of attracting and retaining dedicated and skilled operating and management staff. In particular, career advancement opportunities for operating staff was mentioned as a way to incentivize and retain professionals who have a close working knowledge of the building(s) they are in charge of managing. Green building in general was also cited as a strategy for attracting skilled young professionals who value principles of sustainability.

The night’s panelists represented a diverse set of professions and perspectives. Here’s a sampling:

Steffan Plesser is head of the Energy Efficient Non-Residential Buildings Group at the Institute for Energy Design and Building Services at Technical University, Braunschweig, Germany. Steffan’s comments centered largely on building issues in Germany and provided an academic perspective that differed somewhat from the other panelists. Although his statements were not strictly applicable to buildings in NYC, his key talking points provide food for thought on the green building movement in general. Key points:

  • Mandatory codes in Germany continue to be more stringent with respect to energy efficient insulation and building envelope design. And, while this is having a positive effect on building performance, Steffan warns that gains come at the price of increased design complexity and engineering effort and documentation.
  • In turn, this increasing complexity and interconnection of building systems makes operation of buildings more challenging.
  • Buildings continue to fail to meet their design targets, and calculated energy use of completed buildings is often significantly different from the actual energy use based on POE.

Donald J. Winston, PE is Vice President, Technical Services at The Durst Organization here in NYC and helps to oversee a portfolio of Class A commercial and high-end residential buildings. Key points:

  • An analysis of the Durst portfolio of buildings indicates that building usage is likely more important than building age regarding POE energy usage, a surprising finding that highlights the importance of tenant behavior in achieving high performance buildings.
  • Don points out that buildings are often overdesigned in order to meet maximum loads, but then perform poorly when run under normal loads.
  • The metrics used during the building design and energy audit stages are not always accurate or of sufficient detail to properly model actual building performance. Don suggests exploring the use of metrics that are more closely associated with occupant density and use, rather than relying on metrics associated solely with physical building characteristics (such as square footage).
  • When there is a discrepancy between the design of a building and the way it is operated, Don suggests that the operator will always “win” in the sense that operational staff will inevitably run the building in whatever way suits them, or however they can best meet the demands of building tenants.

Brian Schwagerl is the Director of Corporate Real Estate and Facilities Planning for the Hearst Corporation. Key point:

  • Sharing of POE building information is one of the best ways to ensure that the industry as a whole moves in a positive direction.
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