The importance of Post-Occupancy Evaluation (POE)
Do buildings designed for high performance function as intended? Do energy savings, improved occupants’ productivity and comfort materialize as promised? Green buildings offer a lot of benefits, but building owners and tenants increasingly want proof that these benefits are actually achieved.
This is where post-occupancy evaluation (POE) comes in. The objective of POE is to learn whether the building is performing as designed and whether it meets the occupants’ needs as intended.
POE originated in the 1960s, as a part of a movement to apply scientific approach to architecture and to explore the new-found connection between behavioral sciences and design. Designers saw POE as a tool to test their hypotheses as they tried to use design to change people’s behavior and relationship with the built environment. It was used to evaluate building systems as well as occupants’ responses to those systems. After the peak of popularity in the 1970s and early ’80s, the use of POE declined, until the sustainability movement reclaimed it. Today, building owners rather than building designers are driving POE. For a building owner it is one thing to read in a study that green buildings on average perform 25-30% better, or that they command higher rents and occupancy rates, but it is another to be able to verify that their own building does so.
At the same time, growing popularity of building ratings, as well as the increase in local and state disclosure ordinances requiring building owners to publicly disclose actual energy consumption, makes POE almost a necessity.
This means that there will be pressure on building designers to incorporate features that will allow building owners to operate the building to design specifications. Buildings will need to have feedback systems to help facility managers and occupants understand how their choices affect the building’s performance. In this task, “smart” buildings have an enormous potential, as they can use the data they are constantly generating to engage users’ by providing real-time, visually appealing and easy to understand performance feedback via dashboards.
The classic POE involves surveys, targeted interviews, focus groups, and direct observation of the building and its occupants.
POE of the occupants’ comfort typically focuses on the work environment, elements such as lighting, acoustics, thermal comfort, privacy, and convenience. POE of the building performance, also called “building performance evaluation”, focuses on energy and water use, and even financial performance. In “smart” buildings, POE will include quantitative testing and measurements of building conditions, such as illuminance and temperature. Depending on the interests and needs of the building owner, other sources of information, such as utility bills, maintenance records, and financial statements, might also be analyzed.
POE can range from one person walking through with a notepad and doing some interviews, to a team of environmental psychologists, sociologists, cultural anthropologists, architects, and engineers collecting data and conducting in-depth focus groups and extensive surveys.
Usually, POE is undertaken after the building systems are commissioned and fine-tuned so that occupant reactions are not distracted by technical problems with equipment. However, it might also be beneficial to use POE-style occupant surveys as a part of a commissioning process.
LEED and POE
Green and high-performance buildings are especially good candidates for POE, as it allows to document the results of using innovative technologies and materials that might so far have limited or no track record.
POE creates hard evidence that green building advocates can use to make their case to skeptical clients, owners, investors, or tenants. With data on the table, the conversations evolves from the argument that “this is the right thing to do” to using facts to demonstrate how green design meets clients’ financial or other critical interests.
POE is an important tool for supporting the LEED rating system. Many of LEED requirements are normative, that is, they are based on theory, but largely haven’t yet been validated by practice. There is a lot of interest in seeing whether LEED-certified and other green buildings really deliver on their promises.
The 2012 update to LEED has a newly created “Performance” category which includes two LEED credits: “Reconcile Projected and Actual Energy Performance” and “Occupant Experience Survey”. This development shows that, as the green building market matures, LEED guidelines adjust accordingly. LEED seeks to serve both the energy reduction goals and occupants’ comfort and wellbeing. In this, POE has become a valuable tool which allows to measure satisfaction and integrate occupant comfort with energy performance.
The rating system that is currently best suited to incorporate POE is LEED for Existing Building Operations and Maintenance (LEED-EBOM)
LEED-EBOM (Existing Buildings – Operations and Maintenance)
LEED-EBOM is the fastest growing of the LEED Rating System. It sets performance standards for the operation of existing buildings that are not undergoing major renovations. It is different from the other LEED rating systems in that it documents the actual building performance, rather than an estimated performance based on design.
The first time the building goes through the certification is called the initial certification. The initial certification happens in two phases:
- Establishment period – assess the building, do cost-benefit analysis, select credits to pursue
- Performance Period (PP) – implement new policies and building changes, as well as track ongoing building performance.
All buildings, even those that were LEED-certified for Design and Construction, must go through the initial certification.
A successful LEED-EBOM certification requires a collaboration from a variety of stakeholders: building owners, property and facility managers, general contractors, vendors and tenants. This team will set up policies, procedures and targets to achieve for the certification. This process is normally facilitated by a LEED AP specializing in EBOM.
LEED-EBOM is also the only LEED rating system that requires re-certification. Re-certification verifies that the building has been operated and maintained in accordance with the standards achieved during the initial certification, or, ideally, that its performance has improved over time. Buildings must get re-certified at least every 5 years, although more frequent re-certification is encouraged. Once a building receives the initial EBOM certification, the re-certification process begins. There is no fee to re-certify, and it should be fairly easy, since all the policies and procedures are already in place. During the re-certification, a building performance evaluation is conducted in the form of audits, surveys and testing to track the on-going performance of policies established during the initial certification. This evaluation may open up the opportunity to increase the building’s certification level.
Looking into the future: LEED and POE
Benefits of POE work well with the priorities of green buildings. In the short term, POE can suggest adjustments to improve performance and occupants’ experience. In the long term, designers and their clients can use the feedback to improve the design of subsequent projects.
As the performance evaluation tools are perfected and commoditized, they will inevitably become more widely used. When they are more widely used, the great flow of information will serve to improve our understanding of how buildings work. Incorporating POE into LEED will help to ascertain that our buildings are serving their intended functions. Shouldn’t that be a prerequisite for green buildings?