Architects and engineers strive to create energy-efficient buildings by controlling physical features like insulation, windows, and HVAC systems. To deliver great energy performance in buildings, however, building operations and occupant behavior have to be addressed, and the policy and technological tools to do that are just starting to emerge.
Illustration by Gavin Potenza
New Buildings Institute and Ecotope, Inc., recently analyzed the relative energy impact of a series of typical design features, compared to a set of operations and maintenance practices and occupant habits also affecting building energy use. We found that the impact on building energy use from poor (but not atypical) operations and maintenance practices can increase energy use by more than 50 percent in some climates. Occupant behavior can increase energy use by a whopping 80 percent over the predicted use based on anticipated behavior during the design process. In most cases, the magnitude of these ranges is larger than the total savings impact of all the physical efficiency features of the building.
Post-construction impacts are, by nature, more likely to fall short from the anticipated outcome than to improve it, because the design community, energy modelers, and energy code all tend to work from a best-case scenario when imagining maintenance and occupant activities. It's no surprise that owners and occupants play a major role in building energy use, and that these actions take place outside the control or influence of the design team. Now we have data that shows just how significant that energy use is.
As the role of post-construction characteristics becomes more widely recognized in the marketplace, there are likely to be significant changes to design practice, and to building codes and incentive programs. The design community will have to more effectively communicate the role of operations and occupants in building performance, and features such as better metering and feedback systems will become design imperatives. The study also has significant implications for the practice of energy modeling, which struggles to predict building energy use—a situation that will change if the energy modeler can get a realistic picture of how the building will really be used and maintained. In addition, we have to recognize that the aggressive goals we have set for energy codes will be impossible to meet without directly addressing post-construction energy-use patterns, which have so far been well outside the scope of code language and enforcement procedures. In response, codes will evolve not only to include more features that allow for better building operation, like commissioning, metering, and feedback systems, but may also start to incorporate energy-performance outcome targets into the code-enforcement process.
Perhaps nothing will more effectively drive the recognition of the role of building operations and occupants in building energy use than the proliferation of the disclosure ordinances now being adopted around the country. These ordinances will bring a much more intense, market-based focus on the issues really driving building energy performance. In the meantime, the findings of this study can help the building community begin to align their priorities with those building features and operational characteristics that have the most impact on building energy-use outcome.