DOE's Commercial Building Benchmarks: Development of Typical Construction Practices for Building Envelope and Mechanical Systems from the 2003 Commercial Building Energy Consumption Survey

The U.S. Department of Energy (DOE) developed a series of prototypical commercial building models in 2007. These models, referred to as DOE Benchmarks, are intended for both internal DOE use in tracking progress toward zero-energy buildings and for external use by other stakeholders in the commercial buildings sector. These models are currently being used in the development of new requirements in building codes and standards, for tracking progress of building codes and standards, and to provide guidance to states contemplating adoption of new building codes and standards. One important aspect of the DOE Benchmarks is that they attempt to replicate “typical” construction practices. With regard to “typical” construction practice in building envelope and mechanical systems, the primary source of information analyzed was the 2003 Commercial Building Energy Consumption Survey (CBECS). The 2003 CBECS provides considerable information related to the appearance of the building envelope, but relatively little in terms of how the building envelope is constructed. The 2003 CBECS also provides limited data on building shapes and ranges (rather than actual) of window-to-wall area values for buildings. CBECS also provides detailed information on building mechanical systems that can be used directly in the Benchmarks, but only after careful consideration of the diversity of systems used in commercial buildings. This paper discusses the analysis of the 2003 CBECS dataset in determining “typical” construction practice in commercial buildings. Background In 2005, the U.S. Department of Energy (DOE) began creating a series of commercial building prototypes called Commercial Benchmarks that were intended for use in tracking the progress of all commercial programs in DOE’s Building Technologies program. These Benchmarks were intended to provide a consistent set of building prototypes that could be used to evaluate the effectiveness of DOE’s research and development activities as well as provide the basis for proposing new activities. DOE has developed a set of standard Benchmark building descriptions for both new construction and for existing buildings (representing both pre-1980 and post-1980 building stock). These are a complete revision of the DOE Benchmark buildings originally developed in 2006, with building shape, thermal zoning, and operation of the models more indicative of real buildings than those provided in the initial 2006 Benchmark buildings. The development of these commercial Benchmarks was conducted by staff from three of DOE’s national laboratories—Lawrence Berkeley National Laboratory (LBNL), National Renewable Energy Laboratory (NREL), and Pacific Northwest National Laboratory (PNNL). The Benchmarks are being developed in DOE’s EnergyPlus simulation tool and are accompanied by documentation of each Benchmark building in the form of spreadsheet “scorecards” that provide descriptions, parameter values, and source data for all parts of the simulation model. This paper deals solely with choosing the building envelope and building