Benchmarking Performance Assessment for Small-Commercial Buildings

A benchmarking report for small commercial buildings was completed in August, 2002. It specifically examines billing data from public schools in one school district near San Francisco. The district includes thirty-nine elementary schools, five middle schools, and five high schools. Alternative and special education schools are not considered in the study.

The following table provides a summary of the basic school characteristic statistics:

Energy consumption analysis for the schools was performed for two sources of energy in the schools, natural gas and electricity, and their combined total in terms of absolute annual values (energy/year) as well as in relative terms (energy/area and energy/student). Additionally, the ENERGY STAR® For Schools benchmarking tools developed by the Environmental Protection Agency (EPA) and the US Department of Energy (DOE) and available on the World Wide Web (http://www.energystar.gov) were used to rate the schools in order to compare the results of the energy analysis performed on the school data.

The following graph plots the energy use per student, ENERGY STAR score (0 to 100 rank) and kBtu/sf energy use intensity (EUI):

Non-Intrusive Load Monitoring machines (NILM) were installed at two schools in the same school district. The NILM machines record electrical power consumption at the supply point of an electrical distribution panel. Two NILM machines were installed at each school, one monitoring whole school electricity consumption, and the other monitoring the electricity consumption at a secondary electrical distribution panel serving a group of classrooms from the schools. The NILM machines are accessed remotely via the Internet. Commercially available power metering and logging systems were also installed at the schools to provide parallel sub-metering of the monitored distribution panels in order to validate the observations made using the NILM machines.

Benchmarking of the energy consumption of the schools was performed using multiple indicators of energy and cost efficiency. As mention earlier, absolute and relative indicators were used. Absolute indicators were annual energy and consumption and cost for gas and electricity. The relative indicators were cost and energy consumption per unit of reference (student population and building area) as well as energy intensities and densities per hours of operation of the schools. A ranking index was defined using the benchmarking results obtained using the various indicators in order to present the benchmarking results using a single figure.

The benchmarking results helped identify the schools that would benefit the most from applying energy saving measures. These energy saving measures could range from simple building user education and equipment scheduling changes to equipment retrofits and building modifications.

Requests for a copy of this Benchmarking Report can be submitted to Mary Ann Piette, Lawrence Berkeley National Laboratory (LBNL).

Contact: Les Norford, Massachusetts Institute of Technology (MIT)