Testing a Building's Energy Efficiency
Most buildings in the U.S. don’t perform as energy-efficiently as they could simply because energy-using equipment in the building have never been set up to maximize energy performance. Thermostat setpoints are too low or too high, so rooftop units (RTUs) cool buildings down below recommended temperatures, or keep them too warm (or both). Or, there is no difference in the setpoint during hours when the building is unoccupied versus occupied—turning the heat and space conditioning down during unoccupied hours helps lower energy bills substantially. Lights may be left on at night when no one is in the building, or there may be daytime opportunities in spaces that are not continuously occupied.
These are only a few of the problems that energy performance professionals see in the field, problems they can correct through retrocommissioning—the process of assessing the energy performance of an existing building, and then tuning its systems, and implementing no or low-cost energy efficiency improvements. When this is done to a new building, it is called commissioning. Research published in 2009 by scientists at Lawrence Berkeley National Laboratory (Berkeley Lab), demonstrated that in a large sample of existing buildings, retrocommissioning could save as much as 15 percent of a building’s annual energy use, and pay for itself in less than a year, through the resulting utility cost savings.
In large commercial buildings, where the cost-effectiveness of this process is highest, retrocommissioning is beginning to become more common, thanks to growing awareness of its economic benefits to building owners and operators, as well as a thriving industry of building energy performance professionals.
In smaller commercial buildings efficiency efforts, including retrocommissioning have been hampered by several factors. “Small commercial buildings do not typically have budget or business economics that allow investing in enhancements such as comfort and energy improvements,” says Jessica Granderson, a scientist in the Environmental Energy Technologies Division of Berkeley Lab. “They also don’t have in-house staff with the expertise in building systems who can perform retrocommissioning or identify improvement opportunities.”
Granderson, the Deputy Leader of EETD’s Building Technologies and Urban Systems Department, is working with Michael Brambley of Pacific Northwest National Laboratory to develop a technological solution: the Retrocommissioning Sensor Suitcase.
“The Suitcase,” she says, “is a turn-key hardware and software solution that non-experts can use to generate low or no-cost recommendations automatically on how to improve a building’s operating costs, comfort and energy performance.” The project is funded by the Department of Energy’s Office of Energy Efficiency and Renewable Energy, Building Technologies Office.
"The Retro-commissioning Suitcase project is a DOE funded project to reduce the cost of delivering cost effective, energy savings retro-commissioning services to small and medium sized buildings,” says George Hernandez, Chief Engineer, Building Technologies Office in the Department of Energy. This project is accomplished by 'embedding' the knowledge and skills of a highly experienced building commissioning practitioner into a scalable hardware and software package that can be easily deployed by a variety of building services personnel to make it easier for building owners and operators reap the benefits and cost savings for building commissioning."