November Special Focus: Energy Efficiency, Buildings and the Electric Grid
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."
The turnkey under development in this joint Berkeley Lab-PNNL project contains a set of different types of portable, easy-to-install building sensors, a handheld smart pad for documenting the location, placement and sensor type, a battery, and a data control module that can receive and pre-process data from the sensors, which are distributed throughout the building. The data module communicates wirelessly with the smart pad, which launches sensors during their installation. (See Figure 1.)
The Retrocommissioning Sensor Suitcase is targeted for use in small commercial buildings of less than 50,000 square feet of floor space that regularly receive basic services such as maintenance and repair, but don't have in-house energy management staff or buildings experts. The hardware kit is designed to be easy-to-use by building maintenance staff, or other professionals such as telecom and alarm technicians. The sensors in the suitcase include those for lighting, vibration (for measuring the condition of rooftop units), and various types of temperature sensors for internal and external areas of the building. (See Figure 2 - sensor platform prototype.)
In addition to the hardware kit, the turnkey comprises a software application to collect, process, store, and analyze the data. The kit's user, or a third party such as an energy performance contractor can use this software to generate specific recommendations on what actions to take to reduce the building's energy cost, and improve comfort.
"The Suitcase's user would walk through the building, installing the sensors based on guidance from the hand-held," says Granderson. "Simple instructions make it easy for the user to configure the sensors and document their type, and location using the smart pad."
After a month or so of automatic data collection, the user returns and collects the sensors, plugging them into sockets in the suitcase to download their data. (See figure 3.) Entering other basic information into the suitcase's computer, like energy consumption and costs from the building's electricity bill, allows the software to generate recommendations on how to improve the building's performance, and how much energy could be saved by each measure. It's then up to the building's owner or operator to decide which measures to implement.
"Where we are now is that the proof of concept prototype is complete. We're entering into a second phase of work to test the prototype in the field, and improve it based on what we learn." says Granderson. The development team plans to make the hardware and software design available in the public domain, for transfer of the technology to partners who will move it into the marketplace.
This research is funded by the Department of Energy's Office of Energy Efficiency and Renewable Energy.