Anthony R. Florita 1 e-mail: anthony.florita@nrel.gov Larry J. Brackney Electricity, Resources, and Building Systems Integration Center, National Renewable Energy Laboratory, Golden, CO 80401 Todd P. Otanicar Department of Mechanical Engineering, The University of Tulsa, Tulsa, OK 74104 Jeffrey Robertson Department of Mechanical Engineering, Loyola Marymount University, Los Angeles, CA 90045 Classification of Commercial Building Electrical Demand Profiles for Energy Storage Applications Commercial buildings have a significant impact on energy and the environment, being re- sponsible for more than 18% of the annual primary energy consumption in the United States. Analyzing their electrical demand profiles is necessary for the assessment of supply-demand interactions and potential; of particular importance are supply- or demand-side energy storage assets and the value they bring to various stakeholders in the smart grid context. This research developed and applied unsupervised classification of commercial buildings according to their electrical demand profile. A Department of Energy (DOE) database was employed, containing electrical demand profiles represent- ing the United States commercial building stock as detailed in the 2003 Commercial Buildings Consumption Survey (CBECS) and as modeled in the EnergyPlus building energy simulation tool. The essence of the approach was: (1) discrete wavelet transfor- mation of the electrical demand profiles, (2) energy and entropy feature extraction (abso- lute and relative) from the wavelet levels at definitive time frames, and (3) Bayesian probabilistic hierarchical clustering of the features to classify the buildings in terms of similar patterns of electrical demand. The process yielded a categorized and more man- ageable set of representative electrical demand profiles, inference of the characteristics influencing supply-demand interactions, and a test bed for quantifying the impact of applying energy storage technologies. [DOI: 10.1115/1.4024029] Introduction Progress has been made in the awareness and implementation of renewable energy systems in a movement toward a sustainable and clean energy future. However, a large opportunity exists for energy efficiency from an integrated, systems engineering per- spective. Commercial buildings in particular can benefit from enhanced interactions with the electrical grid; commonly research interest lies in the optimization of indoor environmental quality or single building energy/cost performance. Recognizing that energy efficiency extends beyond building-site boundaries, building oper- ators can work with utilities and/or third-parties to use the build- ing as an asset in various forms of load shifting. Largely neglected in many building-as-an-island performance analyses, such research and demonstration projects are scarce but necessary in growth toward the smart grid. With commercial buildings being responsible for more than 18% of the annual primary energy consumption in the United States, there are opportunities for various stakeholders to benefit. The appropriate incentive signaling will trigger their active partic- ipation in whole-system efficiency and allow utilities to defer cap- ital investments while maintaining operational predictability. Quantifying the shared value among stakeholders is a crucial missing element. Concerns have also been voiced about uncertain- ties in securing the raw energy resources needed to maintain “business as usual,” energy conversion emissions leading to harm- ful environmental impacts, and the intelligent dispatch of renew- able energy technologies within the energy infrastructure. Energy storage has been identified as a vital yet largely neglected support for bridging many engineered systems that are orchestrated and optimized for multiple objectives. Proper and cost-effective energy storage can be building or utility scale. Con- founding the issue is the increased adoption of on-site renewable generation equipment in commercial buildings, such as photovol- taic (PV) panels or wind turbines, because the building acts as both a generator and consumer of electricity. Furthermore, higher levels of renewable penetration with intermittent generation ag- gravate whole-system instability because supply is not well matched to demand. Thus, understanding whole-system interac- tions and mobilizing energy storage for superior dispatch of gen- eration equipment are both essential. Ongoing research seeks a greater functional understanding between commercial buildings and the electrical grid. Literature Review With focus placed on commercial buildings as an asset for whole-system energy efficiency within the larger electrical grid context, the examination of literature followed suit. The natural shared value in this supply-demand system can be expressed in monetary terms. By placing the true value (cost) of unit energy conversion on unit energy pricing the utilities incentivize demand response. With proactive energy management this saves consum- ers utility costs and generators inefficient expenditures. A number of building-related studies addressed these points in various forms. Investigations of building thermal energy storage have mostly focused on thermal mass control and chilled water or ice storage. Electrochemical storage can also be helpful for renewable technologies and load shifting applications, but due to its rela- tively high cost current applications are in their infancy. Thermal mass control harnesses the inherent thermal capaci- tance of the building for load shifting through supervisory control of zone temperature set points and existing heating/cooling equip- ment. Lee and Braun [1] experimentally evaluated various strat- egies for a five-hour demand-limiting period; reductions in peak 1 Corresponding author. Contributed by Solar Energy Division of ASME for publication in the JOURNAL OF SOLAR ENERGY ENGINEERING. Manuscript received July 27, 2012; final manuscript received January 31, 2013; published online June 11, 2013. Assoc. Editor: Gregor P. Henze. Journal of Solar Energy Engineering AUGUST 2013, Vol. 135 / 031020-1 Copyright V C 2013 by ASME Downloaded From: http://solarenergyengineering.asmedigitalcollection.asme.org/ on 03/03/2015 Terms of Use: http://asme.org/terms