Commercial Building Energy Saver: An Energy Retrofit Analysis Toolkit

Commercial Building Energy Saver: An Energy Retrofit Analysis Toolkit

Seminar Abstract 

Small commercial buildings in the United States consume 47% of the total primary energy of the buildings sector. However retrofitting these buildings poses a huge challenge for small and medium-sized enterprises as building owners usually lack the expertise and resources to conduct on-site energy audit to identify and evaluate cost-effective energy retrofit technologies. This seminar presents the Commercial Building Energy Saver (CBES), an energy retrofit analysis toolkit, which calculates the energy use of a building, identifies and evaluates retrofit measures in terms of energy savings, energy cost savings and payback. The toolkit provides a rich set of features as follows: (1) Energy Benchmarking provides an ENERGY STAR score for the building and how it compares with other peer buildings in California; (2) Load Shape Analysis identifies potential building operation improvements using statistical analysis of the building’s 15-minute interval electricity use data; (3) Preliminary Retrofit Analysis searches a pre-simulated database for retrofit measures based on investment criteria; and (4) the Detailed Retrofit Analysis performs EnergyPlus simulations to evaluate energy savings of user configurable energy conservation measures considering the actual building characteristics and operation schedules. The CBES Toolkit includes a web app for end users and the CBES Application Programming Interface for integrating CBES with other energy software tools. The object oriented software architecture of CBES enables its expansion to cover more building types, more climates, and more building technologies in future.  


Mary Ann Piette is the Director of the BTUS Division. She is a Staff Scientist and the PI of the CEC sponsored CBES project. Tianzhen Hong is a Staff Scientist and Deputy Lead of the Simulation Research Group. He is the lead of the CBES software development. Yixing Chen is a postdoc and the chief software developer of the CBES. Sang Hoon Lee is a Senior Scientific Engineering Associate and the developer of the Database of Energy Efficiency Performance (DEEP) for preliminary retrofit analysis. Rongpeng Zhang is a postdoc and the developer of the web app for the detailed retrofit analysis. Kaiyu Sun is a Scientific Engineering Associate and the developer of the automatic model calibration for CBES. Sarah Taylor-Lange is a postdoc and the coordinator of the CBES development. Phil Price is a Staff Scientist and the developer of the load shape analysis. William Fisk is a Senior Scientist and led the IEQ measurement task of the project. Rengie Chan is a Research Scientist and the developer of qualitative impact of retrofit measures on IEQ. Norman Bourassa is a Project Manager and led the city partner demonstration task. Margarita (Gari) Kloss is a Program Manager and the CBES project manager.

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Seminar Speaker(s) 

Tianzhen Hong
Computational Staff Scientist/Engineer, Simulation Research Group, Building Technology Department, Building Technology & Urban Systems Division

Dr. Tianzhen Hong is a Staff Scientist, Principal Investigator, and Deputy Head of the Building Technologies Department. He is a registered mechanical engineer in California and a LEED accredited professional. He leads the Urban Systems Group and a research team working on a portfolio of projects, focusing on data, methods, modeling and simulation tools, and policy for design and operation of low energy buildings and sustainable urban systems. He is leading the EnergyPlus development at LBNL, was the chief developer and product manager of VisualDOE version 4.0 (a GUI to DOE-2.1E), and was the founding developer of DeST (a building energy modeling program widely used in China). He was a key member of the teams that developed building energy standards for California, ASHRAE and India. He established and chairs the ASHRAE Multidisciplinary Task Group on occupant behavior in buildings. He actively contributed to international collaborations such as the U.S.-China Clean Energy Research Center on Building Energy Efficiency, IEA EBC Annex 21, 53, 66 and 79. He was Operating Agent of Annex 66 and co-lead of Subtask 3 of Annex 79. One of his software toolkit, CBES, won the 2019 R&D 100 Award. He received B.Eng. and Ph.D. in HVACR, and B.Sc. in Applied Mathematics from Tsinghua University, China.


Urban Systems Research

Urban Systems Group, 

City Building Energy Saver (CityBES),

Occupant Behavior Research


Occupancy Simulator,

IEA EBC Annex 79 (2018-2023): Occupant-centric building design and operation

IEA EBC Annex 66 (2013-2018): Definition and simulation of occupant behavior in buildings

IEA EBC Annex 53 (2008-2013): Total Energy Use in Buildings: Analysis & Evaluation Methods

ASHRAE Multidisciplinary Task Group on Occupant Behavior in Buildings, ASHRAE MTG.OBB

Building Energy Modeling and Analysis Tools

Commercial Building Energy Saver: California version,; National version,




Mary Ann Piette
Scientific Division Director, Demand Response Research Center, FLEXLAB, Commercial Building Systems Group, Whole Building Systems Department, Building Technology & Urban Systems Division

Mary Ann Piette is a Senior Scientist, Director of the Building Technology and Urban Systems Division and Senior Science Advisor to the Associate Lab Director of Energy Technologies Area at Lawrence Berkeley National Laboratory. She oversees LBNL's building energy research activities with the US Department of Energy and over 25 other R&D sponsors. She is also the Director of the Demand Response Research Center. Mary Ann's work involves developing and evaluating new technology and building components, controls, operations, simulation, whole building and electric load shape analysis and behavior. She is also lead researcher at LBNL on the automated demand response technology. Mary Ann has authored over 90 peer reviewed publications related to energy efficiency and demand response and has worked at LBNL since 1983. She has a MS in Mechanical Engineering from UC Berkeley and a Licentiate in Building Services Engineering from the Chalmers University of Technology in Sweden.


Jul 2, 2015 -
12:00pm to 1:00pm