At ERS, energy efficiency is our passion. We started this business as a way to make a difference, and today we use our experience as thinkers and doers to make a difference leading our clients toward sustainable practices.


Gary-Epstein-1-300x300Gary Epstein is the President and Founder of ERS and is a US Green Building Council LEED Accredited Professional. His interdisciplinary skills are in the energy engineering and environmental consulting fields. His current work and areas of expertise include energy technology characterization, impact evaluation, research, and assessment; energy code development and consulting; assessment of environmental impacts of energy use and conservation; and development, planning, and evaluation of utility and government resource conservation programs.

Gary is the past chair of the AESP Energy Services and Technology Committee and his work has been published in numerous professional journals and conference proceedings. Mr. Epstein holds an MS from the University of Massachusetts and a BS from the State University of New York at Buffalo, both in Mechanical Engineering.

Senior Vice President

Mark is the Senior Vice President of Engineering Operations. He is an experienced technical manager of a wide array of energy efficiency services including industrial efficiency and productivity assessments, feasibility studies for renewable and distributed generation projects, compressed air system evaluations, site survey and implementation inspection services, outreach, utility program planning, and energy-related trainings.

Mark’s work has been published in numerous professional journals and conference proceedings. He holds a BS in Mechanical Engineering from the University of Massachusetts and is a LEED Accredited Professional.

Senior Vice President

Brian McCowan, LC, is the Senior Vice President of Technology and Development, with interdisciplinary skills in the energy engineering, lighting, environmental, and renewable technology consulting fields. As a licensed construction supervisor and certified lighting designer, his expertise in project design and management is utilized throughout ERS’s scope of services. Additionally, Brian has over 20 years of experience in the training of energy system professionals.

In recent years, Brian has spent considerable time providing consulting services in support of enhanced compliance with new energy codes. He is currently involved in ERS’s development effort for web-based resources to support energy code understanding and compliance. Mr. McCowan is an active participant in the Association of Energy Service Professionals (AESP) Energy Technology Committee. He holds a bachelor’s degree from the University of Southern Maine.

Vice President

Bruce Harrington is Vice President of Operations and Implementation Services at ERS. He has more than 20 years of experience in energy efficiency program design, implementation, and evaluation for both the residential and commercial and industrial (C&I) markets. He oversees many of the large projects and client relationships throughout the US and provides consulting expertise for C&I program design and implementation projects, baseline studies, pilot and innovation projects, process evaluations, and general program operations. He also has more than 20 years of experience in management positions in fields including sales, marketing, customer service, and multichannel marketing. He holds an AS in agricultural mechanization technology and a BS in business management from the University of Maine.

Vice President

Sue Haselhorst is the Vice President of Project Analytics with over 25 years of experience in the energy efficiency field. She has been project manager for various analytical and technical assessments and multiple evaluations. She has also provided design and construction services for campus energy management systems.

Sue served for eight years as an electric utility program planner and evaluator. She was responsible for the design and implementation of a portfolio of commercial and industrial programs, including the development of strategic account plans for very large customers. She also managed a highly successful community-based pilot program called the Marshfield Energy Challenge. Her areas of expertise include project management, analytics, program impact evaluation, and program design. Sue holds a BS in mechanical engineering from the University of Massachusetts.

Vice President

Jon Maxwell, PE, is Vice President of Engineering and Evaluation with more than 15 years of experience in energy efficiency program evaluation and implementation. He has managed major field data collection efforts for evaluation and load research and has trained more than 200 energy professionals on a wide variety of topics, mostly related to field data collection and analysis. He has conducted more than 100 C/I site visits and led start-up, hiring, training, and project management for four energy audit programs that provided a combined 1,600 audits per year to utility customers.

Jon has published extensively, and he is a Professional Engineer registered in Maryland and Texas, a LEED Accredited Professional, and an EPA Green Lights Surveyor Ally. He holds an MS in Mechanical Engineering from Oregon State University and a BSE in Mechanical Engineering and History from Duke University.

Vice President


Jeff is Vice President of Business Development and has 30 years of experience working with emerging technologies. He has led business activities on four continents across industries including software, semiconductor, and precision mechanics – serving aerospace, medical, automotive, heavy truck, and energy sectors. His experience in energy includes large scale audit implementation and direct involvement in thousands of commercial energy audits. As product manager for automated energy audit software in the late ‘80’s, he was among the early pioneers in automated bill disaggregation and quantification of EE efforts. Jeff holds an MBA from INSEAD and a BSc in Architectural and Building Energy Engineering from CU, Boulder.

Vice President

Mary McElhiney is the Vice President of Business Operations with more than 20 years of project and administration management experience. She has developed business marketing plans for numerous clients and created worldwide business event programs for global business leaders. Her main focus at ERS is project management and development with a strong focus on optimizing business systems and improving overall operations. She also manages talent recruitment, contract negotiations, and the application of computerized database and analysis systems for business and program management. Mary holds a BA from Merrimack College.

David Reynolds
Regional Director

David ReynoldsDavid Reynolds, PE, LEED AP, CEM, is the California Regional Director with more than 15 years of experience in the development, management, and implementation of energy efficiency and renewable energy projects and programs. He has developed energy efficiency programs, marketed customer service programs for energy utilities, created strategic energy plans, performed financial and technical analysis for complex energy retrofit projects, and provided regulatory representation in the development of state and local energy policy. He has also conducted hundreds of commercial and industrial energy surveys and assessments in support of energy performance contracting projects and provided technical expertise for more than fifty utility program administrators. David is a Professional Engineer registered in California, a LEED Accredited Professional, a Certified Energy Manager, and a Certified Residential Plans Examiner. He holds a BS in Mechanical Engineering from California Polytechnic State University at San Luis Obispo, CA.

Regional Director

George Zúñiga, LEED AP, is the New York Regional Director for ERS. His main areas of expertise include the creation and operation of business systems for optimizing energy-project management and operations efficiency, the application of computer database and systems analysis, and the management of energy efficiency and demand response quality assurance reviews for projects addressing lighting, HVAC, building automation and controls, industrial processes, and CHP systems.

Senior Director

Lucy NeimanLucy Neiman oversees the technical staff and first-line managers in ERS’s North Andover headquarters. Her key areas of expertise include energy efficiency program evaluation, development, management, and implementation; sustainability consulting; strategic marketing; and outreach. Her project and line management includes planning, implementation, and oversight of project activities, staff coordination, training, client interactions, analysis, tracking, and reporting. She directs large efficiency program evaluation projects and implementation support efforts, and her marketing and development responsibilities include client relations, LEED certification efforts, and sustainability project development. She previously worked in various marketing and engineering roles for Stone & Webster Engineering, IBM, and Oak Ridge National Laboratory. Lucy is a LEED accredited professional and holds an MBA from Harvard Business School, aMasters in Mechanical Engineering from North Carolina State University, and a BA from the University of North Carolina at Chapel Hill.


Satyen Moray, PE, CEM, CPMP, is an Associate Project Director at ERS, where he currently leads Eversource Connecticut and Western Massachusetts technical support work and NYSERDA’s Combined Heat and Power inspection project and provides technical oversight for Con Edison’s Demand Management Program. He recently led Con Edison’s large commercial and industrial (C&I) energy efficiency program evaluation efforts. Satyen managed the Public Service of New Hampshire’s energy audit program for more than 10 years, during which he managed/led an average of twenty energy audits per year. Satyen’s key areas of expertise include the evaluation of utility programs; reviewing complex technical analyses, development of spreadsheet-based end-use analysis tools associated with loggers, compressed air systems, HVAC systems, boiler systems, and custom measures; and the planning and evaluation of new construction projects. He holds an MS in mechanical engineering from the University of Dayton, Ohio, and a BS from Vishwakarma Institute of Technology in Pune, India.