Management Team

Mr. Sakellaris is the President and Chief Executive Officer, as well as the Chairman of the Board of Directors of Ameresco, Inc. (NYSE:AMRC), a leading energy efficiency and renewable energy company headquartered in Framingham, MA.

A visionary and entrepreneur, Mr. Sakellaris founded Ameresco in April 2000. He aspired to build an entirely product-neutral and supplier-independent energy company that had the skills, capabilities and foresight to create independent energy solutions that went beyond just conservation; one that addressed a customer’s entire energy stream including supply and demand, energy efficiency and renewable energy.

Early in his career, Mr. Sakellaris worked at the utility New England Electric System (NEES), where he welcomed the challenge to establish NEES Energy, a company that would promote energy efficiency, thereby avoiding the need to build new power generation plants. Mr. Sakellaris then purchased the business known as NEES Energy in 1991 and renamed it NORESCO. He built NORESCO into a an industry-leading independent energy services company before selling it to Equitable Resources in 1997, where he continued to lead NORESCO and was also appointed as a Senior Vice President of Equitable Resources (NYSE:EQT), a Fortune 500 Energy Company.

Today, Mr. Sakellaris leads Ameresco, a public company, employing over 1,000. Ameresco continues to grow and thrive, and currently supports more than 70 local offices throughout North America and the United Kingdom.

With more than 30 years of experience in the energy industry, Mr. Sakellaris has worked to create budget-neutral business models for energy efficiency and renewable energy projects. Mr. Sakellaris’ dedication and influence in promoting energy efficiency dates back to his involvement with the Electrical Power Research Institute (EPRI) where he championed the development of demand side management (DSM) programs that were widely implemented across the country. Additionally, he was a founding member of the National Association of Energy Service Companies (NAESCO) where he served as the first president and advocated for the new industry. He remains an active NAESCO member today.

Mr. Sakellaris earned both M.B.A and M.S.E.E. degrees from Northeastern University and a B.S.E.E. degree from the University of Maine – Orono. In May 2012, the University of Maine granted him an Honorary Doctorate for his lifetime of achievements, recognizing his dedication and exemplary leadership in the field of energy efficiency and renewable energy.

Mr. Sakellaris was the recipient of the 2015 Finance Monthly CEO Award, Ernst & Young Entrepreneur of the Year 2011 New England, Energy, Cleantech & Natural Resources Award. In 2012, he was named the Worcester Business Journal’s Business Leader of the Year for large businesses and also honored by The Boston Globe for Ameresco’s Globe-100 Top-performing Public Companies #29 ranking. The Boston Business Journal ranked Ameresco #31 in the Area’s Fastest Growing Public Companies and #49 in Massachusetts’ 150 Top Public Companies. In 2011, Ameresco was honored on the Forbes 100 list as one of America’s Best Small Companies and in 2010, as the New England Clean Energy Council Employer of the Year.

Mr. Bakas is President of Renewable Fuels at Ameresco, a leading cleantech integrator and renewable energy asset developer, owner and operator. He is a member of the founding management team of the 24-year-old public company (NYSE: AMRC) and plays a key role shaping Ameresco’s strategic direction and driving its growth.

With nearly 35 years of experience in the energy industry, Mr. Bakas leads the development and expansion of the company’s renewable fuels assets, which includes one of the most robust pipelines of complex facilities in the country. These comprehensive energy supply assets have been recognized by and won numerous awards from the U.S. EPA, Department of Energy, California Legislature, Energy Vision, Climate Change Business Journal, state agencies, and other leading industry organizations.

A pioneer in the renewable energy industry, Mr. Bakas developed some of the earliest advanced clean energy projects that helped shape the markets in those states that first implemented renewable portfolio standards, beginning in Massachusetts in 2001 with Ameresco’s first “green” biogas-to-energy power plant. Ever since, he has championed the growth of the company’s renewable energy asset portfolio making it one of the leading energy services providers in North America. Ameresco has been recognized multiple times by the U.S. EPA as an Industry Partner of the Year and U.S. House of Representatives for its contribution to environmental stewardship through its innovative green energy projects. In 2024, the California Legislature recognized Ameresco for developing the largest landfill gas-to-renewable natural gas (RNG) project in the state..

Mr. Bakas has been instrumental in fostering and supporting legislation that promotes the use of renewable resources and has served on the Board of Directors for the Northeast Clean Energy Council as well as the Advisory Board for Microgrid Knowledge, the Leadership Advisory Board for Sustainability at the Coalition for Renewable Natural Gas, and the Board of Advisors for the Advanced Energy Group.

He is  frequently called upon by the investment community to discuss relevant market conditions, trends in the green energy sector, and corporate strategies.

Over his career, Mr. Bakas has been tapped to provide his expertise and guidance regarding energy issues throughout the United States and to participate in discussions setting direction for Federal, state, and local energy policy including, but not limited to, providing expert testimony before the Clean Air Congressional Roundtable at the U.S. Capitol.

He is often invited to speak at innovative industry and customer forums on topics such as Energy Efficiency, Distributed Energy Systems, Microgrids, Energy Storage, Renewable Energy Generation, and Public-Private Partnerships. An industry expert, he is regularly sought out for his expertise and opinion by numerous national media outlets, publications, and magazines and is frequently quoted in industry and business publications such as Forbes, Fortune Magazine, Distributed Energy Magazine, and Microgrid Knowledge. Mr. Bakas is a frequent speaker at roundtables, webinars, and conferences including events hosted by Reuters, Barclays, Bank of America, Oppenheimer & Co. Inc., Tudor, Pickering, Holt & Co, Infrastructure Investor, Roth Capital Partners, HASI, Equilibrium Forum, Advanced Bioeconomy Leadership Conference, Coalition of Renewable Natural Gas, World Biogas Association, LDC Gas Forum, and Microgrid Knowledge.

As President of Federal Solutions and Utility Infrastructure, Ms. Bulgarino supports the company’s mission to energize a more sustainable world by helping customers build energy resiliency while leveraging smart, connected technologies.

Ms. Bulgarino is responsible for Ameresco’s leading business unit, which delivers advanced power generation and resilience solutions to Federal government agencies and utilities. Her team is also focused on exploring new market opportunities, including energy infrastructure development for data centers.  

A licensed professional engineer, Ms. Bulgarino has spent over 25 years developing and executing innovative clean technology and distributed energy solutions through diverse contract structures. She has overseen the development and implementation of over $3 billion of energy projects – from a utility-scale solar and battery project for Hawaiian Electric and deep energy retrofits integrating Smart Building controls at courthouses and Federal buildings nationwide to the first comprehensive onsite generation, energy storage, and microgrid projects on U.S. military installations.

As President of Ameresco’s Federal Solutions and Utility Infrastructure, Ms. Bulgarino oversees more than 350 professionals specializing in engineering, commissioning, construction, operations and maintenance, and long-term performance measurement and verification. Under her leadership, Ameresco has guaranteed and delivered more cost savings from energy infrastructure improvements than any other provider, securing repeat business with the Department of Defense, the Department of Energy, the General Services Administration, the Veterans Administration, and the Department of Justice, among other civilian agencies. The utility clients that she and her team support include investor- owned utilities, municipal utilities, and co-ops.

Ms. Bulgarino is a seasoned industry executive with strong leadership, communications, and strategic execution talents.  A recognized leader within the industry, she has developed state-of-the-art solutions, negotiated and executed a broad range of third-party financed contractual arrangements, managed project implementation, and presented on technical and business panels at major conferences and other industry events. As a leading woman in technology, she balances the management of this complex project portfolio with the articulation and pursuit of a strategic, long-term vision for corporate success.  Ms. Bulgarino has been recognized with numerous industry awards and accolades, including the 2021 Environment + Energy Leader 100 list and 2022 Energy Storage Report’s Top 40 Women Leaders in Energy Storage, and S&P Global Platts recently selected her as a finalist for its Rising Star Individual award.

Ms. Bulgarino earned a Bachelor of Science degree in chemical engineering from the University of Tennessee and an Executive Management and Leadership Certificate from the Massachusetts Institute of Technology.

Mr. Mark Chiplock is Executive Vice President, Chief Financial Officer, and Chief Accounting Officer of Ameresco (NYSE:AMRC), a leading independent clean technology integrator.

He is responsible for the company’s financial strategy and capital management, investor relations, corporate finance, accounting and treasury functions, financial and operations analysis, business planning, internal and external financial reporting, and information technology infrastructure and security. Focused on accountability to our stakeholders and Ameresco’s relentless pursuit of a sustainable future, Mr. Chiplock also serves as the Executive Chair of Ameresco’s Impact Ambassadors – the company’s ESG program.

Mark has more than 30 years of progressive business management and strategic financial expertise. He is a proactive leader with extensive experience managing teams to oversee and control systems and operational improvement projects in a multi-site environment. Mr. Chiplock has strong knowledge of, and experience in GAAP revenue recognition, SOX 404 requirements, and SEC Regulations, with a proven track record of assessing and implementing financial controls and reporting.

Mr. Chiplock served as Corporate Controller (2014 to 2016), Vice President of Finance and Corporate Controller (2016 to 2018), held the role of interim CFO from (2018 to 2019), and Senior Vice President and Chief Accounting Officer (2019 to 2024).

Prior to Ameresco, he served as Vice President, Finance of GlassHouse Technologies, a data center infrastructure consulting firm.

Mr. Chiplock is a Certified Public Accountant. He is a member of the New York State Society of Certified Public Accountants (NYSSCPA). Mr. Chiplock earned a Bachelor of Business Administration in Accounting from The State University of New York at Buffalo.

Mr. Corrsin is Executive Vice President and General Counsel of Ameresco. He is also the Corporate Secretary and is a member of the Board of Directors. Mr. Corrsin has extensive experience with energy regulations, federal, state and local regulatory authorities, and complex energy construction and financing projects, gained through more than 23 years of energy-related legal practice. Mr. Corrsin oversees financial and regulatory issues of independent power, utility and energy conservation projects for Ameresco.

Mr. Corrsin was formerly an executive vice president of Public Power International, Inc., an independent developer of power projects in south Asia and Europe. Prior to joining PPI, Mr. Corrsin held various positions at Palmer & Dodge, LLP, where he co-founded the Palmer & Dodge Energy Group and represented independent power and energy conservation developers in the U.S. and overseas. Mr. Corrsin has also held positions at Chadbourne & Parke, Hudson Research, and the National Wildlife Federation; each position having a focus on energy.

Mr. Corrsin earned a J.D. degree from the University of Chicago and an A.B. degree in biology from Brown University.

Ms. Leila Dillon is Senior Vice President – Corporate Marketing and Communications at Ameresco, a leading cleantech integrator focusing on energy efficiency and renewable energy solutions. Ms. Dillon has more than 20 years of experience in leading corporate marketing and communications, investor relations, partner strategy, lead generation and business development initiatives for industry leading global technology companies.

In her role, Ms. Dillon is responsible for strategic initiatives that amplify Ameresco’s market leadership position, driving external communications programs including media and public relations and shaping internal corporate communications and training programs. She guides the development of corporate lead and demand generation programs to drive business opportunities across the organization. Ms. Dillon is a key strategist on the executive team and is actively involved in the company’s investor relations.

Recognizing the prominence of ESG initiatives within Ameresco’s core mission, vision, and values, Ms. Dillon worked to launch Ameresco’s ESG Ambassadors in 2020. This group spearheaded the company’s first ESG report, “Doing Well by Doing Good” and continues to serve as the driving force behind Ameresco’s ESG initiatives. Serving as an ESG Ambassador herself, Ms. Dillon is responsible for identifying, communicating, and reporting on the many ways ESG is embedded in Ameresco’s culture.

Additionally, Ms. Dillon participates in strategic industry initiatives and technology conferences. She has chaired global buildings & infrastructure programs, and led international plenary sessions on women leadership in IoT, Smart City, SaaS, PaaS, EaaS, and multi-purposed smart infrastructure platforms.

Prior to joining Ameresco, Ms. Dillon served as Vice President Marketing and North American Distribution for Bigbelly, Inc., a leading provider of Smart City, Internet of Things (IoT), and smart waste management solutions.

With a core focus in Clean Technology, Energy Solutions, Renewables, Distributed Energy Generation, IoT, Smart City, Cloud, Mobile and Telecommunications, Ms. Dillon is a recognized leader for women in technology.

Mr. Maltezos is an Executive Vice President of Ameresco, supporting the company’s mission to energize a more sustainable world by helping customers decarbonize to net zero and build energy resiliency while leveraging smart, connected technologies. He is responsible for our West Region in the U.S.A. and our wholly owned subsidiary, Ameresco Canada Inc. Within these regions, Mr. Maltezos provides senior management oversight to all sales and operations activities and is responsible for developing and executing the company’s growth strategies.

Mr. Maltezos has been a senior executive with Ameresco since 2004, having joined us through our acquisition of Exelon’s energy savings performance contracting business, where he served as vice president and general manager. He has more than 35 years of industry experience in a variety of engineering, management, and executive roles spanning energy savings performance contracting, energy services, distributed generation, mechanical contracting, and utility businesses.

Mr. Maltezos earned an M.B.A. degree from Northwestern University’s Kellogg Graduate School of Management and a B.S. degree in Electrical Engineering from the University of Illinois Urbana-Champaign.

Mr. Christakis is President of East USA & Greece; Project Risk for Ameresco, a leading energy efficiency and renewable energy company, leading the Eastern USA region and the company’s centralized procurement and project risk initiatives. He also manages the expansion of the Ameresco’s business in Greece.

In his long-standing leadership at Ameresco, Mr. Christakis has managed well over $2 billion in revenue generating projects that comprised complex energy performance contracts, solar installations, large scale infrastructure, and multi-discipline turnkey installations.

With nearly 30 years of experience in the energy industry, Mr. Christakis has been instrumental in expanding Ameresco’s pipeline of solar projects. His deep understanding of the market and commitment to innovation and customer satisfaction have enabled Ameresco to stay at the forefront of the renewable energy sector. Under his leadership, the company has not only increased its project portfolio but also enhanced its reputation as a trusted partner in delivering sustainable energy solutions.

Mr. Christakis earned a Bachelor of Science degree in electrical engineering from Northeastern University. He is a Certified Energy Manager, and holds the following licenses in multiple states:Master Electrician, Journeyman Electrician, Unlimited General Contractor, and Construction Supervisor.

Ms. Lenka Patten is Senior Vice President and Chief Human Resources Officer for Ameresco, a leading cleantech integrator focusing on energy efficiency and renewable energy solutions. Ms. Patten boasts over 20 years of forward-thinking human capital experience, bringing a proven track record of implementing integrated human resource strategies that put people first and support the overall mission and vision of organizations.

In her role, Ms. Patten is responsible for leading the human resources team while supporting the company’s strategic business goals across talent acquisition, professional development, and employee engagement. Joining the company in November 2022, she serves on the executive management team to provide guidance as a personnel advisor to each business unit while cultivating a strong companywide talent strategy and rewarding employee experience.

Prior to joining Ameresco, Ms. Patten served as the head of human resources for Reebok International, where she was responsible for developing and executing global human resource strategy, specifically in the areas of talent management; diversity, equity and inclusion; organization design; performance management; training and development; social purpose and community impact, among others. She’s also held human resources leadership roles at other organizations, including Fidelity Investments and publicly traded State Street Corporation.

Ms. Patten graduated from the University of Economics in Prague, Czech Republic with a bachelor’s degree in economics and comparative politics and a master’s degree in economics. She also holds a master’s degree in organizational development from American University in Washington, D.C. and is a Society for Human Resource Management Senior Certified Professional, a nationally lauded recognition.