Greg played substantial roles in developing the clean energy and green building industries, and is a long-time thought leader and investor in the transition to a low carbon economy. He is MD at ARENA Investments - a clean energy impact investment firm, and President of Capital E - helping institutions to design, scale and implement clean energy and deep decarbonization.

Greg served as Managing Director of Good Energies, a several billion-dollar global clean energy PE/VC fund. He served 5 years as the Director of Financing for Energy Efficiency and Renewable Energy at the US Department of Energy. Greg was the Founding Chairman of IPMVP and built it into the global energy and water efficiency design and verification standard used for $50 billion in building upgrades. Greg Chairs the congressionally established advisory board guiding the greening and energy efficiency of 430,000 federal buildings and served on a National Academy of Sciences board on strengthening US global competitiveness. He is a founder of both the American Council on Renewable Energy (ACORE) and the country’s first green bank.

Greg is the author of several widely refenced studies on the cost effectiveness of greening buildings and cities, including the book Greening Our Built World; Costs Benefits and Strategies.