American DG Energy Inc. owns, operates, distributes, installs, and maintains on-site energy systems that produce electricity, hot water, heat, and cooling energy at customers’ facilities in the United States. The company offers natural gas powered cogeneration systems that produce electricity from an internal combustion engine driving a generator, while the heat from the engine and exhaust is recovered and used to produce heat and hot water for use on-site, as well as distributes and operates water chiller systems for building cooling applications. It also provides natural gas heat pumps; and complementary energy equipment, such as boilers, etc., as well as turnkey installation services for energy producing products. The company offers standardized packages of energy, equipment, and services to property owners and operators in healthcare, hospitality, residential, athletic facilities, and other industrial sites directly. As of December 31, 2016, it operated 92 energy systems, including an aggregate of approximately 5,445 kilowatts or 41.6 million British thermal units of heat and hot water; and 4,500 tons of cooling. The company was incorporated in 2001 and is headquartered in Waltham, Massachusetts. As of May 18, 2017, American DG Energy Inc. operates as a subsidiary of Tecogen Inc.