Tecogen Inc. manufactures, installs, and maintains ultra-clean cogeneration products for multi-family residential, commercial, recreational and industrial use in the United States and internationally. It operates through Products, Services, and Energy Production segments. The Products segment designs, manufactures, and sells industrial and commercial cogeneration systems. Its Services segment provides operations and maintenance services and turn-key installation for products under long term service contracts. Energy Production segment sells energy in the form of electricity, heat, hot water, and cooling to customers under long-term energy sales agreements. The company also offers natural gas-powered cogeneration systems, chillers, and heat pumps products for water and space heating, and air conditioning. Its product portfolio includes InVerde e+ and TecoPower, a cogeneration units for the supply electricity and hot water; Tecochill, an air-conditioning and refrigeration chillers, and hybrid-drive air-cooled and gas engine-driven chillers to produce chilled water and hot water; Tecofrost, a gas engine-driven refrigeration compressors to circulate refrigerant and provide hot water as a byproduct; Ilios, a high-efficiency water heaters; and Ultera, an emissions control technology. In addition, the company provides long-term maintenance contracts, parts sales, and turnkey installation for products through a network of field service centers in California, the Midwest, the Northeast, the Southeast and in Ontario, Canada. It serves healthcare, recreation, housing and hospitality, education and government, industrial and commercial, and indoor growing applications. The company was incorporated in 2000 and is headquartered in Waltham, Massachusetts.