Tecogen Inc. designs, manufactures, markets, and maintains industrial and commercial cogeneration systems for residential, commercial, recreational, and industrial use in the United States and internationally. It operates through three segments: Products, Services, and Energy Production. The company offers InVerde e+ and TecoPower, a cogeneration product that supplies electricity and hot water; TECOCHILL air-conditioning and refrigeration chillers; Tecofrost gas engine-driven refrigeration compressors; and water heaters under the Ilios brand name, as well as emissions control technology under the Ultera brand name. It also provides long-term maintenance contracts, parts sales, and turnkey installation services through a network of eleven field service centers in California, the Midwest, the Northeast, and the Southeast, as well as in Ontario, Canada. In addition, the company installs, owns, operates, and maintains distributed generation of electricity, energy, and other complementary systems. It serves hospitals and nursing homes, colleges, universities, health clubs, spas, hotels, motels, office and retail buildings, food and beverage processors, multi-unit residential buildings, laundries, ice rinks, swimming pools, factories, municipal buildings, military installations, and indoor growing facilities. The company was incorporated in 2000 and is headquartered in Waltham, Massachusetts.