Comfort Systems USA, Inc. engages in the provision of mechanical and electrical contracting services. The company is headquartered in Houston, Texas and currently employs 18,300 full-time employees. The firm operates through two segments: Mechanical and Electrical. The Mechanical segment principally includes heating, ventilation and air conditioning (HVAC), plumbing, piping and controls, as well as off-site construction, monitoring and fire protection. This segment also installs connecting and distribution elements, such as piping and ducting. The Electrical segment includes installation and servicing of electrical systems. The firm builds, installs, maintains, repairs and replaces mechanical, electrical and plumbing (MEP) systems throughout its approximately 44 operating units at 172 locations across the United States. The company is also engaged in offering engineering, design-assist and turnkey, direct hire construction services of modular systems serving the advanced technology, power and industrial sectors. The company also provides mechanical construction services to the commercial and industrial sectors.