Comfort Systems USA, Inc. is a provider of commercial, industrial and institutional heating, ventilation, air conditioning (HVAC) and electrical contracting services. The Company operates through two segments: Mechanical and Electrical. The Mechanical segment includes HVAC, plumbing, piping, and controls, as well as off-site construction, monitoring and fire protection. It also installs connecting and distribution elements, such as piping and ducting. The Electrical segment includes installation and servicing of electrical systems. It builds, installs, maintains, repairs and replaces mechanical, electrical and plumbing (MEP) systems throughout its 47 operating units with 178 locations in 136 cities across the nation. It is engaged in offering engineering, design-assist and turnkey, direct hire construction services of modular systems serving the advanced technology, power and industrial sectors. It also provides mechanical construction services to the commercial and industrial sectors.