Comfort Systems USA, Inc., together with its subsidiaries, provides mechanical and electrical installation, renovation, maintenance, repair, and replacement services for the mechanical and electrical services industry in the United States. It operates through two segments: Mechanical and Electrical. The company offers heating, ventilation, and air conditioning systems, as well as plumbing, electrical, piping and controls, off-site construction, monitoring, and fire protection. It also involved in the design, engineering, integration, installation, and start-up of mechanical, electrical, and plumbing (MEP) and related systems in new buildings; and renovation, expansion, maintenance, monitoring, repair, and replacement of MEP systems in existing buildings.