Comfort Systems USA, Inc. provides mechanical and electrical contracting services. 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. The electrical segment includes installation and servicing of electrical systems. The company builds, installs, maintains, repairs, and replaces mechanical, electrical, and plumbing (MEP) systems through 50 operating units with 190 locations in 142 cities throughout the United States. It operates primarily in the commercial, industrial, and institutional MEP markets and performs most of its services in manufacturing, healthcare, education, office, technology, retail, and government facilities. The firm also emphasizes design and build capabilities and off site fabrication to enhance project efficiency. It leverages centralized administrative functions such as insurance, employee benefits, training, safety programs, and cash management to allow local management to focus on business development.

The company generates revenue from mechanical and electrical contracting services. In 2025, mechanical services accounted for 73.3% of total revenue while electrical services contributed 26.7%. Approximately 63.2% of revenue came from installation services in newly constructed facilities and 36.8% from renovation, expansion, maintenance, repair, and replacement services in existing buildings. Revenue is also diversified by end use sector with technology representing 45.0%, manufacturing 22.1%, healthcare 8.9%, education 7.3%, government 5.0%, office buildings 5.0%, retail restaurants and entertainment 3.7%, multi family and residential 1.4%, and other 1.6%. About 92.7% of revenue is earned on a project basis for installation of systems in newly constructed or existing facilities, with an average contract price of approximately $2.9 million and an average project duration of six to nine months. As of December 31, 2025, there were 8,427 projects in process with an aggregate contract value of roughly $24.17 billion. The top customer represented 12.8% of consolidated 2025 revenue. The remaining revenue is derived from maintenance and service work performed under long term agreements.

The company operates through the following segments: Mechanical Services and Electrical Services.

• Mechanical Services: This segment principally includes heating, ventilation, and air conditioning (HVAC), plumbing, piping, and controls, as well as off site construction, monitoring, and fire protection.

• Electrical Services: This segment includes installation and servicing of electrical systems.

The company holds a notable position in the approximately $700 billion United States mechanical and electrical contracting market. It competes against thousands of local and regional firms as well as divisions of larger contractors, utilities, and equipment manufacturers. Competitive advantages include its scale, design and build expertise, sustainability focus, and ability to provide multi location coverage and a broad service portfolio. The firm believes its size enables it to win contracts based on price, relationships, quality, timeliness, reliability, tenure, financial strength, access to bonding, range of capabilities, and scale of operation.

The company serves building owners and developers, property managers, general contractors, architects, and consulting engineers. Its end use sectors include technology, manufacturing, healthcare, education, government, office, retail, restaurants, entertainment, and multi family residential projects. It also benefits from significant geographical diversification across all regions of the United States.