Business Description

Comfort Systems USA, Inc., a Delaware corporation, was established in 1997. We provide mechanical and electrical contracting services. Our mechanical segment principally includes heating, ventilation and air conditioning (“HVAC”), plumbing, piping and controls, as well as off-site construction, monitoring and fire protection. Our electrical segment includes installation and servicing of electrical systems. We build, install, maintain, repair and replace mechanical, electrical and plumbing (“MEP”) systems through our 50 operating units with 190 locations in 142 cities throughout the United States. We operate primarily in the commercial, industrial and institutional MEP markets and perform most of our services in manufacturing, healthcare, education, office, technology, retail and government facilities. Substantially all of our consolidated 2025 revenue was derived from commercial, industrial and institutional customers and multi-family residential projects. Approximately 63.2% of our revenue was attributable to installation services in newly constructed facilities and 36.8% was attributable to renovation, expansion, maintenance, repair and replacement services in existing buildings. Our consolidated 2025 revenue was derived from the following service industries: ​ ​ ​ ​ ​ ​ ​ ​ Percentage of Service Activity ​ Revenue Mechanical Services 73.3 % Electrical Services ​ 26.7 % Total 100.0 % Industry Overview We believe that commercial, industrial, and institutional mechanical and electrical contracting generate annual revenue in the United States of approximately $700 billion. Mechanical and electrical systems are necessary to virtually all commercial, industrial and institutional buildings. Because most buildings are sealed, HVAC systems provide the primary method of circulating fresh air in such buildings. Replacing an aging building’s existing systems with modern, energy-efficient systems significantly reduces a building’s energy consumption, carbon footprint, and operating costs while improving air quality and overall system effectiveness. Older commercial, industrial and institutional facilities frequently have poor air quality and provide less comfortable environments, and older HVAC systems result in significantly higher energy consumption than modern systems. As electrical systems age, they require service and replacement, and changing building configurations and technological power load requirements lead to the need to reconfigure and improve electrical systems in buildings on a regular basis. Many factors affect mechanical and electrical services industry growth, including but not limited to, (i) population growth, which increases the need for commercial, industrial and institutional space, (ii) an aging installed base of buildings and equipment, (iii) increasing sophistication, complexity and efficiency of mechanical and electrical systems, and (iv) growing emphasis on internal air quality, environmental sustainability and energy efficiency. Our industry can be broadly divided into two categories: ● construction of and installation in new buildings, which provided approximately 63.2% of our revenue in 2025, and ● renovation, expansion, maintenance, repair and replacement in existing buildings, which provided the remaining 36.8% of our 2025 revenue. Construction, Installation, Expansion and Renovation Services —Construction, installation, expansion and renovation services consist of “design and build” and “plan and spec” projects. In “design and build” projects, the commercial MEP company is responsible for designing, engineering and installing a cost-effective, energy-efficient 3 Table of Contents system customized to the specific needs of the building owner. Costs and other project terms are normally negotiated between the building owner or its representative and the contracting company.…