Comfort Systems USA is a mechanical and electrical contracting company that designs, installs, maintains, repairs, and replaces MEP (mechanical, electrical, and plumbing) systems in commercial, industrial, and institutional buildings across the U.S. The mechanical segment (~73% of revenue) covers HVAC, plumbing, piping, and controls, while the electrical segment (~27%) handles electrical installation and servicing. Technology customers — primarily data centers and chip fabrication facilities — represent roughly 45% of revenue, followed by manufacturing at ~22% and healthcare at ~9%. About 63% of revenue comes from new construction and 37% from renovation, maintenance, and repair work. Comfort Systems operates as a decentralized federation of ~50 local operating companies and pursues growth through acquisitions and organic investment. A growing modular construction capability (~17-19% of revenue) — where Comfort Systems prefabricates MEP modules off-site at nearly 3M square feet of production facilities before shipping to job sites — is particularly suited to large data center projects. Service contracts (~14-16% of revenue) provide recurring, stable cash flow. Labor productivity and project selectivity are central to profitability, with gross margin per labor hour serving as the key internal metric. Comfort Systems argues that its scale, workforce depth, design-and-build expertise, and modular capabilities differentiate it from the thousands of smaller, local contractors that dominate this fragmented industry.