Buildings are counted per structure inside Connecticut, from FEMA/ORNL USA Structures, filtered to commercial occupancies over 4,000 square feet and excluding structures under 3.2 meters tall. Counts are a floor because coverage varies by place.
Competitor counts and employment are Census County Business Patterns for NAICS 238220, plumbing, heating, and air-conditioning contractors. They are retained as a clearly labeled mechanical-market comparison, not presented as roofing, electrical, or fire-protection competition.