Key Highlights
- ACCO Engineered Systems has been delivering comprehensive mechanical solutions since 1934, including a high-profile project at SoFi Stadium
- E.M. Duggan Inc. combines over 130 years of experience with innovative services like BIM, laser scanning, and prefabrication to enhance project efficiency
- Harder Mechanical Contractors, with over 90 years of history, specializes in large-scale projects across the western US, including the PDX Airport redevelopment
- Harris, established in 1948, is a leading national contractor known for complex projects like Allegiant Stadium and extensive building automation services
- TDIndustries, founded in 1946, emphasizes quality and safety, earning national awards for projects in healthcare, education, and large-scale renovations
ACCO Engineered Systems—Pasadena, CA — Since 1934, owners and builders have selected ACCO Engineered Systems to design, install, and maintain hundreds of thousands of mechanical projects. ACCO is an employee-owned company dedicated to the design, fabrication, installation, maintenance and service of commercial and industrial HVAC, refrigeration, plumbing, process piping and building automation systems.
ACCO offers complete in-house engineering, fabrication, installation, commissioning, and service capabilities. This integrated delivery system provides customers with the most practical, cost-effective solutions for their particular mechanical and control system requirements.
Opening in August 2020, SoFi stadium, Inglewood, Calif., became one of ACCO’s most high-profile contracting jobs. Replacing the historic Hollywood Park Racetrack, SoFi Stadium was deemed as part of the world’s largest sports entertainment project—LA Stadium & Entertainment District, encompassing 298 acres with 300 hotel rooms, 780,000 sq. ft. of office space, 890,000 sq. ft. of retail space and 2,500 modern residences.
E.M. Duggan Inc.—Canton, MA— E.M. Duggan Inc. is a leading mechanical contractor with a legacy dating back to 1891. For more than 130 years, the company has delivered complex construction projects across a diverse range of sectors, including high-rise residential and commercial buildings, hospitality, healthcare, life sciences, laboratories and large-scale public venues.
"In uncertain or disruptive times, communication really becomes essential to how a business runs. For a company like E.M. Duggan Inc., we’re constantly coordinating between customers, wholesalers, and manufacturers, so keeping everyone informed keeps projects moving and expectations clear,” says John Kulibaba, CFO, E.M Duggan Inc.
With a current reported $275 million in revenue and 450 employees, the company provides a full suite of services, Design, Electrical, Fire Protection, HVAC, Plumbing, Preconstruction, Prefabrication, Service, Software, and Special Projects. An early adopter of prefabrication since 1967, E.M. Duggan now operates over 125,000 sq. ft. of prefab space, enhancing project efficiency, safety and quality.
In recent years, E.M. Duggan has expanded its capabilities to meet evolving industry demands. The launch of Duggan Innovative Solutions (DIS) introduced advanced services such as BIM coordination, laser scanning, custom software development, API integration, and technology consulting to support digital transformation across projects.
Duggan Mechanical Services (DMS) has also broadened its expertise. In addition to providing 24/7 emergency response and a comprehensive range of mechanical services, DMS established a Water Treatment Division focused on optimizing system performance and water quality.
In 2025, the company continued its growth with the introduction of a dedicated Electrical Division and the integration of RTH Mechanical Contractors of New Hampshire.
Harder Mechanical Contractors—Portland, OR — Harder Mechanical Contractors is one of the nation’s largest mechanical contractors with a reputation for jobsite safety, meeting tough schedules and delivering quality. Harder teams work primarily in the western United States with regional offices in Arizona, California, Nevada and Utah.
More than 90 years after the company’s founding, Dustin Harder continues the family legacy as the fifth-generation of Harder leadership.
Boasting an $833 million company revenue in 2023, one of Harder’s more high-profile project was the PDX International Airport Terminal Core Redevelopment, which significantly reconfigured the ticket lobby, security screening, baggage handling, offices and pre-security concessions area.
Harris—St. Paul, MN—Nominated as a top workplace in 2025/2026 by publications such as USA Today and Minnesota’s Star Tribune, Harris is a leading national mechanical contractor specializing in design and engineering, construction, building automation, service, manufacturing, conveyors and end-to-end building systems. The company reports a $994 million company revenue in 2024.
Since opening its doors in 1948 in St. Paul, Minnesota, Harris has grown to 17 regional offices and more than 3,500 employees nationally. Harris designs, builds, controls and maintains plumbing, piping, process piping and HVAC systems for commercial, institutional and industrial customers offering complete design-build and design-assist services for projects that vary in size, scope and complexity.
From high-profile projects—including stadiums such as Allegiant Stadium, home of the Las Vegas Raiders—to concert halls to historic landmark buildings, hospitals and data centers and industrial facilities, Harris works closely with entire construction project teams and draws on the expertise of a skilled, diverse and dedicated workforce.
TDIndustries, Inc.—Dallas, TX—Since 1946, TDIndustries has provided high-quality mechanical systems throughout the design, construction, maintenance and operations stages that deliver exceptional experiences for the end user. TDIndustries is considered one of the premier facilities service and mechanical construction company serving the Southwest.
TDIndustries prides itself on quality work and jobsite safety. Recently, the company earned three national Excellence in Construction (EIC) Awards, presented during the Associated Builders and Contractors (ABC) Convention 2026 in Salt Lake City. The EIC Awards celebrate 86 of the nation’s top construction projects from 2025, including school relocations, large-scale renovations and the construction of science parks, apartments and hospitals.
“Our employee-owners operate in demanding conditions that require innovation, technical expertise, informed decision-making and disciplined attention to safety, often in environments where there is no room for error,” says Frank Musolino, CEO of TDIndustries, Inc. “That level of commitment is how TDIndustries earns trust, delivers exceptional results and strengthens the communities we serve.”