Company lists · Data refreshed September 2026

Top 25 Retrofit engineering companies based in the United States

Name: Retrofit engineering companies based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 17, 2026 290 companies tracked

RevenueBase identified 290 retrofit engineering companies headquartered in the United States as of September 2026 and tracks 12,176 professional contacts across them, including 4,957 with verified work emails. New York is the largest hub.

This list covers retrofit engineering companies headquartered in the United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 17, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 17, 2026 86% judged on-target in blind review

290Companies

12,176Contacts tracked

4,957Verified emails

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The 25 largest retrofit engineering companies based in the United States

Ranked by team size

Top 25 of 290 retrofit engineering companies based in the United States, ranked by team size, largest first. Data refreshed Sep 17, 2026. RevenueBase Smart Search rates how each company's information relates to retrofit engineering companies: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Ameresco	Indirect evidence	Framingham, MA, United StatesHQ checked Sep 17, 2026	1,001-5,000	1,383 contacts →
	Indirect evidence “Ameresco, Inc.(NYSE:AMRC) is a leading energy infrastructure solutions provider dedicated to helping customers reduce costs, enhance resilience, and decarbonize to net zero in the…” Source: RevenueBase Database · checked Sep 17, 2026
2	NPL Construction CO	Indirect evidence	Phoenix, AZ, United StatesHQ checked Sep 17, 2026	5,001-10,000	1,358 contacts →
	Indirect evidence “NPL is a nationally recognized leader in energy infrastructure construction, with 50 years of experience.” Source: RevenueBase Database · checked Sep 17, 2026
3	Structural Technologies	Partial evidence	Columbia, MD, United StatesHQ checked Sep 17, 2026	1,001-5,000	658 contacts →
	Partial evidence “STRUCTURAL TECHNOLOGIES develops, markets, and integrates proprietary products with specialty engineering services to improve, protect, and enhance infrastructure.” Source: RevenueBase Database · checked Sep 17, 2026
4	Baker Group	Indirect evidence	Ankeny, IA, United StatesHQ checked Sep 17, 2026	1,001-5,000	655 contacts →
	Indirect evidence “Established in 1963, Baker Group is Iowa’s premier full-service specialty contractor-serving commercial, industrial, institutional, and mission-critical markets across the country.” Source: RevenueBase Database · checked Sep 17, 2026
5	Structural	Indirect evidence	Columbia, MD, United StatesHQ checked Sep 17, 2026	1,001-5,000	611 contacts →
	Indirect evidence “STRUCTURAL integrates technology-driven solutions into its industry-leading specialty contracting services.” Source: RevenueBase Database · checked Sep 17, 2026
6	Mastec Utility Services	Indirect evidence	Coral Gables, FL, United StatesHQ checked Sep 17, 2026	1,001-5,000	562 contacts →
	Indirect evidence “WE'RE HIRING FOR POWER, GAS, & INFRASTRUCTURE ROLES ACROSS THE COUNTRY!* Join the Team That Keeps Energy and Infrastructure Moving Forward.” Source: RevenueBase Database · checked Sep 17, 2026
7	Noresco	Indirect evidence	Westborough, MA, United StatesHQ checked Sep 17, 2026	201-500	481 contacts →
	Indirect evidence “NORESCO, a part of Carrier Global Corporation, helps customers modernize aging building systems and upgrade energy and water infrastructure to meet evolving demands.” Source: RevenueBase Database · checked Sep 17, 2026
8	Sitelogiq	Partial evidence	Minneapolis, MN, United StatesHQ checked Sep 17, 2026	501-1,000	450 contacts →
	Partial evidence “SitelogIQ provides design, engineering, and construction management services that help organizations nationwide modernize their facilities and infrastructure.” Source: RevenueBase Database · checked Sep 17, 2026
9	Western Industrial Contractors	Indirect evidence	Aurora, CO, United StatesHQ checked Sep 17, 2026	201-500	285 contacts →
	Indirect evidence “Western Industrial Contractors (WIC) is a single-source systems integrator, we design, build, and integrate complex industrial systems under one roof, so you manage one…” Source: RevenueBase Database · checked Sep 17, 2026
10	Palnies	Partial evidence	Schaumburg, IL, United StatesHQ checked Sep 17, 2026	1,001-5,000	231 contacts →
	Partial evidence “PalniES applies technology to deliver unique, cost-effective engineering and design solutions–-and fast.” Source: RevenueBase Database · checked Sep 17, 2026
11	Allana Buick & Bers, INC	Partial evidence	Palo Alto, CA, United StatesHQ checked Sep 17, 2026	201-500	229 contacts →
	Partial evidence “Allana Buick & Bers, Inc.(ABB) is a leading Architectural Engineering firm specializing in making buildings perform better by making them energy efficient and longer lasting with…” Source: RevenueBase Database · checked Sep 17, 2026
12	Robert Derector Associates	Partial evidence	New York, NY, United StatesHQ checked Sep 17, 2026	51-200	186 contacts →
	Partial evidence “Robert Derector Associates is a full service engineering firm with a local feel and a global reach.” Source: RevenueBase Database · checked Sep 17, 2026
13	Mcclure Company	Partial evidence	Harrisburg, PA, United StatesHQ checked Sep 17, 2026	201-500	166 contacts →
	Partial evidence “Headquartered in Harrisburg, Pennsylvania, McClure Company is one of the mid-Atlantic's largest, fully integrated mechanical construction, engineering, maintenance and energy…” Source: RevenueBase Database · checked Sep 17, 2026
14	Voltyx	Indirect evidence	Maryland Heights, MO, United StatesHQ checked Sep 17, 2026	201-500	135 contacts →
	Indirect evidence “Voltyx is an integrated solutions provider focused on guiding our partners through the complex modernization of the electrical infrastructure through vision, strategy, service…” Source: RevenueBase Database · checked Sep 17, 2026
15	Willdan Performance Engineering	Partial evidence	Denver, KS, United StatesHQ checked Sep 17, 2026	51-200	129 contacts →
	Partial evidence “Willdan Performance Engineering specializes in energy and infrastructure improvement projects through design-build and performance contracting.” Source: RevenueBase Database · checked Sep 17, 2026
16	Cypress Envirosystems	Indirect evidence	San Jose, CA, United StatesHQ checked Sep 17, 2026	11-50	128 contacts →
	Indirect evidence “We Make Buildings Brilliant.” Source: RevenueBase Database · checked Sep 17, 2026
17	Neal Electric Corp	Indirect evidence	Carlsbad, CA, United StatesHQ checked Sep 17, 2026	201-500	126 contacts →
	Indirect evidence “For over four decades, Neal Electric has been at the forefront of delivering proficient and reliable electrical services across Southern California.” Source: RevenueBase Database · checked Sep 17, 2026
18	Stronghold Engineering	Partial evidence	Perris, CA, United StatesHQ checked Sep 17, 2026	51-200	103 contacts →
	Partial evidence “Stronghold Engineering (SEI) is an award-winning design and construction firm specializing in renowned projects for some of the nation’s largest organizations.” Source: RevenueBase Database · checked Sep 17, 2026
19	4liberty, INC	Indirect evidence	San Diego, CA, United StatesHQ checked Sep 17, 2026	51-200	93 contacts →
	Indirect evidence “4Liberty is a leading technical & professional services firm focused on energy & infrastructure.” Source: RevenueBase Database · checked Sep 17, 2026
20	The Will Group	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 17, 2026	51-200	93 contacts →
	Indirect evidence “What We Do.” Source: RevenueBase Database · checked Sep 17, 2026
21	HOUCK	Indirect evidence	Harrisburg, PA, United StatesHQ checked Sep 17, 2026	201-500	84 contacts →
	Indirect evidence “Houck has been serving the mid-Atlantic region for over 75 years with offices in Harrisburg and Greencastle, PA.” Source: RevenueBase Database · checked Sep 17, 2026
22	TEI Electrical Solutions	Indirect evidence	Frederick, MD, United StatesHQ checked Sep 17, 2026	51-200	64 contacts →
	Indirect evidence “At TEI our focus is on Electrical Solutions and providing quality workmanship in all aspects of new construction and renovation projects for both the public and private sectors.” Source: RevenueBase Database · checked Sep 17, 2026
23	DFS Construction Corporation	Indirect evidence	Arlington, VA, United StatesHQ checked Sep 17, 2026	51-200	62 contacts →
	Indirect evidence “DFS Construction Corporation was founded on the singular principle of being the most responsible construction choice available to our clients.” Source: RevenueBase Database · checked Sep 17, 2026
24	Taylor & Hill	Indirect evidence	Texas City, TX, United StatesHQ checked Sep 17, 2026	51-200	62 contacts →
	Indirect evidence “Taylor & Hill, Inc.” Source: RevenueBase Database · checked Sep 17, 2026
25	LLI Engineering	Partial evidence	Pittsburgh, PA, United StatesHQ checked Sep 17, 2026	11-50	54 contacts →
	Partial evidence “Founded in 1910 in Pittsburgh, Pennsylvania, LLI Engineering a veteran owned small business, specializes in commercial, critical facilities, infrastructure upgrades, Green…” Source: RevenueBase Database · checked Sep 17, 2026

RevenueBase Smart Search

RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: retrofit engineering companies. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.

Strong evidence: The company's own public description of its business names retrofit engineering companies.
Partial evidence: Its own public description names part of retrofit engineering companies, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name retrofit engineering companies. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.

RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.

Showing 25 of 290 retrofit engineering companies based in the United States

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Retrofit engineering companies based in the United States at a glance

As of Sep 17, 2026

40.7%Verified-email coverage

42.0Average contacts per company

11-50Median size (employees)

2.8%Largest-city concentration · New York

Sep 17, 2026Page data refreshed

Companies by employee count

1-10

11-50

125

51-200

201-500

501-1,000

1,001-5,000

5,001-10,000

Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 290 companies.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among retrofit engineering companies, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
What qualifies: Companies headquartered in the United States whose own description of what they do matches “retrofit engineering companies”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search: RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names retrofit engineering companies), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude: Companies whose own description does not clearly place them among retrofit engineering companies, and records with no verified work email. Companies headquartered outside United States are excluded even when they keep an office there.
Match quality: In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking: Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification: Every listed company carries at least one verified work email, 4,957 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh: This page's figures were pulled from the company graph on September 17, 2026. Lists refresh periodically as the graph is re-checked.
Corrections: Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names retrofit engineering companies, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many retrofit engineering companies are there based in the United States?

RevenueBase identified 290 retrofit engineering companies headquartered in the United States as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

Ameresco, headquartered in Framingham, tops this list with the largest team on record.

Which city has the most retrofit engineering companies?

New York leads with 8 headquartered companies, followed by Los Angeles (7) and Chicago (6).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 4,957 verified decision-maker contacts tracked across these 290 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 17, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.