Company lists · Data refreshed August 2026

Top 25 Clean energy consulting firms based in the United States

Name: Clean energy consulting firms based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Aug 31, 2026 4,875 companies tracked

RevenueBase identified 4,875 clean energy consulting firms headquartered in the United States as of August 2026 and tracks 70,161 professional contacts across them, including 29,539 with verified work emails and 29,278 with mobile numbers. Houston is the largest hub.

This list covers clean energy consulting firms 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 August 31, 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 RevenueBase Smart Search rating on every row Refreshed Aug 31, 2026 86% judged on-target in blind review

4,875Companies

70,161Contacts tracked

29,539Verified emails

29,278Mobile numbers

Explore this list → Free signup · no credit card · 500 free credits

The 25 largest clean energy consulting firms based in the United States

Ranked by team size

Top 25 of 4,875 clean energy consulting firms based in the United States, ranked by team size, largest first. Data refreshed Aug 31, 2026. RevenueBase Smart Search rates how each company's information relates to clean energy consulting firms: 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	Sargent & Lundy	Indirect evidence	Midland, TX, United States	1,001-5,000	4,145 contacts →
	Indirect evidence “Sargent & Lundy is one of the world’s longest-standing full-service architect engineering firms.” Source: RevenueBase Database · checked Aug 31, 2026
2	FTI	Partial evidence	Menasha, WI, United States	1,001-5,000	2,712 contacts →
	Partial evidence “Faith Technologies Incorporated (FTI) is a dynamic organization comprised of construction, engineering, manufacturing and renewable energy experts.” Source: RevenueBase Database · checked Aug 31, 2026
3	Mckinstry	Partial evidence	Scottsdale, AZ, United States	1,001-5,000	2,198 contacts →
	Partial evidence “We're a national construction and energy services company dedicated to innovating the waste and climate harm out of the built environment.” Source: RevenueBase Database · checked Aug 31, 2026
4	Westwood Professional Services	Indirect evidence	Lake Charles, LA, United States	1,001-5,000	1,631 contacts →
	Indirect evidence “At Westwood, our purpose is to create a better world for people through our work.” Source: RevenueBase Database · checked Aug 31, 2026
5	Ameresco	Partial evidence	Framingham, MA, United States	1,001-5,000	1,475 contacts →
	Partial 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 Aug 31, 2026
6	Willdan	Partial evidence	Anaheim, CA, United States	1,001-5,000	838 contacts →
	Partial evidence “Willdan (NASDAQ: WLDN) provides professional consulting and technical services to utilities, public agencies and private industry throughout the United States.” Source: RevenueBase Database · checked Aug 31, 2026
7	Energy Solutions	Partial evidence	Orange, CA, United States	201-500	768 contacts →
	Partial evidence “Our mission is simple - to combat climate change through market-based, cost-effective energy, carbon, and water management solutions that make big impacts.” Source: RevenueBase Database · checked Aug 31, 2026
8	Resource Innovations	Partial evidence	Chandler, AZ, United States	501-1,000	724 contacts →
	Partial evidence “Resource Innovations (RI) is an energy transformation firm.” Source: RevenueBase Database · checked Aug 31, 2026
9	Capco Energy	Strong evidence	Houston, TX, United States	1,001-5,000	711 contacts →
	Strong evidence “For 25 years Capco’s Energy practice has combined innovative thinking with deep industry knowledge to provide business consulting, digital transformation and technology services…” Source: RevenueBase Database · checked Aug 31, 2026
10	Inerco	Indirect evidence	Delaware, United States	1,001-5,000	682 contacts →
	Indirect evidence “INERCO, with 30 years of experience, offers comprehensive services and develops advanced technologies that contribute to sustainable industrial development, acting as a leader in…” Source: RevenueBase Database · checked Aug 31, 2026
11	Depcom Power, INC	Partial evidence	Bedminster, NJ, United States	1,001-5,000	623 contacts →
	Partial evidence “DEPCOM Power, a Koch Engineered Solutions Company, is a leading solar energy solutions partner providing Development Support, Engineering, Procurement & Construction (EPC)…” Source: RevenueBase Database · checked Aug 31, 2026
12	XODUS	Partial evidence	Boston, MA, United States	201-500	527 contacts →
	Partial evidence “As a global energy consultancy, we unite our unique and diverse people to share knowledge, innovate and inspire change within the energy industry.” Source: RevenueBase Database · checked Aug 31, 2026
13	Natural Power	Partial evidence	Seattle, WA, United States	501-1,000	505 contacts →
	Partial evidence “Natural Power is a leading independent consultancy and service provider for the renewable energy sector.” Source: RevenueBase Database · checked Aug 31, 2026
14	Dupont Water Solutions	Indirect evidence	Wilmington, DE, United States	10001+	472 contacts →
	Indirect evidence “We’re helping companies in every industry, in every corner of the globe make real progress.” Source: RevenueBase Database · checked Aug 31, 2026
15	TRIO	Partial evidence	Mclean, VA, United States	201-500	382 contacts →
	Partial evidence “We are Trio – built from Edison Energy, Alfa Energy, and Altenex Energy.” Source: RevenueBase Database · checked Aug 31, 2026
16	Veregy	Partial evidence	Phoenix, AZ, United States	501-1,000	376 contacts →
	Partial evidence “Veregy is an award-winning NAESCO-Accredited decarbonization company focusing on accelerating and simplifying the Energy Transition.” Source: RevenueBase Database · checked Aug 31, 2026
17	Energyscape Renewables	Indirect evidence	Denver, United States	501-1,000	376 contacts →
	Indirect evidence “Established in 2019.” Source: RevenueBase Database · checked Aug 31, 2026
18	Manhard Consulting	Partial evidence	Fort Worth, TX, United States	201-500	373 contacts →
	Partial evidence “Manhard Consulting has joined Atwell, a national consulting, engineering, and construction services firm with 2,100 technical professionals across the country.” Source: RevenueBase Database · checked Aug 31, 2026
19	P2s	Indirect evidence	Irvine, CA, United States	201-500	370 contacts →
	Indirect evidence “P2S has brought forward-thinking, sustainable engineering solutions to California, the Pacific Northwest, and beyond, for over 30 years.” Source: RevenueBase Database · checked Aug 31, 2026
20	Takkion	Partial evidence	Evansville, WY, United States	1,001-5,000	360 contacts →
	Partial evidence “TAKKION is Moving Energy Forward.” Source: RevenueBase Database · checked Aug 31, 2026
21	Wendel Companies	Partial evidence	Middletown, CT, United States	201-500	354 contacts →
	Partial evidence “Wendel is an Architecture, Engineering, Energy Efficiency, and Construction Management Firm that delivers customized solutions and turnkey projects in innovative ways.” Source: RevenueBase Database · checked Aug 31, 2026
22	Customized Energy Solutions	Partial evidence	Boston, MA, United States	201-500	335 contacts →
	Partial evidence “Customized Energy Solutions is at the forefront of competitive energy markets.” Source: RevenueBase Database · checked Aug 31, 2026
23	U.S. Energy	Indirect evidence	Houston, TX, United States	1,001-5,000	327 contacts →
	Indirect evidence “U.S.” Source: RevenueBase Database · checked Aug 31, 2026
24	3degrees Group, INC	Indirect evidence	San Francisco, CA, United States	201-500	325 contacts →
	Indirect evidence “3Degrees is a leading global climate solutions provider, pioneer of environmental markets, and Certified B Corporation.” Source: RevenueBase Database · checked Aug 31, 2026
25	Environmental Consulting & Technology, Inc. ECT	Partial evidence	Tampa, FL, United States	201-500	303 contacts →
	Partial evidence “Environmental Consulting & Technology, Inc.(ECT) is a multi-disciplinary environmental and sustainability consulting firm delivering strategy, permitting, design, and management…” Source: RevenueBase Database · checked Aug 31, 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: clean energy consulting firms. 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 clean energy consulting firms.
Partial evidence: Its own public description names part of clean energy consulting firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name clean energy consulting firms. 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 4,875 clean energy consulting firms based in the United States

See the full list, filter by size, metro and specialty, and get verified emails and direct dials for all 29,539 reachable decision-makers.

Free signup · no credit card

View the full list →

Clean energy consulting firms based in the United States at a glance

As of Aug 31, 2026

42.1%Verified-email coverage

41.7%Mobile-number coverage

14.4Average contacts per company

1-10Median size (employees)

4.6%Largest-city concentration · Houston

Aug 31, 2026Page data refreshed

Companies by employee count

1-10

3,005

11-50

1,333

51-200

382

201-500

501-1,000

1,001-5,000

10001+

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 clean energy consulting firms, 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 “clean energy consulting firms”. 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 clean energy consulting firms), 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 clean energy consulting firms, 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, 29,539 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 August 31, 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.

Clean energy consulting firms by metro

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 clean energy consulting firms, 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 clean energy consulting firms are there based in the United States?

RevenueBase identified 4,875 clean energy consulting firms headquartered in the United States as of August 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?

Sargent & Lundy, headquartered in Midland, tops this list with the largest team on record.

Which city has the most clean energy consulting firms?

Houston leads with 223 headquartered companies, followed by New York (194) and Denver (96).

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 29,539 verified decision-maker contacts tracked across these 4,875 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on August 31, 2026.

Ready to reach these companies? Verified emails and direct dials for all 4,875 clean energy consulting firms based in the United States. Start with a free account, no credit card.

Download this list →

Related lists

Clean energy consulting firms by geography

Browse the directory

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.