Company lists · Data verified 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 Verified Aug 28, 2026 4,875 companies tracked

There are 4,875 clean energy consulting firms headquartered in the United States (RevenueBase, August 2026). RevenueBase 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. Data current as of August 28, 2026.

4,875Companies

70,161Contacts tracked

29,539Verified emails

29,278Mobile numbers

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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 verified Aug 28, 2026. Click a count to unlock that company's people.
#	Company	HQ	Employees	Contacts	Verified emails
1	Sargent & Lundy	Midland, TX	1,001-5,000	4,145	1,118
2	FTI	Menasha, WI	1,001-5,000	2,712	1,126
3	Mckinstry	Scottsdale, AZ	1,001-5,000	2,198	1,583
4	Westwood Professional Services	Lake Charles, LA	1,001-5,000	1,631	1,058
5	Ameresco	Framingham, MA	1,001-5,000	1,475	1,125
6	Willdan	Anaheim, CA	1,001-5,000	838	636
7	Energy Solutions	Orange, CA	201-500	768	419
8	Resource Innovations	Chandler, AZ	501-1,000	724	558
9	Capco Energy	Houston, TX	1,001-5,000	711	152
10	Inerco	Delaware	1,001-5,000	682	90
11	Depcom Power, INC	Bedminster, NJ	1,001-5,000	623	273
12	XODUS	Boston, MA	201-500	527	302
13	Natural Power	Seattle, WA	501-1,000	505	349
14	Dupont Water Solutions	Wilmington, DE	10001+	472	178
15	TRIO	Mclean, VA	201-500	382	245
16	Veregy	Phoenix, AZ	501-1,000	376	284
17	Energyscape Renewables	Denver	501-1,000	376	205
18	Manhard Consulting	Fort Worth, TX	201-500	373	215
19	P2s	Irvine, CA	201-500	370	208
20	Takkion	Evansville, WY	1,001-5,000	360	128
21	Wendel Companies	Middletown, CT	201-500	354	238
22	Customized Energy Solutions	Boston, MA	201-500	335	229
23	U.S. Energy	Houston, TX	1,001-5,000	327	130
24	3degrees Group, INC	San Francisco, CA	201-500	325	216
25	Environmental Consulting & Technology, Inc. ECT	Tampa, FL	201-500	303	176

Showing 25 of 4,875 clean energy consulting firms based in the United States

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

As of Aug 28, 2026

1-10Median size (employees)

HoustonLargest hub · 223 HQs

29,278Contacts with mobile numbers

178Emails re-verified in last 30 days

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+

Clean energy consulting firms by metro

Metro	Companies
Clean energy consulting firms in Houston	223
Clean energy consulting firms in New York	194
Clean energy consulting firms in Denver	96
Clean energy consulting firms in Washington	95
Clean energy consulting firms in Chicago	90
Clean energy consulting firms in Austin	79
Clean energy consulting firms in Los Angeles	69

How this list was built

Source: The RevenueBase company graph: 21.3 million companies and 398.9 million professional contacts resolved from primary sources.
Inclusion: Companies whose own business descriptions match “clean energy consulting firms”, with match quality audited by blind human judging, and headquartered in the United States.
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: Contact records re-verify on a rolling cadence; 178 contacts on this list were re-verified in the last 30 days.
Refresh: Lists are refreshed periodically as the underlying company graph is re-verified. Last verified Aug 28, 2026.

Frequently asked

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

There are 4,875 clean energy consulting firms headquartered in the United States as of August 2026 (RevenueBase).

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 is refreshed periodically as the underlying company graph is re-verified. It was last verified on August 28, 2026.

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About this data

RevenueBase is a B2B contact data platform. Its company graph covers 21.3 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, the same data that powers RevenueBase's B2B data products and the free research portal.