Company lists · Data refreshed September 2026

Top 25 Green energy consulting firms based in the United States

RevenueBase identified 4,315 green energy consulting firms headquartered in the United States as of September 2026 and tracks 52,375 professional contacts across them, including 22,256 with verified work emails and 21,356 with mobile numbers. Houston is the largest hub.

This list covers green 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, how directly it supports the match, and when it was last checked. Data refreshed September 3, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase SmartSearch, 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 Match evidence on every row Refreshed Sep 3, 2026 86% judged on-target in blind review
4,315Companies
52,375Contacts tracked
22,256Verified emails
21,356Mobile numbers
Unlock all 4,315 companies Free signup · no credit card · 500 free credits

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

Ranked by team size
Top 25 of 4,315 green energy consulting firms based in the United States, ranked by team size, largest first. Data refreshed Sep 3, 2026. Evidence rates how directly each company's own description names green energy consulting firms: strong (names it), partial (names part of it), indirect (matched on its full profile rather than the summary shown). Click a count to unlock that company's people.
#CompanyHeadquartersEmployeesContacts
1Plano, LA, United StatesHQ checked Sep 3, 20261,001-5,0001,631

“At Westwood, our purpose is to create a better world for people through our work.”

Source: company website · checked Sep 3, 2026
2Phoenix, AZ, United StatesHQ checked Sep 3, 20261,001-5,0001,618

“Founded on a commitment to sound science and creative solutions, SWCA is a leader in environmental and management consulting services.”

Source: company website · checked Sep 3, 2026
3
AmerescoPartial evidence
Framingham, MA, United StatesHQ checked Sep 3, 20261,001-5,0001,475

“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: company website · checked Sep 3, 2026
4
WilldanPartial evidence
Anaheim, CA, United StatesHQ checked Sep 3, 20261,001-5,000838

“Willdan (NASDAQ: WLDN) provides professional consulting and technical services to utilities, public agencies and private industry throughout the United States.”

Source: company website · checked Sep 3, 2026
5
Energy SolutionsPartial evidence
Oakland, CA, United StatesHQ checked Sep 3, 2026201-500768

“Our mission is simple - to combat climate change through market-based, cost-effective energy, carbon, and water management solutions that make big impacts.”

Source: company website · checked Sep 3, 2026
6
LUMIOIndirect evidence
Lehi, UT, United StatesHQ checked Sep 3, 20265,001-10,000727

“We’re on a mission to make power personal.”

Source: company website · checked Sep 3, 2026
7
Resource InnovationsPartial evidence
Half Moon Bay, AZ, United StatesHQ checked Sep 3, 2026501-1,000724

“Resource Innovations (RI) is an energy transformation firm.”

Source: company website · checked Sep 3, 2026
8Wall Township, NY, United StatesHQ checked Sep 3, 2026201-500452

“We are Groundwater & Environmental Services, Inc, better known as GES.”

Source: company website · checked Sep 3, 2026
9
TRIOPartial evidence
Irvine, VA, United StatesHQ checked Sep 3, 2026201-500382

“We are Trio – built from Edison Energy, Alfa Energy, and Altenex Energy.”

Source: company website · checked Sep 3, 2026
10
Energyscape RenewablesIndirect evidence
Denver, United StatesHQ checked Sep 3, 2026501-1,000376

“Established in 2019.”

Source: company website · checked Sep 3, 2026
11
P2sIndirect evidence
Long Beach, CA, United StatesHQ checked Sep 3, 2026201-500370

“P2S has brought forward-thinking, sustainable engineering solutions to California, the Pacific Northwest, and beyond, for over 30 years.”

Source: company website · checked Sep 3, 2026
12
TakkionPartial evidence
Evansville, WY, United StatesHQ checked Sep 3, 20261,001-5,000360

“TAKKION is Moving Energy Forward.”

Source: company website · checked Sep 3, 2026
13
Wendel CompaniesPartial evidence
Williamsville, CT, United StatesHQ checked Sep 3, 2026201-500354

“Wendel is an Architecture, Engineering, Energy Efficiency, and Construction Management Firm that delivers customized solutions and turnkey projects in innovative ways.”

Source: company website · checked Sep 3, 2026
14Philadelphia, MA, United StatesHQ checked Sep 3, 2026201-500335

“Customized Energy Solutions is at the forefront of competitive energy markets.”

Source: company website · checked Sep 3, 2026
15
3degrees Group, INCIndirect evidence
San Francisco, CA, United StatesHQ checked Sep 3, 2026201-500325

“3Degrees is a leading global climate solutions provider, pioneer of environmental markets, and Certified B Corporation.”

Source: company website · checked Sep 3, 2026
16Gainesville, FL, United StatesHQ checked Sep 3, 2026201-500303

“Environmental Consulting & Technology, Inc.(ECT) is a multi-disciplinary environmental and sustainability consulting firm delivering strategy, permitting, design, and management…”

Source: company website · checked Sep 3, 2026
17
Cascade EnergyPartial evidence
Portland, VT, United StatesHQ checked Sep 3, 2026201-500290

“At Cascade Energy, we believe in better.”

Source: company website · checked Sep 3, 2026
18Lancaster, NY, United StatesHQ checked Sep 3, 20265,001-10,000277

“E&E is now WSP USA.”

Source: company website · checked Sep 3, 2026
19
Meraki SolarIndirect evidence
Pensacola, TX, United StatesHQ checked Sep 3, 20261,001-5,000274

“People.”

Source: company website · checked Sep 3, 2026
20
PSC ConsultingStrong evidence
Kirkland, MA, United StatesHQ checked Sep 3, 2026201-500264

“We provide global renewable energy consulting services, focused on empowering clients to navigate the complexities of the energy transition.”

Source: company website · checked Sep 3, 2026
21
MerjentStrong evidence
Minneapolis, MN, United StatesHQ checked Sep 3, 2026201-500263

“Merjent is an environmental, restoration, and engineering consulting firm with a long history serving the energy industry.”

Source: company website · checked Sep 3, 2026
22
MosaicStrong evidence
Renton, WA, United StatesHQ checked Sep 3, 2026201-500250

“Mosaic is a consulting firm that delivers custom solutions across the energy, utility, grid operations, and grid modernization space.”

Source: company website · checked Sep 3, 2026
23
Kleinschmidt AssociatesPartial evidence
Pittsfield, ME, United StatesHQ checked Sep 3, 2026201-500221

“At Kleinschmidt, we work primarily with energy companies and government agencies in North America to protect and enhance the environment without compromising performance.”

Source: company website · checked Sep 3, 2026
24
Dalkia Energy SolutionsPartial evidence
Beverly, MA, United StatesHQ checked Sep 3, 2026201-500212

“Dalkia Energy Solutions, a subsidiary of the EDF (Électricité de France) Group, is a national leader in energy efficiency and sustainability for commercial, industrial, and…”

Source: company website · checked Sep 3, 2026
25
PEGPartial evidence
Fairfax, VA, United StatesHQ checked Sep 3, 2026201-500211

“PEG presents a comprehensive capacity for the evaluation and understanding of a broad base of energy and environmental sustainability related programs, policies and initiatives.”

Source: company website · checked Sep 3, 2026

Showing 25 of 4,315 green 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 22,256 reachable decision-makers.

Free signup · no credit card

See all 4,315 companies

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

As of Sep 3, 2026
1-10Median size (employees)
HoustonLargest hub · 184 HQs
21,356Contacts with mobile numbers
Sep 3, 2026Data refreshed

Companies by employee count

1-10
2,732
11-50
1,150
51-200
314
201-500
65
501-1,000
12
1,001-5,000
23
5,001-10,000
3

Verified emails by last verification

0–30
0
31–60
1,810
61–90
12,934
90–180
7,412
180+
100

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 green energy consulting firms, so some rows will be adjacent to the category rather than pure plays. The description and evidence 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 SmartSearch, 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 “green energy consulting firms”. Matching reads each company's description, not its industry code or its name.
What we exclude
Companies whose own description does not clearly place them among green 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 an evidence 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, 22,256 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 3, 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.

Green energy consulting firms by metro

  • Green energy consulting firms in Houston184
  • Green energy consulting firms in New York162
  • Green energy consulting firms in Denver90
  • Green energy consulting firms in Chicago86
  • Green energy consulting firms in Washington84
  • Green energy consulting firms in San Francisco64
  • Green energy consulting firms in Austin63

Frequently asked

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

RevenueBase identified 4,315 green energy consulting firms 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?

Westwood Professional Services, headquartered in Lake Charles, tops this list with the largest team on record.

Which city has the most green energy consulting firms?

Houston leads with 184 headquartered companies, followed by New York (162) and Denver (90).

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 22,256 verified decision-maker contacts tracked across these 4,315 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 3, 2026.

Ready to reach these companies? Verified emails and direct dials for all 4,315 green energy consulting firms based in the United States. Start with a free account, no credit card.

Get the full list

Related lists

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 SmartSearch, 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.