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, its RevenueBase Smart Search rating, 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 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 3, 2026 86% judged on-target in blind review
4,315Companies
52,375Contacts tracked
22,256Verified emails
21,356Mobile numbers
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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. RevenueBase Smart Search rates how each company's information relates to green 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.
#CompanyRevenueBase Smart SearchHeadquartersEmployeesContacts
1Indirect evidencePlano, LA, United StatesHQ checked Sep 3, 20261,001-5,0001,631 contacts →

Indirect evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
2Partial evidencePhoenix, AZ, United StatesHQ checked Sep 3, 20261,001-5,0001,618 contacts →

Partial evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
3Partial evidenceFramingham, MA, United StatesHQ checked Sep 3, 20261,001-5,0001,475 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 Sep 3, 2026
4Partial evidenceAnaheim, CA, United StatesHQ checked Sep 3, 20261,001-5,000838 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 Sep 3, 2026
5Partial evidenceOakland, CA, United StatesHQ checked Sep 3, 2026201-500768 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 Sep 3, 2026
6Indirect evidenceLehi, UT, United StatesHQ checked Sep 3, 20265,001-10,000727 contacts →

Indirect evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
7Partial evidenceHalf Moon Bay, AZ, United StatesHQ checked Sep 3, 2026501-1,000724 contacts →

Partial evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
8Indirect evidenceWall Township, NY, United StatesHQ checked Sep 3, 2026201-500452 contacts →

Indirect evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
9Partial evidenceIrvine, VA, United StatesHQ checked Sep 3, 2026201-500382 contacts →

Partial evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
10Indirect evidenceDenver, United StatesHQ checked Sep 3, 2026501-1,000376 contacts →

Indirect evidence

“Established in 2019.”

Source: RevenueBase Database · checked Sep 3, 2026
11Indirect evidenceLong Beach, CA, United StatesHQ checked Sep 3, 2026201-500370 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 Sep 3, 2026
12Partial evidenceEvansville, WY, United StatesHQ checked Sep 3, 20261,001-5,000360 contacts →

Partial evidence

“TAKKION is Moving Energy Forward.”

Source: RevenueBase Database · checked Sep 3, 2026
13Partial evidenceWilliamsville, CT, United StatesHQ checked Sep 3, 2026201-500354 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 Sep 3, 2026
14Partial evidencePhiladelphia, MA, United StatesHQ checked Sep 3, 2026201-500335 contacts →

Partial evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
15Indirect evidenceSan Francisco, CA, United StatesHQ checked Sep 3, 2026201-500325 contacts →

Indirect evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
16Partial evidenceGainesville, FL, United StatesHQ checked Sep 3, 2026201-500303 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 Sep 3, 2026
17Partial evidencePortland, VT, United StatesHQ checked Sep 3, 2026201-500290 contacts →

Partial evidence

“At Cascade Energy, we believe in better.”

Source: RevenueBase Database · checked Sep 3, 2026
18Indirect evidenceLancaster, NY, United StatesHQ checked Sep 3, 20265,001-10,000277 contacts →

Indirect evidence

“E&E is now WSP USA.”

Source: RevenueBase Database · checked Sep 3, 2026
19Indirect evidencePensacola, TX, United StatesHQ checked Sep 3, 20261,001-5,000274 contacts →

Indirect evidence

“People.”

Source: RevenueBase Database · checked Sep 3, 2026
20Strong evidenceKirkland, MA, United StatesHQ checked Sep 3, 2026201-500264 contacts →

Strong evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
21Strong evidenceMinneapolis, MN, United StatesHQ checked Sep 3, 2026201-500263 contacts →

Strong evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
22Strong evidenceRenton, WA, United StatesHQ checked Sep 3, 2026201-500250 contacts →

Strong evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
23Partial evidencePittsfield, ME, United StatesHQ checked Sep 3, 2026201-500221 contacts →

Partial evidence

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

Source: RevenueBase Database · checked Sep 3, 2026
24Partial evidenceBeverly, MA, United StatesHQ checked Sep 3, 2026201-500212 contacts →

Partial evidence

“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: RevenueBase Database · checked Sep 3, 2026
25Partial evidenceFairfax, VA, United StatesHQ checked Sep 3, 2026201-500211 contacts →

Partial evidence

“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: RevenueBase Database · checked Sep 3, 2026

Showing 25 of 4,315 green energy consulting firms based in the United States

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

As of Sep 3, 2026
42.5%Verified-email coverage
40.8%Mobile-number coverage
12.1Average contacts per company
1-10Median size (employees)
4.3%Largest-city concentration · Houston
Sep 3, 2026Page data 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

Freshness & accuracy

How recently the business emails on this list were verified

Email last verified

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 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 “green 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 green 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 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 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, 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.

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 green 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 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.

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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.