Company lists · Data refreshed September 2026

Top 25 Decarbonization consultancies based in the United States

Name: Decarbonization consultancies based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 28, 2026 3,279 companies tracked

RevenueBase identified 3,279 decarbonization consultancies headquartered in the United States as of September 2026 and tracks 56,920 professional contacts across them, including 25,592 with verified work emails. New York is the largest hub.

This list covers decarbonization consultancies 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 28, 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 28, 2026 86% judged on-target in blind review

3,279Companies

56,920Contacts tracked

25,592Verified emails

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The 25 largest decarbonization consultancies based in the United States

Ranked by team size

Top 25 of 3,279 decarbonization consultancies based in the United States, ranked by team size, largest first. Data refreshed Sep 28, 2026. RevenueBase Smart Search rates how each company's information relates to decarbonization consultancies: 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	Chicago, WY, United StatesHQ checked Sep 28, 2026	1,001-5,000	4,156 contacts →
	Indirect evidence “Sargent & Lundy is one of the world’s longest-standing full-service architect engineering firms.” Source: RevenueBase Database · checked Sep 28, 2026
2	Mckinstry	Indirect evidence	Seattle, WA, United StatesHQ checked Sep 28, 2026	1,001-5,000	2,213 contacts →
	Indirect 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 Sep 28, 2026
3	Clearesult	Indirect evidence	Austin, TX, United StatesHQ checked Sep 28, 2026	1,001-5,000	2,121 contacts →
	Indirect evidence “CLEAResult is the largest provider of energy efficiency, energy transition and energy sustainability services in North America.” Source: RevenueBase Database · checked Sep 28, 2026
4	Salas O'brien	Indirect evidence	Irvine, CA, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,843 contacts →
	Indirect evidence “Salas O’Brien is an employee-owned engineering and technical services firm focused on advancing the human experience through the built environment.” Source: RevenueBase Database · checked Sep 28, 2026
5	GE Digital	Indirect evidence	San Ramon, CA, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,763 contacts →
	Indirect evidence “At GE Digital, our focus is clear: delivering software that accelerates a new era of energy.” Source: RevenueBase Database · checked Sep 28, 2026
6	Ameresco	Indirect evidence	Framingham, MA, United StatesHQ checked Sep 28, 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 28, 2026
7	OLA	Indirect evidence	Austin, TX, United StatesHQ checked Sep 28, 2026	n/a	1,145 contacts →
	Indirect evidence “OLA Sustainability, LLC OLA Sustainability is a consulting firm that focuses on integrating sustainable practices into commercial and multifamily design projects.” Source: RevenueBase Database · checked Sep 28, 2026
8	California Resources Corporation	Indirect evidence	Los Angeles, CA, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,095 contacts →
	Indirect evidence “California Resources Corporation (CRC) is an independent energy and carbon management company committed to energy transition.” Source: RevenueBase Database · checked Sep 28, 2026
9	Willdan	Indirect evidence	Anaheim, CA, United StatesHQ checked Sep 28, 2026	1,001-5,000	851 contacts →
	Indirect 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 28, 2026
10	Energy Solutions	Indirect evidence	Oakland, CA, United StatesHQ checked Sep 28, 2026	201-500	772 contacts →
	Indirect 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 28, 2026
11	Resource Innovations	Indirect evidence	Half Moon Bay, CA, United StatesHQ checked Sep 28, 2026	501-1,000	733 contacts →
	Indirect evidence “Resource Innovations (RI) is an energy transformation firm.” Source: RevenueBase Database · checked Sep 28, 2026
12	Watershed	Indirect evidence	San Francisco, CA, United StatesHQ checked Sep 28, 2026	201-500	529 contacts →
	Indirect evidence “Watershed is the enterprise sustainability platform.” Source: RevenueBase Database · checked Sep 28, 2026
13	Synergy Consulting, INC	Indirect evidence	Washington, DC, United StatesHQ checked Sep 28, 2026	51-200	434 contacts →
	Indirect evidence “Synergy Consulting is Global Leader in Financial and Corporate Advisory.” Source: RevenueBase Database · checked Sep 28, 2026
14	Veregy	Partial evidence	Phoenix, MO, United StatesHQ checked Sep 28, 2026	501-1,000	383 contacts →
	Partial evidence “Veregy is an award-winning NAESCO-Accredited decarbonization company focusing on accelerating and simplifying the Energy Transition.” Source: RevenueBase Database · checked Sep 28, 2026
15	TRIO	Indirect evidence	Irvine, CA, United StatesHQ checked Sep 28, 2026	201-500	383 contacts →
	Indirect evidence “We are Trio – built from Edison Energy, Alfa Energy, and Altenex Energy.” Source: RevenueBase Database · checked Sep 28, 2026
16	P2s	Indirect evidence	Long Beach, CA, United StatesHQ checked Sep 28, 2026	201-500	375 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 28, 2026
17	NUS Consulting Group	Indirect evidence	Park Ridge, NJ, United StatesHQ checked Sep 28, 2026	201-500	336 contacts →
	Indirect evidence “National Utility Service, Inc.” Source: RevenueBase Database · checked Sep 28, 2026
18	Customized Energy Solutions	Indirect evidence	Philadelphia, PA, United StatesHQ checked Sep 28, 2026	201-500	330 contacts →
	Indirect evidence “Customized Energy Solutions is at the forefront of competitive energy markets.” Source: RevenueBase Database · checked Sep 28, 2026
19	3degrees Group, INC	Indirect evidence	San Francisco, CA, United StatesHQ checked Sep 28, 2026	201-500	324 contacts →
	Indirect evidence “3Degrees is a leading global climate solutions provider, pioneer of environmental markets, and Certified B Corporation.” Source: RevenueBase Database · checked Sep 28, 2026
20	Greenly	Indirect evidence	New York, NY, United StatesHQ checked Sep 28, 2026	201-500	305 contacts →
	Indirect evidence “Greenly is on a mission to democratize access to science-backed climate intelligence, transforming sustainability from a compliance burden into a strategic competitive advantage.” Source: RevenueBase Database · checked Sep 28, 2026
21	Environmental Consulting & Technology, Inc. ECT	Indirect evidence	Gainesville, FL, United StatesHQ checked Sep 28, 2026	201-500	305 contacts →
	Indirect 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 28, 2026
22	Picarro	Indirect evidence	Santa Clara, CA, United StatesHQ checked Sep 28, 2026	201-500	297 contacts →
	Indirect evidence “Reducing emissions, detecting leaks, mitigating risk, optimizing operations, ensuring compliance and advancing research are some of the challenges facing our clients.” Source: RevenueBase Database · checked Sep 28, 2026
23	Cascade Energy	Indirect evidence	Portland, OR, United StatesHQ checked Sep 28, 2026	201-500	288 contacts →
	Indirect evidence “At Cascade Energy, we believe in better.” Source: RevenueBase Database · checked Sep 28, 2026
24	Climate Policy Initiative	Indirect evidence	San Francisco, CA, United StatesHQ checked Sep 28, 2026	51-200	288 contacts →
	Indirect evidence “CPI is an analysis and advisory organization with deep expertise in finance and policy.” Source: RevenueBase Database · checked Sep 28, 2026
25	Lake Superior Consulting	Indirect evidence	Duluth, MN, United StatesHQ checked Sep 28, 2026	201-500	281 contacts →
	Indirect evidence “We act as an extension of your team, combining deep energy expertise with seamless alignment to your processes to advance projects with confidence.” Source: RevenueBase Database · checked Sep 28, 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: decarbonization consultancies. 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 decarbonization consultancies.
Partial evidence: Its own public description names part of decarbonization consultancies, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name decarbonization consultancies. 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 3,279 decarbonization consultancies based in the United States

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Decarbonization consultancies based in the United States at a glance

As of Sep 28, 2026

45.0%Verified-email coverage

17.4Average contacts per company

1-10Median size (employees)

6.3%Largest-city concentration · New York

Sep 28, 2026Page data refreshed

Companies by employee count

1-10

2,219

11-50

775

51-200

194

201-500

501-1,000

1,001-5,000

5,001-10,000

10001+

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 3,279 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 decarbonization consultancies, 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 “decarbonization consultancies”. 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 decarbonization consultancies), 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 decarbonization consultancies, 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, 25,592 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 28, 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.

Decarbonization consultancies 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 decarbonization consultancies, 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 decarbonization consultancies are there based in the United States?

RevenueBase identified 3,279 decarbonization consultancies 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?

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

Which city has the most decarbonization consultancies?

New York leads with 207 headquartered companies, followed by Houston (198) and Washington (88).

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 25,592 verified decision-maker contacts tracked across these 3,279 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 28, 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.