Company lists · Data refreshed October 2026

Top 25 Energy efficiency engineering firms based in the United States

Name: Energy efficiency engineering firms based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Oct 12, 2026 2,752 companies tracked

RevenueBase identified 2,752 company matches for energy efficiency engineering firms associated with the United States as of October 2026 and tracks 74,626 professional contacts across them, including 34,380 with verified work emails. New York is the largest hub.

This list covers company matches for energy efficiency engineering firms associated with the United States, found by RevenueBase SmartSearch using the meaning of business descriptions in its company graph at Exact. Ranked by professionals tracked, largest first. Rows show recorded descriptions where available, Exact search membership and the snapshot date. Data refreshed October 12, 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 RevenueBase SmartSearch · Exact Recorded Oct 12, 2026 How this list was built

2,752Companies

74,626Contacts tracked

34,380Verified emails

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The 25 largest energy efficiency engineering firms based in the United States

Ranked by team size

Top 25 of 2,752 company matches for energy efficiency engineering firms based in the United States, ordered by professional contacts tracked in RevenueBase, largest first. Recorded Oct 12, 2026. The RevenueBase SmartSearch column shows Exact match membership in this saved search. Click a contact count to view that company's people. Totals use company locations recorded by RevenueBase; the displayed preview is a smaller selection.
#	Company	RevenueBase SmartSearch	Headquarters	Employees	Contacts
1	Southland Industries	Exact match	Garden Grove, CA, United StatesHQ recorded Oct 12, 2026	10001+	3,010 contacts →
	Exact match “As one of the nation's largest building systems experts, Southland Industries provides innovative, practical results for your engineering, construction, service, and energy needs.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
2	FTI	Exact match	Menasha, WI, United StatesHQ recorded Oct 12, 2026	1,001-5,000	2,979 contacts →
	Exact match “Faith Technologies Incorporated (FTI) is a dynamic organization comprised of construction, engineering, manufacturing and renewable energy experts.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
3	Langan Engineering & Environmental Services	Exact match	Parsippany, NJ, United StatesHQ recorded Oct 12, 2026	1,001-5,000	2,402 contacts →
	Exact match “Langan's client-focused, highly entrepreneurial culture cultivates an environment of opportunities in which career growth and teamwork flourish.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
4	Mckinstry	Exact match	Seattle, WA, United StatesHQ recorded Oct 12, 2026	1,001-5,000	2,293 contacts →
	Exact match “We're a national construction and energy services company dedicated to innovating the waste and climate harm out of the built environment.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
5	Clearesult	Exact match	Austin, TX, United StatesHQ recorded Oct 12, 2026	1,001-5,000	2,206 contacts →
	Exact match “CLEAResult is the largest provider of energy efficiency, energy transition and energy sustainability services in North America.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
6	IMEG	Exact match	Rock Island, IL, United StatesHQ recorded Oct 12, 2026	1,001-5,000	2,064 contacts →
	Exact match “Leaders in Engineering and Innovation.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
7	Westwood Professional Services	Exact match	Plano, TX, United StatesHQ recorded Oct 12, 2026	1,001-5,000	1,801 contacts →
	Exact match “At Westwood, our purpose is to create a better world for people through our work.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
8	Ameresco	Exact match	Framingham, MA, United StatesHQ recorded Oct 12, 2026	1,001-5,000	1,513 contacts →
	Exact match “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…” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
9	OLA	Exact match	Austin, TX, United StatesHQ recorded Oct 12, 2026	n/a	1,150 contacts →
	Exact match “OLA Sustainability, LLC OLA Sustainability is a consulting firm that focuses on integrating sustainable practices into commercial and multifamily design projects.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
10	Affiliated Engineers, INC	Exact match	Madison, WI, United StatesHQ recorded Oct 12, 2026	1,001-5,000	1,059 contacts →
	Exact match “Affiliated Engineers, Inc.(AEI) provides engineering leadership and whole-mission solutions for complex building, energy, and utility projects.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
11	Willdan	Exact match	Anaheim, CA, United StatesHQ recorded Oct 12, 2026	1,001-5,000	872 contacts →
	Exact match “Willdan (NASDAQ: WLDN) provides professional consulting and technical services to utilities, public agencies and private industry throughout the United States.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
12	Syska Hennessy Group	Exact match	New York, United StatesHQ recorded Oct 12, 2026	501-1,000	835 contacts →
	Exact match “Consult Engineer Commission At Syska Hennessy Group, we create exceptional environments.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
13	PAE	Exact match	Portland, OR, United StatesHQ recorded Oct 12, 2026	201-500	835 contacts →
	Exact match “PAE provides mechanical and electrical engineering design, technology system design, energy modeling and analysis, and more.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
14	Introba	Exact match	St. Louis, MO, United StatesHQ recorded Oct 12, 2026	1,001-5,000	816 contacts →
	Exact match “Introba is one of the world’s largest building engineering and consulting firms with more than employees in offices across the United States, Canada, the United Kingdom, Serbia…” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
15	Resource Innovations	Exact match	Half Moon Bay, CA, United StatesHQ recorded Oct 12, 2026	501-1,000	774 contacts →
	Exact match “Resource Innovations (RI) is an energy transformation firm.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
16	Albireo Energy	Exact match	Edison, NJ, United StatesHQ recorded Oct 12, 2026	1,001-5,000	658 contacts →
	Exact match “Albireo Energy is a leading independent building controls and energy services provider recognized by customers for creating intelligent, high-performance buildings.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
17	Antea Group USA	Exact match	St. Paul, MN, United StatesHQ recorded Oct 12, 2026	1,001-5,000	658 contacts →
	Exact match “Antea Group is an international engineering and environmental consulting firm specializing in full-service solutions in the fields of environment, health and safety, and…” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
18	Vanderweil Engineers	Exact match	Boston, MA, United StatesHQ recorded Oct 12, 2026	201-500	562 contacts →
	Exact match “Vanderweil is a mechanical, electrical, plumbing, fire protection, technology, sustainability, commissioning, and power engineering firm dedicated to providing customized and…” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
19	EBI Consulting	Exact match	Burlington, MA, United StatesHQ recorded Oct 12, 2026	501-1,000	542 contacts →
	Exact match “For 35 years we have been helping investors, lenders, owners, developers, contractors, and property managers reduce risk and optimize their built facilities, infrastructure and…” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
20	Sitelogiq	Exact match	Minneapolis, MN, United StatesHQ recorded Oct 12, 2026	501-1,000	491 contacts →
	Exact match “SitelogIQ provides design, engineering, and construction management services that help organizations nationwide modernize their facilities and infrastructure.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
21	Noresco	Exact match	Westborough, MA, United StatesHQ recorded Oct 12, 2026	201-500	479 contacts →
	Exact match “NORESCO, an OPTERRA company, helps customers modernize aging building systems and upgrade energy and water infrastructure to meet evolving demands.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
22	UMC	Exact match	Lynnwood, WA, United StatesHQ recorded Oct 12, 2026	201-500	420 contacts →
	Exact match “UMC helps clients solve the complex challenges of built environments and their systems.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
23	Veregy	Exact match	Phoenix, MO, United StatesHQ recorded Oct 12, 2026	501-1,000	403 contacts →
	Exact match “Veregy is an award-winning NAESCO-Accredited decarbonization company focusing on accelerating and simplifying the Energy Transition.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
24	Arcxis	Exact match	Houston, TX, United StatesHQ recorded Oct 12, 2026	501-1,000	392 contacts →
	Exact match “ARCXIS (Formerly DPIS Builder Services), is the largest provider of HERS inspections, ENERGY STAR ratings, engineering and design, construction quality assurance and other builder…” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase
25	Energyscape Renewables	Exact match	Denver, United StatesHQ recorded Oct 12, 2026	501-1,000	388 contacts →
	Exact match “Established in 2019.” Recorded in the RevenueBase company graph · Oct 12, 2026 · View company records in RevenueBase

RevenueBase SmartSearch

Describe a niche business in your own words. RevenueBase SmartSearch compares the meaning of your description with company business descriptions compiled in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit.

This list uses Exact for “energy efficiency engineering firms”. Each Exact match badge shows membership in that saved search; it is not an individual similarity score or a service-quality rating. Recorded descriptions are shown where available.

Showing 25 of 2,752 energy efficiency engineering firms based in the United States

See the full list, filter by size, metro and specialty, and access 34,380 tracked professional contacts with verified work emails. Direct dials are available where recorded.

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Energy efficiency engineering firms based in the United States at a glance

As of Oct 12, 2026

46.1%Verified-email coverage

27.1Average contacts per company

1-10Median size (employees)

4.2%Largest-city concentration · New York

Oct 12, 2026Page data refreshed

Companies by employee count

1-10

1,438

11-50

931

51-200

259

201-500

501-1,000

1,001-5,000

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 2,752 companies.

How this list was built

The recorded descriptions help you assess these company matches. Check a company’s website for its current services and locations.

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: Company records associated with the United States whose business descriptions match “energy efficiency engineering firms” by meaning at the Exact setting. Descriptions are compiled in the RevenueBase company graph from public websites, profiles and company information where available; they are not guaranteed quotations from the company's website.
RevenueBase SmartSearch: Describe a niche company in your own words to find businesses by meaning. Exact, Similar, Related and Broad control the breadth of RevenueBase SmartSearch. This saved list uses Exact. Each row's Exact match badge shows inclusion in that search, not an individual score or a service-quality judgment.
Public preview: The public preview omits records without a verified work email. Where headquarters information is recorded, preview rows are also filtered to this page’s location. Dataset totals and geographic summaries describe the full matched records before these preview filters.
Match quality: RevenueBase's August 25, 2026 study assessed 4,198 description/company pairs across matching settings. The publisher reports 86% good or better at Exact. This evaluates the method across queries; it does not audit this individual list. Recorded company descriptions, where available, help you judge each match yourself. Read the full methodology: how the lists are built and what the study measures.
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 displayed company carries at least one verified work email. RevenueBase tracks 34,380 professional contacts with verified work emails across the full matched dataset. 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 October 12, 2026. Lists refresh periodically as the graph is re-checked.
Record context: Company records and descriptions can change. Check the company's website for its current services and locations.

Energy efficiency engineering firms by metro

Frequently asked

What is RevenueBase SmartSearch?

RevenueBase SmartSearch finds niche companies by the meaning of their business descriptions in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit your description. This list uses Exact for “energy efficiency engineering firms”; each Exact match badge shows search membership, not an individual similarity or quality score.

How many energy efficiency engineering firms are there based in the United States?

RevenueBase identified 2,752 company matches for energy efficiency engineering firms associated with the United States as of October 2026, using the meaning of business descriptions at Exact. This is the recorded matched set in the RevenueBase company graph.

What is the largest company on this list?

Southland Industries tops the displayed preview by professional contacts tracked in RevenueBase. Recorded headquarters appear in the company rows.

Which city has the most energy efficiency engineering firms?

New York leads with 115 company records, followed by Houston (80) and Chicago (49).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work limited free results with 500 credits to start. Upgrading provides access to the 34,380 professional contacts with verified work emails tracked across these 2,752 companies; direct dials are available where recorded.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on October 12, 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 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.