Company lists · Data refreshed September 2026

Top 25 Net-zero retrofit consultants worldwide

RevenueBase identified 2,942 net-zero retrofit consultants worldwide as of September 2026 and tracks 21,912 professional contacts across them, including 7,727 with verified work emails. The United States is the largest market and London the largest hub.

This list covers net-zero retrofit consultants worldwide, 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 29, 2026. Country and city lists for net-zero retrofit consultants follow the table.

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 29, 2026 86% judged on-target in blind review
2,942Companies
21,912Contacts tracked
7,727Verified emails
Explore this list → Free signup · no credit card · 500 free credits

The 25 largest net-zero retrofit consultants worldwide

Ranked by team size
Top 25 of 2,942 net-zero retrofit consultants worldwide, ranked by team size, largest first. Data refreshed Sep 29, 2026. RevenueBase Smart Search rates how each company's information relates to net-zero retrofit consultants: 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 evidenceAustin, TX, United StatesHQ checked Sep 29, 2026n/a1,145 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 29, 2026
2Indirect evidenceRiyadh, Saudi ArabiaHQ checked Sep 29, 2026201-500342 contacts →

Indirect evidence

“The National Energy Services Company (TARSHID) is a national company wholly owned by the Public Investment Fund (PIF).”

Source: RevenueBase Database · checked Sep 29, 2026
3Indirect evidenceBirmingham, United KingdomHQ checked Sep 29, 2026201-500317 contacts →

Indirect evidence

“Climate change is without a doubt the greatest challenge we face in these times.”

Source: RevenueBase Database · checked Sep 29, 2026
4Indirect evidenceBirmingham, United KingdomHQ checked Sep 29, 2026501-1,000253 contacts →

Indirect evidence

Source: RevenueBase Database · checked Sep 29, 2026
5Indirect evidenceQuébec, QC, CanadaHQ checked Sep 29, 2026201-500238 contacts →

Indirect evidence

“At Ecosystem, we believe in building meaningful relationships with both our clients and employees.”

Source: RevenueBase Database · checked Sep 29, 2026
6Indirect evidenceNew York, NY, United StatesHQ checked Sep 29, 2026201-500233 contacts →

Indirect evidence

“As of November of 2025, AMA Group has merged with CMTA!”

Source: RevenueBase Database · checked Sep 29, 2026
7Indirect evidenceBeverly, MA, United StatesHQ checked Sep 29, 2026201-500210 contacts →

Indirect 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 29, 2026
8Indirect evidenceNew York, NY, United StatesHQ checked Sep 29, 202651-200205 contacts →

Indirect evidence

“Bright Power is a leading provider of energy efficiency and decarbonization solutions for the real estate industry.”

Source: RevenueBase Database · checked Sep 29, 2026
9Strong evidenceChilworth, United KingdomHQ checked Sep 29, 202651-200157 contacts →

Strong evidence

“Zenergi supports and empowers your journey to net zero.”

Source: RevenueBase Database · checked Sep 29, 2026
10Indirect evidenceBoulogne-billancourt, FranceHQ checked Sep 29, 202651-200149 contacts →

Indirect evidence

“Accenta aide les acteurs de l’immobilier à maîtriser leurs charges, valoriser leurs actifs et répondre aux exigences réglementaires, grâce à la performance énergie-carbone.”

Source: RevenueBase Database · checked Sep 29, 2026
11Strong evidenceBourne End, United KingdomHQ checked Sep 29, 202651-200144 contacts →

Strong evidence

“Trailblazing the way to net zero smart buildings Our cutting-edge PROActiv Solutions enhance the health, energy efficiency and sustainability of UK businesses and commercial…”

Source: RevenueBase Database · checked Sep 29, 2026
12Indirect evidenceBristol, United KingdomHQ checked Sep 29, 202651-200142 contacts →

Indirect evidence

“Optimised exists to accelerate the shift to a low-carbon future by making energy management work; commercially, operationally and sustainably.”

Source: RevenueBase Database · checked Sep 29, 2026
13Indirect evidenceParis, FranceHQ checked Sep 29, 202651-200139 contacts →

Indirect evidence

“Sénova est "le partenaire de la rénovation énergétique de votre habitat".”

Source: RevenueBase Database · checked Sep 29, 2026
14Indirect evidenceLjubljana, SloveniaHQ checked Sep 29, 202651-200130 contacts →

Indirect evidence

“Resalta is a leading European energy service company (ESCO) helping organizations reduce costs, lower emissions, and optimize energy use.”

Source: RevenueBase Database · checked Sep 29, 2026
15Partial evidenceLeicester, United KingdomHQ checked Sep 29, 202651-200129 contacts →

Partial evidence

“Recognised as the Consultancy of the Year in 2021 by Energy Live News, Consultus delivers world-class consulting, buying and management services for Business Energy and Business…”

Source: RevenueBase Database · checked Sep 29, 2026
16Indirect evidenceSan Jose, CA, United StatesHQ checked Sep 29, 202611-50128 contacts →

Indirect evidence

“We Make Buildings Brilliant.”

Source: RevenueBase Database · checked Sep 29, 2026
17Indirect evidenceBerlin, GermanyHQ checked Sep 29, 202651-200125 contacts →

Indirect evidence

“ecoworks is the trusted partner for the housing sector when it comes to affordable, energy-efficient renovations.”

Source: RevenueBase Database · checked Sep 29, 2026
18Strong evidenceAmsterdam, NetherlandsHQ checked Sep 29, 202651-200123 contacts →

Strong evidence

“OTC Flow is your partner in achieving net zero emissions, providing customized solutions for your financial-environmental obligations and aspirations.”

Source: RevenueBase Database · checked Sep 29, 2026
19Indirect evidenceLa Crosse, WI, United StatesHQ checked Sep 29, 202651-200121 contacts →

Indirect evidence

“Michaels Energy is a veteran-owned energy consulting firm that exists to help businesses minimize waste and maximize value.”

Source: RevenueBase Database · checked Sep 29, 2026
20Partial evidenceLondon, United KingdomHQ checked Sep 29, 202651-200115 contacts →

Partial evidence

“Longevity Partners is a multidisciplinary energy and sustainability consultancy.”

Source: RevenueBase Database · checked Sep 29, 2026
21Indirect evidenceDes Moines, IA, United StatesHQ checked Sep 29, 202651-200109 contacts →

Indirect evidence

“EcoEngineers, an LRQA company, is a consulting, auditing, and advisory firm with an exclusive focus on the energy transition and decarbonization.”

Source: RevenueBase Database · checked Sep 29, 2026
22Indirect evidenceUnited StatesHQ checked Sep 29, 202651-200108 contacts →

Indirect evidence

Source: RevenueBase Database · checked Sep 29, 2026
23Indirect evidenceNew Hope, MN, United StatesHQ checked Sep 29, 202651-200107 contacts →

Indirect evidence

“Apadana was founded in 2013 by electrical and mechanical engineers who committed their expertise to delivering energy conservation and renewable energy generation solutions with a…”

Source: RevenueBase Database · checked Sep 29, 2026
24Strong evidenceGurugram, IndiaHQ checked Sep 29, 202651-20098 contacts →

Strong evidence

“BOOTES - India’s 1st NET-ZERO Company.”

Source: RevenueBase Database · checked Sep 29, 2026
25Partial evidenceBristol, United KingdomHQ checked Sep 29, 2026201-50090 contacts →

Partial evidence

“We are a leading provider of retrofit residential decarbonisation across the UK.”

Source: RevenueBase Database · checked Sep 29, 2026

Showing 25 of 2,942 net-zero retrofit consultants worldwide

See the full list, filter by size, metro and specialty, and get verified emails and direct dials for all 7,727 reachable decision-makers.

Free signup · no credit card

View the full list →

Net-zero retrofit consultants worldwide at a glance

As of Sep 29, 2026
35.3%Verified-email coverage
7.4Average contacts per company
1-10Median size (employees)
2.9%Largest-city concentration · London
Sep 29, 2026Page data refreshed

Companies by employee count

1-10
2,028
11-50
726
51-200
146
201-500
17
501-1,000
6
1,001-5,000
2
10001+
1

Email recency is reported on each country list linked below.

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 net-zero retrofit consultants, 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.
Coverage
Every country. Country and city lists for net-zero retrofit consultants are linked below.
What qualifies
Companies worldwide whose own description of what they do matches “net-zero retrofit consultants”. 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 net-zero retrofit consultants), 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 net-zero retrofit consultants, and records with no verified work email.
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, 7,727 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 29, 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.

Net-zero retrofit consultants by location

17 lists · largest first

Every Net-zero retrofit consultants list RevenueBase publishes, by country and city. Counts are matching companies in each list as of its own refresh date.

Countries

Cities

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 net-zero retrofit consultants, 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 net-zero retrofit consultants are there worldwide?

RevenueBase identified 2,942 net-zero retrofit consultants worldwide 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?

OLA, headquartered in Austin, tops this list with the largest team on record.

Which country has the most net-zero retrofit consultants?

The United States leads with 536 companies, followed by the United Kingdom (407) and France (309). Every net-zero retrofit consultants list by country and city is linked on this page.

Which city has the most net-zero retrofit consultants?

London leads with 84 headquartered companies, followed by Paris (37) and New York (28).

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 7,727 verified decision-maker contacts tracked across these 2,942 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 29, 2026.

Ready to reach these companies? Verified emails and direct dials for all 2,942 net-zero retrofit consultants worldwide. Start with a free account, no credit card.

Download this 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 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.