Ameresco Inc

To the Stockholders and the Board of Directors of Ameresco, Inc.

Opinions on the Financial Statements and Internal Control over Financial Reporting

We have audited the accompanying consolidated balance sheets of Ameresco, Inc. (the "Company") as of December 31, 2023 and 2022, and the related consolidated statements of income, comprehensive income, changes in redeemable non-controlling interests and stockholders' equity and cash flows for each of the years in the three-year period ended December 31, 2023, and the related notes (collectively referred to as the "financial statements"). We also have audited the Company’s internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control - Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission in 2013.

In our opinion, the financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, 2023 and 2022, and the results of its operations and its cash flows for each of the years in the three-year period ended December 31, 2023, in conformity with accounting principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control - Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission in 2013.

Basis for Opinion

The Company's management is responsible for these financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management’s Annual Report on Internal Control over Financial Reporting. Our responsibility is to express an opinion on the Company's financial statements and an opinion on the Company's internal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) ("PCAOB") and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects.

Our audits of the financial statements included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

Definition and Limitations of Internal Control Over Financial Reporting

A company's internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company's internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company's assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Critical Audit Matters

The critical audit matters communicated below are matters arising from the current period audit of the financial statements that were communicated or required to be communicated to the audit committee and that: (1) relate to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matters below, providing separate opinions on the critical audit matters or on the accounts or disclosures to which they relate.

Goodwill Impairment

As described in Notes 2 and 5 to the financial statements, management tests the Company’s goodwill, which had a balance of $75.6 million as of December 31, 2023, for impairment, at the reporting unit level, at October 31 of each fiscal year, or more frequently if events or changes in circumstances indicate the asset might be impaired. To test goodwill for impairment, management compares the estimated fair value of each reporting unit with the carrying amount of each reporting unit, including the recorded goodwill. In estimating the fair value of each reporting unit, management uses a methodology which combines an income approach, using a discounted cash flows method, with a market approach, using a peer-based guideline company method based on the average of published multiples of earnings of comparable entities with similar operations and economic characteristics. During the year ended December 31, 2023, the Company recorded a goodwill impairment of $2,222 at one reporting unit.

We identified the annual goodwill impairment assessment for the Company’s reporting unit where impairment was identified as a critical audit matter because of the significant estimates and assumptions used by management when estimating the fair value of the reporting unit, including management’s forecasts of revenue and expense growth rates, management’s selection of the discount rate for the income approach and management’s estimates of the multiples of earnings of comparable entities with similar operations and economic characteristics for the market approach. Auditing management’s estimates and assumptions involved a high degree of auditor judgment and increased audit effort, including the use of our valuation specialists, due to the impact these assumptions have on the goodwill impairment assessment.

Our audit procedures related to the assessment of goodwill impairment included the following, among others:

•We obtained an understanding of the relevant controls relating to management’s goodwill impairment assessment and tested such controls for design and operating effectiveness, including controls over management’s review of the significant assumptions used in the estimate of fair value, including forecasted revenue and expense growth rates, the selected discount rates, and the selected multiples of earnings.

•We evaluated the reasonableness of management’s forecasts of revenue and expense growth rates by comparing the projections to historical results and testing certain contracts contributing to the revenue forecast.

•We tested the underlying data used by management in their development of forecasts of revenue and expense growth rates for accuracy and completeness by agreeing it to source data.

•We utilized valuation specialists to assist in the following procedures, among others:

◦Evaluating the reasonableness of the discount rate and multiples of earnings by comparing the underlying source information to publicly available market data and verifying the accuracy of the calculations.

◦Developing a market participant discount rate using publicly available market data and comparing that discount rate to the discount rate selected by management.

◦Evaluating the appropriateness of the valuation methods used by management and testing their mathematical accuracy.

Revenue from Contracts with Customers – Project Revenue

As described in Notes 2 and 3 to the financial statements, the Company’s projects line of business, which relates to the construction of energy efficiency projects, including the design, engineering and installation of technologies and techniques to improve energy efficiency and control the operation of a building’s energy-and-water-consuming systems, recognized revenue of $1.37 billion during the year ended December 31, 2023. Typically, the Company provides a service of integrating a complex set of tasks and components such as design, engineering, construction management, and equipment procurement for a project contract. The Company’s project revenues are generated from long-term contracts whereby revenue is recognized over time using the cost-based input method. The Company uses total costs incurred on the project relative to the total expected costs to estimate progression towards the satisfaction of the performance obligation.

Estimating the amount of project revenue to record from the Company’s long-term contracts requires management’s judgment in estimating final construction contract profits, which are driven by the total estimated consideration payable by the customer and total estimated contract costs. The Company estimates the total consideration payable by the customer when the contracts contain variable consideration provisions, which can include liquidated damages and/or penalties, based on the most likely amount anticipated to be recognized for transferring the promised goods or services. As a result, the Company may constrain revenue to the extent that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Anticipated contract costs can be incurred over several years and are largely determined based on negotiated or estimated purchase contract terms and consider factors such as historical performance, estimated subcontractor costs and contingency costs.

We identified the Company’s accounting for revenue recognition from the project line of business to be a critical audit matter due to the significant judgments used by management related to the estimation of final construction profits. Estimating the final construction profit on these long-term contracts requires management to develop estimates of the total consideration payable by the customer, when contracts contain variable consideration provisions, as well as total expected contract costs, including costs associated with labor, materials, equipment, subcontracting and outside engineering cost. Auditing management’s estimates and assumptions involved a high degree of auditor judgment and increased audit effort due to the impact these assumptions have on the revenue recognized.

Our audit procedures related to project revenue included the following, among others:

•We obtained an understanding of the relevant controls related to the recognition of project revenue and tested such controls for design and operating effectiveness, including controls over the determination of the final estimated construction profit, which includes management’s review of the assumptions and key inputs used to recognize revenue on project contracts using the cost-to-cost input method, including costs associated with labor, materials, equipment, subcontracting and outside engineering along with estimates of total consideration payable when contracts contain variable consideration provisions.

•We performed substantive analytical procedures on the Company’s project revenue line of business, with a focus on significant changes in gross margin, contract budgets and contract pricing from the prior year, on contracts open in both the current year and prior year.

•We selected a sample of project contracts and evaluated the estimates of total costs for each of the project contracts by:

◦Testing the initial project budget by the development of an independent margin expectation for the projects combined with inquiry with the project management team and/or comparing selected items from the underlying budget to the source information used to develop the project budget.

◦Evaluating management’s judgments related to the Company’s ability to achieve the estimates of final construction contract profit as well as achievement on project timelines by performing corroborating inquiries with Company personnel, including project managers, and comparing the estimates to documentation such as management’s internal budgets and contract terms.

◦Confirmation of project progression with customers, including identification of any delays in project timeline.

/s/RSM US LLP

We have served as the Company's auditor since 2010.

Boston, Massachusetts

February 29, 2024