AMRC · Ameresco, Inc.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $21.87 to $22.80 , inclusive. The reporting person undertakes to provide to Ameresco, Inc., any security holder of Ameresco, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote 1 to this Form 4.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $22.59 to $23.00 , inclusive. The reporting person undertakes to provide to Ameresco, Inc., any security holder of Ameresco, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in footnotes 1 and 2 to this Form 4.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $21.86 to $21.99, inclusive.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $20.88 to $21.79, inclusive.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $21.80 to $22.15, inclusive. The reporting person undertakes to provide to Ameresco, Inc., any security holder of Ameresco, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in footnotes 1,2 and 3 to this Form 4.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $20.45 to $21.18, inclusive. The reporting person undertakes to provide to Ameresco, Inc., any security holder of Ameresco, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote 1 to this Form 4.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $20.56 to $21.19 , inclusive.

On May 12, 2025, the reporting person was granted an option to purchase 50,000 shares of Class A common stock. The option vested based on performance relative to goals established for the three-year performance period from January 1, 2025 to December 31, 2027, subject to continued service to Ameresco, Inc. In connection with the reporting person's resignation as Ameresco, Inc.'s Executive Vice President, General Counsel and Secretary and transition to Special Legal Advisor to the Company, the Compensation Committee of Ameresco, Inc.'s Board of Directors reviewed the performance criteria achieved to date and accelerated this option such that the option vested as to 25,000 shares effective as of the resignation date and the remaining 25,000 options were forfeited.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $25.70 to $26.00, inclusive. The reporting person undertakes to provide to Ameresco, Inc., any security holder of Ameresco, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in footnotes 1 through 3 to this Form 4.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $25.22 to $25.31, inclusive.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $24.98 to $25.07, inclusive. The reporting person undertakes to provide to Ameresco, Inc., any security holder of Ameresco, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote 1 to this Form 4.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $25.64 to $26.20, inclusive.

Grant pursuant to Ameresco, Inc.'s non-employee director compensation plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

Annual grant pursuant to Ameresco, Inc.'s non-employee director compensaiton plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

Annual grant pursuant to Ameresco, Inc.'s non-employee director compensaiton plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

Annual grant pursuant to Ameresco, Inc.'s non-employee director compensaiton plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

Annual grant pursuant to Ameresco, Inc.'s non-employee director compensaiton plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

Annual grant pursuant to Ameresco, Inc.'s non-employee director compensation plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

Annual grant pursuant to Ameresco, Inc.'s non-employee director compensaiton plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

Annual grant pursuant to Ameresco, Inc.'s non-employee director compensaiton plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

Annual grant pursuant to Ameresco, Inc.'s non-employee director compensation plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

Annual grant pursuant to Ameresco, Inc.'s non-employee director compensaiton plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

Annual grant pursuant to Ameresco, Inc.'s non-employee director compensaiton plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

Annual grant pursuant to Ameresco, Inc.'s non-employee director compensaiton plan.

Each RSU represents a contingent right to receive one share of Ameresco, Inc. Class A Common Stock ("Common Stock").

The RSUs vest in full on the first anniversary of the grant date, assuming continues service through the vesting date.

The shares subject to the option vest fully upon the earlier of (a) the company achieving adjusted EBITDA of at least $100 million or (b) the three year anniversary of the grant.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $30.21 to $30.45, inclusive. The reporting person undertakes to provide to Ameresco, Inc., any security holder of Ameresco, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote to this Form 4.

Of the shares subject to the option, 20% vest on each of anniversary of the grant date of May 18, 2026 over a period of five years.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 6, 2024.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $32.44 to $33.26 , inclusive. The reporting person undertakes to provide to Ameresco, Inc., any security holder of Ameresco, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in footnotes 2 and 3 to this Form 4.

Of the shares subject to the option, 20% vest on each of anniversary of the grant date of May 18, 2026 over a period of five years.

Of the shares subject to the option, 20% vest on each of anniversary of the grant date of May 18, 2026 over a period of five years.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 6, 2024.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $31.57 to $32.43, inclusive.

Of the shares subject to the option, 20% vest on May 26, 2017, and the remainder vest in four equal installments on each of the subsequent four anniversaries of such date.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on September 8, 2025.

Of the shares subject to the option, 20% vest on April 24, 2020, and the remainder vest in four equal installments on each of the subsequent four anniversaries of such date.

Of the shares subject to the option, 20% vest on May 26, 2017, and the remainder vest in four equal installments on each of the subsequent four anniversaries of such date.