SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Ameresco, Inc.

(Name of Issuer)

Class A Common Stock

(Title of Class of Securities)

02361E108

(CUSIP Number)

08/20/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP Number(s):

02361E108

Names of Reporting Persons

Gagnon Securities LLC

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 951,125.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 999,794.00

Aggregate Amount Beneficially Owned by Each Reporting Person

999,794.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

2.9 %

Type of Reporting Person (See Instructions)

BD, IA

SCHEDULE 13G

CUSIP Number(s):

02361E108

Names of Reporting Persons

Gagnon Advisors, LLC

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 472,798.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 472,798.00

Aggregate Amount Beneficially Owned by Each Reporting Person

472,798.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

1.3 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

02361E108

Names of Reporting Persons

Neil Gagnon

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 153,541.00
6	Shared Voting Power 1,551,948.00
7	Sole Dispositive Power 153,541.00
8	Shared Dispositive Power 1,609,325.00

Aggregate Amount Beneficially Owned by Each Reporting Person

1,762,866.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

5.0 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

Item 1.

(a)

Name of issuer:

Ameresco, Inc.

(b)

Address of issuer's principal executive offices:

111 Speen Street, Framingham, Massachusetts 01701

Item 2.

(a)

Name of person filing:

Neil Gagnon has sole voting and dispositive power over 153,541 shares of the Issuer's Class A Common Stock (the "Common Stock"). In addition, Mr. Gagnon has shared voting power over 1,551,948 shares of Common Stock and shared dispositive power over 1,609,325 shares of Common Stock. Mr. Gagnon is the Chief Executive Officer and principal owner of Gagnon Securities LLC ("GS"), an investment adviser registered with the U.S. Securities and Exchange Commission ("SEC") under the Investment Advisers Act of 1940, as amended (the "Advisers Act"), and a registered broker-dealer, in its role as investment manager to several customer accounts, foundations, partnerships and trusts (collectively, the "Accounts") to which it furnishes investment advice. GS and Mr. Gagnon may be deemed to share voting power with respect to 951,125 shares of Common Stock held in the Accounts and dispositive power with respect to 999,794 shares of Common Stock held in the Accounts. GS and Mr. Gagnon expressly disclaim beneficial ownership of all securities held in the Accounts. Mr. Gagnon is also the managing member of Gagnon Advisors, LLC ("Gagnon Advisors"), an investment adviser registered with the SEC under the Advisers Act. Mr. Gagnon and Gagnon Advisors, in its role as investment manager to Gagnon Investment Associates, LLC ("GIA"), a private investment fund, may be deemed to share voting and dispositive power with respect to the 472,798 shares of Common Stock held by GIA. Gagnon Advisors and Mr. Gagnon expressly disclaim beneficial ownership of all securities held by GIA.

(b)

Address or principal business office or, if none, residence:

1370 Ave. of Americas, 26th Floor, New York, NY 10019

(c)

Citizenship:

Gagnon Securities LLC Delaware limited liability company Gagnon Advisors, LLC Delaware limited liability company Neil Gagnon USA

(d)

Title of class of securities:

Class A Common Stock

(e)

CUSIP Number(s):

02361E108

Item 3.

If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);

(b)

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

(c)

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);

(d)

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);

(e)

An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);

(f)

An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);

(g)

A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);

(h)

A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:

(k)

Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).

Item 4.

Ownership

(a)

Amount beneficially owned:

Gagnon Securities LLC 999,794 Gagnon Advisors, LLC 472,798 Neil Gagnon 1,762,866

(b)

Percent of class:

Gagnon Securities LLC 2.9% Gagnon Advisors, LLC 1.3% Neil Gagnon 5.0% Calculation of percentage of beneficial ownership is based on 35,066,211 Common Stock outstanding as of July 31, 2026, based on the Issuer's Form 10-Q filed with the Securities and Exchange Commission on August 4, 2026.

(c)

Number of shares as to which the person has:

(i) Sole power to vote or to direct the vote:

Gagnon Securities LLC 0 Gagnon Advisors, LLC 0 Neil Gagnon 153,541

(ii) Shared power to vote or to direct the vote:

Gagnon Securities LLC 951,125 Gagnon Advisors, LLC 472,798 Neil Gagnon 1,551,948

(iii) Sole power to dispose or to direct the disposition of:

Gagnon Securities LLC 0 Gagnon Advisors, LLC 0 Neil Gagnon 153,541

(iv) Shared power to dispose or to direct the disposition of:

Gagnon Securities LLC 999,794 Gagnon Advisors, LLC 472,798 Neil Gagnon 1,609,325

Item 5.

Ownership of 5 Percent or Less of a Class.

Not Applicable

Item 6.

Ownership of more than 5 Percent on Behalf of Another Person.

If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.

The Accounts described above in Item 2 have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, securities held in their respective accounts. To the knowledge of the Reporting Persons, the interest in any such account does not exceed 5% of the class of securities. Except to the extent described herein, the Reporting Person disclaims beneficial ownership of all such securities.

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.

Not Applicable

Item 8.

Identification and Classification of Members of the Group.

Not Applicable

Item 9.

Notice of Dissolution of Group.

Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Gagnon Securities LLC

Signature:	/s/ Neil Gagnon
Name/Title:	Neil Gagnon/Managing Member
Date:	08/27/2026

Gagnon Advisors, LLC

Signature:	/s/ Neil Gagnon
Name/Title:	Neil Gagnon/Chief Executive Officer
Date:	08/27/2026

Neil Gagnon

Signature:	/s/ Neil Gagnon
Name/Title:	Neil Gagnon
Date:	08/27/2026