Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the Registration Statement on Form S-8 (File No. 333-169100) of our report dated March 31, 2011, relating to our audit of the consolidated financial statements, included in this Annual Report on Form 10-K of Ameresco, Inc. and Subsidiaries for the year ended December 31, 2010.

/s/McGladrey & Pullen, LLP

MCGLADREY & PULLEN, LLP

Boston, Massachusetts

March 31, 2011