Hannon Armstrong Sustainable Infrastructure Capital (HASI) 10-K 2017 FY Annual report

EXHIBIT 32.1

CERTIFICATION PURSUANT TO SECTION 906

OF THE SARBANES-OXLEY ACT OF 2002, 10 U.S.C. SECTION 1350

In connection with the Annual Report on Form10-K of Hannon Armstrong Sustainable Infrastructure Capital, Inc. (the “Company”) for the period ended December 31, 2017 to be filed with the Securities and Exchange Commission on or about the date hereof (the “report”), I, Jeffrey W. Eckel, Chief Executive Officer and President of the Company, certify, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, 18 U.S.C. Section 1350, that:

1. The report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the report fairly presents, in all material respects, the financial condition and results of operations of the Company.

It is not intended that this statement be deemed to be filed for purposes of the Securities Exchange Act of 1934.

Date: February 23, 2018

By:	/s/ Jeffrey W. Eckel
	Name: Jeffrey W. Eckel
	Title: Chief Executive Officer and President

Exh. 32.1-1