POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints each of Barry R.
Goldman, Senior Vice President and General Counsel; Lisa Wyn, Senior Vice President, Corporate
Controller and Treasurer; and Jill A. Gilmer, Vice President, Corporate Secretary, signing singly, the
undersigned's true and lawful attorney-in-fact to:

1.    execute for and on behalf of the undersigned, in the undersigned's capacity as an officer and/or
director of Acuity Brands, Inc. (the "Company"), Forms 3, 4, and 5 in accordance with
Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder;

2.    do and perform any and all acts for and on behalf of the undersigned which may be necessary or
desirable to complete and execute any such Form 3, 4, or 5, complete and execute any
amendment or amendments thereto, and timely file such form with the United States Securities
and Exchange Commission and any stock exchange or similar authority; and

3.    take any other action of any type whatsoever in connection with the foregoing which, in the
opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required
by, the undersigned, it being understood that the documents executed by such attorney-in-fact on
behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall
contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's
discretion.

The undersigned hereby grants to each such attorney-in-fact full power and authority to do and
perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise
of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned
might or could do if personally present, with full power of substitution or revocation, hereby ratifying and
confirming all that such attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall
lawfully do or cause to be done by virtue of this power of attorney and the rights and powers herein
granted.  The undersigned acknowledges that the foregoing attorneys-in-fact, in serving in such capacity
at the request of the undersigned, are not assuming, nor is the Company assuming, any of the undersigned's
responsibilities to comply with Section 16 of the Securities Exchange Act of 1934.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer
required to file Forms 3, 4, and 5 with respect to the undersigned's holdings of and transactions in
securities issued by the Company, unless earlier revoked by the undersigned in a signed writing
delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of
February 21, 2020.




/s/ Dianne Mills
Signature

Dianne Mills
Print Name