The Ministry of Energy has published their mandatory energy and water reporting guidelines here. The program will launch in phases with the largest commercial, multi-unit residential and some industrial having to report by July 1, 2018.
As the program rolls out the idea is to generate increased transparency of building's efficiency to the public. Understanding how you're doing compared to similar buildings is the first step in getting your energy consumption and energy costs under control - this program makes understanding those numbers mandatory - and by putting the data out for the public to see, the province is essentially nudging the market to push for higher efficiency buildings.
By 2020, any building in the list which is larger than 50,000 square feet will be mandated to compile these reports. Click here to see if you're in the list of mandatory participants.