Ontario is proposing to follow the US lead, and require mandatory greenhouse gas emission reporting from organizations and facilities that emit more than 25,000 tonnes of CO2e per year. (Our federal reporting threshold has just dropped from 100,000 tonnes to 50,000.)
Even 25,000 tonnes will catch only large firms, burning more than, for example, 58,000 barrels of oil per year. For an excellent sectoral analysis of what this threshold means in the US, see http://nicholas.duke.edu/institute/25Kton.pdf. The Nicholas Institute has also analyzed who would be affected by a 10,000 tonne threshold, the group that Ontario is asking to report voluntarily. The bottom line: Most industries with fewer than 50 employees and no smoke stack would be exempt from reporting in either case.