About the IESO

Ontario's Independent Electricity System Operator (IESO) balances the supply of and demand for electricity in Ontario and then directs its flow across the province's transmission lines.

Every hour of the day, the IESO forecasts consumption throughout the province and then directs the least expensive generators to provide electricity to meet that demand. This process continues throughout the day and night, seven days a week. During Earth Hour, the IESO will closely monitor provincial demand to track the impact of the Earth Hour initiative. The province’s electricity use is frequently updated on this site.

The IESO also issues regular assessments of the reliability of the province’s electricity system through its Ontario Reliability Outlook.

For more information about the IESO’s responsibilities visit www.ieso.ca/about.