Demand response programs pay or incentivize electricity consumers to reduce their power usage during periods of high demand or system stress. When electricity demand approaches system capacity (typically hot summer afternoons when air conditioning peaks), grid operators can call on enrolled participants to temporarily decrease consumption rather than activating expensive or polluting backup power plants. Participants might include large industrial users who can shift production schedules, commercial buildings that can reduce lighting or raise thermostat settings, or residential customers with smart thermostats. In Ontario, the Independent Electricity System Operator runs demand response programs as part of grid management. These programs help maintain grid stability, reduce the need for new power plants, lower overall electricity costs, and decrease emissions from backup generation.