There may be times when extreme weather or unexpected transmission or generation outages stretch the system's ability to
provide enough electricity to meet demand and required reserves. Ontario's IESO has a number of options available to maintain
reliability of the system. For example, we can arrange emergency imports of electricity and call on specific companies who
have agreed to cut back on their electricity use on short notice. We may also choose to issue a public appeal to all businesses
and consumers to reduce their consumption. The appeals help to smooth out spikes in demand during high-peak periods.
Weather conditions affect the demand for electricity considerably, which is why Public Appeals are often issued during extreme cold spells and heat waves.
For example, each degree above 16°C creates an additional 380 MW of demand.
And that's not counting the impact of humidity, which can also have a significant impact on demand.
Appeals to reduce consumption are issued to the news media.
These appeals and tips on how to conserve energy are also posted on the IESO website.