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Adopt good habits that will benefit everyone.

Postponing the use of appliances and turning the heat down are concrete actions that will help optimize electricity distribution throughout the system when demand is high.

Little things that make a big difference during winter peaks…

From 6 a.m. to 9 a.m. and 4 p.m. to 8 p.m., it’s best to:

  • lower the temperature in your home by a degree or two (Celsius), especially in rooms that aren’t in use
  • postpone the use of major appliances—especially the dryer and dishwasher—for a few hours
  • limit hot water consumption as much as possible

Reducing demand: a collective challenge

Québec’s electricity demand is highest in winter. Energy-smart consumption choices help limit the spike in demand. Hydro-Québec can then avoid or defer additional costs brought about by:

  • purchasing power at higher prices from neighboring grids
  • installing new equipment in existing generating stations
  • building new facilities to generate electricity

Video : What is a peak?

Peaks occur when electricity demand is highest—when Hydro-Québec’s grid is under the greatest pressure. There are daily and annual peaks.

In Québec, more electricity is consumed in winter because of heating needs. There are simple ways to consume electricity responsibly without sacrificing your comfort.

Daily peaks occur when Hydro-Québec’s network is under the greatest loads during the day: in the mornings, from 6 a.m. to 9 a.m., and in the evenings, from 4 p.m. to 8 p.m., on weekdays.

Annual peaks occur at the time of year when Hydro-Québec’s network is under the greatest pressure, especially during periods of low temperatures and high winds. Cold snaps lasting several days also increase demand.

In Québec, more electricity is consumed in winter because of heating needs. There are simple ways to consume electricity responsibly without sacrificing your comfort.

Video : Power, capacity and energy

Like a restaurant

Another good analogy is a restaurant with a specific number of tables (capacity) and a specific amount of food (energy). But our collective appetite for electricity can spoil the broth!

When everyone is famished at the same time, the restaurant may have enough food but won’t have enough tables to seat everyone. Rather than renting additional tables to meet the high but momentary demand (power), the restaurant may ask certain patrons to dine earlier or later. The restaurant will be able to serve everyone, just not at the same time.

In exceptional peak periods, Hydro-Québec may ask Quebecers to help reduce the demand for electricity for a few days to avoid a system overload.

Why save energy if there are surpluses?

Hydro-Québec has surplus energy, but rarely in winter when demand is high. From time to time, all the power generated by its facilities cannot meet the demand and there is a power deficit. Hydro-Québec must then purchase electricity from neighboring grids to meet the needs of Quebecers.

In summer, the demand is lower and Hydro-Québec has more leeway. The grids in southern Québec rely on our electricity delivery to meet peak consumption for cooling.

More on power and energy



In the electricity grid, power is the effort deployed by generating stations at any given moment to meet customer demand. Power is expressed in watts (W) and multiples of watts: kilowatts (kW; 1,000 watts) and megawatts (MW; 1000 kilowatts or 1 million watts).

Installed Capacity


The installed capacity of a generating station is the maximum effort it can deploy. However, the power that is actually generated by stations varies continuously to stay perfectly in synch with consumption.



Energy is the cumulative effort made in a given period. Calculated by multiplying power by time, energy is expressed in watthours (Wh) and multiples of watthours: kilowatthours (kWh; 1,000 watthours) and terawatthours (TWh; 1 billion kilowatthours). The amount of energy is measured by Hydro-Québec’s residential meters and serves as the basis for billing.

Accumulated Energy


Certain types of energy may be accumulated. For example, in hydropower facilities like those operated by Hydro-Québec, dams retain water in reservoirs. The amount of water in a reservoir represents the energy that could potentially be converted into electricity by the generating station when there is an increase in electricity consumption.