It was a hot week this week, very hot and that means expensive electricity. When demand goes up the grid has to ramp up production on smaller less efficient generator stations or buy power from other provinces/states.

Ontario Electricity Demand Friday July 31 at 11:00


– From – or search for the app to see how much Electricity Ontario is using right now!


For large utility customers it’s a big issue, as their demand charges are based on their share of the provincial demand. There are five peak hours that the province uses for their Class A Global Adjustment Charges, so if large customers can reduce their demand at these times, they can reduce their overall electricity charges for the following year. The costs show up as a Class A Global Adjustment charge on utility bills for Toronto General, Princess Margaret, and Toronto Western.


Peak Electricity

Last week Ontario saw a peak of 22,516 MW at 5:00pm on July 28th, which was followed by a peak of 22,460 MW at 5:00pm on July 29th. Note that those values are MW = mega watts = 1,000,000 watts. That’s equivalent to 225 million 100watt bulbs (which you hopefully aren’t using anymore). The numbers are massive, for example the five operational reactors at the Pickering Nuclear Plant have a maximum output of 2,430 MW.   The maximum allowable solar installation on a home is 0.01MW.

Ontario Demand

– July 26 to July 31 2015  –



Timing Matters!

Toronto General Hospital had a peak of 10.5MW last week (100,000 of those 100watt bulbs or 1000 homes with large solar installations). The key thing is that on each day this occurred between 11:00am and 2:00pm (just around lunch). That’s good, because it mean’s we aren’t peaking when the province is peaking. However we still have a large 5:00pm demand and there are things we can do to reduce it. There are things we did do this week to reduce it.


TGH Demand


– TGH Demand – blue vertical lines are at noon, dark vertical lines are at midnight


What did we do this week?

Knowing that peaks occur around 5:00, last week at 3:30 each day we instituted the following measures to help reduce TGH’s electricity demand. The key thing to note is that reducing fan speed saves the cube of the energy, that means if we slow the fan down to 50% speed, we save 88% of the fan energy.

  1. We reduced fan speed in non critical areas like RFE and Eaton North
  2. We reduced fan speed in the Munk Atrium
  3. We reduced cooling and reheat by adjusting temperatures on specific fans
  4. People turned off lights and computers

What are we doing next:

  1. Fixing variable speed drives to give more control over fan speeds
  2. Fixing an absorption chiller than uses steam to create cooling, instead of electricity. This will offset over 1MW of electricity use.
  3. Installing LED lights which produce less heat
  4. Installing occupancy sensors to turn off lights
  5. Installing better controls on renovated projects to allow controls to turn off areas when unoccupied, or adjust temperatures based on need.

What can you do:

  1. Turn off lights, computers, and printers (anything that produces heat)
  2. Setback your air conditioning in your office and at home
  3. Call Facilities if your office is too cold


There are still some big hurdles though. Buildings that were constructed in 1978 like the Eaton building have very poor zoning.  Multiple offices are controlled off one thermostat, so that one room is hot while the other is too cold. There is also the common scenario where one air handling unit will provide air and cooling to many floors, resulting in poor control and energy waste.  These problems are being tackled though and new renovations are seeing much more efficient systems being installed.


Keep those peaks down!