The following will give you the formulae for figuring out how much it costs to run your A/C during the summer.

With the installation of the hydro "Smart Meters" you pay a variable rate based upon usage or consumption at different periods of the day and night. Your hydro meter measures your usage in "Watts". One thousand watts = 1 kilowatt (1KW) At present, your hydro rate can range from about $0.035 per KW to around $0.09 at peak daytime periods. The number of "watts" that any appliance uses from toasters, TV's, stoves, air conditioners etc. can be calculated by multiplying the voltage (120 or 230 volts for appliances in Canada) times the current rating of an appliance (measured in Amps). The nameplate of any appliance will provide you with the voltage and operating amperage of the unit. For an example a 2 ton A/C operates on 230 volts and draws a current of about 12 amps. The wattage used in one hour is 230 x 12 = 2,760 watts or 2.76 KW. At peak times your smart meter will factor 2.76 KW x's the rate of $0.09 per KW and cost $0.2484 cents per hour to operate. This is only part of the cost as the fan in your furnace is also operating to circulate the air. The typical furnace fan operates on 120 volts and draws about 8 amps. At peak times this will cost 0.09 cents x's (120V. x 8A. divided by 1,000 watts) = $0.09 X 0.96 = $0.0864 per hour. The A/C in this example is costing 24.84 cents + 8.64 cents = 33.5 cents per hour. This cost can be reduced by almost 2/3rds. after 7:00 PM at night. In this example the cost to operate your A/C for the month of July could add in excess of $130.00 to your hydro bill.