Using Energy Wisely Section 12.2 Your Hydro (Energy) Bill Time
of Use Summer/ Winter Rates. The cost of electricity is higher in
the winter because of greater demand The amount of power used in
your home depends on: Power Rating of appliance The setting (high,
low, medium) Amount of time it is run for Power rating Electrical
power the rate at which an appliance uses electrical energy -
Measured in watts (W) or kilowatts (kW) 1000 W = 1 kW 60 W = kW
Amount of Use Electrical energy energy used by an appliance at a
given setting for a specific amount of time Power (kW) x Time (h) =
Energy Used (kW h) kW h x price = COST EnerGuide Label Gives
details about how much energy an appliance uses in one year of
normal use Power Ratings of Appliances ApplianceAverage Power (W)
Monthly Energy Use (kW h) Approximate costs ($) Clothes Dryer
coffee maker9004 2.17 Computer (monitor & printer) 6005 2.89
Electric kettle15003 W light bulb605 1.60 television805 1.20
toaster10001 0.41 Power Ratings of Appliances ApplianceAverage
Power (W) Monthly Energy Use (kW h) Approximate costs ($) Clothes
Dryer coffee maker9004 2.17 Computer (monitor & printer) 6005
2.89 Electric kettle15003 W light bulb605 1.60 television805 1.20
toaster10001 0.41 Power Ratings of Appliances ApplianceAverage
Power (W) Monthly Energy Use (kW h) Approximate costs ($) Clothes
Dryer coffee maker9004 2.17 Computer (monitor & printer) 6005
2.89 Electric kettle15003 W light bulb605 1.60 television805 1.20
toaster10001 0.41 Time of use (summer): Peak time11.8 Mid time9.9
Off peak6.3 Example Converting Power from W to kW 1kW = 1000 W
1500W = 1.5 kW Example Find the energy used by a 5.0kW clothes
dryer that runs for 40 minutes. (Energy is measured in kW h)
Convert 40 minutes to hours 40 min = 60 min/h Energy used = Power X
Time = 5.0kW x 0.66 h = 3.3kW h 0.66 h Example A)A dishwasher uses
1800 W. On average, it runs for 50 minutes every day at 8pm. What
is the cost of the dishwasher for 1 week? B) Compare the price of
running the dishwasher for 1 year at off peak versus on peak time.
Time of use: Peak time11.8 Mid time9.9 Off peak6.3 In your home
Read pages Circuit breakers, fuses and other safety devices in the
home Phantom Loads The electricity that is consumed by an appliance
when it is turned off Efficiency The ratio of useful energy output
to total energy input, expressed as a percentage Percent Efficiency
= useful energy output total energy input X 100 Electrical Energy
SI Unit of energy is a joule (J) 1 J = 1 Watt operating for 1
second (W s) 1 J = 1 W s 1kJ = 1 kW s Example Compare the
efficiency of a kettle to a microwave. It takes 168kJ to boil
water. The kettle has a power rating of 1.5kW and took 150s to boil
the water. The microwave has a power rating of 1.2kW and took 310s
to boil the water. Which is more efficient?
