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?