Energy Consumption: CO$T

kWh Efficiency EnerGuide OUTCOME QUESTION(S): S1-3-22: How can you lower electrical energy use of a household? Vocabulary and People kWh Efficiency EnerGuide

Purchasing Electrical Energy Energy companies charge a fee for total energy consumption (usually) per month – “hydro” bill Total energy is calculated by multiplying power by time used E t P is the power in kilowatts (kW) t is the time in hours t E = P · t P = t Notice the units: Time is in hours – seconds are not useful for home billing Power is in kilowatts – watts are too small to be useful

The same energy formula is used but the units must match (kWh) You make smoothies every day in September (30 days) using a 900 W blender for 5 min. How much energy did the blender use that month? E = P · t 900 W · 1 kW = 1000 W 0.9 kW 5 min · 1 h · 30 (days) = 60 min 2.5 hours The same energy formula is used but the units must match (kWh) E = 0.9 kW · 2.5 h E = 2.25 kWh

“Hydro” charges about $0.08 for every kilowatt-hour (kWh) used Reading a Hydro Meter Hydro meter uses 5 dials to measure energy usage: far right dial is “ones” - far left dial is “ten thousands” a reading is taken every 1-2 months Reading 23 930 (kWh) 20 769 (kWh) 3161 (kWh) energy used this month “Hydro” charges about $0.08 for every kilowatt-hour (kWh) used = $253 this month

Sample Hydro bill: kWh used Time rate This household uses natural gas for heat and has a second bill for the total amount of gas used.

It is more efficient if it does the same work with less input energy Efficiency measures how well a device converts energy into work: every device wastes some energy lost as heat, sound, poor insulation… It is more efficient if it does the same work with less input energy

This appliance will use 125 kWh of electricity per month of normal use EnerGuide labels give consumers an idea of the efficiency of an appliance: gives energy usage for regular use over time (month/yr) efficient devices will have a lower energy usage allows consumer to estimate cost of using the device This appliance will use 125 kWh of electricity per month of normal use Energy star: government-regulated symbol used to identify most efficient devices (based on tests).

CAN YOU ANSWER THESE QUESTIONS? S1-3-22: How can you lower electrical energy use of a household? Vocabulary and People kWh Efficiency EnerGuide