SC 6.4

• Energy efficiency

  • Percentage of energy input converted to useful form of energy output
  • Formula
  • Energy efficiency = (Useful energy output / Energy input supplied) * 100 %
• Energy efficiency:

  • The efficiency of an electrical appliance refers to how much electrical energy supplied to it can be used beneficially
  • Not all of the electrical energy supplied is used by electrical equipment, some of the electrical energy is used to overcome resistance and is lost as thermal energy
  • Efficient electrical appliances will experience minimal heat loss when in use
  • Examples of LED bulbs are more efficient than fluorescent lamps and filament bulbs
• Energy efficiency:

  • The Energy Commission (ST) was established to regulate the energy sector of the electricity and piped gas supply industry in Peninsular Malaysia and Sabah Sarawak
  • Ensure the energy industry is developed, efficient, and supply at affordable prices to consumers
• Electricity consumption:

  • The quantity of electrical energy depends on the power rating of the electrical equipment and the length of time the electrical equipment is used
  • Power refers to the rate of electricity consumption within one second
  • Formula: Electrical power (Watt) = Electrical energy consumed (Joule) / Duration of Consumption (s)
  • Therefore, the electrical energy used
  • Formula: (J) = Power (W) x Time (s)
  • Electrical power depends on the value of voltage and current used by electrical equipment
  • Formula: Electric power (W) = Voltage (V) x Electric current (A)
• Cost of electrical energy used

  • One kilowatt-hour is the amount of electricity used by an electrical appliance within an hour
  • 1 kWh = 1 unit of electrical energy = 3600 J
  • Total electricity consumption and its cost
  • kWh = kW * h
  • Cost of electricity consumption = kWh * cost per unit (cents)
• Action that waste electricity

  • Air conditioners are switched on throughout the day
  • Turning on the decorative light all night without purpose
  • Washing only a few pieces of clothes in the washing machine
  • Bathing with the water heater on hot days
  • Turning on radio and television without the intention of listening or watching the program
  • Ironing only a few pieces of clothing at one time
  • Using high power electric lamps and appliances
• Ways to save electrical consumption

  • Turn off electrical appliances and lights when not in use
  • Use compact fluorescent lamps or low power lamps
  • Avoid opening the refrigerator door and cold frozen parts regularly
  • Wash clothes and iron in large quantities
  • Use water heater only in cold weather
  • Use the fan and reduce the use of air conditioners
  • Always clean and replace air conditioner filters
  • Always observe energy-efficiency labels when buying electrical equipment