鶹Լ

Household electricity - CCEACost of household electricity using meter readings

Electricity is an essential part of our daily lives. In our homes, we use it for lighting, heating and using appliances - but how is electric power converted into other forms of energy and how is this measured?

Part of Combined ScienceElectrical circuits

Cost of household electricity using meter readings

Electricity companies bill customers for the electrical energy they use.

A joule is much too small a unit of energy and so the electricity companies use another unit of energy called the kilowatt-hour, kWh.

One unit of electrical energy is one kilowatt-hour, or 1 kWh.

Electricity meters

An old style electricity meter
Image caption,
An old-style electricity meter
Modern digital smart meter
Image caption,
Modern digital smart meter

Domestic electricity meters, similar to those above, measure the number of kilowatt-hours of electrical energy used in a home or other building.

The more kilowatt-hours (or units) used, the greater the cost.

The cost of the electricity used is calculated using this equation:

Total cost = energy in kWh × cost per unit

The cost per unit is set by the electricity company, for example 14.78 p per kWh.

This means that each unit, or kilowatt-hour, of electricity costs 14.87 p.

An electricity bill has two important numbers: present meter reading and previous meter reading.

The number of units used is the difference between these two readings.

Electricity bill: present reading = 40745 kWh; previous reading = 39990 kWh

Present reading = 40745 kWh

Previous reading = 39990 kWh

Energy in kWh = present meter reading - previous meter reading

= 40745 – 39990

= 755 kWh

Total cost = energy in kWh × cost per unit

= 755 x 14.78 p

= 11159 p

The cost of electricity used is £111.59

Question

Use the following information to calculate the cost of electricity used.

Previous reading = 37070 kWh

Present reading = 38217 kWh

Units at 14.78p per kWh.

In 2019, the average household electricity bill for the year cost around £590, in comparison to 2013 when it cost around £650 - this could be caused by many household items becoming more energy efficient.

Ways of reducing electricity bills:

  • Use energy efficient light bulbs such as LED bulbs.
  • Switch off and unplug devices on stand-by.
  • Switch off and unplug chargers when not in use.
  • If you are replacing an electrical appliance such as a tumble dryer, kettle or hair dryer choose an energy efficient model.
  • Minimize the time spent in an electric shower.
  • If possible, hang washing out to dry rather than use a tumble dryer.

Related links