Saving energy
Saving energy means using energy wisely without waste; it saves money and protects the environment because less fuel is burned. A device’s power (P) shows how much energy it uses every second; the unit is the watt (W). Energy used is E = P × t, measured in watt-hours (W·h) or kilowatt-hours (kW·h): 1 kW·h = 1000 W·h. An incandescent lamp turns most of its energy into heat, while an LED turns most into light; a 10 W LED lights as well as a 60 W incandescent lamp and uses 6 times less energy. Ways to save: switch off lights, TV and computers when not needed; unplug devices left on standby (they also use some energy); keep windows closed when an air conditioner runs; turn off taps and save hot water; choose appliances of an energy-saving class (A, A+ and so on); seal windows and doors. Safety: do not overload a socket and never pull a plug or cord with wet hands.
Home energy audit: write the power (from its label) and daily running hours of 5 devices at home; calculate E = P × t for each and find the biggest energy user. Safety: unplug devices only by the plug; work with an adult; never open electrical devices.