1. Lesson 5: Efficiency

2.  MUST calculate efficiency for electrical devices and power stations  SHOULD suggest ways of reducing use of energy  COULD understand how the impact of human activity on the environment can be reduced

3.  You need to be able to define the following:  Efficiency

5. 1)5% or 0.05 2)0.8 3)30% 4)Any sensible suggestions – e.g. walk to school; turn off lights; don’t leave equipment on standby. 5)More efficient goods use less energy; users pay lower electricity/fuel bills. 6)Recycling methods developed; use of renewable fuels for transport; use of renewable resources to generate electricity. 7)Less land is used to grow or produce raw materials; less land for landfill sites; more land can be used for food production or housing; less energy used in processing raw materials; less waste.

6. Activity 1 (Low demand) 1)kettle (0.93, 93%); iron (0.90, 90%); diode lamp (0.80, 80%); fan (0.75; 75%); washing machine (0.70, 70%); lamp (0.04, 4%) 2)Some energy is always transferred to the surroundings. Activity 2 (Standard demand) a) An Energy Performance Certificate indicates how efficiently a house or flat uses energy and what its environmental impact is; one is needed when a house or flat is to be sold or rented. b) The efficiency rating and the environmental impact rating (based on CO 2 emissions) now, and the potential ratings if energy-saving measures are put in place. c) Results are prepared after a survey of the building and its heating system etc. d) The certificate includes recommendations that can be used to target specific measures (e.g. more insulation or double glazing). e) It isn’t always practical or affordable to put these measures in place, especially in older homes.