How much power per household? Group 1 Activity. Objective: To estimate the average power of electric lights in an average house.

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1 Group 1 Activity To estimate the average power of electric lights in an average house. Using the power meter, record the power of each of the bulbs provided Warning: always switch off the lamp before changing the bulb. Use your group judgement to make the following decisions: 1. Which bulb(s) represent the average brightness of lights in a typical house? 2. How many lights of this brightness are there in a typical house? 3. How many hours in the day are these lights switched on? Use your decisions 1, 2 and 3 above to calculate the average power consumed by traditional filament lights in a typical house. Also calculate the average power consumed by equivalent energy saving lamps. Average power consumption of filament lamps in a typical house = Average power consumption of energy-saving lamps in a typical house =

2 Group 2 Activity To estimate the average power of televisions in an average house. Using the power meter, record the power consumed by the television provided: a) When switched on and operating normally. b) When on standby. Use your group judgement to make the following decisions: 1. How many TVs are there in a typical house? 2. How many hours in the day are these TVs switched on? 3. How many hours a day are these TVs in standby? Using the decisions 1, 2 and 3 above to calculate the average power consumed by TVs in a typical house. Average power consumption of TVs s in a typical house = Extra thoughts: Is the energy used by a TV in standby mode significant? If every TV in the country were in standby mode would that be significant?

3 Group 3 Activity To estimate the average power of computers in an average house. Using the power meter, record the power of the computer provided Use your group judgement to make the following decisions: 1. How many computers (including playstations) are there in a typical house? 2. How many hours in the day are these computers switched on? Using the decisions 1 and 2 above to calculate the average power consumed by computers in a typical house. Average power consumption of computers in a typical house = Optional extra: If you have got time, answer these questions. What other electronic gadgets do we use in the house? Make a list. Do you think any of them consume significant power compared to a computer?

4 Group 4 Activity To estimate the average power used by cooking in an average house. Empty the kettle and add ½ litre of water from the cold tap. Using the power meter, record the power consumed by the kettle when switched on. Also record the time taken to boil the water. Use your group judgement to make the following decisions (don t spend lots of time, if in doubt make a best guess): 1. How many litres of water does it take to cook spaghetti for your family? 2. How many litres of hot drinks does your family consume in the day? 3. What other cooking is done in your house? How many litres of boiling water do you think that is equivalent to? Have a guess! Use your decisions 1, 2 and 3 above to calculate the total litres of boiling water that is equivalent to the total daily energy used by cooking in a typical house. Total number of litres of boiling water needed for daily cooking = Using the total number of litres required and the time taken to boil ½ litre, calculate the time taken to boil that amount of water using the kettle provided. Total time taken to boil litres of water = minutes Use the total time taken and the power reading recorded above to calculate the average power consumed by cooking in a typical day. Average power consumption of cooking in a typical house =

5 Group 5 Activity To estimate the average power of washing in an average house. Look at the washing machine instruction booklet provided to find the energy used by various washing cycles. Use your group judgement to make the following decision: 1. What would be a typical wash cycle used by a family? 2. How many washes does a family do in a week? Use your decision above to calculate the total energy used by a typical family washing machine in a week. Using the energy calculated above, calculate the average power consumed by washing machines. Average power = Average rate of energy use Average power consumption of washing machines in a typical house = Extra: If you have time, think of other kitchen appliances that consume electricity. How do you think these appliances compare to a washing machine in their power consumption?

6 Group 6 Activity To estimate the average power of cars owned by an average family. With the information provided on the attached sheet, use your judgement to make the following decisions: 1. What is the average power consumption of a car when driving (look very carefully at the information at the top of the attached sheet)? 2. How many hours does a car run on an average day? 3. How many cars does an average family have? Use your decisions 1, 2 and 3 above to calculate the average car power used by a typical household. Average power consumption of cars in a typical household = Extra thought: Would it make much difference if everyone used a smaller, more efficient car?

7 Information sheet for group 6 activity Definition: One horsepower is equal to about 746 watts. Brake horse power (bhp) is used to measure the power of car engines. For example, a 100bhp car has a maximum power consumption of 75kW (75,000 watts). The average power consumption of a car is about ¼ of the maximum power. The following are a typical range of small, family and more sporty cars. 1 VW Lupo 3L TDi Engine: Diesel, 1200cc 3-cylinder turbo direct injection Power: 61 bhp@4000 rpm Torque: 14.3 kgm@ rpm Performance: Top speed: 163 kph 2 Toyota Prius Engine: Petrol-electric, 1497cc, DOHC VVTi, 16 valve inline 4 Power: 76 bhp@5000 rpm Torque: 11.3 kgm@4,200 rpm Performance: 0-96 kph: secs, Top speed: 160 kph 3 Opel Astra Caravan ECO4 Engine: Diesel, 1700 cc turbo common rail direct injection, DOHC inline 4 Power: 80 bhp Torque: 17.3 kgm Performance: Top speed: 173 kph Ford Escape Hybrid Engine: Petrol, 2300 cc DOHC 16-valve, Atkinson cycle inline 4, 65-kW electric assist motor Power: 133 bhp@6000 rpm, 155 bhp (petrol+electric) Torque: 17.8 kgm@4500 rpm Performance: NA 5 BMW 330d Engine: Diesel, 2926cc, turbo 24-valve, 6 cylinder Power: 204 bhp@4000 rpm Torque: 42 kgm@ Performance: kph: 7.8 secs, Top speed: 227 kph 6 VW Phaeton V10 TDi Engine: Diesel, 5000cc bi-turbo, independent 'Pumpe deuse' direct injection V10 Power: 313 bhp Torque: 76.5 kgm@2000 rpm upwards Performance: 0-96 kph: 7 secs, Top speed: 248 kph

8 Group 7 Activity To estimate the average power of food consumed by an average family. Look at the energy content of the foods provided and use your judgement to make the following decisions: 1. How much energy in joules (J) is consumed by an average person in a day? 2. How much energy in joules (J) is consumed by an average household in a day? Use your decision 2 above to calculate the average food power consumed by a typical household. Average power = Average rate of energy use Average food power consumption in a typical household = Extra thought: Does everyone consume a similar amount of food? How much less food power would you imagine is consumed in Africa?