1 Chapter 8 Introduction This section compromises a set of activities that focuses on saving energy in our homes. The activities illustrate: Finding the ways to reduce energy consumption in our homes Saving energy through the energy efficient appliances Understanding cost-benefit calculations for energy efficient appliances
2 Activity 8.1: Electrical Detective Within this activity you should be able to borrow an energy meter, which can measure the electricity consumption of various appliances at school and at home. The energy meter is able to measure the electricity consumption of the appliances in your home even when they are in stand by mode. That is also important for appliances, which are switched on and off continuously such as a fridge, a washing machine or boiler. You will be able to calculate how much you pay for the electricity as well, once you enter the unit price into the meter. Note that you do not have to measure for a whole hour such as using the iron. You may measure for a certain time period and then calculate the consumption over one hour Task 1: stand-by mode of appliances Many appliances consume energy even when they are on stand-by mode. This happens when they are not working but ready to be switched on by using remote controller. Your task is to find out how many such appliances do you have at home and what is their power demand in stand-by mode. When you find out fill in the table in your worksheet. Task 2: computer Try filling the tables in the worksheet with the help of energy meter. If your monitor is connected to the computer, fill in only the first table. Note: Don t forget!!: Screen saver does not save energy, but really only protects the screen. When there would be the same picture on it, the same points would be burnt and thus the screen would have been damaged. That is why the screen saver always moves.
3 In Windows in the control panel settings you can (in screen saver menu) set up after how many minutes of the idle your monitor and hard discs fall asleep. And such mode when your screen completely darkens saves energy. You can prove it by measurement. If you set falling asleep after 10 minutes, you would not even need the screen saver. Task 3: high-speed kettle How much energy must be consumed to boil 1 litre of water in a high-speed kettle? If you have an electric cooker, measure the consumption necessary for boiling 1 litre on the hotplate. What is preferable? Task 4: washing machine With your energy meter compare the energy consumption for washing at different temperatures. If there is an energy saving mode for your washing machine for small loads, then measure the energy consumption for the normal mode with say 2 kg of washing and compare with the efficient mode. Which uses less energy and why? Task 5: fridge How much energy is consumed per hour? What effect would different settings of the thermostat and temperature have on the energy consumption and the preservation of food? Task 6: iron How much energy is used per hour for ironing your school shirts? And what happens when you iron at a lower temperature, for example nylon scarves? Task7: microwave oven How much energy does microwave consume to warm up a lunch? Do you think it is more efficient to warm up using a microwave oven or the electric cooker? Task8: drinks machine If you have a machine which allows you to buy cold drinks at school, measure its energy consumption like you would a refrigerator. Overall Task You have already measured or calculated the energy use of many appliances. Now estimate the electricity demand of any other appliances in your house using the energy meter where possible. Complte the tables in the worksheet. If you measure the consumption per hour, calculate how much you would pay over a full year. Notes for teachers: Background: This activity is to study the electricity consumption in our houses. The students can measure many appliances at home and at school. The measurements can be put into various graphs and tables and discover interesting facts and they should then discuss this within their groups. Teachers are often willing to lend the measuring meter to active and reliable pupils so that they can make some measurements at home.
4 If the meters are lent to the students, it is important that a clear set of instructions is given as to show how to use the energy meter and how to read results. Before using the meter, switch off at the socket then insert the plug of the meter and then the plug of the appliance you wish to measure. Whilst the meters are capable of reading very small currents, care must be taken with appliances that use large amounts of energy such as kettles. Most cookers are permanently wired and so their energy usage can only be estimated from label information or from time usage and assuming each plate averages about 1 kw per hour. From a previous experience of this activity at schools, students discovered that the drinks machine, which was in a trial period at the school, consumed much more energy than the producer had indicated. The school then asked the supplier to find a machine which was more efficient. The aim of the activity is; Understanding the electricity consumption of the household appliances Experiencing the measurements of the electricity consumption rates for several appliances Understanding the concept of stand-by consumption Comparing the electricity use of various modes for each appliance, such as stand by, full, half loaded, with maximum temperature etc. Comparing the consumption rates between the appliances Finding out the total consumption figures of all appliances in a house Material: tables for completion, energy meter device to measure electricity Key words: stand by mode, ambiance temperature, full load, half load, saving mode, kwh, power, consumption Skills: working individually, setting links between the elements, observation, experimenting, discussion, interpretation and analysis, National curriculum subjects: Science, geography, natural sciences, social sciences, citizenship Age Range: 10-15, key stage 2-3
5 Activity 8.2: Energy efficient appliances: Home Research This is a follow up activity of research in shops and electric detective. In the research in shops you found out about the consumption rates of efficient and non-efficient appliances. In electric detective you discovered with the help of an energy meter, how much energy is consumed by the appliances at your home or school. In this activity you will estimate how much money you can save by buying energy efficient appliance. As you probably already know, when you buy an appliance you pay a different price depends on the energy class of the appliance (from A to C typically). It might be more expensive to buy an energy efficient appliance with A+ or even A++ rating however, during its operational life you will pay less running costs. Task 1: home appliance survey Before you start calculating, compile a list of the electrical appliances you have at home and how often you use them. Ask your parents assistance if necessary. Then fill in the table in your worksheet. Task 2: How much energy can we save? Now we can compare our estimate of the energy usage of existing appliances with new appliances. Energy consumption data for such appliances can be found from the activity research in shops or by consulting the European appliance database at Then answer the questions in your worksheet. Notes for teachers: Background: The potential for saving energy in the home is usually quite large. Most people only buy new appliances when their old appliance no longer works. This means that not only ore most appliances quite old, but also maybe performing less efficiently than when they were bought. The amount of energy they consume can only be estimated unless one is able to borrow a wattmeter. This activity is designed to calculate these potential savings. T
6 The aim of the activity is: Understanding the potential energy savings through the usage of energy efficient appliances Parental Help Students will need help from their parents because they may need to have some idea of how old is the appliance. Also parents are more likely to know how often they use appliances like washing machines. Estimating the number of hours that light bulbs are used is quite difficult and so it might be easiest for the students to check at say two different times during the evening. Impact of new appliances There is a lot of information available about new appliance as these all now carry the EU label. This information can be obtained from a visit to a shop or consulting web sites on the internet such as It is useful to discuss why new appliances are much more efficient and have a better performance and so look at the activity designing a low energy kitchen. Try to encourage the students to discuss their findings with their parents. After all parents like to save money and to make their contribution to save the environment. Material: worksheet, appliances, parents, appliances at home Key words:: energy savings, CO2 emissions, energy efficient appliances, Kyoto protocol, energy ratings, A++, A+, A, B, C, D rated appliances Skills: Working individually, recognition of similarities and differences, comparison, information management, observation, cause-effect associations, setting links between the elements, information management and presentation. National curriculum subjects: mathematics, science, social sciences, physics, citizenship Age Range: 10-15, key stage 2-4 Activity 8.3: conservation saves money Task: Use the worksheet to make some simple cost and savings calculations through the use of energy efficient appliances, especially fridges. Please read the information carefully and seek help if necessary Notes for teachers: Background: This activity is an exercise to calculate potential savings of a specific appliance: fridges. Fridges are the most energy consuming appliances of our houses. They work 24 hours a day, seven days a week. Therefore it is important to find out possible energy savings from these appliances. Students may need assistance with the calculations. The aim of the activity is: Understanding the potential energy savings through the usage of energy efficient fridges. Material: worksheet, calculator Key words: energy savings, CO2 emissions, energy efficient appliances, Kyoto protocol, energy ratings, A++, A+, A, B, C, D rated appliances, energy efficient fridges Skills: Working individually, recognition of similarities and differences, comparison, information management, observation,, cause-effect associations, setting links between the elements, observation, information management and presentation. National curriculum subjects: mathematics, science, social sciences, physics, citizenship Age Range: 10-15, key stage 2-4
7 Activity 8.4: life time cost When you buy an energy efficient appliance it has a lower operating cost because it uses less electricity, water and detergent. Therefore you will save some money every year. This money that you save, adds up over the years. Eventually these savings may repay you for making the initial purchase. Simple payback is calculated by dividing the total cost by these annual savings. Tasks: Visit an appliance store and select three refrigerators. Write down the information on the EU energy label and calculate the running costs for each model for a 15 year lifetime. Identify which is the cheapest to operate and whether the lower running cost allows one to recover the difference in the purchase price. Perform the same task for 3 washing machines and three dishwashers. Use the following costs - electricity 8p/kWh, water 7p/50 litres and detergent p/wash Notes for teachers: Background: This activity is an exercise to calculate payback times of energy efficient appliances and to learn how to evaluate purchases in terms of cost-effectiveness. The concepts should be explained to the students such as payback times. You may also wish to enhance the experience by inviting a salesperson of energy related products to speak to the class. The other benefits should also be discussed which motivate people to buy a new appliance. The aim of the activity is: Understanding the concept of payback time and payback times of energy efficient appliances. Material: worksheet, calculator Skills: Discussion, Application, Calculation, Data Collection, Analyze, and Computer Literacy. Key words: energy savings, CO2 emissions, energy efficient appliances, Kyoto protocol, energy ratings, A++, A+, B, C, D rated appliances, energy efficient fridges, payback time, life time cost of a product, National curriculum subjects: mathematics, science, social sciences, physics Age Range: 10-15, key stage 2-4
8 Activity 8.5: choosing low energy lamps There are now available low energy lamps which are much more efficient at converting electricity to light as conventional filament lamps and last much longer. The EU energy label for lamps provides information which enables one to compare energy efficiency, performance and cost Task Select each lamp in turn and discuss its characteristics with your group Look carefully at the description of each. Decide where each could be used and why Evaluate how much energy, money and pollution one can save per year between the least and most efficient lamp. Notes for teachers: Background: This activity is to identify where it is best to use certain types of lamps. The lamp characteristics should include the length, shape of the lamp, life time and cost. For the room, one should consider the quality of the light required (background, reading, watching TV, working), the number of hours per day the lamp is likely to be used and the ease with which the lamp can be changed. The aim of the activity is: Understanding how to select lamps for a particular room and function Material: worksheet, calculator Skills: Discussion, Application, Calculation, and Analysis. Key words: energy savings, CO2 emissions, energy efficient appliances, energy ratings, A to G, payback time, life time cost of a product, National curriculum subjects: mathematics, science, social sciences, physics Age Range: 10-15, key stage 2-4
9 Activity 8.6: design your low energy kitchen This is your chance to design your own low energy kitchen. The aim of this activity is to help you to create an environmentally friendly and also a low cost kitchen by using information available on the web and from retail shops. This will help you or your parents to buy an appliance or design a new kitchen, which meets your needs and has a low environmental impact. Follow the instructions below step-by-step. They will help you to create your energy efficient kitchen Consider the characteristics of your family and your needs. How many people are there in your family? What are their ages? Decide which of the following appliances you need and why Refrigerator Freezer Washing machine Dishwasher Tumble dryer Oven/ Cooker Light bulbs After deciding which appliances you may like to buy, consider and follow the instructions below: Is there enough space for your appliances you have selected? Decide the shape of your kitchen, which should have an average area of 9 m 2, that is length and width of 3m by 3m Decide the space available for each appliance you wish to select Is your budget enough to pay for all of these? Add up the purchase cost of all your appliances and find out whether this is within budget? If not decide what options are available. If the models meet your needs and criteria start completing tables 1-2 for each appliance. Most of the information comes from the label or fiche, but some information such as the amount of detergent will come from the label on the detergent package. Notes for teachers: Background: This activity is an activity to design a low energy kitchen through the use of energy efficient Students may need assistance with the calculations. The aim of the activity is: Understanding the potential energy savings in the kitchen Understanding the potential savings through the usage of energy efficient appliances What s new in household appliances Potential for energy efficiency Selecting appliances using energy label and fiche Use of web based information systems Calculating lifetime costs, savings and emissions Material: worksheet, calculator
10 Key words: energy savings, CO2 emissions, energy efficient appliances, Kyoto protocol, energy ratings, A++, A+, B, C, D rated appliances, energy efficient fridges, Skills: Discussion, Application, Calculation, Data Collection, Analyse, and Computer Literacy, Working alone and in groups, observation and interpretation, comparison, information sharing National curriculum subjects: mathematics, science, social sciences, physics Age Range: 11-18, key stage 2-4
11 Worksheet 8.1: Electrical Detective Please complete the tables below Task 1: stand by mode of the appliances Name of the appliance Power demand in stand-by mode How many hours do you leave it stand-by per a day/week/month How much power does it waste in stand by mode per a day/week/month Task2: computer Measure energy consumption for each phase of operation Computer Maximum instant power demand (W) Switching on (first 20 seconds) Starting up basic programs with switch on Opening of programs in idle operating with the switched off monitor switched off hard discs (the computer is on but the screen is still on) Monitor Maximum instant power demand (W) Switch on (first 20 seconds) Normal operating Screen saver Efficient mode Task3: high-speed kettle How much energy is consumed to boil 1 litre of water in a kettle. If you have an electric kettle, measure how much energy is used for boiling 1 litre water Will boiling water in a pot on the cooker be more or less efficient.?
12 Worksheet 8.1: Electrical Detective Task4: washing machine Washing temperature 40 C 60 C 95 C How much laundry [kg] Energy use with full washing machine Energy use with efficient mode Task5: fridge Energy use for 1 hour Energy use for 1 week Energy use for 1 year Minimum Average Maximum Task6: iron Temperatures How many hours a week Energy use for 1 hour Energy use for 1 week with low temperatures (for nylon and wool) with high temperatures (for cottons) With maximum Temperatures Energy use for 1 year Task7: microwave oven How much energy does microwave consume to warm up a lunch? Answer: Do you think it is more preferable warming up in the microwave oven or on the electric cooker? Answer: Task8: drinks machine Consumption per hour: Consumption per a year
13 Worksheet 8.1: Electrical Detective Overall Task Name of the appliance Power demand of the appliance How many hours do you use it per week? / how much electricity does it use? How many hours do you use it per year?/ how much electricity does it use? Tumble Drier Fridge Washing Machine Dishwasher Kettle Televis ion Lighting How much money does it cost per a week How much money does it cost per a year?
14 Worksheet 8.2: Energy efficient appliances: Home Research Before you start calculating, to get the idea, it would be good to count how many electric appliances you have at home and how often you use them. You will fill in the table in your worksheet. Ask your parents help if necessary. Appliance How many we have at home How many days a week is it used How many hours approximately per day Answer the questions below 1) Calculate how much energy can be saved per month and per year. 2) Taking the electricity price at 8p/kWh you can work out the annual amount of money that can be saved. 3) Assuming that each kwh electricity results in release of 0.5 kg carbon dioxide to the atmosphere how much pollution can be saved? 4) If we multiply this by 150 million, the number of households in Europe, how much energy can be saved? 5) Do you think such a saving would help Europe to meet its Kyoto target for greenhouse gas reduction so reducing the likelihood of global warming?
15 Worksheet 8.3: conservation saves money Refrigerator1 is rated as class C and cost 500 and uses 100 worth of electricity each year. Refrigerator2 is rated as class A (which is more energy efficient) cost 600 and uses 75 worth of electricity each year. 1. At the end of the first year, how much will Refrigerator 1 have cost? 2. How much will Refrigerator2 have cost? 3. At the end of the second year, how much will Refrigerator1 have cost? 4. How much will Refrigerator2 have cost? Both refrigerators should last for 15 years. You can easily calculate how much each refrigerator will cost for its entire lifetime. Refrigerator1 Refrigerator2 Cost = Cost = Operating Cost = Operating Cost = Total cost after: Total cost after: Year 1 Year 1 Year 2 Year 2 Year 3 Year 3 Year 4 Year 4 Year 5 Year 5 Year 6 Year 6 Year 7 Year 7 Year 8 Year 8 Year 9 Year 9 Year 10 Year 10 Year 11 Year 11 Year 12 Year 12 Year 13 Year 13 Year 14 Year 14 Year 15 Year 15 Which refrigerator really costs more? How much money did the higher purchase price refrigerator save during its lifetime?
16 Worksheet 8.4: cost-effective buying The money you save by replacing a worn-out energy consuming system with a more efficient one adds up and will eventually repay you for making the purchase, if the payback time is less than the system s lifetime. Simple payback is computed by dividing the total installed dollar cost by the annual dollar savings. The first year rate of return is the inverse of the payback time in percent or may be computed by dividing the annual dollar savings by the system s total installed dollar cost. Calculate payback and the percentage rate of return in the following problems: (1) You can choose one of the following insulations with the following results: Insulation #1 Installed Cost = 200 Annual Savings * = 120 *Savings from reduced fuel bills due to added insulation. Insulation #2 Installed Cost = 235 Annual Savings = 145 Payback: Insulation #1 = yrs. Insulation #2 = yrs. Rate of Return on your investment: Insulation #1 = % Insulation #2 = % Which one do you choose? (2) You can choose one of the following water heaters with the following results. Water Heater #1 Installed Cost = 325 Annual Savings* = 19 *Thicker wall insulation in the new water heater. Water Heater #2 Installed Cost = 1475 Annual Savings* 150 *Solar water heater that only uses purchased energy when not enough solar energy is available Payback: Water Heater #1 = Water Heater #2 = Rate of Return: Water Heater #1 = Water Heater #2 = Which one will you choose? (3) You can choose one of the following room air-conditioners with the following results Air-conditioner #1 Installed Cost = 220 Annual Savings = 15 Air-conditioner #2 Installed Cost = 435 Annual Savings = 35 Payback: Air-conditioner #1 = Air-conditioner #2 = Rate of Return: Air-conditioner #1 = Air
17 Worksheet 8.5 Choosing low energy lamps Complete table filling in information where it is available from the lamp package or the lamp Model - manufacturer & type Power - consumption of lamp - units are watts Brightness - light intensity - units are lumens Energy efficiency class - from EU energy label - classes range from A to G Lifetime - average lifetime assuming one year is equal to 1000 hours of use Purchase cost - marked on the package Which room & why - from this information plus other information on package like dimensions and shape decide in which room this lamp could be used and why Selecting lamps Model & type Filament lamp Power rating (watts) Brightness (lumens) Energy Efficiency Class Lifetime (hours) Purchase cost ( ) Which room and why