Cost of Computers in Various Modes
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Summary: Students calculate and compare electrical costs of computers Cost of Computers in various modes. Objectives is that screen-savers save energy. In fact, Grade Level: 5–8 By the end of this activity, students it takes the same amount of electricity to will be able to: move that fish around your screen as it Subject Areas: English • explain that different types of does to do any word processing. Language Arts, Mathematics, computers use different amounts of Science electricity; Another myth is that it takes more energy to turn off and restart your computer than Setting: Classroom • compare and contrast computer mode it does to just leave it on all the time. It settings and their electricity use; and Time: is more likely that your computer will be Preparation: 1 hour • identify ways to conserve electricity when outdated before it is worn out by turning Activity: Two 50-minute periods using computers. it off and on. There are some school districts that require computers to be left Rationale Vocabulary: Blended on at night for software upgrades and Calculating the cost of computers will help rate, CPU, Electric rate, network maintenance; these units are often students realize potential energy savings Kilowatt-hour, Sleep/standby automatically shutdown after the upgrades both at school and at home. mode, Watt, Watt meter are complete. Although the computer Materials will most likely be using some electricity Major Concept Areas: because it is left plugged in, it may be • Copies of Calculating Computer • Quality of life the only alternative available in your Costs activity sheet • Management of energy school district. • Calculator (optional) resource use Some people believe that turning off the Background monitor will save as much energy as turning Getting Ready: A Wattage Chart for Typical How many hours do you use a computer off the whole computer. Although it will save Computers & Monitors in each day? Each week? How many different some electricity, the Central Processing Different Modes is provided. Use computers do you use on a regular basis Unit (CPU) will still be operating as if the a watt meter for a more accurate (at home, at school, at the library, etc.)? monitor is on, generally using approximately measurement of a computer’s How much do you think it costs to operate 74 watts. It is more energy efficient to put energy use in different modes (see the computer? Do you think all computers the computer into standby mode, which Using a Watt Meter to Determine cost the same to run? What is the puts the computer in a low-power use Actual Energy Use). Obtain a watt difference between putting your computer in mode. This recommended mode also allows meter (Kill-A-Watt and Watts Up? sleep or standby mode and turning it off? the computer to be easily woken up when are popular brands) from your local required. However, in computer lab settings public library or contact KEEP to These days, computers are considered with short breaks between classes, staff borrow one. It may be useful to a common household appliance and an purchase one for the classroom may be able to have the monitors plugged integral teaching tool in the classroom. or school if this activity will be into an outlet that can be controlled by a People use computers all the time but conducted year after year. Contact toggle switch. This way, the teacher can turn rarely think about how much it costs to the facilities manager to request a off all of the monitors with one flip of the keep those computers running. copy of a typical electric bill for switch and they don’t have to worry about your school. Although the amount of electricity generally rebooting all of the CPUs. wasted by an average classroom computer If the blended electric rate is not One more computer myth is that saving provided on the bill, calculate the may be insignificant, typically around $18 energy by powering down one computer rate as follows. Use the total cost annually for each desktop computer, the won’t make a difference. In fact, if all the due for electricity and divide by the sum of wasted electricity by computers computers in an entire school district are total number of kWh used for the throughout a school district can amount to operated at their highest energy efficiency, billing period found on your hundreds or thousands of dollars. electricity bills could be significantly Continued on next page There are many computer myths that have lowered. Every little bit helps and this been dispelled over the years. One myth activity is designed to help reinforce that message. 1 CostSeeking of Computers Inhabitable l SchoolsEnergy andl Energy Your Schooland Your School There are several variables to consider 3. Hand out the Calculating Computer Costs Continued from previous page when calculating the cost of computers. activity sheet. Review the (I.) Introduction Some of these include the energy efficiency and complete questions A through D of school’s electric bill. Your blended of monitors and CPUs, mode in which the the (II.) Classroom Computer(s) section rate will likely be in the $0.09/ computer is in, electric rate, and hours as a class. Provide the blended electric kWh - $0.14/kWh range, which will of use, which are described in Computer rate for the school (see Getting Ready). be higher than the on-peak and off- Variables. peak electric rates (if your school is 4. Have students complete questions charged, and most are) shown on Conserving energy by operating computers E through H of the (II.) Classroom your bill. The blended rate is higher efficiently is a great way to contribute to Computer(s) section in class. A calculator because it takes into account the a school district’s goal of reducing energy may be used to assist with calculations. demand charges and other fees consumption and lowering utility bills. On Be sure students show their math when found on your school’s electric bill. If you do not know your school’s average, computers make up seven to doing calculations. blended rate use $0.12/kWh. fourteen percent of a school’s electricity consumption. Although computers are 5. Assign students to complete the (III.) Talk to the district Information not the highest electrical consumers in a Home Computer(s) section of the activity Technology department to find out school, it is easier for individuals to manage sheet. Encourage students to have adult approximately how many computers computers efficiently than the heating and family members assist with the project. are in the district. Calculations air conditioning systems. See the activity NOTE: It is advisable to secure parental made during this activity will be “Light and Your Load” for more ideas on permission prior to conducting surveys. more accurate if you can find out how to conserve energy in your classroom. how many of each kind of computer Closure there are (LCD/LED screens, Procedure After students complete the Calculating laptops and tablets). Orientation Computer Costs activity sheet, review the Have students consider all the costs results as a class. Use the (IV.) Comparing Work through the Classroom involved with buying and using a computer. Computer Costs at Home and at School Computer Example calculations questions to generate class discussion. to prepare for questions students Ask them if all computers cost the same. may have when completing the What makes one computer more expensive Assessment than another? Calculating Computer Costs Formative activity sheet. Help students understand that the energy • How well did students complete the Related KEEP Activities: used by a computer will continue to be a Calculating Computer Costs activity “The Cost of Using Energy,” factor after it is bought and paid for. Ask sheet? “Demanding School Electric Bills,” students how they can reduce the energy • Were students able to provide ways “Light and Your Load,” “At Watt cost of their computers. to lower the electricity costs of the Rate?” classroom computer(s) or their home Steps computer? 1. Inform students that a computer’s energy use, like most appliances, is • Were students able to identify ways to measured in watts. Remind students that educate other students and staff about a computer’s energy consumption will the cost of computers? be part of an overall electric bill that is Summative recorded as kilowatt-hours (kWh). Review Have students calculate the cost savings the definitions of kWh, watt, and other if they were to operate the classroom energy terms as needed. computer(s) more efficiently. What are the 2. Discuss different ways a computer savings/costs associated with upgrading can be shut down, identifying these as the classroom computer with a more energy different computer modes (see Computer efficient CPU and monitor? Mode Definitions). Energy and Your School l CostCost ofof ComputersComputers 2 Extensions Involve students in a thorough computer Computer Variables survey of the entire building and meet with the Information Technology staff Energy Efficiency of Monitors and CPUs to determine the standard operating Standard LCD flat screen monitors are more energy efficient than the procedures and options to maximize older, TV-like, CRT monitors (refer to the Wattage Chart for Typical efficiency of computer usage for the Computers & Monitors in Different Modes). More and more school school. districts are using laptops and tablets instead of traditional desktop units. As mentioned earlier, many computers use power even when they If more efficient computer operating procedures are needed, have students are off, but still plugged in, or in standby mode (see Using a Watt Meter report their findings to the superintendent to Determine Actual Energy Use). Note: ENERGY STAR® monitors and or school board with recommendations.