The Cost of Using Computers

Summary: Students calculate and compare electrical costs of computers in various modes. Cost of Computers Grade Level: 5-8 Subject Areas: English Objectives puters, lights, and monitors when they’re not (Media and Technology, Research By the end of this activity, students will be in use reduces the number of comfort com- and Inquiry), Mathematics, able to plaints and air conditioning costs. Science (Physical) • explain that different types of computers use different amounts of electricity; There are many computer myths that have been dispelled over the years. One myth is Setting: Classroom • compare and contrast computer mode settings and their electricity use; and that screen-savers save energy. In fact, it Time: • identify ways to conserve electricity when takes the same amount of electricity to move that fish around your screen as it does to do Preparation: 1 hour using computers. any word processing. Activity: two 50-minute periods Rationale Vocabulary: Another myth is that it takes more energy to Calculating the cost of computers will help turn off and restart your computer than it Blended rate, CPU, Electric rate, students realize potential energy savings both does to just leave it on all the time. It is more Kilowatt-hour, Sleep mode, at school and at home. likely that your computer will be outdated Standby consumption, Watt, Watt before it is worn out by turning it off and on. meter Materials There are some school districts that require • Copies of Calculating Computer Costs Major Concept Areas: computers to be left on at night for software Activity Sheet upgrades and network maintenance; these • Quality of life • Calculator (optional) units are often automatically shut down after • Management of energy the upgrades are complete. Although the resource use Background computer will most likely be using some elec- How many hours do you use a computer Academic Standards: tricity because it is left plugged in, it may be each day? Each week? How many different the only alternative available in your school English: E.8.1, E.8.2, F.8.1 computers do you use on a regular basis (at district. EE: A.8.1, A.8.4, A.8.5 home, at school, at the library, etc.)? How Math: D.8.4 much do you think it costs to operate the Some people believe that turning off the Science: D.8.7, D.8.8, D.8.9 computer? Do you think all computers cost monitor will save as much energy as turning the same to run? What is the difference off the whole computer. Although it will save Related KEEP between putting your computer in sleep or some electricity, the Central Processing Unit Activities: standby mode and turning it off? (CPU) will still be operating as if the monitor Have students participate in “The is on, generally using approximately 120 Cost of Using Energy,” These days, computers are considered a watts. It is more energy efficient to put the “Demanding School Electric Bills,” common household appliance and an inte- computer into standby mode, which puts the and “Light and Your Load.” gral teaching tool in the classroom. People computer in a low-power use mode. This rec- use computers all the time but rarely think ommended mode also allows the computer Getting Ready: about how much it costs to keep those com- to be easily woken up when required. •A Wattage Chart for Typical puters running. However, in computer lab settings with short Computers & Monitors in breaks between classes, staff may be able to Different Modes is provided. Use Although the amount of electricity generally have the monitors plugged into an outlet that a watt meter for a more accurate wasted by an average classroom computer can be controlled by a toggle switch. This measurement of a computer's may be insignificant, typically around $20 way, the teacher can turn off all of the moni- energy use in different modes annually, the sum of wasted electricity by tors with one flip of the switch and they don’t (see Using a Watt Meter to computers throughout a school district can have to worry about rebooting all of the CPUs. Determine Actual Energy Use). amount to hundreds or thousands of dollars. Obtain a watt meter (Kill-A-Watt One more computer myth is that saving and Watts Up? are popular In addition to the direct energy savings, com- energy by powering down one computer won’t continued on next page puter labs often overheat so turning off com- make a difference. In fact, if all the comput- Energy and Your School l Cost of Computers 61 Getting Ready Continued: brands) from your local public library or contact the KEEP office ers in an entire school district are operated at bill that is recorded as kilowatt-hours (kWh). to borrow one. It may be useful to their highest energy efficiency, electricity bills Review the definitions of kWh, watt, and purchase one for the classroom or could be significantly lowered. Every little bit other energy terms as needed (see Glossary). school if this activity will be con- helps and this activity is designed to help ducted year after year. reinforce that message. 2. Discuss different ways a computer can be shut down, identifying these as different com- • Contact the Facilities Manager There are several variables to consider when puter modes (see Computer Mode to request a copy of a typical calculating the cost of computers. Some of Definitions). electric bill for your school. these include the energy efficiency of monitors and CPUs, mode in which the computer 3. Hand out the Calculating Computer Costs • If the blended electric rate is is in, electric rate, and hours of use, which Activity Sheet. Review the (I.) Introduction not provided on the bill, calculate are described in Computer Variables. and complete questions A through D of the the rate as follows. Use the total (II.) Classroom Computer(s) section as a amount due and divide by the Conserving energy by operating computers class. Provide the blended electric rate for total number of kWh used for the efficiently is a great way to contribute to a the school (see Getting Ready). billing period. If your school is school district’s goal of reducing energy con- charged on-peak and off-peak sumption and lowering utility bills. Although 4. Have students complete questions E rates (most schools are), add the computers are probably not the highest elec- through I of the (II.) Classroom Computer(s) kWh used at each rate. Your trical consumers in a school, it is easier for section in class. A calculator may be used to blended rate will likely be in the individuals to manage computers efficiently assist with calculations. Be sure students $0.05/kWh - $0.10/kWh range, than the heating and air conditioning systems. show their math when doing calculations. which is higher than the listed See the activity “Light and Your Load” for electric on-peak and off-peak elec- more ideas on how to conserve energy in 5. Assign students to complete the (III.) Home tric rates. The blended rate is your classroom. Computer(s) section of the activity sheet. higher because it takes into Encourage students to have adult family account the demand charges and For additional information, refer to the members assist with the project. NOTE: It is other charges found on your Reducing Appliance Energy Use and Are Your advisable to secure parental permission prior school’s electric bill. Appliances Wasting Energy? fact sheets in to conducting surveys. the Appendix - Support Materials. • Talk to the district Information Closure Technology department to find out After students complete the Calculating Procedure approximately how many comput- Orientation Computer Costs Activity Sheet, review the ers are in the district. Calculations Have students consider all the costs involved results as a class. Use the (IV.) Comparing made during this activity will be with buying and using a computer. Ask them Computer Costs at Home and at School ques- more accurate if you can find out if all computers cost the same. What makes tions to generate class discussion. how many of each kind of comput- one computer more expensive than another? Assessment er there are (old CRT monitor, LCD screens, and laptops). Help students understand that the energy Formative used by a computer will continue to be a fac- • How well did students complete the • Work through the Classroom tor after it is bought and paid for. Ask stu- Calculating Computer Costs Activity Computer Example calculations dents how they can reduce the energy cost of Sheet? to prepare for questions students their computers. • Were students able to provide ways to may have when completing the lower the electricity costs of the classroom Calculating Computer Costs Steps computer(s) or their home computer? Activity Sheet. 1. Inform students that a computer's energy • Were students able to identify ways to edu- use, like most appliances, is measured in watts. cate other students and staff about the Remind students that a computer's energy cost of computers? consumption will be part of an overall electric 62 Cost of Computers l Energy and Your School Summative Computer Variables Have students calculate the cost savings if they were to operate the classroom computer(s) more efficiently. What are the sav- Energy Efficiency of Monitors and CPUs ings/costs associated with upgrading the There are still some older, TV-like, CRT monitors in use that are less energy efficient classroom computer with a more energy effi- than the newer, more standard LCD flat screen monitors (refer to the Wattage Chart for cient CPU and monitor? Typical Computers & Monitors in Different Modes).

Load more