Lesson Description:
Consider conducting an audit of the computers and printers in your school. If your school has a computer lab, conduct the audit in the computer lab. If each classroom has one or more computers or printers, you may want to take a look at the energy used by the computers on a room by room basis.(Note: Be sure to enlist the support of the administration, the custodial staff, and other teachers as needed to complete this audit.)

Step 1. Inventory of computers, printers, and monitors
Count the number of computers in the computer lab or in each classroom.
Room # : ________
Number of computers: ________
Number of printers: ________
Number of monitors: _________

On the side of each printer should be a UL sticker. This sticker should indicate the number of watts.
(Note: Take note of the different kinds of computers. You will want to look at each type separately in this audit. You’ll tally up the total at the end.)

Step 2. Printers: Total watts for printers of this type
Look at the printers: (note: take note of the types of printers in the room. There may be more than one. If so, you’ll need to conduct each step below for the different types.)

a. Multiply the watts by the number of printers. This gives the total watts of printers on an equivalent rating.
Printer type 1
________ watts x # of printers = total watts for printers of this type

Printer type 2
________ watts x # of printers = total watts for printers of this type

b. Total watts for all printers

• Add the total watts for all printers.
• Multiply by .30 to calculate actual watts used since most machines use on average 30% of their rated energy usage.

c. Total watts per day for all printers
Multiply watts for all printers x number of hours used per day = total watts per day.

d. kwh per day for all printers in one classroom

Convert watts to kilowatts by dividing by 1000.
_________________________ ÷ 1000 = _________________________
kwh all printers in one classroom kwh per day for all printers in one classroom


Step 3: Computer monitors
Measure the energy used by standard computer monitors. (Note: take note of the different types of computer monitors. Do the following calculations for each of the different types of monitors.)

a. Locate the number of watts
Determine the number of monitors of the same type in one area. Locate the ul sticker on the back of one of the monitors. On this sticker locate the number of watts.

b. Total watts of each monitor type
Multiply the watts by the number of monitors with an equivalent rating to find the total watts of monitors of an equivalent rating.

Monitor type 1
________ x _________________ = _______________
watts # of monitors total watts

monitor type 2
________ x _________________ = _______________
watts # of monitors total watts

Repeat if there are more than 2 types of monitors in the room.

c. Total watts for all monitors

• Add the total watts for all monitors.
• Multiply by .30 to calculate actual watts used since most machines use on average 30% of their rated energy usage.

d. total watts per day for all monitors

• Multiply watts for all monitors x number of hours used per day = total watts per day.

e. Total kwh per day for all monitors
Convert watts to kilowatts by dividing by 1000.
_________________________ ÷ 1000 = _________________________
kwh all monitors in one classroom total kwh per day

Step 4: Classroom computer CPUs (tower or desk-top)
Measure the energy used in standard classroom computer CPUs (tower or desk-top).
(Note: Some computer types, such as the iMac, are considered “combined units”, that is, the monitor and CPU are all one piece. If that is the case, there will be one ul sticker for the combined energy use of the monitor and CPU.)

a. Total watts for each computer type

• Multiply the watts by the number of computers with an equivalent rating to find the total watts of computers of an equivalent rating.

CPU type 1
________ x _________________ = _______________
watts # of computers total watts

CPU type 2
________ x _________________ = _______________
watts # of computers total watts

Repeat if there are more than 2 types of computers in the room.

b. Total watts for all computer CPUs

• Add the total watts for all computer CPUs.
• Multiply by .30 to actual watts used since most machines use on average 30% of their rated energy usage.

c. Total watts per day for all computers
Multiply watts for all computer CPUs x number of hours used per day = total watts per day.

d. Total kwh per day
Convert watts to kilowatts by dividing by 1000.
_________________________ ÷ 1000 = _________________________
kwh all computers in one classroom total kwh per day

Step 5: Combined total energy use of all computer components

• Calculate combined energy use and requirements for all computer components in one area (total from steps 2, 3, and 4).
• Add the totals kwh for printers + total kwh for monitors + total kwh for computer CPUs.

What else can be done?
This is a lot of data you have collected and calculated. There are a few simple things to check for after you have examined your numbers. These are probably easy to do and inexpensive changes your school can make to reduce these numbers.

• Are the computers “sleep modes” being used? Check with the computer lab staff to ensure that the computers are set to go into “sleep mode” after a few minutes of inactivity.
• What happens to the computers at night or on the weekends? Are they shut down? Are they switched off? Is the power turned off? Consider connecting the computers and printers to a power strip that can be turned off at night and don’t the weekend. Again check with the computer lab staff to determine what energy saving practices relating to computers can be implemented throughout your school.

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Lesson Type:

• Audit

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Sustainability Topic:

• Energy
• Green Building

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GEF Program Category:

• Green Building Program
• Green Energy Challenge

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