How Green is My Computer?

Table of Contents

1 Introduction

These are the notes for a short course in assessment of the carbon emissions from a computer. The first half of the course is on how to assess the carbon emissions. The second half covers how to reduce the carbon emissions.

Learning Outcomes

At the completion of this subject the student can:

  1. Evaluate the carbon emissions of a computer,

  2. Suggest ways to reduce the carbon emissions of a computer.


This course is designed to teach Skills Framework for the Information Age (SIFA) Level 1 competencies (SFIA 2009). The learning outcomes correspond to SFIA skills "Sustainability assessment" [SUAS] and "Sustainability strategy" [SUST] (SFIA 2009).

Pre-requisites, Co-requisites

It is assumed that the student has primary school mathematics and is familiar with the use of the Internet, academic writing and referencing.


The course consists of two parts, corresponding to the skills, with one part per week:

  1. Sustainability Assessment
    1. Understanding climate science
    2. Estimating the Greenhouse Gas Emissions from Computers
  2. Sustainability Strategy
    1. Reducing The Energy Use of Your Computer
    2. Buying an Energy Efficient Computer


To complete the subject you will need to spend 3 hours over two weeks, communicating with colleagues and your tutor. You are required to post at six items to the course on-line forums.

Evaluation Methods

You will be assessed on your contributions to the discussion forum (see "Assessment" for details. You are required to post an answer to each question in the readings by the end of Wednesday each week and reply to at least one posting from another student on each topic, by the end of each week. The tutor will send some tips to help you as the course progresses, and a weekly summary.

Teaching Strategies

The course is divided into modules. The equivalent of four printed pages of notes are provided. Further readings (which the notes have been prepared from) and questions for the student are also provided for each module.

On-line learning is the main delivery method, moderated and supported by a tutor, mentor, student discussion forums and feedback. Students are grouped in cohorts of six to twenty.

Specialist Features or Equipment

The subject is supported by a website where the online learning takes place. Learning materials plus discussion forums are available through this site. Set readings elsewhere on the web are linked from the site.

Course Designer

Tom WorthingtonTom Worthington is an independent ICT consultant and an Adjunct Senior Lecturer in the Research School of Computer Science at the Australian National University, where he teaches the design of web sites, e-commerce and professional ethics. In 2010 Tom received the Canberra ICT Award for Education, in recognition of his green ICT course. In 1999 he was elected a Fellow of the Australian Computer Society for his contribution to the development of public Internet policy. He is a past president, Fellow and Honorary Life Member of the Australian Computer Society, a voting member of the Association for Computing Machinery and a member of the Institute of Electrical and Electronics Engineers.


The notes for this course are adapted from the 12 week course: "ICT Sustainability: Assessment and Strategies for a Low Carbon Future" (Worthington, 2011). Further readings, most of which are available on-line, are detailed in the notes. Students may be provided with an updated copy of these notes via the Learning Management System of their education provider.

Changes from Previous Version

This is version 0.1, 19 April 2012.

2 Sustainability Assessment

Understanding climate science

The Intergovernmental Panel on Climate Change (IPCC) has reported that during the 20th Century, the temperature has been increasing due to rising greenhouse gas concentrations. This is most likely due to human activity.

The major greenhouse gas is carbon dioxide (CO2). One source of CO2 is burning fossil fuels, such as coal, oil and natural gas in power stations to generate electricity.

Estimating the Greenhouse Gas Emissions from Computers

Computers and telecommunications equipment (ICT) contributed 1.52% to greenhouse gas emissions in 2005 (ACS 2007).

The Australian Government ICT Sustainability Plan 2010 - 2015 (DEWHA 2010) defines ICT sustainability as:

"... the responsible acquisition, installation, use and disposal of information and communications technologies and services so as to utilise resources more effectively, improve efficiency and increase productivity, and reduce the environmental impact of operations. It also includes the effective use of information and communications technology to promote more sustainable practices in industry and the community. is the study and practice of using computers and telecommunications in a way which maximises positive environmental benefit and minimise the negative impact."

Calculate the Energy use of Your Computer

The amount of energy used by a computer can be measured and from this an estimate of greenhouse gas emissions calculated, in Kilograms of Carbon dioxide Equivalent (KgCO2e).

The energy used by a computer is calculated from the power use multiplied by time used:

Energy = Power x Time

The power used can be measured directly with a power meter, read from the specifications of the computer or estimated from industry averages. Power use of a computer is measured in Watts (W) or Kilowatts (kw or thousands of watts), Time in Hours per year (hr per year) and so energy is in kWhr per year.

For example a small desktop computer might consume 50 Watts of power and be used for 8 hours a day:

50 Watt x 8 Hours a day x 365.25 days a year / 1,000 Watt in Kilowatt = 146.1 kWhr per year

A Greenhouse gas conversion factor is then used to convert energy consumed in Kilowatt Hours (kWh) to kg of equivalent carbon dioxide. The conversion factor is about 1 Kg CO2/kWh for electricity generated by burning coal.

For example, our small desktop computer is in Multiplying by a conversion factor of 0.89 Kg CO2/kWh (typical for Australia) produces:

146.1 kWhr per year x .89 Kg CO2/kWh = 130 Kg CO2 per year (rounded to the nearest kilogram)

Use an energy usage calculator

The Foundation for IT Sustainability (FFITS) provide two versions of an Energy Savings Calculator (FFITS, 2011b) to estimate the energy used by a computer. The Consortium for School Networking provide an Energy Usage Calculator (CoSN, 2010) specifically tailored for schools.

It should be noted that these calculators use a fixed conversion factor for estimating carbon dioxide emissions from electricity used. The conversion factor varies from state to state in Australia and country to country around the world, depending on how electricity is generated. As Australia uses predominately coal fired power, an Australian calculator will give a higher estimate than a US calculator, where less coal is used.

Suggested Readings

  1. The Policy Statement on Green ICT from the Australian Computer Society (ACS 2007).

  2. Chapter 2 "Understanding climate science", of the Climate Change Review Final Report (Garnaut 2008).


  1. Suggest an outcomes from this activity: List at one outcome you want and expect from this subject in the forum.

  2. Search for articles and papers: Search for documents, articles, papers and videos about "Green Computing". List three items in the forum and briefly say what they cover and why they are worth reading.

  3. Estimate the Energy use of Your Computer: Use one,or more, of these methods to estimate the energy use of your computer and report the results in the forum:
    1. Measure the Energy Use With a Meter: Many local libraries loan out an energy meter. Use this to measure the energy us of your computer. Watch as it changes as you use the computer. Multiply by the number of Watts by the number of hours a year you use your computer and divide by 1,000 to give the annual kWHr figure. Multiply this by the conversion factor of 0.89 Kg CO2/kWh to give a figure in Kg CO2.
    2. Calculate the Energy use of Your Computer: If you do not have an energy meter, you can look up the power use in the computer's manual (look for a figure in Watts, or "W"). If there is a separate monitor and add these in as well.
    3. Use an energy usage calculator: Use the Energy Savings Calculator (FFITS, 2011b) or Energy Usage Calculator (CoSN, 2010) to estimate the energy use of your computer.

3 Sustainability Strategy

Reducing The Energy Use of Your Computer

The Foundation for IT Sustainability (FFITS) provide instructions to Activate power management on Windows 7 (FFITS, 2011a).

FFITS provide instructions to configure power management for operating systems including Apple Mac and Microsoft Windows. They recommend setting computers to enter system standby or hibernate after 15 to 30 minutes of inactivity and set monitors to enter sleep mode after 5 to 20 minutes of inactivity. On laptops, these need to be activated in the AC power profile, as well as battery power) profile.

The Natural Edge Project (2008) suggests four steps to minimise energy use in Client Equipment:

  1. Assess energy consumption by monitoring client equipment

  2. Consolidate operating client equipment only when necessary and removing unnecessary equipment

  3. Innovate by:
    1. Right-sized client equipment: do not buy more, or more powerful, equipment than needed

    2. Power management strategies: Turn off client equipment when not needed and turn on power management options in the equipment.

    3. Low-energy equipment: Select low energy component and equipment, such as processors, monitors, power supplies, RAM, flash memory and hard disks.

    4. Eco-Labels: Look for equipment meeting low energy standards.

  4. Manage and monitor the equipment and schedule high energy activities out of peak periods.

Buying an Energy Efficient Computer

The Energy Star Program, Version 5 (2008), required that a small desktop computer use no more than 148 kWh of electricity per year. The program also covers netbooks. Purchasing polices of many copies and governments require purchase of Energy Star rated equipment.

Suggested Readings

  1. Activate Power Management on Your Computer


  1. Configure power management for your computer: Check the power management settings on your computer, as outlined by the Foundation for IT Sustainability (FFITS) provide instructions to Activate power management (FFITS, 2011a). Were you able to do this? Were they already set? How much power do you think you will save?

  2. Buying an Energy Efficient Computer: What steps will you take when buying your next computer to reduce energy use? Are there any downsides with this?

4 Assessment

Following tasks are required of each student each week:

  1. Read the course notes for this week and the additional readings.
  2. Submit answers to each of the discussion questions in the Discussion Forum for that week.

Submit your answers before reading the answers from other students. Read the answers from other students and submit at least one reply to a posting your fellow students in the Discussion Forum, for each of that week's questions.

Contributions to weekly discussion forums are assessed by each student individually and then an average calculated.


The forums are for students to post answers to questions posed during and discuss the answer of other students. The questions are at the end of each week's notes. The student should first answer the questions and only then look at the answers from other students and discuss them.

Each student's contributions are marked on a three point scale:

Numerical Mark Standard
2 Greater than expectation: Work of good quality, displaying an understanding of the subject matter and a grasp of relevant skills that is above average: all questions answered and at least one reply to another student's posting on each topic.
1 At expectation: Work of satisfactory quality, which displays an adequate understanding of most of the subject matter and a sufficient grasp of relevant skills: most questions were answered, and at least one reply to another student's posting on each topic.
0 Limited contribution: Work which is incomplete or displays an inadequate understanding of the subject matter or an inadequate grasp of relevant skills. Few or no postings to the forums, or postings with content which not acceptable. In particular material which is not correctly referenced, or cited.


Marks are determined both on the answers to questions and extent to which the student fosters further discussion of the issues.

Marks are by peer assessment, will all students marking all postings and the result being an average (reviewed by the tutor).

Material posted should be relevant to the purpose of the forum and conform to the code of conduct of the institution offering the course.

5 Notes for the Tutor

This short course was prepared as a student exercise for University of Southern Queensland, Online Pedagogy in Practice EDU8114, Semester 1, 2012. As a result these notes contain more theory than need for a typical course. The tutor need not read the references.

Background to the Learning Technique

This course is designed to synchronise the student's at several points. The first point is at the beginning of the course when they all start at the same time with a minimum assumed level of knowledge. They then work asynchronously, being synchronised each half week by the tutor posting a summary of the discussion, to signal it is time to move on.

The course design is modelled on Salmon's e-tivities (2002), having:

  1. The Spark: A description of the activity, including the topic area and the expected contributions from students and resources available
  2. Individual contributions: Usually students posting to an on-line forum
  3. Interactions: usually students responding to each others postings
  4. Plenary: A summary from the tutor to the group, summarizing the discussion and commenting on the process.

This process is explicitly described to the student in the course notes, and built into the bi-weekly flow of the course (topic posted at the start, student discussion, tutor summary).

Pelz (2004) suggests at least three forms of social presence:

  1. Affective — The expression of emotion, feelings, and mood
  2. Interactive — Evidence of reading, attending, understanding, thinking about other's responses
  3. Cohesive — Responses that build and sustain a sense of 'belongingness', group commitment, ore common goals and objectives

However, the tutor cannot neatly divide their activities into these categories, nor expect it of the student. Any contribution will involve affective, interactive and cohesive elements. Also this is not a course in education and so students cannot be assessed on these forms of social presence.

Tasks for the Tutor

  1. Establish and maintain presence
    There are no face to face or real-time activities for this course, so the tutor has to rely on posting material to the forums and responding to students to maintain a presence. While text based forums might seem very impersonal, Rourke, Anderson, Garrison & Archer, (1999) pointed out that:
    "... Computer-mediated conferencing (CMC) is unique among distance education media because of its ability to support high levels of responsive, intelligent interaction between and among faculty and students while simultaneously providing high levels of freedom of time and place to engage in this interactivity."

    Social presence (SP): It is suggested the tutor create an online profile in the Learning Management System (LMS) and place a link to this from the course web site. Then post an introduction using much the same content, but in a less formal style to the general discussion forum of the course, with a link to the profile. This is is to establish for the students that the tutor is a real person who can be communicated with. While it is possible to have a computer mimic a person (Reeves & Nass, 1996), for the purposes of this coruse it is assumed the tutor is human.
    Cognitive presence (CP): It is suggested the tutor summarise the discussion at four points in the course. This should not only just excerpt what students say but offer extra information and analysis from the tutor, to show they are also engaged with the material and what the students are discussing.
    eaching presence (TP):
    As well as administrative reminders in the half weekly postings, the tutor should comment on teaching aspects of what the students have discussed.
  2. Provides a stimulating topic and stimulus for learning/participation
    The course notes provide key concepts, theories and models. However, the tutor should also highlight these in postings, ideally with reference to personal experience or current events.
  3. Supportive facilitation which leads and maintains critical dialogue within the community
    Expectations and participation protocols for the students are detailed in the notes. However, the tutor should reinforce these in postings and in feedback to the class. Feedback should indicate where the student did well and suggest how they could do better. Any negative feedback of an individual student should not be presented to the class. The course is designed to be solutions orientated, being reduce the energy use of a computer. However, it is also intended to foster critical thinking, with the task not simply o come up with a good number.
  4. Engagement of audience and recognize balanced contributions of others
    The forum topics are designed to
    keep students engaged with the material. The student should be able to see that the notes are there to help them do the tasks. But there will still be a need to point this out in feedback.

Before the Course Begins

Provide the Notes to Students

Place a copy of these notes in the learning management system used and check the links to referenced material are accessible. The notes are prepared using a basic web format suitable for smart phones and tablet computers as well as desktop and laptop computers. The notes can be converted to PDF<, standalone web pages, an IMS Content Package, or provided as printed notes. The format does not matter, the important point is to provide all the notes to the students at the beginning of the course.

Set Up Course Forum

The course requires students to carry out a number of tasks over two weeks. Some form of store and forward (asynchronous) forums will be required for the students to post to.

Create the following forum before the course commences: "General Discussion and Announcements". Techniques from Pelz (2004) for maintaining an online social presence would suggest an additional informal online "lounge" for delegates to mingle between formal sessions. If such a facility is available, students should be encouraged to use it. But such a facility is not justified for just this one short course.

When the Course Starts

Post a welcome message to the general forum, including:

  1. A welcome to the course (including the name of the course) and saying the course has started,
  2. Point out where the course notes are,
  3. Point out where the assessment details are,
  4. Invite students to post a welcome message to the general discussion forum (pointing out this is not required and is not for assessment),
  5. As the students to read the first module,
  6. Remind the students what the first task is and when it is due.

At the Beginning of Each Module

Create a forum thread for each task in the course notes and copy the title of the task to the forum to create a thread for the students to reply to.

Each Business Day

Read every posting from every student. If the discussion has stalled, or gone off topic, post a message to correct it, otherwise keep out of the discussion.

Mid and End Module

Summarise the postings from students for each thread and post it to the thread. Make every comment positive. If a student is clearly not understanding the material or is adversely effecting the class, content them individually.

Check the marks awarded by students to their peers, to see if these seem reasonable and make adjustments as required. Some students (and staff) may be uncomfortable with peer assessment and want more individual formative feedback. They may need some reassurance this is educationally valid.

Strumpel (2012) suggests that peer assessment produces results consistent with teacher based assessment. Dr Nerilee Flint's research at University of South Australia also indicates that brief feedback accompanied by marks is more effective and appreciated by students than extensive comments with no mark (Flint 2011).

End of Course

In the general forum summarise the discussion. Thank the students. Report the assessment through the provider's assessment system.


Flint, N. (2011). Towards Fairer University Assessment: Recognizing the Concerns of Students. Routledge. Retrieved from

Pelz, Bill. (2004). My Three principles of effective online pedagogy. Journal of Asynchronous Learning Networks, 8(3). Retrieved from

Reeves, Byron. & Nass, Clifford. (1996). The Media Equation: How People Treat Computers, Television, and New Media Like Real People and Places. Cambridge University Press, New York, NY, USA.

Rourke, L., Anderson, T., Garrison, D., & Archer, W. (1999). Assessing Social Presence In Asynchronous Text-based Computer Conferencing. The Journal Of Distance Education / Revue De L'ÉDucation à Distance, 14(2). Retrieved April 5, 2012, from

Salmon, G (2002), e-tivities: The key to active online learning, Kogan Page Limited, London.

Strumpel, C. (2012). Peer Assessment in the Team-Based Learning Classroom. [text]. doi:

6 Bibliography

ACS. (2007). Policy Statement on Green ICT. Available: Last accessed 21 July 2011.

CoSN. (2010). CoSN Energy Usage Calculator. Available: Last accessed 16 March 2016.

FFITS. (2011a). Activate power management on Windows 7. Available: Last accessed 26 July 2011.

FFITS. (2011b). Calculate Your Computer Carbon Emissions. Available: Last accessed 26 July 2011.

Garnaut, R. (2008). Understanding climate science. Available: Last accessed 21 July 2011.

IPCC. (2006). IPCC Guidelines for National Greenhouse Gas Inventories. Available: Last accessed 25 July 2011.

US Department of Energy. (2010). History of ENERGY STAR. Available: Last accessed 3 August 2011.

Worthington, T. (2011). ICT Sustainability: Assessment and Strategies for a Low Carbon Future. Available: Last accessed 27 July 2011.

7 About this Book

This asynchronous learning event will take the participants through the practical steps to estimate the carbon emissions of their computer and the the computer they are using. This asynchronous learning event will explore online tools used in the workplace to deliver job specific training. Participants will be asked to share experiences via a discussion forum. This learning event will take place over two weeks.

Copyright © Tom Worthington, 2012

Version 1, 25 April 2012:

The web version of How Green is My Computer? by Tom Worthington is licensed under a Creative Commons Attribution-ShareAlike 3.0 Australia License.