Going ‘Green’ Saves Money

When I am asked to help districts save money or financially justify the paradigm shift to One to One computing, I suggest they audit their technology energy use. Shifting from traditional desktop PC’s to laptops, netbooks, or thin clients can save significant amounts of money, to say nothing of it being the environmentally correct thing to do.

A typical desktop computer uses between 65w-250w of electricity. A typical CRT monitor uses 80w and LCD 35w of electricity. You can get the actual amount of energy usage by checking the label on the specific device, or you can use a watt-meter to measure real energy consumption.

So, if we use 158w as an average for desktops and 58w as an average for monitors our total energy use is 216w per computer.

Let’s compute the energy cost of running just ONE computer for a typical school year.


1. The computer is in use 6hrs per day. (6hrs x 216w = 1296w)

2. The computer is left in power saver mode over night. (18hrs x 35w = 630w)

3. The computer is in use 200 days per year. (200 days x (1296w+630w) = 385,000w)

4. The computer is in power saver mode on weekends and holidays, approximately 100 days. (24hrs x 35w = 840w) x 100 days = 84,000w)

5. The computer uses no energy 65 days of the year.

Total yearly energy cost for ONE computer is 469,000w or 469 kilowatt hrs.

Estimated yearly cost for ONE computer @ .17 per kw hour = $80.

Energy cost for ONE computer over a (5) year lifespan = $400.

Total annual energy cost for ONE THOUSAND computers = $79,730.

Total energy cost of ONE THOUSAND computers over (5) years = $398,650.

Now, lets look at alternatives to the energy hungry desktop PC approach that is so prevalent in our schools today.

A laptop or netbook averages about 30w, most of it related to the display.

A thin client and display also averages about 30w.

Thus replacing a standard desktop with a laptop, netbook, or thin client device theoretically produces an 86% reduction in energy consumption.

Estimated yearly cost for ONE device @ .17 per kw hour = $11

(Savings =$69)

Energy cost of ONE device over a (5) year lifespan = $55

(Savings =$345)

Total annual energy cost of ONE THOUSAND computers = $11,000


Total energy cost of ONE THOUSAND computers over (5) years = $56,000


Even if we take the ‘best case’ desktop scenario: a 65w computer and 35w display, the energy savings for shifting to laptop, netbook, or thin client devices is 54% resulting in a savings of $227,230.

In One to One implementations, if students use battery power during the day and are required to charge their devices at home, the energy savings can be more than 95% and a cost savings of $378,717.

The yearly $68,530 savings in energy costs (ONE THOUSAND computers) can purchase:

An additional (228) netbooks, or thin clients per year. (@$300 per device)

Over (5) years a school can DOUBLE the number of devices available to students (1140) based on energy savings generated by switching to netbooks or thin clients.

If you are more interested in the traditional route you can purchase laptops and add an additional (86) devices per year (@$800 per laptop) and increase your network by (430) devices over (5) years.

Anyway you look at it there is a good case to be made to go “Green”.

It’s time to shift our technology energy paradigm.


15 thoughts on “Going ‘Green’ Saves Money

  1. Interesting numbers. I’m thinking about this from an enterprise rather than educational perspective though, and ergonomically laptop use typically quite suboptimal – eg not at recommended viewing height; netbooks with tiny keyboards…

    Might $227k in savings over 5 years in an organisation of 1000 people be eaten by additional injuries, sick leave, compensation/medical costs due to long term (6+ hours/day) of laptop use?

  2. c
    I don’t have any formal data to rebut your hypothesis. However, I can say that I used a laptop with an attached full size keyboard and mouse in my office for more than 10 years; and for the last three years have been using a laptop without the extra keyboard and mouse, with no harmful effects.

    I would not recommend netbooks for use in an enterprise business environment; but for elementary, middle school, and some high school students, they are just fine.


  3. Good approach, although there are considerations over useful life of laptops, and other TCO expenses in infrastructure and support.
    CoSN has a Leadership Initiative dedicated to K-12 green computing which contains an easy-to-use energy use calculator for schools.

  4. A couple of years ago, I worked on a web-based decision-making toolkit meant to help make cost-effective decisions regarding choices of computers for developing country environments where electricity is either not available, unreliably or expensive. It is called “POWERING ICT” and the tool is still available @ http://www.dot-com-alliance.org/POWERING_ICT/. You would need to do the research to plug in current costs but the tool was developed to be flexible and allow for local costs to be entered.

  5. I knew that the old clunky monitors used a lot of energy, but I had no idea it was so much energy! Also, by getting rid of the big monitor and/or computer to replace it with a laptop or a slimmer monitor, I had no idea was so green. Also, by saving all the money schools, or even at home, there would be no excuse for poor technology, because we would have the ability to stay up-to-date. We wouldn’t be paying such high energy bills leaving us with money to purchase tutoring or enriching software. We need more people out there computing number and saying, “Hey! There is money here!!! Let’s make a change!”

    I have a laptop that the battery went on and now I need a new one but can’t afford it. As a result, I’m stuck plugged into the wall most of the time sucking away energy as if it were soda. I also feel like rechargeable batteries should be designed to not deplete effectiveness over time. I know the new macbooks have that feature but I can’t afford a macbook, nor is mac really user friendly for me. Studying to be a teacher, I know I’m going to need and probably rely on my laptop in my future profession.

    I’m observing in a classroom, and school, that has implemented a one to one computing system and they have seen good results. The students are eager to learn and use the computers and they are also very eager to learn while using the computer which is probably most important. Along with the savings school systems are saving without having computer labs the school will be able to be the forerunner for other schools to come. As well as being an example for how to run and start such programs.

  6. Think as the battery as a small expense for convenience of anytime anywhere computing access.
    Then the lower power consumption for a laptop is a great deal. Schools need to deal with security and a shorter life for laptops, but the power savings over desktop coputers are there (whether your battery is dead or not). Any rechargable battery with today’s technology will lose its juice over a couple of years.
    Another non-portable approach that takes advantage of reduced power consumption is virtual desktop infrastructure (VDI) which uses a thin client approach.
    BTW, as a project director nearly 3000 miles away fom CoSN’s office, I exclusively use my laptop at my home office and on the road – no problem.

  7. Rich,
    I am working with a number of schools who are using thin clients and netbooks with virtual desktops. I believe that virtualization and cloud computing are the keys to opening the door to ‘ubiquitous’ computing.

    The Virtualization and Cloud computing paradigm shifts offer:
    1. Lower initial device purchase costs ($300)
    2. Lower energy costs (See above article)
    3. Lower support and maintenance costs.
    4. Fewer device replacement cycles.
    5. 24x7x7 access to the school network. (applications and storage)

    These benefits make it possible to exponentially increase the number of devices available to students.


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