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Tuesday, April 19, 2011

Turn Off School Computers, Turn On Savings

Next week, voters will head to the polls to cast their votes.  The $91 million school budget will be on the minds of voters along with what candidates to vote for to fill the Westfield Board of Education seats up for election.

The Fact of The Matter recently received an email from one of our readers suggesting one way for the Bd. of Education to save money and perhaps cut a few $$$ off the proposed $91,000,000 budget.  After all, if voters defeat the budget at the polls, it will be up to the Westfield Town Council to review the school budget and make some cost cutting suggestions.

TFoTM presents one cost cutting plan here.  Information was copied and pasted from the Internet to address the cost of leaving school office and classroom computers on.

After lighting, computers and monitors have the highest energy consumption in office environments. Studies have shown that power management of computers and monitors can significantly reduce their energy consumption, saving hundreds or thousands of dollars a year on electricity costs.

The energy consumption of computers and monitors is determined by the amount of energy they require to operate and how they are used. While the energy requirements of a device make an important contribution to its overall energy consumption, the key to reducing energy consumption is changing how devices are used.

Approximately half of all office computers are left on overnight and on weekends. Evenings and weekends account for 75% of the week, so ensuring computers are turned off at night dramatically reduces their energy consumption. Further savings are made by ensuring computers enter low power mode when they are idle during the day.

Energy wasted by computers and monitors costs public school districts in this country more than $145 million dollars each year. School administrators and energy managers will find the solution to this problem is only a mouse click away. By activating their school computers’ built-in power management features, K-12 educational facilities can reduce their operating expenses while contributing to a cleaner environment.

ENERGY STAR, a program jointly managed by the US Environmental Protection Agency and the Department of Energy to promote energy efficiency encourages organizations and individuals to eliminate waste with power management. This nationwide program allows classroom computer monitors to enter a low-power "sleep" mode when inactive. For every 1,000 monitors using ENERGY STAR’s free, easy-to-use power management software tools, enough energy is saved to light 160 households. Additionally, sleeping computer monitors help the environment by preventing air pollution associated with the burning of coal, oil, and gas to generate electricity.

Dozens of school systems nationwide have implemented power management, including the Albuquerque Public School system in New Mexico and California’s Winton School District. Watt Watchers of Texas, a school energy management organization, is leading a statewide power management effort that expects to save school districts in that state an estimated $4 million per year in energy costs.

Save 200,000 kWh of Energy All in a Day's Rest — Energy Star ¨ Monitor Power Management

Organizations can save energy and money by enabling power management on their computer monitors. Free software tools and services from Energy Star automatically put monitors to rest organization-wide when not in use—saving a significant amount of energy and money. What's more, monitor power management will not affect your computer or network performance. A simple touch of the mouse or keyboard "wakes" the machine within seconds.

Save Energy and Money With Monitor Power Management. Enabling monitor power management could save your organization approximately 200,000 kWh per year for every 1,000 monitors. This amounts to:

$20,000 per year saved at 10 cents/kWh.
Enough energy to power 230 households for one month

Enable Power Management Organization Wide Quickly and Easily. Energy Star monitor power management offers software tools and services to:

Turn on monitor power management through the network rather than machine-by-machine using the EZ Save software tool.
Use the capability of Windows 2000 to enable power management throughout your organization.
Allow end users to individually enable monitor power management quickly and easily through the EZ Wizard web-based software tool.

Inform Your Organization About Monitor Power Management. To help educate employees about monitor power management and its benefits, Energy Star offers a set of educational materials including posters, a fact sheet, a case study, and desktop reminders. For more information visit

Read more to view mathematical equations detailing energy savings.

Cost of Running SETI 24/7 on a home PC.

Part 1

There has been much discussion about this very topic and there are many who give
their opinion, however there is nowhere that gives the facts for potential users to read
this information which they can then show to those who may complain about the use
of Electricity.

Lets start by explaining the simple principles of Electricity and the power consumed.

As we all know, electrical circuits consume power (va), one Watt of Electricity is also
1va. Calculating the voltage in a circuit and multiply it by the current used arrives at
this figure.

Example 1:

Circuit A has a supply rated at 12V (Vn) and measurement shows it draws some 4.5A
(In) from the supply. To determine the power rating of the circuit you simply multiply
the Voltage by the Current thus..

P = Vn * In = 12 * 4.5 = 54 watts or 54va

Now we understand that, there is one important point to make at this stage. If you
alter the Voltage, you will also alter the current drawn from the circuit, however the
power will remain the same at 54va.

Example 2:

P = Vn * In = 200 * 0.27 = 54 watts or 54 va.

If you are wondering about the 0.27, then that is the current drawn from the circuit.
As I said, the power must remain constant for the circuit, so by increasing the voltage
you are reducing the load taken from the circuit.

If you have any doubts about this then do the calculation in reverse.

Example 3:

In = P / V = 0.27A

Part 2:

Now we have the basics out of the way, lets go on to the important part of cost.

Lets assume you turn your monitor off manually when not in use, so we can just
concern ourselves with the actual computer itself.

Please bear in mind these are rough figures with regards power used and only as an
example. The maths are correct, but the power used by each users machine will
depend on the hardware and the setup of the machine.

Your computer has a 300W (300Va) PSU and runs at 120V, therefore it will draw
some 2.5A from the supply

Remember Examples 2 and 3 above.

300 / 120 = 2.5 where

300 is the maximum power of the PSU
120 is your supply Voltage.

There are things inherent in all electrical circuits that have a bearing on the actual
power used and these are called losses. They occur due to electrical circuits being far
from perfect and take the many forms. The average PSU in a computer will operate at
about 80% efficiency due to the nature of the circuits employed. This means that for
the PSU to deliver 300W (va) as rated then it will actually draw about 375W (375va).

Now we have that information, we can begin to look at a more accurate cost running

Whilst we know that your Computer will not run at full PSU load, if ever, we will use
the full load to give the MAXIMUM cost that should be seen to any user.

Your PSU, as we have shown above, uses 375W (va) of electrical energy from the
supply. Therefore to do the cost calculation is rather simple.

Example 4:

Power used at maximum (Pmax) = 375va

So now calculate the total power used in 24 hours,

P(max) * 24hrs = 375 * 24 = 9000va or 9000W (9Kva or 9Kw)

If you pay, for example, 10 cents for each unit of electricity, then your cost of running
the machine is :

9 * 10 = 90c per day

If you wish to know the monthly cost, then calculate as follows:

90 * 7 * 4.3 = 2709c or $27.09 per Calendar month.

The 4.3 in the above equation is the multiplier required to calculate any figure on a
calendar month basis.

Now we all know that electricity costs vary across the nation and from supplier to
supplier. If you have a look at your last bill, you should see the unit cost of electricity
clearly indicated on there. This is the figure you need to use to calculate the
approximate cost of running a PC 24/7 for a month.

Some of the information at the top of this in Part 1 may seem a little irrelevant to the
cost calculation, however that is information that you can use to calculate all sorts of
costings if you know the rating of various pieces of equipment.

Part 3. Estimates:

The following are based on the following figures.

That all of the PSU's run at 80% efficiency, about average, and that each Kw/h of electricity will cost $0.06c per Kw/h.

Please note that you will need to adjust the calculation for your given tarrif of costs from your electricity supplier. This information will be available on your electricity bill.

235w PSU

Assumed maximum demand due to losses. 293w

In one calendar month this would consume 211.6632 Kw/h

at a cost of 0.06c per Kw/h, the maximum cost is $12.70

300w PSU

Assumed maximum demand due to losses. 375w

In one calendar month this would consume 270.90 Kw/h

at a cost of 0.06c per Kw/h, the maximum cost is $16.25

350w PSU

Assumed maximum demand due to losses. 437.5w

In one calendar month this would consume 316.050Kw/h

at a cost of 0.06c per Kw/h, the maximum cost is $18.96

400w PSU

Assumed maximum demand due to losses. 500w

In one calendar month this would consume 361.20Kw/h

at a cost of 0.06c per Kw/h, the maximum cost is $21.67

450w PSU

Assumed maximum demand due to losses. 562.5w

In one calendar month this would consume 406.35Kw/h

at a cost of 0.06c per Kw/h, the maximum cost is $24.38

500w PSU

Assumed maximum demand due to losses. 625w

In one calendar month this would consume 451.50Kw/h

at a cost of 0.06c per Kw/h, the maximum cost is $27.09

As you can see the costs escalate incrementally as you would expect. These costs do not include the cost of running a monitor, however as this is not on 24 hours a day these costs are minimal, a few extra dollars a month. The figures quoted above are only if the machine is running at maximum potential load at all times. In most cases the machine will probably consume only about 50% of the estimated maximum and thus cost, however this will vary due to hardware differences and usage. The maximum you can use is listed above and is accurate for consumed power, actual cost will vary with supplier costs per Kw/h.

Read more: How much electricity does a computer left on all the time consume? | Answerbag

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