EarthCARE Energy Related FAQs

1. What can I do to save energy in the use of my computer?
2. Is it better to turn my computer off or put it in sleep mode?
3. Are there any risks to turning off my computer often?
4. Is it more efficient  to set the thermostat higher to heat a room quickly?
5. Is temperature set back a proven method of energy savings?
6. What is the best set point for cooling?
7. What is a good temperature setting for hot water heaters?
8. How much does it cost to run 30 computers 24/7?
9. What is the cost of running a refrigerator for one year?

1. What can I do to save energy in the use of my computer?
The following practices apply to the computers that usually sit on your desk and that you normally use for your day-to-day work. More often than not these computers are Windows or Macintosh systems.

Shut down your computer and monitor when the workday is over. This single action will result in significant energy savings.

Shut down computers and printers for the weekend and other holiday periods when the schools are closed, when you're on vacation or during other periods of extended absence from the office.

Switch the monitor off when you will not be using it for several hours. {Older style CRT monitors are one of the most power-hungry components of a computer. LCD (commonly called "flat panel") displays generally consume about half as much energy as CRT monitors (and generate less heat). Hence, turning them off for relatively short periods when you are away from your desk is not as critical, but you should still turn them off at the end of the workday.} Note that using a screen saver results in no power savings.

Over the course of a year, these simple steps will result in considerable power savings for your computer only. Given that there are several thousand computers deployed within the Board, this can easily result in annual savings of $500,000 in electrical costs for computers alone. And that is a conservative estimate given the rising electricity costs.

Switching your computer, or even just the monitor off also saves power indirectly. The computer equipment generates a considerable amount of heat. In buildings with lots of computers the climate control system has to work harder to compensate. Especially in the summer, cooling costs can increase significantly.

Visit http://www.ocdsb.ca/General_Info/Conservation/index2.html where you will find on the left hand menu a link to a "computer energy calculator". You can use this to calculate the savings that will result shutting down one to 20,000 computers.

top

2. Is it better to turn my computer off or put it in sleep mode?
Computers with energy saving features became more common about 10 years ago. The objective was to curb the energy use of computers and related equipment that were growing in numbers and increasing in complexity. In a common office computing environment the devices largely responsible for energy consumption are desktop computers and laser printers. Energy is saved by switching the device into a low power consumption mode, often called "sleep mode," after a specified idle period. When activity is detected, it only takes a few seconds for the device to power back up from sleep mode. Sleep mode still utilizes approximately 25 to 40 watts. "COMPUTERS OFF" is the real solution.

3. Are there any risks to turning off my computer often?
There have been claims that turning your computer on and off ultimately shortens its lifetime. The truth is computers are designed to be powered up and down as needed. You certainly will not harm your computer by switching it on and off just once per day.

top

4. Is it more efficient to set the thermostat higher to heat a room quickly?
The heating output of most furnaces is 100% on or off. The thermostat cannot make the furnace heat up the space quicker. (Note: some new high efficiency furnaces have variable heat output). Regardless, setting the thermostat too high will result in overheating. The same principle applies to cooling mode.

5. Is temperature set back a proven method of energy savings?
A typical furnace does not work harder; its output is always the same (exception above noted). Heat loss is a function of temperature differential between the outside wall and the inside wall and the outside and inside ventilation air. Temperature setback is a proven method of energy savings.

top

6. What is the best set point for cooling?
Cooling of air is meant to provide a comfort zone. Temperature to cool wastes energy and damage your cooling unit. A comfort cooling set point of 20°C or lower can cause the DX coil in the A/C unit to freeze because of insufficient load. When the ice melts, it can cause a small flood and serious damage to a furnace unit. Further, the compressor can be damaged. Expensive repairs and inconvenience can result.

7. What is a good temperature setting for hot water heaters?
120°C is all that is needed. Have you noticed, that you always turn on the hot water and then add cold to it to reach a comfortable temperature.

8. How much does it cost to run 30 computers 24/7?
The cost depends on what you pay for electricity in your area and the wattage of the computers being used. Suppose you have 30 computers on every day for a year (365 days) for 24 hours each day and that these computers are very efficient (150 watts) and there are no peripherals operating (e.g., scanners, printers, etc.) and that you are paying 10 cents per kWh for electricity. This would cost $3942.00. If the computers use more electricity or you are operating printers, etc., or you pay more for your hydro, then the cost would be higher.

9. What is the cost of running a refrigerator for one year?
The cost of running any appliance depends on the efficiency of the appliance and how well it is operated. Do you open the door often? Is the refrigerator overloaded? How often is the motor on (usually 40 - 60%)? You also need to determine how many watts per hour the refrigerator uses. You can find the wattage of your appliance on its serial plate. If wattage is not listed, look for amperage and voltage ratings on the same plate. Multiply amperage (amps) times voltage (volts) to get the wattage (watts).

You need to know your cost of electricity per kilowatt hour in your area. Check your hydro bill for this.

To calculate the cost per hour when the fridge motor is operating:

[(# watts)/1000] x (cost per kWh of hydro in your area)

For the cost per year:

[cost per hour] x [24] x [365] x [%age of time the appliance motor is running]

For example, if a refrigerator uses 350 watts, powers on about 50% of the time, and runs for 24 hours per day every day of the year, and electricity costs 10 cents per kWh, the cost for the year would be:

[350/1000] x [0.10] x 24 x 365 x 0.50 = $153.30

top