The environmental benefits of going green notwithstanding, most businesses approach this concept on a purely materialistic basis. They effect a trade off between the cost of going green compared to not, and the returns in terms of energy savings, better productivity, increased sales owing to a better public image, reduced taxes and subsidies.
Green initiatives such as deployment of energy efficient devices and peripherals, server virtualization, and data center redesign require substantial upfront investment. Calculating energy savings allows for a direct cost benefit analysis. The method to do so follows:
- Refer to the nameplate, bottom, or back of the monitor, printer, or other device to determine the wattage, or the maximum power that the device draws. If the wattage does not find mention, use a tong-tester to find current draw in amperes, and multiply the same by voltage to obtain the wattage. Most IT equipment in the United States uses 120 volts.
- Estimate the energy used by the device. Wattage x Hours used per day / 1000 provides the daily Kilowatt-hour (kWh). One kilowatt is 1,000 Watts.
- Multiply the resultant figure by the period, and the resultant figure by the local utility’s energy rate per kWh for the same period.
Assume a personal computer and monitor uses 140 Watts and 160 Watts respectively, and is used for six hours a day. The total energy consumption is (140 Watts + 160 Watts × 6 hours / 1000) x 365 days = 657. Assuming that energy costs 10 cents per kWh, the total annual energy cost is $65.70.
Now, if a laptop consuming just 50 Watts replaces the personal computer and monitor, and everything else remains the same, the annual energy consumption becomes (50 x 6 hours /1000) x 365 = 109.5 kWh, and at 10 cents per kwh, costs just under $11. The green computing initiative of switching over to a laptop, therefore, results in direct cost savings of 65.7 – 11 = $ 54.70.