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That Softphone is an Energy Hog

If you are considering the elimination of the hard phone for the softphone, you may not be saving as much money as you thought. I have posted nojitter.com blogs on VoIP power issues in the past that cover associated considerations: "Saving 25% on Your VoIP Energy Bill," "Who Pays the Power Bill?"The lowest power consumer is the legacy analog phone, followed by the legacy digital phone. These generally consume less than 1 watt of power. There are two power classes for IP hard phones. Class 2 IP phones consume less than 7 watts. Class 3 IP phones consume more than 7 watts. The more features an IP phone has, such as color touch-sensitive screen, high fidelity voice, 1Gbps connection and multiple ports, the more likely it is a Class 3 phone. There are some newer IP phones that have these features and are Class 2 in operation. I found one from Avaya that has all these features and uses less than 5 watts.

The cost of electrical power varies greatly across the country. You can find the electrical energy rates for your state by going to http://tonto.eia.doe.gov/state/. The rates range can be from 8 cents per kilowatt hour to 20 cents per kilowatt hour (kwh).

It was predicted in 2007, that the electrical rates would increase by 3% for 2008. The actual increase was 10%. The national average went from 10 cents/kwh to a little over 11 cents/kwh. The rapid increase in electrical energy rates demands attention and cost management. The expenses for energy are second only to the expenses for the IT staff salaries.

If you have installed a 5 watt IP phone, then the average annual electrical cost (at 11 cents/kwh) is $4.84/year. However the electrical bill can be as low as $3.52/year or as high as $8.80/year depending on your geographic location. This does not include the PoE power consumption at the LAN switch. Adding PoE at the switch end of the cable uses another 1.5 to 3 watts per PoE port to account for the inefficiencies in the power generation and the energy loss in the LAN cable. This adds another $1.45 to $2.90/year for 11 cents/kwh per IP phone. All told, the legacy phone costs between 70 cents and $1.75/year to power.

The cost of cooling IT equipment is not factored in by the vendors when they specify the IP phone energy consumption. The cost of cooling is about .86 the cost to power the IT devices. This means that all the above energy cost must be multiplied by .86 and added to the IP phone energy cost to get a true estimate of the IP phone energy consumption.

The table above was calculated to provide a baseline to compare with the energy consumption of a desktop PC acting as a softphone.

Desktop PC energy consumption varies, with an average of 150 watts for the computer and an additional 75 watts for a CRT monitor or 40 watts for a LCD monitor. Assuming a computer plus a LCD monitor, the power consumption is 150 + 40 for a total of 190 watts (source DoE.gov). Look up your PC power consumption at: http://www.energystar.gov/index.cfm?fuseaction=find_a_product.ShowProductGroup&pgw_code=CO.

Obviously, the PC will be doing work other than the softphone function. In sleep mode, the PC consumes 10 watts and the LCD monitor consumes 2 watts for a total of 12 watts. What is important is the energy consumed by leaving the PC on for softphone operation when work is not performed.

If the desktop PC is in use for 12 hours per day for 5 days a week, then there will 3,120 hours of operation. This leaves 5,646 hours of time when no work is being performed, but the PC is running the softphone software. The following table mirrors the energy cost compared to the IP hard phone.

The first conclusion is leaving a desktop PC on outside of business hours is a foolish waste of the energy budget. The second conclusion is that putting the PC into sleep mode will dramatically reduce the energy bill. However, even in sleep mode, the softphone PC draws more energy than an operating hard phone, 10% more energy.

In the next blog, I will provide solutions to reducing the energy consumption of the PC softphone.