Apple

Moving to iPads will reduce the cost of your electric bill

Scott Lowe compares the electricity usage at the endpoint level between desktops, laptops, and iPads.

We all know that iPads are magical and revolutionary devices — after all, Apple has told us so! Personally, I'm a big fan of the iPad and have somehow managed to talk my wife into letting me upgrade as each new version is released. On my iPads, I've installed tools like LogMeIn Ignition, which I use in conjunction with the LogMeIn service, to control quite a few other systems, including my home desktop, the servers in my lab, and a couple of servers I work on for clients.

This week, let's do a little thought exercise and, for the moment, make the following assumptions:

  • Your company has decided to replace all PCs and laptops with iPads
  • Your company has deployed a VDI environment to support this initiative
  • All hard infrastructure and software costs are exactly equal to what they were when employees had traditional desktops and laptops
  • All licensing issues have been taken care of as well

I realize that these assumptions are a bit out there, but our goal in this article is to compare electricity usage at the endpoint level and nothing else. It's for this reason that we'll make the assumption that all "old" costs equal new costs.

For comparative purposes, we're going to assume that the old desktop/laptop environment consisted of the following types of hardware:

  • 15-inch MacBook Pros (2011)
    • Boot time: 50 watts
    • Typical operation: 12 watts
    • Standby/sleep: 1 watt
    • Source
  • Dell OptiPlex 980 desktops with LCD monitor
    • Boot time: 94 watts
    • Typical operation: 96 watts
    • Standby/sleep: 1 watt
    • Source
  • Dell Latitude XT2 XFR
    • Boot time: 37 watts
    • Typical operational: 30 watts
    • Standby/sleep: 1.5 watts
    • Source
  • iPad
    • Typical operational: 9 watts
    • Standby/sleep: 0.5 watts
    • Multiple sources indicate that the new iPad (2012 model) uses 7 watts of power just for the Retina display, so we'll use 9 watts for calculations

Just from the information in the list, it's really easy to see that the iPads — even the new iPad, which uses more power than its predecessor, will win this battle. Let's do some math at scale to see what this might mean.

Here are some other assumptions we'll make:

  • Cost of electricity. According to WhiteFence, the 2011 national average commercial price for electricity was 10.11 cents per kilowatt hour, so we'll use that figure in our calculations here.
  • Workday. The workday will be 8 hours long all the time. For the other 16 hours, systems will be in standby or sleeping.
  • iPads will always be plugged in at work and always remain at work. Of course, since people are likely to take them home, this actually means that we'll somewhat overestimate electricity costs, but that's okay.

We'll use the following formula to determine the various costs:

(Watts x Hours Used) / 1000 * Cost per kilowatt-hour = Total Cost per day

The two tables below give you a look at our assumptions and a number of calculations, including how much each device costs to operate per day, per month, and per year.

Model

Op Watts

Standby

$/KWh

Op hrs/day

15 inch MacBook Pro (2011)

12

1

0.1011

8

Dell Optiplex 980 desktop/LCD

96

1

0.1011

8

Dell Latitude XT2 XFR

30

1.5

0.1011

8

iPad 3

9

0.5

0.1011

8

Model

$/day/op

$/day/sleep

$/day/total

$/month

$/year

15 inch MacBook Pro (2011)

0.0097

0.0016

0.0113

0.34

4.13

Dell Optiplex 980 desktop/LCD

0.0776

0.0016

0.0793

2.38

28.93

Dell Latitude XT2 XFR

0.0243

0.0024

0.0267

0.80

9.74

iPad 3

0.0073

0.0008

0.0081

0.24

2.95

As you can see, on per-unit basis, a new iPad can save you a whole lot of money when it comes to comparing power costs between it and a traditional desktop with an LCD monitor. It doesn't fare quite as well against laptops, but there are still savings.

Model

1000 units

iPad savings

15 inch MacBook Pro (2011)

4,132.97

1,180.85

Dell Optiplex 980 desktop/LCD

28,930.78

25,978.66

Dell Latitude XT2 XFR

9,742.00

6,789.88

iPad 3

2,952.12

When you look at the desktop savings, that's a good number. Of course, we started by saying that the old and new environment carried exactly equal costs. In most cases, they won't be exactly equal, but potential power savings should be one cost aspect that you consider. It is tough to nail down all of the various assumptions, since things are different from organization to organization, but I highly recommend that you give it a shot!

About

Since 1994, Scott Lowe has been providing technology solutions to a variety of organizations. After spending 10 years in multiple CIO roles, Scott is now an independent consultant, blogger, author, owner of The 1610 Group, and a Senior IT Executive w...

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