Computers, printers, fax machines and copiers consume energy even while they are not in use. The following table provides a summary of typical electrical power requirements:

Equipment

Typical Power Requirements (Watts)

Energy consumption per day (8 working hours)/KWh

Fluorescent Lights

36

0.288

Computer

55

0.44

Monitor (15")

75

0.6

Laser printer

60

0.48

Fax machine

35

0.28

Copier (small)

115

0.92

Copier (large)

310

2.48

The pie chart below illustrates the proportion of energy used by different typical office equipment and hence gives us an indication which are the “areas’ that we need to tackle first.


Source: Energy Saving fact, Carbon Trust (2006)

As an example, for a typical office having 2 Fluorescent lights, 1 personal computer being used daily for 8 hours on average, the total energy consumption is as follows:

Energy consumption by Fluorescent Lights = 2 x 0.036 x 8h = 0.576 kWh per day
Energy consumption by Personal Computer = (0.055 W + 0.075 W) x 8 h = 1.04 kWh per day
Total energy consumption = 1.616 kWh per day of which 36% is for lighting and 64% is for personal computing.

Energy consumption by Fan during summer = 0.058 x 8 h = 0.464 kWh