Office networks and UPS

Office networks

Dedicated "always on" servers and power backups are big energy users. Try to avoid or minimize their use as much as you can.

Most dedicated office servers, although idle most of the time, have their power management features disabled. In a typical example of a dual processor server for a small/medium sized workgroup this results continuous power consumption 200 W plus a minimum of 25 W for a separate Uninterruptible Power Supply (UPS), altogether using more than 2000 kWh per year. If the server room is cooled by air conditioning, another 300-400 kWh/year can be added. The total energy use of this server equals that of 10 client-side desktop PCs or over 30 laptops. In other words, the server could uses more energy than all the client-side computing put together!

The obvious energy saving action is to buy the most energy efficient server and enable the power management features, but perhaps re-thinking the network may avoid dedicated servers altogether in small and medium-sized offices:

• Decentralize, i.e. run all application software from the client-side computers and make each worker responsible to back up their data locally, using a CD (700 Mb) or DVD (4.7 GB) writer.
• Use laptops instead of desktop client-side PCs, not only because of the 50-80% saving, but also the battery is a perfect protection against blackouts and power surges, avoiding a UPS.
• Use networked peripherals (printers/modems/etc.), i.e. not needing a server.
• Alternatively, e.g. if you need the power backup, fit one of the client-side laptops that is permanently in the office (e.g. secretary) with a USB2 powered modem.
• Re-think your centralized database/intranet tasks. E.g. do you really need them or do you use your voice/phone/e-mail to make appointments like the rest of us?
• If a central database is essential (e.g. stock management), do you need it in-house or can you outsource this task to an external service provider? Apart from other benefits, a provider is much better placed to optimize energy consumption.
• Use your imagination: The examples in the diagrams show that savings with a smart network could be up to a factor 10!

Power backups (UPS), based on rated Thermal Heat Dissipation

Typical backup for (UPS specs)	Power [ kW]	Energy use [MWh/year]
Single PC (650 VA, 400W)	0.008	0.07
Small Home server (1000 VA, 400W)	0.025	0.22
Small/Medium Server (3 kVA, 2.2kW)	0.1	0.9
Midrange Server (5 kA, 3.7 kW)	0.3	2.7
Class A Data Center, Standard UPS	265	2320
of which, direct electricity UPS	200	1750
of which, air conditioning caused by UPS	65	570
Class A Data Center, High Efficiency UPS	152	1330
of which, direct electricity UPS	114	1000
of which, air conditioning caused by UPS	38	330
1 kW= 1000 W, 1 MWh= 1000 kWh. Air conditioning electricity only calculated with data centers. Source data centers: TED Magazine, Jan. 2002, pp 35.

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Office UPS

The following data are based on the rated Thermal Heat Dissipation of typical models:

• Single PC Back Up (650VA, 400W max.) : 8 W (70 kWh/year)
• Small Home/Office Server (1000VA, 600W max.): 25 W (220 kWh/year)
• Small/Medium Size Office Server (3000 VA, 2250W max.) : ca. 100W (900 kWh/yr)
• Midrange Office Server (5000 VA, 3750W max.) : ca. 300W (2700 kWh/yr)

Typical Class A Data Center with Standard UPS

2.320.000 kWh/yr (2,32 GWh), split up in:

• Direct annual electricity use 1,75 GWh
• Indirect annual electricity use (airconditioning) 0.57 GWh

Typical Class A Data Center with High Efficiency UPS

1.330.000 kWh/yr (2,32 GWh), split up in:

• Direct annual electricity use 1 GWh
• Indirect annual electricity use (airconditioning) 0.33 GWh

See also technical UPS page for definition.