R&M Data Center Handbook

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3.6.5. Energy Requirements of Copper and Fiber Optic Interfaces
Acquisition costs for active network components with fiber optic connections are significantly higher than those for
active network components with RJ45 connections for copper cables. However, one also must not ignore their
different energy requirements. If you compare a copper solution to a fiber optic solution on the basis of their power
consumption, a surprising picture results.
Energy requirement when using a 10 Gbit/s switch chassis:
336 fiber optic connections Power
7 modules with 48 FO ports at 2 W* 672 W
Total ventilation
188 W
NMS module
89 W
10 Gb fiber uplinks 587 W
336 copper connections Power
7 modules with 48 copper ports at 6 W* 2,016 W
Total ventilation
188 W
NMS module
89 W
10 Gb fiber uplinks 587 W
Total (with fiber optic ports)
1.54 kW
Total (with copper ports)
2.88 kW
* Average based on manufacturer specifications
A switch equipped with fiber optic ports needs only half the energy of that required by a copper solution!
If you take total energy requirements into consideration (see section 1.9), the following image now results:
Power consumption – FO switch
1.54 kW
Power consumption – copper switch
2.88 kW
DC/DC conversion
0.28 kW
DC/DC conversion
0.52 kW
AC/DC conversion
0.48 kW
AC/DC conversion
0.89 W
Power distribution
0.06 kW
Power distribution
0.12 W
Uninterrupted power supply
0.22 kW
Uninterrupted power supply
0.40 W
Cooling
1.65 kW
Cooling
3.08 W
Switchgear in energy distribution
0.15 kW
Switchgear in energy distribution
0.29 W
Total power requirement
4.4 kW
Total power requirement
8.2 kW
If these values are now compared using different PUE factors, significant differences in operating costs result (see
section 2.4.3). Operating costs exceed acquisition costs after only a few years. The proportionate data center costs
(like maintenance, monitoring, room costs, etc.) have yet to be considered.
Power costs for switching hardware
Fiber optic switch Copper switch
Power consumption (during operation) 4.4 kW 8.2 kW
Hours per year
24 h x 30.5 days x 12
months = 8,784 h
Power consumption per year 38,650 kWh 72,029 kWh
Power costs per kWh 0,15 €
Power costs per year 5,797.50 € 10,804.35 €
Energy costs by energy efficiency
PUE factor = 3.0 17,392.50 € / year 32,413.05 € / year
PUE factor = 2.2 12,754.50 € / year 23,769.55 € / year
PUE factor = 1.6 9,276.00 € / year 17,286.95 € / year
R&M Data Center Handbook V2.0 © 08/2011 Reichle & De-Massari AG Page 89 of 156