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Figure 18 – Power reduction effectiveness
2.1.1.9 Requirements of the technology
(i) To be able to reduce the overall power consumption
PUE (Power Usage Effectiveness) is often used as an indicator to measure the energy
effectiveness of air‐conditioning of data centers. PUE is the ratio between power
consumption of overall data center and that of ICT equipment in the data center. If the
figure of PUE gets lower, it means the effectiveness improves. As electricity consumption
for internal fans is counted as that of ICT equipment, the larger the internal fans are, the
smaller PUE is and the better the energy effectiveness. In contrast to this, it is required to
reduce the overall power consumption of data centers, not to limit to lower PUE values.
(ii) To be able to use regardless of climate conditions
Temperature or humidity of external ambient air varies according to locations and seasons.
It is required to be able to reduce power consumption in a wide range of temperatures and
humidity levels.
Figure 19 – Hourly climate data for 2010 observed at locations of
direct fresh‐air‐cooled data centers
Source: Hiroshi Endo et.al. (2013). Effect of climatic conditions on energy consumption in direct fresh‐air container data centers; IEEE.
234 ITU‐T's Technical Reports and Specifications
