Huawei’s Smart Modular Data Centre has an annual power usage effectiveness (PUE) of 1.111 in tests. The company have said this is an improvement over a previous record of 1.245, recorded in November 2018. In fact, PUE figures lower than that have been reported: notably a 1.018 PUE by the EU-funded Boden Type data centre in Sweden, which also claimed to be the world’s most efficient facility.
Boden’s 1.018 figure relied on Sweden’s cold climate, which circumvented the need for any powered cooling system. It also used a novel “holistic cooling” scheme, which tailored the heat removal to individual parts of the data centre precisely according to the heat generated there.
Comparatively, the Huawei figure covered temperatures ranging from –5°C to 35°C, to test PUE under different climates and loads. According to the company, the actual figures were calculated using climate distribution coefficients for different regions, to give an annual average PUE in any given region.
The PUE metric divides the total power consumption of the data centre, by the IT load, giving an idea of the excess power used in other areas, mostly cooling. When PUE was first proposed, most data centres were over-cooling, and sometimes using more energy in cooling than they delivered to the racks, resulting in PUEs of 2.0 or more.
PUE was first proposed in 2006 and it was widely taken up by the industry, with measured PUEs falling rapidly as measures like free cooling were adopted. New data centres in comfortable climates now have PUEs closer to 1.0 than the average, and the PUE metric has been criticized for not addressing the more difficult task of using energy more efficiently once it reaches the IT equipment.