Power Usage Effectiveness (PUE) is the most commonly used indicator of Data Centre efficiency.
It is the ratio of how much energy is used by the facility and its infrastructure against the IT load.
A Data Centre’s PUE is calculated by: Total DC Energy Use / IT Equipment energy use = PUE
A PUE of 1.0 is perfect, but not feasible in the real world. The average PUE for most data centres is 2.0, which means that for every 1kW of IT load, they use another 1kW for cooling, electrical losses etc.
The graph below is a live feed of our Kent Data Centre’s PUE:
Graph Analysis: We run regular checks which causes short-term increases in our PUE, which you will see periodically on the graph. These checks include generator systems, chillers, UPS system, fire systems and general monitoring systems.
We achieve this efficiency in a number of ways. For example our award winning fresh air cooling systems use filtered fresh air rather than chillers for 95% of the year. So if it’s below 21°C outside, then we are just running on multiple UPS powered fans. Another upside of this is that chiller failures (that would cripple other facilities) are not an issue to us. We use contained hot aisles to make sure that we only use energy supplying the right amount of air to the right place and we use LED lighting with sensors which minimise lighting costs.
We can’t get to a PUE of 1.0 because ……..our dual path Tier 4 electrical infrastructure uses twice the number of Uninterruptable Power Supplies, running at less than half load (in case of failover). This means our electrical losses are higher than facilities with less resilient power layouts.
So what does this all mean?
- Reduced Carbon footprint compared to other facilities
- More competitive pricing for our customers
- Greater Resilience