In-house data centres are generally not as efficient as those in Managed Service IT data centres.

This is a direct cost to your organisation, and in the case of supercomputing sites this is a very significant cost:

Power Usage Effectiveness (PUE): A PUE of 1.9 means for every 1kW you need to power your server your data centre requires an extra 0.9kW for ancillary power and cooling.

It also means that even if your electricity unit costs are 12pence per kWh your real cost per unit is 12pence x 1.9 = 22.8pence per hour per kW to power the same server. A PUE of 1.9 is very high, but is typical of many in-house data centres and is often higher than 2, sometimes 2.5 (an extra 1.5kW of ancillary electricity to power a 1kW server!).

The above table clearly demonstrates the need for highly efficient data centres. More efficient data centres immediately translate into significant costs savings over the competitive lifetime (3 years) of your supercomputer. An electricity unit cost of even 5pence per kWh is still high if the PUE is 2.5.

The above figures represent a conservative calculation. We are familiar with clients paying 15pence and even 20pence per kWh. Electricity costs were kept constant in the above table; a more realistic scenario is for power costs to rise over the next 3 years which would mean the savings above are even greater.