What is the significance of PUE and DCiE of a Data Center? How to Calculate them?

Data centers appear close to the top of the list of corporate infrastructure that consumes the maximum amount of power. As a result, to become better corporate citizens we are all trying to make our data centers green.

So, what do we do when the clients ask us what are we doing to decrease the carbon footprint in our data centers? You can tell them you opt for liquid immersion cooling. Apart from great technologies, we also need to quantify how much more energy-efficient our data center is when compared to the next one?

This is where Green Grid came and provided standard measuring methods – PUE (Power Usage Effectiveness) and DCiE (Data Center infrastructure Efficiency), to establish a baseline and measure the efficiency of data center equipment and operating process changes with respect to power consumption.

How to Calculate PUE and DCiE of your Data Center?

PUE measures the efficiency of your data center in using the input power. It is the ratio of the total amount of energy used by the data center to the amount of energy utilized by the computing equipment. This ratio will always yield a value greater than 1 and the larger the number, the less efficient your data center is. It can be calculated with the following formula.

And DCiE is the inverse of PUE. It is the ratio of the amount of energy utilized by the computing equipment to the total power available. It can be calculated as follows.

PUE and DCiE are the opposite faces of the same coin, which means for your data center to be energy efficient you are aiming for a lower PUE and a higher DCiE.

The following table explains the relationship between PUE and DCiE. Usually, the value of PUE falls between 1.2 and 2.5. The table below shows the relationship between PUE and DCiE.

Factors affecting PUE and DCiE

Data centers are attracting a lot of pressure to bring down their carbon emissions, which approximately accounts for 200 million metric tons of carbon dioxide in a year. Also, rising rack density has spiked the power bill, making OPEX a costly affair. As all the data center managers are focusing to optimize their power usage, they first need to measure energy consumption, which is done by PUE and DCiE, and the factors contributing towards it.

1. The energy efficiency of the computing equipment in the data center – The newer equipment utilizes lower power and tackles higher workloads. The age and design of equipment also directly define its power efficiency.
2. The ratio of computing equipment to other equipment – If the facility houses a lot of IT equipment in comparison to other equipment it will have a lower PUE and higher DCiE.
3. Efficiency of cooling equipment – While efficiency of IT equipment is very important to bring the PUE down, data center cooling is also critical. It is the second most energy-intensive task in a data center (More than 1/3^rd of the power in a data center goes towards cooling), so efficient cooling goes a long way in bringing you close to the lower end of the PUE scale.

There are still many business owners who not consider power consumption by the equipment while planning for a data center and end up with higher TCO and OPEX. Multiple OEMs focus on futuristic equipment and solutions that offer great energy efficiency and power saving over their lifetimes, which lowers the TCO and OPEX for the data center.

A lower PUE and higher DCiE indicate that the data center is working efficiently not just to reduce its operational costs but also reducing the carbon footprint of the data centers. Measuring the PUE is the first step enabling data centers to embark on the journey towards better power utilization and power savings.

References

https://submer.com/blog/how-to-calculate-the-pue-of-a-data-center