Sunday, 20 May 2012

Why is Data Center Design Important for Going Green?

Data Center Design
The need for data servers is constantly growing. Take for example Facebook or Google and try to visualise the size and the number of data centers that these companies need to run their daily activities and to process the amount of information available on their webpages.

The phenomenon is huge and the implications on the environment are considerable due to the important use of resources (energy and water). To give you a rough idea, in 2007 the entire information and communication technology sector represents approximately 2% of the global greenhouse gas emission, about 14% of this amount was due to data centers[1]. Optimizing the resources consumption is not only important from an environmental perspective, it can also enable savings of millions of dollars at a global scale.

In the following few paragraphs will give you  a brief introduction to data center design by going through the Google data center best practices[2]:

1)    Measure PUE
The first important point is to have the required instruments to measure the Power Usage Efficiency (“PUE”) equivalent to the Total Facility Energy divided by the IT Equipment Energy.

PUE    =          Total Facility Energy
                                    IT Equipment Energy

This figure measures the effectiveness of the delivery of power in cooling to the IT equipment. It is important to measure this ratio to be able to keep track on the level of efficiency of the power used. The closer this number gets to 1.00, the better.

2)    Manage Air Flow
To properly manage the air flow in your data center, you will have to elimitate the mixing of hot and cold air flows. There are several ways to achieve such a containment, but it is paramount to first analyse and understand how the air flows between the data servers. Google has been able to save USD 65’000 in energy costs yearly by investing USD 25’000 (one time investment) in components enabling such a containment of the air flows.

3)    Adjust Thermostat
To the contrary of what has been believed for long by data center managers, Google raises the temperature of the cold aisle which results in a reduction of the facility energy use.

4)    Use Free Cooling
It is recommended to use the “free cooling” available from lower ambient temperatures outside of the data center to avoid the requirement of energy intensive cooling systems. For example, Google uses see water cooling in Finland where the water comes from the nearby bay.

5)    Optimize Power Distribution
Losses occur in the power distribution at each step of the a power conversion. If you eliminate a power conversion step, you spare energy. Google has achieve this by reducing the steps at the level of the Uninterruptible Power Supply (“UPS”) which is the system enabling the servers to continue to run in case of electricity interruption. By putting batteries directly into the servers, it reduces three steps of unnecessary power conversions. With this method, Google saves USD 30 per year and per sever!

We are thrilled to follow the evolution and see when Google will achieve a PUE of 1.00!

See how Google follows these PUE measurements:

[1] GeSi Smart 2020 report, p. 02/17 and 02/18, 
[2] For a more detailed overview, please see: