By Rik WIlliams, Data Centre Operations Manager

How do you make a 3.5MVA N+1 data center Green, yet still cost effective?

That’s the big question that Node4 have been wrestling with over the last few months, but we reckon we’ve come up with the solution. Our brand new data centre (DC3) in Wakefield will be one of the first in the country to combine 2 of the latest energy saving technologies throughout the site: cold aisle containment and free cooling chillers.

By using these methods, we hope to make DC3 one of the most energy efficient data centres in Europe with a PUE of 1.3 to 1.4 (i.e. only about 1/3 of the total power to the site is used on cooling and power conversion).

Click for Cold Aisle Containment Diagram

Cold aisle containment is a new but relatively simple idea to get the best efficiency from air conditioning units. The data hall is set up as a standard hot / cold aisle arrangement but the cold aisles are then sealed off at either end and a transparent ceiling is installed to trap the cold air in front of the racks where it is needed the most. The rest of the room becomes a hot aisle as the air is returned to the air conditioning units, so the room itself will be between 30 and 35 degrees C.

Although that might be a bit warmer than the average techie is used to, the air flowing through the front of all the servers will be about 20 degrees C which is just as it should be.

This kind of arrangement gives a number of advantages over a non-contained room

• Hot air can’t re-circulate and mix with the cold air. We are only cooling the air once
• We can use a higher output air temperature from the air conditioning unit, saving on power
• Temperature differences between the top and bottom of the racks are much smaller meaning that equipment at the top of the racks is less likely to fail

We estimate that this could save between 40% and 60% on our air conditioning bill, and will be far more environmentally friendly than a normal data centre.

We’ll talk more about how we actually cool the air using our new free cooling chillers and take advantage of the Yorkshire weather in a future blog post.