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Winter Datacenter Efficiency
- Authors
- Name
- Alex Lee
- @alexjoelee
In short, yes, datacenters become more efficient and draw less power to cool themselves when it's cold outside. Let's examine exactly how they use the cool outside air to reduce temperatures in an insulated, secure space.
Basic Datacenter Cooling Loop
As we covered in the Datacenter Components post, servers and networking equipment are cooled inside of the datacenter with cool air supplied by computer room air conditioner (CRAC) or computer room air handler (CRAH) units. These units are just half of this cooling system - the other side is a dry cooler unit on the outside of the building. On a continuous cycle, the CRAC unit expels cool air and warms up the water in the loop. This water is pumped out to a dry cooler unit outside, where it is cooled back down using a series of high speed fans. The loop repeats continously to effectively transfer heat from the datacenter equipment to the outside air.
With this in mind, you may be starting to see that a lower outside air temperature means that the fans on the outside cooler units just don't have to work as hard. Further, the compressors inside of the CRAC units (or the chiller for the CRAH units) won't have to work as hard to maintain temperature.
Maximizing Efficiency with a Fan Wall
A datacenter fan wall is a simple series of high-speed fans that bring outside air into a datacenter. The air is usually filtered and humidifed, and sometimes mixed with existing air to maintain a constant temperature. Fan walls are typically installed in addition to a normal air conditioning system as a way to boost efficiency, especially during the winter months. Datacenter operators can use a fan wall to bring in naturally cold air and effectively replace a portion of their active cooling system while the outside temperature is low.