So what has this got to do with choosing direct fresh air free cooling?
As a vendor neutral data centre designer there are a huge number of products and solutions available to help me reduce a data centre’s PUE. Often an effective place to start is by incorporating compressor free cooling. These cooling systems fundamentally fall in to two camps – direct and indirect.
Indirect systems use cooling coils or heat exchanges to transfer a data centres waste heat to atmosphere. These cooling systems maintain separation between the data centre’s clean environment and the outside world.
Direct air systems remove the data centre’s hot air by replacing it with cooler air from outside.
Direct fresh air cooling systems have been used for many years and there is no doubt they can be very energy efficient. Future-tech has installed a broad range of these systems over the years and achieved annualised, full facility, PUEs of 1.12. Many of these solutions have been retro fitted to existing live data centres resulting in significant energy savings for their owner operators.
Although these systems have worked well it should be noted that direct fresh air solutions are definitely not a silver bullet for energy efficient data centre cooling.
Over the last 5 years I have seen a number of direct fresh air systems installed by data centre design companies and owner operators who have not thought the risks through properly. Where this has gone wrong has been with regard to external contaminants found in the local environment and the inability for standard filtration to remove such contaminants.
The most common contaminant I have experienced has been sea salt. I have met and spoken with a number of data centre owner operators with facilities located up to 5 miles from the sea who have experienced high saline levels in their data centre’s incoming air. Some of these data centres have been located further from the coast but within a similar distance of tidal estuaries or rivers.
When talking about the risks presented by high saline levels it is often difficult to provide “real world” evidence. This is because organisations that have experienced such problems don’t really want to make it public knowledge. On this occasion, though, an organisation has.
The photos below were provided by an organisation who, against Future-tech’s advice, installed a direct fresh air system and, although they will remain nameless, wanted to get the evidence out there to help other owner operators avoid the same issues. Below is the result after just 3 years of operation in an area that is not deemed to be a “maritime environment” and has a moderate saline content.