Economizers – Outside air saves $$$

http://blog.modius.com/2010/04/05/105/

In the facilities world, an ‘Economizer’ is any device that is used to reduce energy consumption through the ability to transfer heat at a lower cost that traditional fan/chilling technology. Today it is a ‘Hot’ discussion topic when considering energy conservation approaches within a data center and most commonly refers to the mixing of lower-temperature outside air with warmer inside air and the associated chilling technology. It can also be applied to the idea of running chilling loops through large bodies of water to transfer the heat effectively eliminating the costs associated with chilling. Essentially heat is being transferred at lower cost from inside a datacenter to a large reservoir of ‘unlimited’ capacity. In all cases, there are still costs for economizers, whether it is FANS or PUMPS, but these tend to consume only about HALF of the more traditional complete cooling expenditure.

While not intuitively obvious, all places on earth have some portion of each year where the outside air temperatures are below the server manufacturer’s ‘Stage-1′ recommended inlet temperatures for their IT gear (approximately 78-degrees F). Consider fall, winter and spring months, as well as the nighttime hours. In the US for example, everything above the 30-degree north latitudinal line has perhaps two-thirds of the year with real value for air economizing, with most primary cities above that latitude having an opportunity of 75% of the time or more.

There are some camps today that insist that building open-air datacenters in places like Silicon Valley or Reading England where the economizer opportunity is greater than 85% might be the wave of the future. Google in fact has applied for patents on the water-based equivalent where a data center could be cooled entirely by using water-based loops that transfer energy to oceans or rivers or other large water sources which typically run at 45-55 degrees continuously. A high profile energy management corporation has the most extreme proof of concept installed today with a project named “Deep Lake Water Cooling” in Toronto Canada. It basically takes 40-degree F water from 3 miles offshore at the bottom of Lake Ontario and runs this water through all of the ‘coils’ in their high-rise downtown buildings. It then returns the now higher temperature water elsewhere back into the lake. Just one building, the 27 story Metro Hall, was documented to save more than 3 Million KW per year!

For datacenters we see the same opportunity. a large silicon valley based CPU chip manufacturer recently released a video which demonstrates their savings. The regional data center manager walks through his facility in New Mexico that has tested the effectiveness of air-side economizers side-by-side with traditional cooling systems. The 10 month test yielded compelling results, including a 74% reduction in power consumption in a 10 megawatt high density facility (with 90% CPU utilization).

A California-based colocation company has more than 2 million square feet of data center space (about 35 football fields in size) in the U.S. and has deployed economizers in 8 of them (mostly north of the Mason-Dixon line). The company says it saves up to 80% in annual cooling costs in these eight data centers where economizers were deployed, and is continuing to study the remainder of their 19 facilities to see where the economies make sense as technology moves forward.

What are the downsides to this magical opportunity? Well, constructions costs for retro-fits are non-trivial. Retro-fitting many of these existing facilities for air or water based economizing can be prohibitive. Structures are very different where extreme volumes of air must be moved great distances. The ducting and fan technology is very different. Additionally, weather protection, humidification and particulate filters must all be considered when taking this approach.

That said, for any new facility being designed today, these implementation details are all easily handled and economizing is a natural…

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