By David Hamilton, theWHIR.com
September 19, 2008 — (WEB HOST INDUSTRY REVIEW) — Challenging the current industry assumption that data center air economizers are only useful when outside air is cool, Intel has released the results of an experiment showing that air economizers represent a promising way to reduce data center power consumption and cooling costs in even hot climates.
Instead of cooling hot air from the servers and recirculating it, air economizers simply blow the hot air outdoors and draw in outside air to cool the IT equipment. Intel`s test showed they contribute a 74 percent reduction in energy consumption.
To perform the test, Intel created two data centers, a control one with warehouse-grade direct expansion air conditioning equipment, and the test one with with air economizers. They were housed in a trailer in a temperate desert climate that ranged from 64 to 92 degrees with generally low relative humidity and ran between October 2007 and August 2008.
The test system used only the economizer until the supply air exceeded the 90 degrees, at which point, air conditioning would cool the air to 90 degrees, however there was no attempt to control humidity and there was minimal filtering of incoming air. The inside temperature was below 90 degrees 91 percent of the time, meaning that the air economizer was sufficient most of the time.
While researchers were concerned about humidity because the humidity of outside air can change rapidly, they saw no consistent increase in server failure rates as a result of the greater variation in temperature and humidity.
Particulate counts in outside air is also a concern for data center managers. At the end of the study period, servers and the interior of the compartment became covered in a layer of dust, however, the decrease in air quality did not result in greater failure rates.
Despite the dust and variation in humidity and temperature, there was only a 4.46 percent failure rate in the economizer compartment compared to the 3.83 percent failure rate in Intel’s main data center over the same period.
Reducing energy consumption about almost three quarters, air economization would reduce the annual cost operating cost of a small, 500 KW data center by approximately $143,000 based on electricity costs of 0.08 per KWH. In a larger, 10 MW data center, the estimated annual cost reduction would be approximately $2.87 million.
According to the test, researchers recommend air economizers for temperate climates with low humidity. In dry climates, traditional air-conditioned data centers typically include evaporative cooling using water in the pre-cooling stage. An economizer could save up to 76 million gallons of water annually in a 10 MW data center.
After further testing, including a proposed 1 MW demonstration data center, Intel plans to include air economizers in future, operational data center designs.
