Why Data Centers Don’t Need to Be Cooled to Arctic Temperatures

By Justine Burt

In March, thought leaders at the Green Grid Forum in San Jose, California, explained how their industry is decoupling the growth of data centers from carbon emissions. Data centers use over 2 percent of the nation’s electricity and that number is climbing quickly. We need data centers to store our growing number of YouTube videos, Wikipedia entries and financial transactions. Unfortunately, more data centers means rising electricity consumption which results in rising carbon emissions.

Typically, air cooling and server processing consume large amounts of electricity in data centers. There was a time in the not so distant past when you needed a parka to walk inside a server room or data center. IT staff maintained server room temperatures near 60°F to keep the server processors from overheating.

A new industry standard developed by a group of original equipment manufacturers (OEMs) has determined that servers can handle temperatures much higher than previously believed.

ASHRAE TC 9.9 Approved Temperature and Relative Humidity Ranges

Source: Don Beaty, DLB Associates Consulting

Think about the implications of wider data center temperature ranges for companies like eBay. Their customers are buying and selling items in a marketplace that essentially lives inside their data centers. This marketplace has a carbon footprint.

At the Green Grid Forum, Dean Nelson from eBay reported that their data centers contribute half of the company’s carbon footprint. eBay’s carbon impact would be much higher if they had to cool their server rooms to the low 60s, but they do not. They use outside air for cooling now. Their servers are robust enough to sit in containers on Phoenix rooftops without air conditioning. Clearly this has yielded huge cost savings and carbon reductions.

In the past, perceived risks of equipment outages or voiding IT equipment warranties were the main reasons data center managers kept their server rooms at chilly temperatures. Then in 2004, the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) standard TC 9.9  was approved by a group of IT OEMs. This standard said that a server room could handle a temperature range of 68°F to 77°F without voiding equipment warranties. In 2008, the standard widened the temperature range to 64.4°F to 80.6°F. Then in 2011, an ASHRAE TC 9.9 white paper described scenarios within which servers could function well between 41°F and 113°F.

At the Green Grid Forum, data center cooling expert Don Beaty described the benefits of economizers, which allow outside air to provide free cooling, over refrigerant-cooled air conditioning systems. In many U.S. cities, outside air can be used to cool data centers most of the year as long as there are also filters to keep out combustion pollution, pollen and dirt. One study Beaty described found that the IT hardware failure rate in a San Jose data center with variable temperatures was lower than a data center operating at a tightly controlled temperature of 68°F. (Approximately 4 percent of servers typically fail each year.)

Data center cooling efficiency represents one step on the road to greener IT. The data center industry has now moved on to vetting green ideas to maximize server efficiency, use less water and exploring ways to create site facilities where they can access affordable renewable energy. While many green data center debates still rage, at least the ASHRAE TC 9.9 standard has settled the question of whether data centers with newer servers can handle warmer temperatures.

Justine Burt is a sustainability consultant in Silicon Valley who specializes in sustainability management systems. www.justineburt.com

image: Tunde Pecsvari via Flickr cc (some rights reserved)