With each passing year, more organizations seek out green service providers both for the sake of reducing overhead and as a reflection of corporate sustainability values. A recent Green House Data survey revealed that 36 percent of respondents chose what they perceived to be green service providers in 2017, an 8 percent increase over 2015.
Data centers, though indispensable to organizations in every conceivable industry, are voracious energy consumers. This fact has generated interest in sustainable facilities – which raises an important question: What is a green data center?
In broad strokes, it’s a data center that maximizes energy efficiency. But to give you a more exact sense of what that means, we’ve identified some of the factors that contribute to data center sustainability.
The source of the energy
First, it’s worth asking where the energy comes from. Hydroelectricity, for example, is widely accepted as a renewable source of power. It also has the benefit of being affordable. A data center with hydroelectricity simultaneously minimizes its carbon footprint and its cost of services provided. In other words, the facility would be sustainable while also being cost-effective for the tenants just by virtue of running on clean energy.
Case in point, Sabey’s data center campuses in Washington State are powered by some of the cheapest hydroelectricity in the country, if not the world. This low cost of energy carries over to clients in the form of a low total cost of ownership for tenants. Just as crucially, the clean source of power boosts the facility’s sustainability before efficiency even enters the equation.
Power Usage Effectiveness rating
Data centers are projected to consume an astonishing one-fifth of the world’s energy by 2025, according to Data Economy. A green data center endeavors to conserve energy by using as little as possible on non-IT functions such as cooling. The Green Grid’s Power Usage Effectiveness (PUE) metric is central to this effort.
To calculate PUE, divide the total amount of electricity entering a facility by the amount specifically powering the IT load. A perfect PUE rating of 1 would mean all a facility’s energy goes to the IT load. This is more wishful thinking than a reality at this point; however, some of the most efficient data centers in the world boast an average annual PUE in the 1.1 range. One of Sabey’s most efficient Washington facilities, for example, has an average annual PUE of 1.13. Make sure that the PUE you examine is based on actual operating conditions, and is not a theoretical calculation.
Cooling-related energy-saving methods will be captured in the average annual PUE, but they’re worth examining because they illuminate the types of efforts that go into managing a green data center.
Servers, network switches and other IT equipment inevitably generate heat. Heat must be rejected by a fluid (typically air), with that fluid treated and circulated in the most efficient manner possible. Enter hot-aisle containment. Rows of cabinets are positioned back-to-back so that they’re separated by a hot aisle (hence the name) and isolated from the cool aisles with blanking panels. Exhaust from the rear of servers is expelled into this aisle, where it naturally rises into overhead return plenums and is passively directed into air handlers. The air handlers reject heat and discharge the conditioned air back into the cool aisle, where it can be pulled through the IT equipment, by the IT equipment’s fans, and blown into the hot aisle again.
That brings us to the actual cooling units, which should be selected based on the climate. Indirect evaporative cooling, for instance, is a highly efficient process in moderate-to-dry climates that have abundant access to water (e.g., Central Washington). It involves adding water to the air to lower its temperature. Efficient data centers also use economizers that, on chilly days, deactivate the compressor and instead use the cold outside air to provide cool air to the servers – either directly or through a heat exchanger of some kind. Think of it as turning the air conditioner off and putting a fan in the window.
Other key considerations
Other indicators of a green data center include Energy Star certification, as well as a general commitment to reduction of waste and recycling. It’s also worth noting that IT equipment efficiencies can contribute to a green data center, but it is the responsibility of the tenant in a colocation data center to select efficient technology, and to avoid running idle or “zombie” servers whenever possible. While comatose or inefficient IT loads won’t degrade PUE, they still contribute to waste and are therefore worth addressing for sustainability and cost-saving purposes.
For additional insights into green data centers, or for information about Sabey’s most energy-efficient facilities, contact us today.