Digital Realty Trust sets new standard for green datacenter design
Digital Realty Trust made green datacenter history in 2007 with the completion of the world's first LEED (Leadership in Energy and Environmental Design) Gold-certified datacenter in the United States. In 2008, the company achieved another laudable milestone, earning the first BREEAM (Building Research Establishment Environmental Assessment Method) Excellent rating for a datacenter facility in the United Kingdom.
The BREEAM certification recognizes the 11,000-square-meter datacenter, based in Welwyn, England, for its energy efficiency, environmentally sound construction, and efficient operation practices.
Notably, BREEAM certification for datacenters did not exist when Digital Realty Trust started to build the facility in Welwyn, notes Jim Smith, CTO at Digital Realty Trust. Rather, there was only a general standard for commercial buildings. Working with Digital Realty on the project, the Building Research Establishment -- a U.K. construction industry consortium -- was able to create BREEAM certification criteria specific to datacenters. Thus, companies in Europe now have a template to follow for building the green datacenters of the future.
Constructing an energy-efficient datacenter in an environmentally friendly manner isn't just good for the planet -- it can also result in significant savings on utility bills by reducing the amount of electricity needed to power and cool the IT hardware. Those costs have soared in recent years as machines have become denser and run hotter -- to the point that some datacenter operators find that for each dollar they spend to power a machine, they must spend another dollar to cool it.
Digital Realty Trust used several techniques to maximize the Welwyn datacenter's energy efficiency. For example, the facility uses chilled-water cooling instead of cooled air, which results in an energy savings of 29 percent. The facility's room-ventilation cooling design, as opposed to standard UPS-supported air conditioning, delivers an energy savings rate of 72 percent. Additionally, the facility uses a custom-designed heat-recovery system in which heat pumps take returned chilled water at 61 degrees Fahrenheit and cool it to 50 degrees. This enables the condenser side of the heat pump to provide the water at 122 degrees for heating. Through this approach, the Welwyn facility should realize energy savings of up to 83 percent when compared to the alternative use of a gas-fire condensing boiler.
Measuring performance on an ongoing basis is a critical step toward boosting efficiency and sleuthing out inefficiencies. To that end, the datacenter uses metering devices from all power sources through to each power distribution unit in the building. This lets the datacenter operator actively monitor the efficiency of delivered power throughout the system and identify any areas in which effective power delivery may be compromised.
Moreover, the building's automation system contributes to the facility's energy efficiency, automatically responding to changing conditions. For example, it can shift to free-cooling mode -- drawing on free outside air to cool the IT equipment -- based on atmospheric changes. It can also adjust internal temperatures, including the raised floor areas, based on time of day or customer-defined thresholds.
Digital Realty Trust found other ways to reduce waste with this new datacenter facility. For example, the external and ancillary lighting are all powered by photovoltaic cells located on the roof. Fifty-three percent of the site was constructed from recycled material. Furthermore, the company preserved the surrounding indigenous flora and fauna, and irrigation of the Welwyn facility's landscaping is provided through a rainwater-harvesting system that also supports interior applications.
All these techniques add up to significant savings and environmental benefits. The Welwyn facility is expected to enjoy annual energy savings of 48.2 million kWh, cost savings of $4.7 million, and an annual CO2 emission reduction of 20,090 tons.