Digital Realty Trust (DRT) announced this week that one of their Santa Clara data centers has been awarded LEED-gold certification. There has been much debate over LEED certification and its role in the data center -- many LEED-platinum buildings have received an exemption from the USGBC to ignore data center energy in the LEED-platinum certification procedure.

DRT's new data center at 1500 Space Park in Santa Clara (located in a building previously occupied by Analog Devices) has also received incentives from Silicon Valley Power for verifiable steps they've taken to reduce the energy consumed by their data centers compared to industry averages. These rebates are estimated between $750,000 and $1,000,000 for the Santa Clara location. In a discussion I had with Mark Bramfitt at PG&E, he confirmed that they too are offering significant incentives for data centers that come to PG&E with verifiable kilowatt-hour savings. Incentive rates for 2009 are typically $0.05 to $0.15 per kwh saved, according to PG&E.

Let's break down DRT's incentive to understand how much energy they've really saved over a traditional data center. First, let's figure out the total amount of energy that may have been saved, based on the $750,000 incentive. On average, incentives are offered at $0.10 per kwh saved and offered on your annualized kwh reduction. Thus, DRT reduced their consumption over a typical data center by 7.5 million kwh over a 1 year period. Put another way, that's a reduction of 856,000 Watts of constant power draw.

That's certainly a lot of power, but to put it in perspective, we need to look at what the entire facility consumed. While DRT has the option to build out over 343,000 square feet of data center space, the initial use of the facility is centered on 34,000 square feet of existing space. According to data from Intel and Nova, a low density data center has a median power usage of 125 Watts per square foot, and we'll give DRT the benefit of the doubt rather than assume their DC is packed with high density equipment and blades. That means the 34,000 square foot facility consumes 4.25MW of power. In fact, this is probably a low estimate, as 1500 Space Park has capacity for 9MW, with expansion on a third feed to 13.5MW.

If you add all this up, it means that 1500 Space Park uses 856,000 Watts less than a traditional datacenter. This is a savings of 16.7% on their energy bills in the best case (plus a nice check from the utility company for $750,000). Not too bad, but there's an opportunity to do better. Savings between 20% and 30% have been seen (for reference, Sentilla has reduced our IT consumption by 24%). But don't take our word for it, Intel touts 23-30% savings for one of their server strategies and VMWare quotes the completely unrealistic number of 80%.