Best Practices for Data Centers: Lessons Learned from Benchmarking 22 Data Centers

TLDR

The authors benchmarked 22 data center buildings, studied the most efficient ones, and compiled a suite of best‑practice technologies—including improved air management, rightsized central plants, optimized chillers, free cooling, advanced humidity control, high‑efficiency power supplies, on‑site generation, liquid cooling, and reduced standby losses—to enhance energy efficiency. The benchmarking revealed that data centers are over 40 times more energy intensive than office buildings, with power densities from 5 to nearly 100 W/ft² and a five‑to‑one variation in cooling effectiveness, highlighting the substantial energy‑saving potential of adopting the identified best practices.

Abstract

Over the past few years, the authors benchmarked 22 data center buildings. From this effort, we have determined that data centers can be over 40 times as energy intensive as conventional office buildings. Studying the more efficient of these facilities enabled us to compile a set of “best-practice” technologies for energy efficiency. These best practices include: improved air management, emphasizing control and isolation of hot and cold air streams; rightsizing central plants and ventilation systems to operate efficiently both at inception and as the data center load increases over time; optimized central chiller plants, designed and controlled to maximize overall cooling plant efficiency, central air-handling units, in lieu of distributed units; “free cooling” from either air-side or water-side economizers; alternative humidity control, including elimination of control conflicts and the use of direct evaporative cooling; improved uninterruptible power supplies; high-efficiency computer power supplies; on-site generation combined with special chillers for cooling using the waste heat; direct liquid cooling of racks or computers; and lowering the standby losses of standby generation systems. Other benchmarking findings include power densities from 5 to nearly 100 Watts per square foot; though lower than originally predicted, these densities are growing. A 5:1 variation in cooling effectiveness index (ratio of cooling power to computer power) was found, as well as large variations in power distribution efficiency and overall center performance (ratio of computer power to total building power). These observed variations indicate the potential of energy savings achievable through the implementation of best practices in the design and operation of data centers.