“Green” and “data centers” don’t often appear together in the same sentence. Data centers are often criticized for the amount of electrical power they use, both to run the devices in them and cool off the buildings. But an increasing number of organizations are working to make their data centers more sustainable by using a set of specifications and best practices in constructing, maintenance, and operations.

The specifications are called Leadership in Energy and Environmental Design (LEED), a voluntary rating system for energy-efficient buildings from the U.S. Green Building Council (USGBC). “Although the two aspects of this topic—Data Centers and Green Design—seem almost antithetical to each other, a properly designed data center makes good use of sustainable design,” the organization writes in its introduction to its data center specification. “With a limited amount of incremental effort, sustainable design efforts can be paired with a good working knowledge of LEED to provide a LEED certified critical facility environment.”

Buildings become LEED-certified by following certain construction practices, such as using materials that are less likely to outgas, recycling building materials, and using locally sourced materials. Another specification allows building operators to obtain LEED certification by using sustainable practices to run their buildings once they’re built.

Designers, builders, and maintainers earn points for environmental design (and documentation, which even LEED supporters admit is the most arduous part of the process) in five areas: sustainable site development, water savings, energy efficiency, materials selection, and indoor environmental quality, writes Rich Miller in Data Center Knowledge. Beyond just basic LEED certification, buildings can be certified on one of three increasingly stringent levels: Silver, Gold, and Platinum.

The organization has been developing LEED specifications since 2000, and its LEED v4 version, released in 2013, specifically addressed data centers. However, data centers had been earning LEED certifications long before. The first data center to achieve LEED certification did so in 2005, and the first to achieve a LEED Platinum rating was Citigroup in April, 2009. (The company had already achieved a LEED Gold rating for an Austin data center in 2008.)

Data centers are a different kettle of fish from other buildings, the USGBC notes. “What makes data centers such a unique project type? Data centers have very few occupants, and they are huge energy users: a data center can use as much energy as a small town (really),” the organization writes. “Whereas a typical building is designed to meet heating and cooling needs for occupant comfort, a data center must provide massive cooling power for its servers. Water use is also a key target area for data centers, if the facility utilizes water for cooling. These specific building needs are built in to the data center adaption for LEED.”

The desire to save money and appear sustainable is driving LEED-certified data centers to become big business, with hundreds of them pursuing LEED worldwide, according to USGBC. Data Center Knowledge found a baker’s dozen of LEED Platinum data centers alone. LEED-certified data centers include:

Apple’s LEED Platinum data center in Maiden, N.C. It plans to use primarily renewable energy, including building its own solar array and fuel cell installation. “Along with real time power monitoring and analytics during operations, the Maiden data center features a chilled water storage system that improves chiller efficiency by transferring 10,400 kWh of electricity consumption from peak to off-peak hours daily,” writes Facilities.Net. “Outside air cooling through a waterside economizer operation, along with water storage, allows the chillers to be turned off more than 75 percent of the time.”

Facebook’s Prineville data center. It uses outside air evaporative cooling, with no cooling towers or chillers, according to Facilities.Net. “Custom servers use 38 percent less energy and operate at higher temperatures, reducing mechanical cooling needs. The low energy design extracts cool outside air from the atmosphere where it is cooled further by evaporation.” The result is that the facility uses 70 percent less water for cooling purposes than an average data center.

Penn State. Earlier this month, the University broke ground on a $54 million data center that is scheduled to open next year, which is also intended to serve as a disaster recovery facility. “Measures incorporated into the center’s design are expected to result in using at least 60 percent less power for critical systems than typical data centers,” the University notes in a press release.

It may be a while before you can design or build a new data center (though some LEED-certified data centers also rent out space to other organizations). But it’s nice to dream, isn’t it?