Facebook has joined the chorus of major data center operators opposing new guidelines on data center cooling being considered by a key industry standards body. The debate focuses on technical details of a standard being proposed by the Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).
Major data center operators say one of the provisions of the new standard could limit innovation in developing energy-efficient cooling systems. In April, seven of the leading data center companies issued an unusual joint statement opposing a provision that favors a specific cooling design using economizers. The ASHRAE
Guidelines Could Affect Site Selection
In a letter this week to ASHRAE this week, Facebook Vice President for Technical Operations Jonathan Heiliger said this approach could be problematic. "From our own testing and development, I agree that air or water-side economization is a proven method to an energy efficient HVAC system," Heiliger writes. "However, I am concerned that prescribing air or water-side economizers for data centers with fan systems may limit energy efficiency innovation in data center design. In addition, this prescription may also limit the viability of some sites as data center locations."
Using outside air economizers to cool data centers – also known as free cooling - allows data center operators to save money by using fresh air to cool server rooms, rather than relying upon chillers that use large amounts of energy.
ASHRAE Says Workarounds Are Possible
ASHRAE has said said the proposed changes would not force data center builders to use economizers in new facilities, but will leave room for companies to use other designs through an approach called the Energy Cost Budget method.
Heiliger says ASHRAE can and should strive for a standard based on performance and efficiency, rather than favoring one design approach over another and focring companies to work around the standard, which is used as a reference for many local building code officials.
"The Energy Cost Budget method does not produce accurate data center baseline energy cases and therefore, doesn’t produce the best path to the most energy efficient design," Heiliger writes. "I urge you to help ASHRAE work towards an energy efficiency standard that is founded on more current and accurate data center energy usage baselines and on a performance based system that is measured against a defined PUE requirement."
Heiliger offered a specific scenario in which an innovative approach wouldn't fit within the proposed standards.
"As an example, imagine an innovative design such as exchanging heat via thermal mass from an underground shaft or cave to create cool supply air," Heiliger writes. "This design would not include an air-side economizer but would save a tremendous amount of energy. This is an example of the prescriptive method putting up a barrier to beneficial innovation."