ANSI/ASHRAE/IESNA Standard-90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, has been amended by the Standing Standard Project Committee (SSPC) to include data centers within the scope of the 2010 edition following approval of Addenda AQ. Addenda BU was also approved, which establishes some specific criteria for data centers, including some key exemptions for economizers. As a result, any jurisdictions that adopt the 2010 edition of Standard-90.1 for their energy code compliance will result in a substantial change for the "Datacom" industry. Prior to this change, the Datacom industry was left to its own devices and discretion on energy efficiency strategies, which has been gaining significant momentum in recent years resulting in rapid and noteworthy innovation on the energy efficiency front (Google blog, 2010). The changes introduced within 90.1 raise concern over the possible squelching of innovation brought about by prescriptive based industry standards. There is even greater concern over the potential for unintended consequences brought about by the prescriptive requirements and subsequent enforcement from AHJ's on process cooling facilities, many of which serve a critical mission. One such prescriptive requirement is the application of economizers in many cases for Datacom facilities.

Thus far, most Datacom facilities have gone without economizers, so there is little experience by end-users or design professionals alike on applying and operating economizers in mission critical facilities where extremely high availability and reliability are core requirements. Aside from the potential concerns surrounding gaseous and particulate contamination from the introduction of large quantities of outside air (ASHRAE TC9.9, 2009), there are also real concerns related to the design, construction, and operation of economizers that can result in unacceptable failure conditions (Quirk, 2010). This is not to detract from the numerous successful installations of economizers within Datacom facilities today, only to draw caution to the application given the additional complexities involved.

Fortunately there are some exceptions to economizers for specific types of Datacom facilities, in addition to the alternative compliance paths within 90.1. This paper will attempt to outline the essential decision making processes for the application of economizers in Datacom facilities as well as outline how to navigate ANSI/ASHRAE/IESNA Standard-90.1 paths to energy code compliance for Datacom facilities.