The 2013 version of ANSI/ASHRAE Standard 62.1-2013, Ventilation for Acceptable Indoor Air Quality, consolidates the 2010 standard and 10 published addenda. Significant changes to the newly published version include the modification of the Zone Air Distribution Effectiveness table to increase the ventilation effectiveness of certain underfloor air distribution systems, modification of the requirements for the quality of water used in humidification systems, and clarification of building level pressurization requirements.