Major revisions for design and measurement of comfortable spaces are included in the newly published ANSI/ASHRAE Standard 55-2013, Thermal Environmental Conditions for Human Occupancy. The 2013 version adds 18 addenda to the 2010 standard. Sections 4 and 5 specify methods to determine thermal environmental conditions (temperature, humidity, air speed and radiant effects) in buildings and other spaces that a significant proportion of the occupants will find acceptable at a certain metabolic rate and clothing level. Section 7 of the standard includes new requirements for the measurement and evaluation of existing thermal environments and is also applicable to commissioning. (Source: The HVAC&R Industry, December 12, 2013)