ASHRAE/IES Standard 90.1 is cited in the U.S. Energy Policy Act as the national energy standard for buildings, except for low-rise residential buildings. Consequently, ASHRAE/IES Standard 90.1 has a significant impact on building construction. ASHRAE and IES update Standard 90.1 continuously and republish every three years. This paper provides a review of key changes in the 2013 version of ASHRAE/IES Standard 90.1, and indicates potential impacts on indoor environmental quality.

Over the last several years, the Project Committee developed more than 60 addenda to the 2010 version of Standard 90.1. The adopted addenda addressed building envelope, mechanical systems (HVAC – heating, ventilating, and air conditioning), lighting systems, and other sections of Standard 90.1. For example, for the building envelope, the 2013 version of Standard 90.1 requires better fenestration (windows, skylights, and doors) with lower U-factors. The impact is that the interior surface of the fenestration is closer to room temperature thereby reducing radiant temperature asymmetry within the space, resulting in better thermal comfort for occupants. Also, dynamic glazing is addressed, an option where the fenestration automatically reduces undesired solar gain and glare during peak sun hours, resulting in better thermal and visual comfort. As an example for other systems, minimum efficiencies are included for the first time for commercial refrigerators and freezers. The impact is less heat put into the kitchen space from the compressors, resulting in better thermal comfort for restaurant workers in commercial kitchens. In addition, requirements are established for monitoring of electrical energy usage for HVAC and lighting systems. The impact is that malfunctioning equipment should be identified sooner and potential negative impacts on the indoor environmental quality of the occupants remedied sooner. The paper addresses these and other specific addenda.