Later this year, the Denver building code will be updated, and the 2015 International Energy Conversation Code (IECC) will replace the 2006 IECC with respect to the minimum required mechanical efficiency of all HVAC units. This multi-part post will compare the 2006 requirements to those in the 2015. Here, we look at IECC 2015 Table C403.2.3 (1), addressing the change in required efficiency for air conditioner and condensing units. Note that the 2015 IECC is a two-stepped update. Slightly more lenient requirements are in effect place upon adoption, and the second required level of efficiency takes effect on January 1, 2016.