USGBC allows projects registered under LEED-NC v2.1 to use LEED-NC v2.2 credits. USGBC also decided after this initial decision that certain credits must be a group because they were logically linked together. In this case EQ Prerequisite 1, Credit 1 and Credit 2 are a linked group. Some LEED-NC v2.1 projects pursuing EQ Credit 1 that completed design before the credits were grouped together by the USGBC. This means that CO2 sensors were designed into the system and construction was completed before the credit grouping occurred. If CO2 sensors were installed for every mechanical ventilation system that monitor non-densely occupied spaces, and those sensors provide monitoring in the breathing zone as defined by LEED-NC v2.2 (3 feet to 6 feet above the floor), can the sensors be used to obtain credit under v2.2 in lieu of the required direct outdoor airflow measurement devices? In essence, can CO2 monitoring be used non-densely occupied spaces, so long as the sensors meet the requirements for densely occupied spaces? Approving an approach as described above would help prevent v2.1 projects, which determined long ago that they meet the requirements of v2.2 for EQ Prerequisite 1 and Credit 2 more effectively than the v2.1 requirements, from ripping out properly placed and operational CO2 sensors to install OA sensors simply because a grouping of credits occurred after a project was designed and constructed.