Group project

Hi - I think it makes sense to start by looking at the prerequisite requirements. The Group Approach guidance (from the Reference Guide) for the prerequisite states: "Submit separate documentation for each building; however, K-12 schools, hospitals, hotels, resorts, and resort properties with multiple structures, as defined by ENERGY STAR, may submit one ENERGY STAR score." Assuming that your project is not one of the property types called out, you'll need to document that each building individually meets the minimum ENERGY STAR score required by the prerequisite (75).  For the credit, the Group Approach guidance states "All buildings in the group may be documented as one." Not a lot of information, but you can get more by checking out the LEED Campus Guidance (https://www.usgbc.org/resources/leed-campus-guidance). Based on this resource, points for the credit are based on a square footage weighted average of the ENERGY STAR ratings for each building in the Group project (if they're the same ENERGY STAR space type). I recommend taking a look at that document for more info and an example.  So long story short, both buildings need to individually achieve an ENERGY STAR score of 75 or above in order to earn the prerequisite. From there, you can calculate the combined single ENERGY STAR score, and resulting LEED points, by using a square footage weighted average.