What are the criteria for Group Certification

Hello Deborah, Yes, you are correct, that the 'similarity' criterion applies only to O+M projects using the group approach. As noted in the last bullet point on page 10 of the latest Campus Guidance document (released in April of 2014), however, "Each building or space in the group project must independently qualify for the chosen LEED rating system." Thus, even for the BD+C rating systems, if one building qualifies only for NC and the other only for SCH (LEED for Schools), they cannot be included in the same group project.

As to your question about energy savings, you should refer to the appendices for guidance on calculations for particular prerequisites and credits. For instance, for LEED v3/2009 BD+C projects (e.g. LEED-NC) pursuing the group approach, Appendix A of the Campus Guidance indicates that each building in the group will have to individually demonstrate compliance with EAp2--in other words, each new construction building has to demonstrate at least a 10% savings over the energy cost of the baseline. However, the number of points earned in EAc1 for a group project is based upon aggregate performance, not the lowest performing building. As noted in the group certification guidance for EAc1: "The number of points earned shall be based on the ASHRAE 90.1 Appendix G performance improvement calculated based on the sum total Baseline and Proposed Case energy cost for all buildings or spaces within the LEED project boundary, including all site lighting and parking structures within the LEED project boundary."