The LEED 2009 “Size Gap”

Green Building

The LEED 2009 “Size Gap”

For any project to be eligible for LEED certification, it must meet the minimum program requirements (MRP) as approved by the U.S. Green Building Council’s LEED Steering Committee (LSC). The MPR can be accessed at:

According to the MPR, new additions to existing buildings may be certified separately and independently from the existing buildings to which they are adjoined, provided that they are physically distinct and each has a unique address or name. Similarly, the existing structure can be certified separately and independently of the addition if the two are physically distinct and each has a unique address or name. If these conditions are not met, the existing structure and addition must be certified as one building.

Horizontally attached buildings may be certified separately and independently if two conditions are met:

a) Each building is “physically distinct.” USGBC defines the term physically distinct as:

The condition in which a building has both of the following: a) exterior walls that are party walls or are separate from adjoining buildings by air space; b) lighting, HVAC, plumbing, and other mechanical systems that are separate from the systems of adjoining buildings.

b) The buildings have “unique addresses or names.”

According to USGBC, if considering LEED 2009 for New Construction and Major Renovation (LEED-NC&MR), the project must include “the ground-up design and construction or major renovation of >60% of the [total] project square footage.”

Moreover, for projects with building additions to be eligible for LEED 2009 for Existing Buildings: Operations and Maintenance (LEED-EB: O&M), the addition cannot be more than “50% of the existing building SF.”

In a recent building addition project that I worked, I determined that the new addition actually falls into a size gap loophole between what is required for LEED-NC&MR and LEED-EB: O&M. I verified the validity of the “size gap” with GBCI, even though this caveat is not identified in any published materials from USGBC or GBCI that I am aware of. The figure below illustrates the “size gap” issue at play.

In order for both the new addition and existing building to qualify for LEED-EB: O&M post-construction, the following requirements, among others, must be met:

  • The project must be in a state of typical physical occupancy for a period that includes all performance periods as well as at least the 12 continuous months immediately preceding the first submission for a review.
  • The project must meet all of the LEED-EB: O&M Prerequisites, including achieving an Energy Star performance rating of 69 or higher.

Therefore, the owners of the existing building and the new addition may apply for LEED-EB: O&M certification after 12 months of typical physical occupancy, assuming all other requirements and prerequisites are met, including the Energy Star performance rating of 69 or greater. However, any energy analyses should be mindful of the LEED-EB: O&M prerequisite for fundamental refrigerant management, etc.

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