What Is 40/60 Rule in LEED?

The 40/60 rule is used to choose the appropriate rating system for the project if the project seems to fit under multiple rating systems. In the 40/60 rule, a project should be divided into sections according to the appropriate rating system each section fits. Then, the total floor area corresponding to each rating system should be calculated.

If the total floor area of one of the applicable rating systems is less than 40% of the project’s total floor area, that rating system cannot be used. If the total floor area of one of the applicable rating systems is more than 60% of the project’s total area, that rating system must be used. If it falls between 40% and 60%, then the project teams can decide on the rating system to be used for the project.

Let’s consider a forty-story high-rise building project example, which contains a hotel on the first twenty floors and residential units on the floors above twenty. Since 50% of the project’s total area is appropriate for one rating system and the other 50% is appropriate for the other, the project teams will decide which rating system to use. The project teams can look at the requirements of LEED BD+C: Hospitality and LEED BD+C: New Construction and Major Renovation to decide on the rating system they will pursue. USGBC may ask the project teams to change their rating system if it’s not chosen adequately.