Hello! I have a question regarding the inclusion of Vestibules (double entrances to buildings to prevent heat loss), in a Court House building project we’re working on. This project is located in a 3C climate zone, with a built surface area of 30.000 sqft aproximately, 3 stories above ground and 1 underground, and is being certified for LEED v4.

The main building entrance (for the general public and with the highest use frecuency) has a vestibule which complies with the requirements described in ASHRAE 90.1-2010, section Vestibules. However, there are about 7 other doors that connect to the outisde of the building that don’t consider vestibules, and we’re not sure whether they should be implemented as they're not main building entrances. These include: door in the underground floor to enter from the parking lot into the building (only for workers), doors on the second and third floor that connect office spaces to outside terraces (only for workers), and a secondary building entrance on the ground floor only for workers.

Based on the Exceptions for section, we think point b, "Doors not intended to be used as a building entrance”, could be applied to the other entrances, as they’ll have considerably lower usage than the main building entrance; however, we're unsure if we're understanding the criteria correctly for the exceptions, and if there are any additional criteria or ways to identify whether the other entrances should have vestibules (for example, being able to define it based on usage frecuency). 

Any help would be kindly appreciated! Thank you!