Entry Type ID Date Applicable Rating System Applicable Credit Inquiry (LIs) Ruling (LIs) Related Addenda/LIs Related Resources Campus Applicable Internationally Applicable Country Applicability Reference Guide (Addenda) Page (Addenda) Location (Addenda) Description of Change (Addenda) "LEED Interpretation" "1642" "2007-01-02" "Commercial Interiors" "EQc1 - Outdoor air delivery monitoring" "Our project is a Federal Courthouse remodeling project seeking LEED-CI v2.0 certification. The project consists of 371,768 gsf and contains specialized and general office space, courtrooms, jury assembly rooms, conference rooms and prisoner transport and holding areas. We are seeking clarification on the requirements for credit EQ 1 Outdoor Air Delivery Monitoring. The project will replace nearly all of the HVAC systems in the building. When complete, the 7-story building will have new ductwork, a new building automation system and two new air-handling units per floor. All of the spaces inside the building will be mechanically ventilated. Every air-handling unit is equipped with continuous measurement of outdoor airflow, regardless of the occupant density it serves. Define densely occupied spaces as spaces with at least 25 occupants per 1000 square feet. Some of the new air-handling units serve densely occupied spaces exclusively. Others serve mixed occupancies, meaning that some spaces are densely occupied (conference rooms and courtrooms) and some are not (lobbies, open office space and private offices). For every air-handling unit that serves a mixed occupancy, at design conditions more than half of its supply airflow serves spaces with low occupant densities. Page 271 of the LEED-CI v2.0 Reference Guide and the Letter Template both define the Requirements for this Credit as follows: ""For mechanical ventilation systems that predominantly serve densely occupied spaces (those with a design occupant density greater than or equal to 25 people per 1000 ft2), install a CO2 sensor within each densely occupied space."" ""For all other mechanical ventilation systems, provide an outdoor airflow measurement device capable of measuring the minimum outdoor airflow rate at all expected systems operating conditions within 15% of the design minimum outdoor air rate."" The Guide does not appear to define the term, ""mechanical ventilation system."" We interpret the term to mean a single air-handling unit, along with its distribution ductwork, motor-driven equipment and associated controls. On page 275 of the LEED-CI v2.0 Reference Guide in the \'Approach and Implementation\' narrative for this Credit the paragraph on CO2 Monitoring in Densely Occupied Spaces states the following: ""Within buildings that are mechanically ventilated, the CO2 level within each densely occupied space needs to be monitored to satisfy the credit requirements."" The language in the Reference Guide and the Letter Template requires CO2 sensors to be used only in densely occupied spaces that are part of a mechanical ventilation system, serving spaces that are mostly densely occupied. However, the language in the paragraph from Approach and Implementation calls for CO2 sensors in every densely occupied space, regardless of the predominant occupant density in the spaces that mechanical ventilation system serves. Therefore, with respect to the above, we request Credit Interpretation Rulings on the following: 1. Verify that the word ""predominantly"" means that, when a system predominantly serves a certain type of space, more than half of the system\'s design airflow goes to that type of space, the type the system predominantly serves. 2. Verify that a CO2 sensor is not required within each densely occupied space when the mechanical ventilation system that serves that space does not predominantly serve densely occupied spaces." "All densely occupied spaces must include CO2 sensors. If the AHU predominantly serves densely occupied spaces, outdoor airflow measurement at the AHU is not required. If the AHU predominantly serves non-densely occupied spaces, outdoor airflow measurement at the AHU is required, in addition to CO2 sensors in the densely occupied spaces. Applicable Internationally." "None" "None" "X"