We have a new multi story app 195,000 sq ft College level school building. The building and the air-conditioning system are zoned to match similar functions. We have 7 air-conditioning systems: 1. Office areas: 5-story, two air-handling units combined into one system. 50,000 sq ft. This includes mostly private offices. There are just a couple of small open office/reception areas, two computer type 30 people classrooms, and four 20 people conference rooms. 2. Classroom areas: 4-story, two air-handling units combined into one system. 72,000 sq ft total. This includes 42 classrooms. Classroom size vary from 28-occupants to 60-occupants, and one 120-occupants classroom. 3. Library: 1-floor, one air-handling unit, 23,000 sq ft total, this includes stack areas, various reading areas, and few small meeting rooms 4. Atrium: 5-story, one air-handling unit, 17,000 sq ft total 5. Dinning room: 1-floor, one air-handling unit, 8,000 sq ft total, for 190 people. 6. Kitchen: 1-floor, one air-handling unit, 2,000 sq ft total 7. Retail space: 1-story, one-dedicated air-conditioning unit. 2,000 sq ft total We propose to have one CO2 sensor per each air-handling unit. Is the sufficient to achieve the intent of the IEQ credit 1? If not, what would it be required to achieve this point. Do we need to add more sensors? What would be the criteria/requirements for placing these sensors. Are there any particular locations where these sensors are required? In the case of the kitchen we proposed not to use a sensor since the kitchen is 100% exhaust air during operating hours.
NOTE: THIS RULING HAS BEEN AMENDED ON 12/21/04, AS NOTED BELOW. The scale of the project, and the diversity of uses and space types suggest that 7 CO2 sensors will not adequately address the achievement of this credit. From the perspective of LEED, the requirement is that that project install CO2 sensors that allow the project to manually or automatically maintain indoor CO2 levels at 530 ppm above ambient. This implies that you need to monitor ambient CO2 levels in order to keep track of the differential. Therefore you must have an outdoor CO2 sensor, or a sensor in the fresh air intake to track outdoor conditions. [NOTE: THE PRECEDING PARAGRAPH IS SUPERCEDED BY EQc1 RULING DATED 12/21/04.] On the interior, a more efficient distribution system would allow for fewer CO2 sensors to achieve a meaningful result. Functionally, there should be a sensor in each independent zone, with additional sensors in isolated spaces, or spaces with significantly variable occupancy rates. (Especially classroom spaces where the occupant load is highly variable.) LEED does not identify specific locations that are required for CO2 sensors; instead the professional judgement of the engineer is relied upon to optimize the control strategy for CO2. However, if it were clear that the sensor quantity and location could not achieve the intent of the credit, the approach would be questioned, and potentially the credit denied. Note that the kitchen is a special case, and if a high outside air ventilation rate is present there, a CO2 sensor would not be necessary. Applicable internationally.
Related Addenda (Corrections & Interpretations)