The project is a 455,000 square foot hospital with 12 airhandlers. Due to health care code requirements each patient room, recovery room, and observation room will be required to have 2 AC/hour of outside air. Invasive rooms such as operating rooms have higher outside air requirements. To meet this requirement outside air percentages in airhandler are maintained year round at a minimum of 33% or more for ALL patient care areas. This will cover about 80% of the hospital. Would installing CO2 sensors in all of the airhandlers, in spaces with variable occupancies such as dining rooms, nurse stations, conference rooms, and waiting areas meet the intent of the credit. We don\'t see a benefit to installing a CO2 sensor in each patient care area or surgical area due to the high outside air amounts delivered to each room.
As was stated in the EQc1 CIR dated 8/4/03, "The primary intent of the credit is to provide indoor air quality monitoring to sustain long-term occupant health." While the CIR identifies monitoring as the primary function for this credit, the underlying reason for CO2 monitoring is that it can be used as an HVAC system operational diagnostic tool and is valuable as an indicator of acceptable IAQ in otherwise chemically benign office spaces. If the patient care rooms constitute 80% of the building, then it is reasonable to expect monitoring of CO2 in these spaces in order to fulfill the spirit of the credit. In keeping with the Design Approach Strategies listed in the LEED v2.1 Reference Guide, pages 250 and 251, the following approach may be helpful. If it can be demonstrated that the patient rooms and invasive rooms maintain "static occupant densities" and these rooms can be blocked out into "small combined floor areas", then a more centralized monitoring arrangement of the return duct system may be a reasonable compromise to providing CO2 monitoring in every room. Installing CO2 sensors in the airhandlers for spaces with variable occupancies such as dining rooms, nurse stations, conference rooms, and waiting rooms does not follow the Design Approach Strategies listed in the LEED v2.0 or 2.1 Reference Guides. Originally in the v2.0 Reference Guide page 226, the required sensor locations were in return air vents or within spaces with monitoring locations in building areas with high occupant densities. The LEED v2.1 Reference Guide corrects this on pages 250 and 251 by stating that sensor locations must be selected so that they provide representative readings of the CO2 concentrations in the occupied spaces served by each HVAC system used in the building. The CO2 sensors should not be located in the return air inlets because they can be fooled by short-circuiting (low air change effectiveness, e.g. in heating mode). Instead, the sensors should be located in the breathing zone of the space to provide proper monitoring and feedback. Also note that CO2 sensors at central locations near the airhandlers presents potential for artificially diluting the CO2 readings from areas of high occupancy with adjacent areas of low occupancy and therefore does not meet the intent of this credit.