Our project is a Acute Care Hospital which we will be submitting under LEED-NC v2.1. We intend to meet the requirements of this credit using the following two systems: System 1) Floors 2 through 9. This represents the majority of the building and houses the clinical treatment and patient care areas. The occupancy consists of patient rooms, diagnostic treatments sites such as MRI, and Catheterization Labs, Operating Theaters, and associated ancilliary spaces. There are some meeting rooms, waiting areas, and an atrium typically found in a large scale acute care center. The ventilation system for this portion of the building consists of a series of air handling units serving a common distribution system. All of the ventilation units are 100% outside air supply with 100% exhaust air. There is no recirculation of air for this system. We will provide CO2 sensors for all spaces that are anticipated to have variable occupancy such as: meeting rooms, waiting areas, gathering spaces such as atriums, and staff support areas such as staff lounges and nursing stations. Air volume will be increased to maintain acceptable CO2 levels. For spaces where a constant occupancy is expected such as operating rooms, patient rooms, diagnostic areas etc, a calculation as prescribed by ASHRAE Standard #62 will be conducted to demonstrate that the design air supply to the room is well above acceptable ASHRAE prescribed volumes. Since these areas are not designed as variable air volume zones, CO2 monitors will not be employed. Rather, the Building Management System will monitor the terminal units for each of these zones and signal an alarm to the Building Operator in the event that air flow slows below the design volume. System #2) Level 0 and 1. This space consists of some clinical diagnostic space such as examination rooms and simple diagnostic imaging as well as circulation space such as waiting rooms and a cafeteria. This area is fed by an air system consisting of 4 air handling units which supply a common distribution system. These units operate using a mixture of outdoor air and return air. We will provide CO2 sensors in the return air ductwork for zones of similar occupancy: examination rooms, diagnostic imaging rooms, waiting rooms, and cafeteria. An outdoor air CO2 sensor will also be provided as a reference point. Alarms will be provided to the building operator through the building management system should anyone of the return duct CO2 sensors measure an unacceptable CO2 level. Does the method of monitoring the supply air flow rate to the constant volume zones in system #1 to ensure that design supply air flow is maintained satisfy the requirements of this credit? Does the combining of similar rooms by monitoring the return air CO2 levels for those room types satisfy the requirements of this credit?
This CIR is requesting confirmation that their design approach meets the intent of EQc1. As described, the design does NOT meet the requirements of the credit under LEED-NC v2.1. The design may be better suited for submission under the EQc1 requirements of LEED-NC v2.2. The design team may want to consider that compliance path, though it also requires that EQp1 and EQc2 be submitted using the v2.2 requirements. In response to your specific questions: Q1 - Does the method of monitoring the supply air flow rate to the constant volume zones in system #1 to ensure that design supply air flow is maintained satisfy the requirements of this credit? A - No. Under NC v2.1, CO2 monitoring is required - it is not sufficient to monitor airflow. (This would be acceptable under NCv2.2, however) Q2- Does the combining of similar rooms by monitoring the return air CO2 levels for those room types satisfy the requirements of this credit? A - Perhaps. The grouping of multiple spaces utilizing one CO2 sensor is only allowed if it can be shown that the areas have similar, static occupancy. An independent CO2 sensor is required for spaces with dynamic occupancy. CO2 sensors must be located so as to provide representative readings for the spaces being monitored. CO2 sensors located in central locations (such as gathered return ducts or at the AHU) present potential for artificially diluting the CO2 readings from areas of high occupancy with adjacent areas of low occupancy and therefore do not meet the intent of this credit. In order to achieve this credit, your documentation submission will have to demonstrate how these requirements have been met.
Related Addenda (Corrections & Interpretations)