IEQ2: Demand Controlled Ventilation

(1-2 points)

PURPOSE

Maintain air quality and decrease energy consumption by delivering outside air (OA) based on occupancy.

CRITERIA

Ventilation of outside air (OA) shall be automatically adjusted based on occupancy. Sensors shall be tied to the ventilation control and increase/decrease OA flow rates in response to occupancy. Install a minimum of one sensor per each 500 CFM of OA. Refer to ASHRAE Standard 62.1-2016, Table 6.2.2.1 Minimum Ventilation Rates in Breathing Zone and 6.2.7.1 Demand Control Ventilation. See also ASHRAE 90.1-2013, Section 6.4.3.8 Ventilation Controls for High Occupancy Areas.

Projects to fulfill applicable options:

Option A. Carbon dioxide (CO2) sensor based demand control ventilation (2 points) 

• In rooms requiring 500 CFM of outside air (OA) 
• In rooms greater than 500 sf with an occupant density of 25 people per 1000 sq.ft. (40 sq.ft. per person) 
• CO2 sensors must measure CO2 levels in the breathing zone relative to OA levels 
• Wall-mounted CO2 sensors are acceptable

Option B. Occupancy sensor based demand control ventilation (1 point) 

• Occupancy sensor controlled ventilation can be reduced to zero at times of no occupancy for all allowed spaces denoted by Note H in ASHRAE 62.1-2016 Table 6.2.2.1 
• Example spaces include lecture halls, classrooms, offices, corridors, lobbies, breakrooms, etc 
• For a list of all allowable spaces in ASHRAE 62.1-2016, refer to Appendix E. Prescriptive Outside Air Requirements

VERIFICATION 

• Construction Documents indicate locations of CO2 sensors and mechanical notes describing control sequence 
• Site Inspection by ECLC Technical Advisor DEFINITION Breathing zone – the zone in occupied space between three inches and 72 inches (6 ft.) above the floor and more than two ft. from fixed AC equipment.

RESOURCES

American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) www.ashrae.org

Energy Codes https://www.benergycodes.gov/sites/default/files/documents/cn_demand_control_ventilation.pdf