Next Generation Thermostats with IAQ Controls for Commercial HVAC

Indoor Air Quality (IAQ) is critical for the design and management of buildings and their Heating Ventilation & Air Conditioning (HVAC) systems for ensuring occupants' health and well-being. A large body of literature reveals that IAQ conditions are statistically related to occupant health and cognitive performance in both the short-term and long-term. From this literature, a number of IAQ conditions emerge as most important to occupants' health and well-being, including carbon dioxide as an indication of ventilation effectiveness, particulate matter such as PM2.5 and PMl0, and Total Volatile Organic Compounds (TVOCs), among others. Currently, HVAC controls are driven by temperature readings from thermostats in each occupied zone, with no input from any indoor air quality conditions beyond thermal. The introduction of Demand Control Ventilation (DCV) did add indoor carbon dioxide (CO₂) sensors to control ventilation in variable occupancy spaces such as conference rooms, but these were predominantly focused on saving energy when spaces are empty. Even if CO₂ were introduced in every zone, this would be an inadequate record of key IAQ metrics to comprehensively represent indoor air quality. This study evaluates both existing sensor suites that facilitate the monitoring of lAQ and the potential control points in the HVAC system that could respond to these inputs. The Phipps Exhibit Staging Center, a Living Building™ in Pittsburgh Pennsylvania, offers an excellent test, with dedicated HVAC systems and ongoing Aircuity monitoring of indoor air quality. This thesis introduces the potential of an IAQ metric-centered control system by connecting real-time measured IAQ indexes to the HVAC control logic. The control logic is tested in the contaminant simulation environment CONTAM to quantify the IAQ improvements. Introducing more comprehensive IAQ input into HVAC control by replacing conventional thermostats with next-generation Temp+IAQ stats can play a transformative role in prioritizing IAQ performance in smart buildings