Title: Improve Traditional CO2-DCV with Outdoor Airflow Measurement
Abstract: ASHRAE Standard 90.1-2019, various energy standards and energy codes require demand control ventilation (DCV) of high occupant density spaces. DCV is defined in the Ventilation Rate Procedure (VRP) or ASHRAE Standard 62.1-2019.
DCV adjusts ventilation rates based on the ventilation zone population, however, many industry professionals are convinced that DCV requires that ventilation zone CO2 levels are maintained.
This paper clarifies industry misconceptions regarding DCV and exposes the significant uncertainties associated with CO2-DVC. The paper also offers two improved methods for those who want to use CO2 as a method of demand control ventilation. Both methods use outdoor airflow measurement either at the air handler (recirculating air systems) or ventilation zone (DOAS). Finally, the paper suggests that the industry considers using direct occupancy measurement, rather than CO2, as a method of DVC when feasible.
File: Improved CO2-DCV
Title: The Importance of Controlled Ventilation in Schools
Abstract: Outdoor Air Ventilation in schools promotes health and wellbeing. Each individual requires a set amount of ventilation. The means to achieve ventilation is typically through mechanical HVAC systems. The minimum amount of ventilation required for schools is determined by state, provincial, and municipal codes. Many studies have determined that increased ventilation beyond the minimum may promote better health and improved performance. However, there is a cost to ventilation as it requires that the air be conditioned and filtered for the indoor environment. Therefore, efforts are made to reduce ventilation when the population in the building is reduced and when the building is unoccupied. Furthermore, the ventilation rate is impacted by the environment internal and external to the building, and by degradation and changes in the operation of the HVAC systems. The result is, the amount of actual ventilation is always subjected to dynamic changes and thereby a method to measure and control the ventilation should be integrated into every system to provide the desired correct and efficient ventilation rate.