Continuous operation
Many buildings have mechanical systems capable of cycling on or off depending on the demands (typically temperature) of the space. Ventilation and air quality are critical to managing risk in spaces. ParticleOne recommends, and the simulation assumes, that mechanical systems are programmed for continuous operation (airflow) when the space is occupied.
Supply airflow rate
Supply airflow rate is the total quantity of air delivered to a space by a mechanical system in a stipulated amount of time. Supply airflow rate is typically specified in terms of cubic feet per minute (CFM), litres per second (L/s),
cubic meters per second (m3/s), or occasionally as a number of air changes per hour (ACH). Air change per hour estimates of flow rate should be checked carefully to ensure accuracy as the value is specific to both the flow of
air and volume of the room. The default option calculates a supply airflow rate based on an estimated outside air flow minimum, and an assumed outside air (OA) fraction. Outside air flow is calculated with methods from ASHRAE 62.1 using inputs of
occupancy, floor area and corresponding flow rates sourced from the standard. The default option then assumes a mixing system where supply air is a combination of outside and recirculated air with an outside air (OA) fraction of 33%. Stated alternatively, outside air (OA) is estimated using ASHRAE 62.1 methods, then multiplied by three (3) to establish a supply airflow rate. Supply air is typically made up of a mixture of outside air (OA), and recirculated air (i.e., return air). Both sources are filtered and conditioned (heated or cooled) before being delivered to a space (see figure 1) . The supply airflow rate can be determined from the building automation system (BAS), as built mechanical drawings, equipment specifications, or from validation reports available through the building operator. There are many instances where the supply air for the space will be from a mechanical system that serves multiple spaces or areas of the building. In those situations, it is important to input only the supply that goes to the specific space being simulated. Otherwise, the platform will overestimate the benefit of the mechanical system.
