Where do I define outdoor air flow?

Defining outdoor air flow

In Simergy/EnergyPlus there are various ways to define outdoor air requirements. The so-called Design Outdoor Air Specification object allows to define the air flow per floor area, per person, per zone, and per hour (etc.).

This object can be referenced by various components as shown in the figure below. At the system level in the Idea load object or in an air loop at the outside air controller. At the zone level at some of the air terminals and for zone sizing.

Zone Sizing

The Zone Sizing object allows the definition of data needed for sizing calculations for design days. The description of the object and the relevant parameters are below:

Zone Level

Some air terminals include the option to specify a Design Specification Outdoor Air Object. You can find details on the related property here:

In a similar manner the Ideal loads object can reference these specifications.

System (Air loop) Level

The main component to control outdoor air flow is the Outdoor air Controller.

This controller is a powerful component with quite a range of options, the InputOutputReference.pdf illustrates the following logic:

More details on the following parameters:

The Mechanical Ventilation Controller specifies one or more design specification objects outdoor air that define outdoor air according to ASHREA 62.1: