Updated over a week ago

Ventilation load refers to the energy demand to condition the amount of outside air that needs to be introduced into a space to meet requirements. This load is critical for HVAC (Heating, Ventilation, and Air Conditioning) engineers to consider as it influences the design and operation of HVAC systems in buildings.

Here is where to determine the ventilation load depending on the air system chosen for the project:

When an Ideal Air Loads system is chosen (default option) to serve thermal zones, the ventilation load is reported directly within Room & Zone Cooling and Heating Breakdown. The following screenshot shows an example:

FAQ:

Q. How does the air balance work for an Ideal Air System? Which type of airflow values can be customized?

A. The airflow values for a thermal zone are always balanced with the Ideal Air System. Since the ideal air loads are a simplified piece of conditioning equipment, the outdoor air flow rates can be edited directly by users as it equals the supply air. And since the air is balanced, the exhaust airflow rates will be the same as well.

# Air System

## Local Air System

When a local air system is assigned, the ventilation load can be calculated from the zone results page with the following formula:

Ventilation Cooling Load [Btu/hr (IP) or Watts (SI)] =

Local Air System Total Cooling Coil Capacity - Zone Total Cooling Load

The same formula can be using to find the Ventilation Heating Load.

For the example zone above the ventilation load for cooling would be 1,597 Btu/hr (IP) or 468 Watts (SI).

Important Note: For Heating Ventilation Load calculation, consider the absolute difference between `Local Air System Total Heating Capacity and Zone Total Heating Load`. This will result in a negative value matching the platforms convention.

## Central Air System

For central air systems, the ventilation load can be calculated from the air systems results page with the following formula:

Ventilation Cooling Load [Btu/hr (IP) or Watts (SI)] =

Primary Cooling Coil Total Capacity - Primary Total Cooling Load

The same formula can be using to find the Ventilation Heating Load.

Important Note: For Heating Ventilation Load calculation, consider the absolute difference between `Primary Heating Coil Total Capacity and Primary System Total Heating Load. `This will result in a negative value matching the platforms convention.