Set Infiltration

Infiltration is the unintentional entry of outside air into a building through cracks, gaps, and openings in the building envelope. This can affect energy use, especially for heating and cooling.

Construction quality plays a big role. Well-sealed buildings have lower infiltration, while poorly built or older buildings often have more leaks. Weather also influences infiltration, with wind, temperature, and pressure differences driving air movement.

In some cases, infiltration may be excluded from certain building code calculations, depending on how the code is structured.

Define Infiltration

To define Infiltration, navigate to 'Spaces' and select the 'Default' Space or any other space available. Then navigate to 'Infiltration' and either 'Select from Template' or 'Create Custom' from the 'Set Infiltration' menu. 'Select from Template' gives access to templates linked to your workflow. To view all templates, you must be in Designer Mode. In this example, select 'Create Custom'.

Next, select the Infiltration 'Type', being either 'Design Flow Rate' or 'HVAC based Design Flow Rate'. 'Design Flow Rate' modifies Infiltration by a schedule fraction, temperature difference and wind speed. A 'HVAC Based Design Flow Rate' varies based on HVAC availability, defined for the zone via two schedules. 1) Design level when HVAC is on 2) design level when HVAC is off. If the Space has no HVAC, the off design level is selected. Select 'HVAC based Design Flow Rate' in this example and hit 'Create'.

Next, after returning to the Spaces area, you can nominate 'Design Level (On)' and 'Design Level (Off)' within the sliders in air changes per hour (ACH).