This is a legacy version of the WELL Building Standard. Please check the latest version here.

Ventilation effectiveness

Ventilation effectiveness


To ensure adequate ventilation and high indoor air quality.

The WELL requirement is only applicable within the project boundary, but the nature of balancing is such that the project may have to include parts of the system outside of the project boundary in order to properly balance the system. For example, the Air Handling Unit may need to be rebalanced if the balancing for the existing tenancy ends up using more or less total supply air than it was previously balanced to require. Additionally, the components related to outside air will frequently be outside of the project boundary for an interiors project.

IWBI is not looking at specific criteria other than that balancing has occurred or will occur within 5 years. For guidance on completing system balancing, projects can refer to ASHRAE 62.1-2013 Section 7.2.2 and ASHRAE 111, or to the relevant balancing professional organization (such as NEBB, TABB, or AABC, etc.).

Yes, the ventilation rate procedure did not change substantively between ASHRAE 62.1-2010 and ASHRAE 62.1-2013. Therefore, for the purposes of Feature 03, Part 1, a project can meet this requirement if it complies with ASHRAE 62.1-2010.

If a project team knows the ventilation rates for the project, the rates can be compared with those required for an office space (or other building environment) in ASHRAE 62.1-2013. A mechanical engineer can confirm compliance with ASHRAE 62.1-2013. In addition, many projects that are designed to earlier versions of ASHRAE may still be compliant with the 2013 version.

Yes, all regularly used spaces including active stairwells, lobbies and corridors would need to meet the ventilation rate requirements. However, stairwells that are meant solely as a fire escape do not need to comply.

No, only projects that rely on natural ventilation would need to comply with the ASHRAE natural ventilation rates. Mechanically ventilated projects should comply with the mechanical ventilation rates in Feature 03 Part 1a.

When pursuing natural ventilation methods, the project team would need to confirm that for 95% of hours in the previous year, the ambient air quality was below the WELL Air Quality standards in Feature 01, or was compliant with the U.S. EPA NAAQS.

The strategy outlined in this feature is to install CO2 sensors to continuously measure CO2 levels. The CO2 monitor should be monitored and trigger an increase in ventilation when CO2 levels approach 800ppm. This could be done automatically through the building management system (BMS) or manually through monitoring from the building management team.

Yes, the project team may be able to retrofit the existing ventilation system to be demand-controlled. The project team would need to review adding CO2 sensors to the high occupancy spaces, and possibly additional components to increase air flow (dampers, controllers, VAV boxes, additional ductwork, etc.). Demand-controlled ventilation systems are often also used to create more efficient systems and may result in energy cost savings.