It is a certification focused on the health of people inside buildings. The certification is divided into different categories or concepts, with air quality being the most heavily weighted.

What is evaluated is the quality of the air inside the building, not the ventilation system itself, although the ventilation system is important to meet two of the four prerequisites required to score in this category:

Ensuring a basic/correct level of indoor air quality by regulating various particles, gases, etc. through filters. The better the indoor air quality, the higher the score — so having a good ventilation system with good filters is almost a guarantee of earning these points.

Ensuring that the ventilation is appropriate for each area of the building (zoned ventilation). A well-designed ventilation system is also almost a guarantee of earning these points.

Once the prerequisites are met, it is possible to begin scoring in the air quality category, where a dual-flow mechanical ventilation system is key, as it allows for the regulation of VOCs inside the building and renewal of stale air.

It allows users to isolate from outside noise by enabling air renewal without needing to open windows.

Another category where a ventilation system can directly influence is thermal comfort, where the ability to monitor the system and control CO2 and humidity levels is valued (CO2 and humidity sensors would be required).

In a more indirect way, a dual-flow mechanical ventilation system can also contribute to scoring in the following categories:

Although WELL scores positively the ability for users to open and close windows, a dual-flow mechanical ventilation system allows avoiding the need to open windows, thus isolating from external noise.

The materials used in building interiors emit more or fewer VOCs, which are harmful to health. By renewing the air, we can remove them and improve indoor air quality.