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

Microbe and mold control

Microbe and mold control


To reduce mold and bacteria growth within buildings, particularly from water damage or condensation on cooling coils.

Part 1 applies to all cooling coils and drain pans located within the primary air handling unit and any secondary equipment downstream. Note, a combination of UV lights and/or quarterly inspections is acceptable to comply​ with the part. ​

IWBI recognizes that tenants may not have control of or access to base building cooling coils. In such instances, Feature 06 Part 1 is considered outside the scope of the project, and therefore not applicable. The project team will need to provide documentation confirming the scope concern, such as a letter from the building owner that they are not allowed to make changes to the mechanical system.

Additionally, the project will still need to pass the Feature 06 Part 2 visual inspection. Therefore, it is in the project's best interest to ensure that the maintenance services provided by the landlord do address cooling coils.

Projects need to inspect the cooling coils in each quarter in which the cooling system is in operation.

To comply with Part 1 Option b, the Multi-family developer / landlord would need to offer a quarterly inspection to residents at no additional charge. Individual households are free to opt out of this service, and this should be recorded in the maintenance log to demonstrate that effort was made to communicate and extend the inspection offer to residents but that access was denied to complete the checks. The maintenance log, along with photos of successful inspections, still need to be submitted to the IWBI once a year as part of ongoing documentation requirements.

WELL does not specify or recommend a specific method or methods for modeling irradiance reaching the coils. The project team must identify the appropriate method for their specific project circumstances, which may include working with the manufacturer of the system or other specialists. The MEP Drawings submitted for documentation review will need to at a minimum identify the components being installed and include a graphical representation confirming adequate coverage of coil and drain pan surfaces.

Yes, in order to demonstrate compliance with the preventative maintenance plan requirement, photos must be taken during the quarterly inspection. These photos will then need to be submitted to the IWBI once a year as part of the ongoing documentation requirements.

No, a mold inspection will be conducted by the WELL Assessor during the projects Performance Verification.

All air handling units and fan coil units with cooling capabilities must meet either Part 1a (UV systems) or Part 2a (regular inspection and cleaning). Not all units are required to use the same option.

Yes, projects which meet the cleaning and reporting requirements outlined in option b of part 1 are not required to use UV lamps.