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.


Mold often grows on cooling coils in HVAC systems due to moisture condensation and can be introduced into the building’s indoor air. It can also occur on or within wall assemblies due to water damage or improper detailing in humid locations, for example kitchens and bathrooms. Mold spores can trigger asthma, headaches, allergies and other respiratory system disorders.

Part 1
Cooling Coil Mold Reduction

In buildings that rely on a mechanical system for cooling, one of the following requirements is met:
Ultraviolet lamps (using a wavelength of 254 nm so as not to generate ozone) are employed on the cooling coils and drain pans of the mechanical system supplies. Irradiance reaching the cooling coil and drain pan, including the plenum corners, is modeled.
Building policy states that all cooling coils are inspected on a quarterly basis for mold growth and cleaned if necessary. Dated photos demonstrating adherence are provided to the IWBI on an annual basis.

Part 2
Mold Inspections

The following are not present:
Signs of discoloration and mold on ceilings, walls or floors.
Signs of water damage or pooling.