A modular fan housing configured to hold an array of motors and fans is provided. The modular fan housing is configured for use in an air-handling system that delivers air to a ventilation system for at least a portion of a building. The fan housing comprises a plurality of modular units configured to be stacked adjacent to one another in at least one row or column to form an array. The modular units each include an interior surface and have a front end and a back end that define a chamber. The chambers are configured to receive the motors and fans. Sound attenuation layers extend along at least a portion of the interior surface of the corresponding chambers. The sound attenuation layers are positioned between at least some of the adjacent chambers.