A method of providing doses of light sufficient to deactivate bacteria throughout a volumetric space. The method includes: (1) receiving data associated with a desired illuminance level for the space, indicative of an estimated occupancy of the volumetric space over a pre-determined period of time, and indicative of dimensions of the space； (2) determining, based on the received data, an arrangement of one or more lighting fixtures in the volumetric space, the one or more lighting fixtures configured to at least partially emit disinfecting light having a wavelength of between 400 nm and 420 nm, and a total radiometric power to be applied via the one or more lighting fixtures to produce a desired power density at any exposed surface within the volumetric space during the period of time； and (3) installing the determined arrangement of one or more lighting fixtures in the volumetric space.
