A method of providing doses of light sufficient to deactivate bacteria throughout a volumetric space over a period of time, the method comprising: - receiving first data associated with a desired illuminance level for the space, second data indicative of an estimated occupancy of the volumetric space over a predetermined period of time, and third data indicative of the dimensions of the space； - determining, based on the first 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； - determining based on the second and third data 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, the desired power density comprising a minimum integrated irradiance of the disinfecting light equal to 0.01 mW/cm
