The aim of the invention is to devise a method for selectively activating photocatalytic layers wherein the activation process can be carried out individually and as needed using simple means, while the photocatalytic effect is created optimally and the emission of light associated therewith is adapted to ambient conditions. The method for selectively activating photocatalytic layers by the effect of the light emitted by at least one light source in the UV spectrum and/or visible spectrum makes dynamic use, in respect of the spectral components and/or intensity of the light, of the effect of the light for photocatalytic excitation, the photocatalytically active spectrum and/or intensity of the light being controlled. Furthermore, the emission of light for photocatalytic excitation is dynamic, the emitted spectrum and/or intensity of the light being controlled. The spectral component for blue light and the spectral component for UV light are adjusted independently of each other.
