It is the one that is switched off, focusing us all on the fact that even efficient light sources waste energy (lighting empty rooms or unused corridors). One of the lesser known advantages of LED’s is the fact that continuous switching has no negative impact on the life of the light source and in fact actually prolongs the life by switching it off, even if only for seconds or minutes. Fluorescent lighting technology cannot be continually switched on and off in this way because the lamp life is retarded by this action so the saving of energy results in more lamp change costs over time.