Lighting energy conservation: Simple analytic methods with time-lapse photography

Although time-lapse photography offers great potential for providing information on lighting energy conservation, it has been undeveloped because the quantity and detail of the data demand a great deal of time for analysis. Two simple analytic procedures are described to make time-lapse photography more useful: (1) a sampling procedure for data reduction, and (2) a formula for computing wasted lighting energy based upon occupancy and light usage. It is argued that poor utilisation of lighting energy can be addressed with these procedures.