Image processing for overnight lighting quantification in buildings.

The application of time lapse photography and image processing for counting lit windows at night is described, in order to establish lighting usage patterns, and to validate the hypothesis that office lighting outside normal office hours in the UK is a prevalent waste of electricity.

Abstract

For non-domestic buildings, the issue of the spread of unused office lighting has become topical, whereby a significant amount of electricity may be wasted, as suggested by initial surveys in London. In order to understand the extent of the problem, one approach involved night-time surveying of office buildings. The process of surveying buildings from the outside is laborious and expensive, and as such has been limited in the past to a small percentage of the national stock. This paper describes the application of time lapse photography and image processing for counting lit windows at night, in order to establish lighting usage patterns. Sample results are presented showing system performance, and illustrating the extent of unoccupied office lighting. These results also begin to validate the hypothesis that office lighting outside normal office hours in the UK is a prevalent waste of electricity, offering a considerable opportunity for energy savings.