This tool has proven valuable to those wishing to improve the effectiveness of lighting on their premises. Recent updates have made the tool more user friendly and provide new options for internal and external lighting, including street lighting. The tool carries out an array of calculations to determine the capital costs, annual savings (kWh, £, CO2) and payback periods for the proposed replacement fittings, and generates a series of reports that summarise the potential benefits. The recommendations and data in these reports can then be included in an 'outline business case', and as evidence in capital investment proposals. There is also a short video which summarises the tool and how to use it.