This version of the NCC 2019 Lighting Calculator assists in understanding and applying the NCC Volume One Part J6 Artificial lighting DTS Provisions for energy efficiency. The calculator is a MS Excel file containing two separate worksheets. The first is titled 'Residential Lighting Calculator' and applies to sole-occupancy units of a Class 2 building or Class 4 part of a building. The second is titled 'Non-Residential Lighting Calculator', which covers Class 3 and Class 5 to 9 buildings. This calculator has been created and designed for Excel 2010, and newer, for Windows. Compatibility with other versions and operating systems is not guaranteed. This calculator is for use with NCC 2019 Volume One.