Impact of Different Illuminance Typical Years Models on a Climate Based Method for the Calculation of Artificial Lighting Energy Use in Office Buildings

Artificial lighting has a relevant impact on the electricity uses in not residential buildings. The method to assess such uses is based on standards, which hardly take into account the daylighting contribution and the time evolution of the outdoor illuminance conditions. Different models were adopted to build diffuse illuminance reference years, starting from satellite images. These models lead to different daylight availability during the year. The paper explores the impact that these models have on the artificial lighting energy uses by hourly monthly mean calculations. The test was carried out with a climate based method, which takes into account: the outdoor luminous environment, the reference indoor visual task and the building daylight characteristics. A typical office building was used for the test in Rome, Italy. Results allowed to compare the impact of each model and to select the most suitable one to be implemented in the climate based method to predict artificial lighting use in buildings.