Obtaining Outdoor Illuminance Values with Solar Irradiation Transformation Models

Daylighting is one of the important aspects of sustainable building, but architectural daylighting in China is obstructed because of shortage of daylight meteorological measurement record. However, there are many data of solar irradiation. Therefore solar irradiance values are used to calculate outdoor illumination values. Luminous efficacy is introduced to show the relation between solar irradiance and outdoor illumination. Sunny index is used to represent the meteorological states of the sky. On the basis of measurement data in Chongqing from 1991 to 1992, new luminous efficacy calculation model is built to obtain the outdoor global illuminance values and the diffuse illuminance values. Measurement data in Chongqing in 1993 is used to evaluate the proposed mode, which shows the proposed models are reliable. In order to prove possibility of calculating illuminance in other places in China, the measurement data records of annually average global illuminance values in 32 cites are used to examine the calculation results. If the real-time solar irradiation data was input, the real-time illuminance values could be obtained with this model in China, thus millions of illuminance values could be used in future daylighting design.