Model predicting the state of the lighting with the illuminance on the working plane and occupancy.
When the space is unoccupied, the light is always off. When the space is occupied, the probability to switch on the light depends on the illuminance level on the working plane. The lower the illuminance level, the higher the chance to switch on the lighting.
The probability to switch on the lighting is different when subjects just arrived and when subjects have stayed indoor for a while. The probability to switch lights is higher when subjects just arrived. Accordingly, two different probability functions have been applied.
The switch-off probability is found to be very low in this research, which may be because occupants failed to notice the lighting is on when the indoor daylight illuminance levels were high. Therefore, in this model, the lighting would be switched off only when the space is unoccupied.
The model is documented in the paper "Reinhart, C.F. and Voss, K., 2003. Monitoring manual control of electric lighting and blinds. Lighting research & technology, 35(3), pp.243-258."
The model parameters are regressed from the field study in 10 offices in Germany from Mar. to Dec. 2000.