Study of effect of daylight on Building User's Performance Based on Electroencephalograph Signal

The use of daylighting in building nowadays has become one alternative to save electric energy consumption, particularly during daytime. Daylight is not only useful for reducing cost from electric light sources, but also give benefits both physiologically and psychologically for building users. Studies in various countries showed that daylight was more preferable as main light source, compared to light from electric lamps. Effect of daylight on performance of building users might be evaluated based on variation of electroencephalograph (EEG) signal, specifically alpha and beta waves. In this research, EEG signal was used to evaluate brain response of the participant while doing activity of solving jigsaw puzzle under daylight condition inside a room. Several factors were varied, i.e. average illuminance on work plane (1000 and 300 lux), orientation of the participant with regard to the window (perpendicular and parallel to the window plane), and timing of the experiments (at noon [12.00~13.00 WIB] and in the afternoon [14.30~15.30 WIB]). The measured EEG signal was then analyzed using power spectral density (PSD), to determine the alpha and beta waves. From the experiments result, it was proven that EEG signal variation had existed, based on electrode locations and lighting quality factors, i.e. average illuminance on work plane and timing. On primary visual cortex, average of beta waves increased, relative to idle condition. Combination of "1000 lux, perpendicular, noon" was found to increase the participant’s performance at most, as well as beta waves. Combination of "1000 lux, noon" was found to increase alpha waves at most, resulted in relax and calm condition, even though the participant was doing physical activity. Generally, daylight and fluorescent lamp light did not give any significant difference