From the hypothesis that water can reduce the surface temperature of glass roof either in the air conditioned room and non – air conditioned room, formed the concept of studying surface temperature variation on water spraying glass roof. The objective of this research was finding the way to reduce the glass roof surface temperature by spraying water that effect to indoor surface temperature of glass roof. The methodology if this research was constructing block up model with glass roof being set in 15 degree against the horizon facing south in order to collect the solar radiation at perpendicular angle of incidence at midday. The roof which was an assembly of 4 pieces of glass with 1.00 meter width by 2.50 meter length was installed for the comparison of each glass surface temperature within the same time period. The low conductivity materials were used as the walls of the experimental model in order to reduce the heat transfer from outside to inside of the model. The block – up model had 2.50 meter width, 5.30 meter length and the average height of 2.70 meters that was similar to a real working room. Air temperature in the model was controlled by air-conditioned system, so the study of surface temperature variation could be concerned within both air-conditioned model and non air-conditioned model. The indoor glass surface temperature of air-conditioned model and non-air condition model was measured by controlling the indoor air temperature constantly within 24 hours to analyze the glass surface temperature variation. The glass which used at this study was reflective glass with shading coefficient 0.26, reflective glass with shading coefficient 0.39, tinted glass with shading coefficient 0.63 and tinted glass with shading coefficient 0.65. In the study of non-air conditioned model without water spraying, the result showed that the surface temperature at peak was about 60 Celsius, the average surface temperature was 47 Celsius at 6.00 – 18.00 and 29 Celsius at 18.00 – 6.00. And in the study of air-conditioned model, the surface temperature at peak was about 51 Celsius, the average surface temperature was 41 Celsius at 6.00 – 18.00 and 25 Celsius at 18.00 – 6.00. When water was run over the glass roof surface of both air-conditioned and non-air conditioned model, the glass roof surface temperature of both conditions were similar, the average surface temperature was 33 Celsius at 6.00 – 18.00, 26 Celsius at 18.00 – 6.00. The surface temperature at peak of non-air conditioned model was approximately 40 Celsius and of air-conditioned model was approximately 37 Celsius. The conclusion of the study showed that the water spraying over the glass roof uniformly with constant rate of flow (4 liters per square meter per minute) could reduce the glass surface temperature up to 23 Celsius. In non-air conditioned model at 6.00 – 18.00 the surface temperature decreased at the average about 14 Celsius and about 3 Celsius at 18.00 – 6.00. In air-conditioned model, water could reduce the glass surface temperature at the average about 8 Celsius at 6.00 – 18.00 and at 18.00 – 6.00 the temperature of non-water spraying surface was lower than the temperature of water spraying surface. From the water spraying capability that could reduce the glass roof surface temperature, the effect of mean radian temperature was reduced. This study will be advantageous to apply these information to glass roof which have the idea of water spraying to reduce the glass roof surface temperature. However, this study did not cover to a water quality control process and system maintenance which should be researched more in order to be information sources for applying efficient in the future.
