[M-IS07] Geomaterials in cultural heritage: weathering, investigation techniques, and conservation

[MIS07-P05] An Experimental Study on Temperature Reduction Effect in Evaporation and Cooling of Building Stones

Shunsuke Ogawa², *Chiaki T. Oguchi¹ (1.Institute for Environmental Science and Technology, Graduate School of Science and Engineering, Saitama University, 2.Department of Engineering, Saitama University)

Keywords:tuff, limestone, mortar, building stones, temperature reduction effect, discomfort index

Due to global warming, energy consumption in Japan is increasing because of the intense summer heat. There is a potential to reduce energy consumption by using building stones that have a higher evaporative cooling effect than concrete houses. Therefore, in this study, we experimented to investigate the evaporative cooling effect of different types of stone and mortar. Four types of materials with different pore characteristics were used in the experiment: Oya stone (tuff), Ashino stone (welded tuff), Savonnières limestone, and cement mortar. These stones were first shaped into 50 x 50 x 1.2 mm stone slabs, and five of these were used to make a stone box. A self-recording button-type temperature and humidity sensor were placed inside the stone box, which was then sealed with a stone slab of the same size, and the following three experiments were carried out five times each.
- Experiment 1: The stone box is placed in a drying oven at about 40°C.
- Experiment 2: The stone box is immersed in water at about 20°C and left until the temperature of the stone is equal to that of the water. The box is then placed in a drying oven at about 40°C.
- Experiment 3: After immersing the stone box in water at about 20°C, it is placed in an incubator at about 0°C.
In all experiments, the results were organized using the temperature and humidity data recorded by the sensors inside the stone box, and the discomfort index (an index that quantitatively expresses the hot and humid summer weather and is one of the thermal comfort indices) was calculated. As a result, from the perspective of the discomfort index, Savonnières limestone, and Ashino stone were highly rated in Experiment 1, Oya stone and Ashino stone were highly rated in Experiment 2, and Oya stone was highly rated in Experiment 3. This is considered to be due to differences in pore size distributions.