Presentation Information
[O12-P71]Regarding the use of Teppei stone on roof surface as a measure against global warming
*SHUSUKE SAKATA1 (1. SUWA SEIRYO HIGH SCHOOL)
1. Research Motivation
Teppei stone is an andesite produced in Nagano, and has been used as a roofing material in the Suwa. That roofs made of Teppei stone, which has a high specific heat and water retention, are effective as a countermeasure against global warming and the heat island effect, and I wanted to demonstrate this and increase the usage rate of Teppei stone. The purpose of this study was to investigate whether roofs made of Teppei stone are effective for combating global warming.
2. Experiment 1
Method 1
(i) Four polystyrene foam boxes (18cm x 13cm x 12cm) were prepared to resemble buildings.
(ii) As shown in Figure 1, polystyrene foam, iron plate, wood, and Teppei stone were placed on top of each box to represent the roof surface, and a thermometer was also placed inside the box to measure the air temperature.
(iii) For 11 days from October 7 to October 17, 2025, the room temperature and the surface temperature of the roof were measured at 7:00, 12:00, 17:00 and 22:00.
Result 1
In Figures 2-4, the room temperature, the difference between room temperature and ambient temperature, and the surface temperature of the Teppei stone were higher at 12 o'clock, when the sun was shining the most, compared to the other materials. From the results in Figure 4, the surface temperature of iron at 12 o'clock was lower compared to the other materials.
Investigation 1
The reason why the room temperature and surface temperature of Teppei stone were higher than those of other materials is thought to be due to the influence of heat absorption by color, as Teppei stone is a dark color. The lower the brightness of an object, the more easily its temperature rises. Since Teppei stone is a dark color, its heat absorption rate due to color is higher than that of other materials, which explains why its room temperature was higher than that of other materials.
3. Experiment 2
Method 2
(i) As shown in Figure 5, all roof surfaces were painted black with lacquer spray.
(ii) The installation location and measurement time were the same as in Experiment Method 1, and the experiment was conducted for 19 days from October 21 to November 11, 2025.
Result 2
In Figures 3 and 7, painting all the roofs black increased the heat absorption rate, and the room temperature at 12 o'clock was higher than the ambient temperature for all materials. At 12 o'clock, as shown in the graph in Figure 6, the room temperature was highest for Teppei stone, wood, sheet metal, and polystyrene foam, and as shown in the graph in Figure 8, the surface temperature of wood was higher than that of the other materials.
Investigation 2
The rise in room temperature of the Teppei stone and wood is thought to be due to the reflectivity of these materials. Of the four materials, iron had the highest reflectivity and Teppei stone had the lowest reflectivity. Teppei stone and wood, with their low reflectivity, can be said to absorb heat easily. Also, the low surface temperature of iron likely contributed to its high reflectivity and difficulty in absorbing heat. However, despite the low reflectivity of polystyrene foam, the room temperature did not rise easily. This is likely because, compared to the other materials, it has a very low thermal conductivity and is less affected by reflectivity.
4. Experiment 3
Method 3
(i) The room temperature and surface temperature of the four roofing materials used so far were measured at 13:00 in the same location as in Experiments 1 and 2.
(ii) After (i), water (200 mL) was poured onto the roofing surface of each material, and the room temperature and surface temperature were measured after 15 minutes and 30 minutes.
Result 3
In Figures 9 and 10 show that the room temperature and surface temperature of the iron after water was applied were higher than those of the other materials. The graphs in Figures 9 and 10 also show that 15 minutes after water was applied, the room temperature of the Teppei stone was the second lowest after the polystyrene foam, but its surface temperature was the highest. The graph in Figure 9 shows that 30 minutes after water was applied, the difference in both room temperature and surface temperature narrowed.
Investigation 3
Materials like Teppei stone and wood retain water well, the effect of evaporative cooling-where water absorbs heat from the surroundings as it evaporates-lasts longer, making it difficult for the temperature to rise. The fact that the room temperature returned to the same level after 30 minutes is thought to be because all the water had evaporated and matched the ambient temperature.
5. Summary
It was found that Teppei stone tends to raise room temperature and surface temperature due to its heat absorption and reflectivity, while it tends to lower room temperature due to its water retention capacity.
Teppei stone is an andesite produced in Nagano, and has been used as a roofing material in the Suwa. That roofs made of Teppei stone, which has a high specific heat and water retention, are effective as a countermeasure against global warming and the heat island effect, and I wanted to demonstrate this and increase the usage rate of Teppei stone. The purpose of this study was to investigate whether roofs made of Teppei stone are effective for combating global warming.
2. Experiment 1
Method 1
(i) Four polystyrene foam boxes (18cm x 13cm x 12cm) were prepared to resemble buildings.
(ii) As shown in Figure 1, polystyrene foam, iron plate, wood, and Teppei stone were placed on top of each box to represent the roof surface, and a thermometer was also placed inside the box to measure the air temperature.
(iii) For 11 days from October 7 to October 17, 2025, the room temperature and the surface temperature of the roof were measured at 7:00, 12:00, 17:00 and 22:00.
Result 1
In Figures 2-4, the room temperature, the difference between room temperature and ambient temperature, and the surface temperature of the Teppei stone were higher at 12 o'clock, when the sun was shining the most, compared to the other materials. From the results in Figure 4, the surface temperature of iron at 12 o'clock was lower compared to the other materials.
Investigation 1
The reason why the room temperature and surface temperature of Teppei stone were higher than those of other materials is thought to be due to the influence of heat absorption by color, as Teppei stone is a dark color. The lower the brightness of an object, the more easily its temperature rises. Since Teppei stone is a dark color, its heat absorption rate due to color is higher than that of other materials, which explains why its room temperature was higher than that of other materials.
3. Experiment 2
Method 2
(i) As shown in Figure 5, all roof surfaces were painted black with lacquer spray.
(ii) The installation location and measurement time were the same as in Experiment Method 1, and the experiment was conducted for 19 days from October 21 to November 11, 2025.
Result 2
In Figures 3 and 7, painting all the roofs black increased the heat absorption rate, and the room temperature at 12 o'clock was higher than the ambient temperature for all materials. At 12 o'clock, as shown in the graph in Figure 6, the room temperature was highest for Teppei stone, wood, sheet metal, and polystyrene foam, and as shown in the graph in Figure 8, the surface temperature of wood was higher than that of the other materials.
Investigation 2
The rise in room temperature of the Teppei stone and wood is thought to be due to the reflectivity of these materials. Of the four materials, iron had the highest reflectivity and Teppei stone had the lowest reflectivity. Teppei stone and wood, with their low reflectivity, can be said to absorb heat easily. Also, the low surface temperature of iron likely contributed to its high reflectivity and difficulty in absorbing heat. However, despite the low reflectivity of polystyrene foam, the room temperature did not rise easily. This is likely because, compared to the other materials, it has a very low thermal conductivity and is less affected by reflectivity.
4. Experiment 3
Method 3
(i) The room temperature and surface temperature of the four roofing materials used so far were measured at 13:00 in the same location as in Experiments 1 and 2.
(ii) After (i), water (200 mL) was poured onto the roofing surface of each material, and the room temperature and surface temperature were measured after 15 minutes and 30 minutes.
Result 3
In Figures 9 and 10 show that the room temperature and surface temperature of the iron after water was applied were higher than those of the other materials. The graphs in Figures 9 and 10 also show that 15 minutes after water was applied, the room temperature of the Teppei stone was the second lowest after the polystyrene foam, but its surface temperature was the highest. The graph in Figure 9 shows that 30 minutes after water was applied, the difference in both room temperature and surface temperature narrowed.
Investigation 3
Materials like Teppei stone and wood retain water well, the effect of evaporative cooling-where water absorbs heat from the surroundings as it evaporates-lasts longer, making it difficult for the temperature to rise. The fact that the room temperature returned to the same level after 30 minutes is thought to be because all the water had evaporated and matched the ambient temperature.
5. Summary
It was found that Teppei stone tends to raise room temperature and surface temperature due to its heat absorption and reflectivity, while it tends to lower room temperature due to its water retention capacity.