再帰反射材の照り返し抑制効果  [in Japanese] REDUCTION OF REFLECTED HEAT BY RETROREFLECTIVE MATERIALS  [in Japanese]

We show experimentally that retroreflective materials reduce the reflected heat. They can be used as the building materials to reduce urban heat island effect. We measure the retroreflective component of retroreflective materials for the first time. The procedures are as follows. First, the total reflectance is deduced from the thermal measurement. Then, the reflectance without retroreflection is measured by using a spectrophotometer with the integrating sphere. Finally, the retroreflective component is calculated by subtracting the latter from the former. The measured retroreflective components are about 10 percent for bead-embedded type, and 20 percent for capsule-lens type.