<p>To recycle silica byproducts and to moderate the heat-island phenomenon, a porous ceramic was made by mixing waste silica powder with clay before firing the resultant mixture. The high water-absorption capacity of the ceramic was used to produce a greening material of moss-covered porous ceramic. To examine the restraining ability of the temperature increase caused by solar-radiant heat on the moss-covered ceramic, the surface-temperature change of a moss-covered sample during solar-radiant-heat reception and the amount of water evaporated from the sample were measured simultaneously, and were compared with those of a mortar sample without moss in the water-absorbing state. To clarify the quantitative influence of the water-evaporation heat on the temperature change of the moss-covered sample, the sample temperature change was simulated by performing a thermal-conductivity analysis and by considering the heat of evaporation using finite-element-methods analysis. The experimental results confirmed that the moss-covered sample that could absorb sufficient water could constrain the temperature increase caused by solar-radiant heat for a long time compared with the mortar sample. The finite-element-simulation results indicate that the restraining effect on the temperature increase by the moss-covered sample resulted from heat of water evaporation. It is expected that the moss-covered ceramic with a high water-absorption capacity and a low conductivity could be used as a greening material on building rooftops.</p>