We studied effects of the low-emissivity (low-E) interior surface material on interior thermal environment using radiant heating by comparing two real-size experimental rooms with the same thermal insulation: one is covered with a low-E material, (Low-E room), and the other is covered with a normal interior material (Std-E room). As a result, the globe and air temperatures of the Low-E room increased rapidly and showed about 0.8℃ higher temperatures than those of Std-room. The increase in temperatures of the Low-E room may be because the whole Low-E surface, except for floor, of the room become pseudo radiant heating surface.