A unique seasonal collection method of sky radiation energy was proposed. This method is especially effective in the humid area where the radiative cooling could not be expected. To collect the cooling energy for space cooling, the sky radiator is operated from April–June when humidity is much less than in August. The simulation has shown that this long-term shortage system provides sufficient space cooling energy for a standard home. An experiment was carried out with a black-painted sky radiator to obtain data under actual meteorological conditions. The results were then compared with various empirical equations presented hitherto.