The radiant time factors are used to calculate radiant cooling load in the radiant time series method. Based on measurement data of hourly heat gain and cooling load collected within 24 hours

radiant heat gain and radiant cooling load can be calculated by separating convection with radiation . Transfer function is obtained and a 24 term radiant time factors can be calculated by transfer function coefficients matrix. By comparing the results with experiment

it shows that the calculation method of radiant time factors is feasible. The first value of radiant time factors decreases as supply air volume decreases and the sum of the first five factors is more than 0.75. For the radiant time factors calculated by ASHRAE software

the improvement method can be used to calculate radiant cooling load under different air circulation after correcting the first five factors.