A radiant heating system model has been developed for use in the BLAST energy analysis computer program. The model considers gas or electric radiant heaters, which give off directional infrared radiant energy. Three thermal comfort models have also been incorporated in to BLAST, so that thermal comfort can be used to control the amount of heating needed in a room. A theoretical justification of the new radiant heating model is presented which is based on the principles of radiant heating and the structure of the current BLAST zone heat balance algorithm. Results of BLAST runs comparing a convective heater with two radiant heating systems are presented. Guidelines are set forth for using the radiant modeland the three thermal comfort models. The proper use of these features will allow system designers to compare the relative cost of radiant heaters and convective heaters in order to design the heating systems of buildings based on thermal comfort.

Units: SI