Abstract: A method and apparatus for controlling the temperature of a space. The actual heat load for a space under the conditions prevailing at a time is determined based upon information available to a temperature sensor. The average heating/cooling percentage rate for relatively short duty cycles is adjusted based on this information whereby the actual heating/cooling load during this duty cycle interval may be approximately matched. The percentage rate may be overridden in the event an abnormal temperature situation exists. The method and apparatus of this invention has particular application when utilized with radiant heaters.