Because of the permanent dilemma whether residential buildings using district heating should be heated continually or discontinuously, we evaluated how the yearly heating load and the peak heating load of a small building in Serbia depend on the duration of thermal comfort provision. Using HTB2 software, a product of the Welsh School of Architecture, it was found that an increase in the duration of thermal comfort provision in the building from 16 It to 24 h increases the yearly heating load by 20%, reduces the peak heating load by up to 40% and may increase the number of new customers served with the same heating plant by up to 40%. (C) 2007 Elsevier Ltd. All rights reserved.