Due to space restrictions in Serbian cities near the city centers, additional storey may be constructed on the top of old multi-storey buildings that give new apartments. To investigate its influence to the heat consumption and the indoor air temperature in the below apartments, space heating of four buildings is investigated by using EnergyPlus simulations. All buildings are heated by using convection-type radiators with district hot water whose temperature is controlled by the outside temperature. The old building (5S) has 5 stories and does not have additional control of the hot water temperature. Each of other 3 new buildings presents the 5S plus the additional storey (a new-at-roof construction (NRC)) on top of it. The first 6-storey building (6S) is without any additional control of the hot water temperature. The second 6-storey building (6ST) has the additional control by thermostatic valves. The third 6-storey building (6S4T) has the additional control by thermostatic valves, and large radiators. The simulation of the 6S shows that the NRC increases the indoor air temperatures in the apartments and thus some heat is unnecessary wasted. The simulation of 6ST and 6S4T shows that the NRC may decrease the heating needs of the apartments below. (C) 2012 Elsevier B.V. All rights reserved.