In this study, a comparative study between floor heating system and wall heating system is carried out. Air flow and heat transfer inside a room which is heated by floor heating and wall heating systems are investigated numerically for a residential building located in Kocaeli province, Turkey. Computations are performed for three different water temperatures, namely 30 degrees C, 40 degrees C and 50 degrees C. Computations show that a strong circulation occurs in the room for the floor heating system which covers the whole occupied zone and may exceed the thermal comfort conditions while a weak circulation forms in the room for the wall heating system which is gentle enough to be unnoticed for human body. It is also observed that a homogenous temperature distribution occurs in the room for the floor heating system. Although a thermal stratification occurs in the room for the wall heating system, the temperature gradient is less than 1 degrees C/m, which does not cause discomfort. It is concluded that engineers should consider wall heating system rather than floor heating system since better thermal performance and thermal comfort conditions can be achieved with lower water temperature, thus the fuel consumption and consequently emissions of greenhouse gases can be reduced considerably. (C) 2013 Elsevier B.V. All rights reserved.