Energy saving is one of the most important research directions in the building sector. Daily new HVAC solutions and equipments are developed aiming higher efficiency and lower fossil fuel utilisation. There are cases when only the energy quantity is taken into account and the human side of the problem is neglected. The new energy saving ideas should be analysed from thermal comfort point too. The aim of our research was to see which the influence of the room geometry on the mean radiant temperature is, assuming similar heating systems and thermal properties of the building envelope. It was found that mean radiant temperature has a parabolic variation with the room height and length, so for a room shape there is a certain height for which the mean radiant temperature is minimal. The occupant position in the room influences the obtained values. Lower mean radiant temperature values are obtained for surface heating systems. After thermal refurbishment of buildings the mean radiant temperature will be lower (C) 2012 Elsevier B.V. All rights reserved.