The main objective of the paper is to assess the impact of different factors which include building and human comfort parameters on indoor temperature conditions and energy need for heating for complex system "heat source - human comfort - building envelope". The proposed method of mean radiant temperature calculation for human comfort models, which takes into account incoming solar radiation, will increase the accuracy of calculations by 13%-4.7%. Regression models for comfort room air temperature determination, developed on the basis of energy and exergy human comfort approaches, significantly simplify further calculations and can be incorporated in complex system. As comfort temperature, determined in accordance with exergy approach is lower than based on energy one, the exergy concept use for providing comfort conditions accounts for less energy need for heating. Modelling results of various factors impact on energy need for heating are obtained based on energy and exergy approach to human comfort. (C) 2017 Elsevier B.V. All rights reserved.