The paper concerns thermal energy consumption in residential buildings. Heat consumption data of 2280 buildings are compared. Special attention is given to compare heat consumption in identical buildings. Heat consumption variability analysis enables to evaluate inherent heat consumption for space heating dissipation which exists even if design and construction requirements are met. The attempt is made to find the numeral value of heat consumption dissipation caused by design and construction allowances. The analysis of multiflat panel sister-buildings annual heat consumption reveals that minimal value of maximal and minimal heat consumption ratio in identical panel buildings reaches 1.22 (95% confidence level). Data scatter testify erratic quality of construction works, in other words, maximal and minimal heat consumption ratio trend reflects quality of construction works as a whole. On the other hand awareness of inherent unavoidable heat consumption difference in similar houses may strengthen residents' and policy makers' confidence in energy saving tools and enhance thermal renovation of residential buildings. (C) 2009 Elsevier B.V. All rights reserved.