This article presents the results of the research project financed by the Polish Ministry of Science and Higher Education (N N309 078138) and coordinated by the Wood Technology Institute in Poznan. A key point of this project was LCA study performed for four detached single-family dwellings with a particular emphasis on the use stage. The life-cycle assessment involved various types of activity made within a hundred years of use and related to: operation (energy and water consumption), replacements and repairs, renovations and maintenance, land occupation, waste transport and waste management. Two of the four analyzed buildings met passive house standards and their energy demands in the use stage were several times lower than those of their conventional counterparts. The aim of the studies was to demonstrate whether lower nominal energy consumption is sufficient to get the best results of the environmental impact of passive buildings, or whether a type of energy used to cover the demand also plays an important role. (C) 2013 Elsevier B.V. All rights reserved.