The online numerical tool Ener-Habitat, designed to evaluate the thermal performance of homogeneous and non-homogeneous walls or roofs of the building envelope using a time-dependent heat transfer model, is presented. This tool is useful in evaluating constructive systems composed by up to seven homogeneous layers and also constructive systems composed by one non-homogeneous layer plus up to six homogeneous layers. The non-homogeneous layer can be either filled or hollow block type. Ener-Habitat solves the time-dependent heat transfer equation with convective boundary conditions on both sides, in one-dimension for homogeneous constructive systems and in two-dimensions for constructive systems containing one non-homogeneous layer. It takes into consideration that the constructive system is either in a non air-conditioned room or in an air-conditioned one. The one-dimensional model for homogeneous multilayered constructive systems is validated by comparison with EnergyPlus results. The two-dimensional model is validated by calculating the heat transfer through a concrete hollow block wall in steady-state and the comparison with experimental results. Ener-Habitat is proved to be a reliable tool. (C) 2015 Elsevier Ltd. All rights reserved.