Within this thesis, an integral model of the impact assessment of household heterogeneity on the implementation of measures and energy efficiency policies and energy consumption has been developed. This implies that it is a comprehensive model that combines the relationship between socio-economic characteristics of households and their behavior, and household energy consumption. The objective of such a model is to quantify and properly understand the interaction between the energy efficiency policy and end-user behavior and the effects of that relationship on energy consumption. The methodology described within this thesis, i.e. the process of modeling the energy consumption in the household sector includes the determination of the reference parameters of energy consumption in households, the description of the decision making process and the definition of the impact of the household energy consumption characteristics. The decision process is described with two models: logistic regression and discrete choice model. The developed model was used in case study analysis for Croatia. The thesis concludes by analyzing the results and discussing the repercussions that the results have on creating new energy efficiency policies. The results show a strong dependence on the probability of a decision that the energy efficiency measures are implemented, on the possible savings that this measure achieves at the expense of the measure itself or the time of the investment return. At the same time, households belonging to lower income classes show different patterns of decision making and the use of energy from households belonging to higher income classes. This is reflected in the diversity of energy consumption in these households as well as on various decisions when investing in energy efficiency measures. Such outcomes point to the importance of taking into account the heterogeneity of the household sector when modeling and analyzing energy consumption. The described approach can be used for improved energy consumption analysis and evaluation of the energy efficiency measurements on energy consumption in the future. Also, the approach described can be used to estimate the cost efficiency of an energy efficiency program and correct existing ones, giving the answer to the question of what is the minimum amount of subsidy needed to make households think this investment is desirable, that is, the smallest budget needed for subsidies so that the body or institution which the program leads, achieved the desired effect in terms of total energy savings. Applied approach is interesting and useful for public bodies and institutions as well as for businesses that have an interest or obligation to encourage energy efficiency measures in households. In order for both sectors to maximize the cost-effectiveness of allocation of their budget funds with the achievement of the energy consumption targets, and the proposed model just makes this possible.