Introduction: People in the modern developed world spend most of their time indoors. The quality of the indoor environment has a potential impact on people's health and capacity to work, which is why the quality of the space in which we spend most of our time is of significant importance. The quality of the indoor environment is also influenced by the socio-economic status of those who occupy the space within it. The impact of socio-economic status on the indoor environmental quality has been proven by researchers from several countries. Purpose: The purpose of the master's thesis is to determine how socio-economic indicators influence the indoor environmental quality, by means of a pilot study, since a research of this kind has not yet been carried out in Slovenia, and make recommendations for the improvement of the indoor environmental quality. Method of analysis: The master's thesis was based on a descriptive method of analysis. Relevant scientific and professional literature on the indoor environmental quality and the energy efficiency of buildings in relation to socio-economic indicators was reviewed as well as an online survey carried out. The obtained data were statistically analysed with the Chi-square test and compared with the results of an already existing research. In conclusion, recommendations for a better indoor environmental quality were suggested. Results: The online survey was fully completed by 714 respondents from all Slovenian regions. Included were households from rural, suburban and urban communities with different average total net household income, different degrees of education and different status of employment. The results of the online survey show that households with a better socio-economic status spend more household income for a better living comfort and consequently stay in facilities with better indoor environmental quality. A better indoor environmental quality is also detected in buildings with higher energy efficiency. Based on the results of the online survey, the socio-economic status of a household does not influence the energy efficiency of a building. The main reason for the investment in increased energy efficiency of buildings is a lower energy consumption for heating, to which respondents give priority over the indoor environmental quality. Discussion and conclusion: The results of the online survey showed that the socio-economic status of a household influences the indoor environmental quality. The most significant deviation between the results of our survey and the results of already performed researches occurred in the length of time the windows were opened and the frequency of how many times the windows were opened for at least 5 minutes. For a quality indoor environment, comprehensive measures are necessary and should be supported by the user's activities listed in the recommendations. Households need to be made aware that with small and simple measures the quality of indoor environment in which most of our time is spent can be significantly improved. This aspect is more important than the use of energy, which is, judging by the results of the survey, not the current opinion of Slovenians.