The energy consumed in the building is the energy at the end of the chain of changes and energy losses carried out during a number of processes, starting with the conversion of chemical energy (primary) fuels for various types of final energy which are electricity or heat. In the case of heating, the overall efficiency is lowered by the losses in converting chemical energy into useful energy, transmission losses, losses related to improper functioning or lack of internal installation regulation systems and losses due to uneven temperature distribution in rooms and improper location of radiators.
All the above losses occur simultaneously and only heat, which is at the very end of the chain of changes and losses, is that heat, which escapes through the building's partitions and is discharged with the ventilation air. Thus, each reduction in the amount of heat consumed translates into a multiple reduction in the amount of fuel consumed. Ways of energy consumption in a single-family building can be divided into four main groups:
• eksploatację urządzeń gospodarstwa domowego (Household appliances, cooking),
• oświetlenie,
• ogrzewanie,
• przygotowanie cieplej wody użytkowej (c. w. u.).
Factors causing energy consumption, and therefore space heating, preparation of hot utility water, lighting and powering household appliances are becoming more and more of equal importance. As a result of a reduction in specific energy consumption for heating, the importance of other elements of energy consumption is growing. Reducing the total energy consumption of a passive house to 30 kWh / m2 per year, against the assumption that the cost of building a house is reasonable, is a very difficult challenge. It is necessary to implement pilot facilities, experiments and their monitoring.