The measure of the energy standard of a building is an indicator called the seasonal heat demand for heating E, which determines the amount of heat related to the area or volume)’ the building needed to be heated during the year. It is expressed in kWh /(m2 • rock) or in kWh /(m3 • rock).

There are two types of E indicators:

1. Wskaźnik E0 opisuje ilość ciepła konieczną do ogrzania jednostkowej powierzchni pomieszczeń w budynku. This indicator determines the quality and energy standard of the building (external partitions).

2. Wskaźnik E5 opisuje ilość ciepła zawartego w paliwie, necessary to supply the building's heat source, a takes into account the losses resulting from the quality and correct operation of the heating system in the building.

This indicator makes it possible to evaluate the energy standard of the entire building, including the heating system.

These coefficients can be calculated on the basis of:
– thermal calculations of the building and quality assessment of the existing heating system or
– measurements of the actual energy consumption of the building.

The issues of efficient use of energy have been gaining more and more importance over the years. This trend is reflected in the changes in the requirements for thermal insulation of partitions in buildings,