An energy certificate is an official document that represents the assessment of a building in terms of energy consumption and its inclusion in the energy class. It is mandatory from 1 January 2008 for family houses and apartment buildings in case of new, significantly renewed, leased and sold buildings. Their total usable area must be more than 50 m2. The obligation arises from Act No. 555/2005 and Act no. 300/2012. It is carried out according to Decree no. 364/2012. Under the law, energy certificates for sold buildings are required to be passed on to new owners. In the case of leased buildings, certified copies of energy certificates are obligatorily attached to lease agreements. In the case of large buildings owned by natural or legal persons and attended by a large number of people, it is the responsibility of the owner of the building to display the so-called Energy Label of the Building in a visible and accessible place, which is an excerpt of the energy certificate of the building.