There are basically two types of energy performance certificates, which differ in terms of their informative value. The consumption certificate is based on the energy consumption values for heating and water from the billing periods of the last three years and is therefore strongly influenced by individual user behavior. The demand certificate, on the other hand, is based on a technical report that evaluates the condition of the building fabric, windows, and building services and calculates a theoretical energy requirement.
You can conveniently order an energy performance certificate (both demand and consumption) yourself on my website under Services.