Factors such as the building's thermal characteristics, use of renewable energy sources, building automation and control systems, ventilation, cooling and energy recovery are considered when assessing building performance. This methodology aims to reflect the operating conditions of the building and use the measured energy data to calibrate theoretical models. The energy performance of a building is represented by a numerical indicator of primary energy consumption per unit area per year, in kWh/(m2a), used for energy performance certification and verification of compliance with minimum requirements. Additional indicators such as final energy consumption and energy demand are also taken into account. Member States are therefore obliged to update national calculation methodologies, in accordance with European standards, ensuring transparency, replicability and the possibility of comparing buildings located in different national contexts.

Pybuildingenergy aimed at assessing the energy and comfort performance of buildings, based on ISO 52016-1:2017: energy requirements for heating and cooling, indoor temperature, heating and cooling sensible load, and supply air conditions for humidification and dehumidificationThe calculation is applicable to both residential and non-residential buildings and can be used at various stages of building development, from design to use. ISO 52016-1:2017 also provides guidelines for the evaluation of thermal zones within a building, whether new or existing.