The evaluation of HVAC performance in buildings can be a continuous process that starts in planning and design, is used in commissioning, and is continued in maintenance throughout the building's life. This can be achieved using a component-based framework in which HVAC systems are evaluated for their energy effort. Characteristic of this component-based framework is a data model that separates the building and installations from calculation components. When implemented, the data model provides a stable and consistent definition of the building and installations, and is used for the exchange of information among components. The data model is based on the latest version of the IFC object data model and extended with definitions of HVAC equipment and systems. Different calculation components can be selected in the framework; results of calculations are given as time series that can be compared with measured data. The data model and the calculation components are integrated in an application that uses a scripting language.