This document discusses data models for energy efficiency projects. It explains that data models are like recipes that specify ingredients and how to present them. It provides examples of ingredients like buildings data, cadastral data, and energy resources that are relevant to energy efficiency. The document also discusses standards like INSPIRE that can be used to structure this data and notes open data sources that can provide some of these ingredients. However, it acknowledges that current data coverage is incomplete and that harmonizing various data sources is needed to fully understand energy usage and effectively target efficiency projects.