Criteria and structure of a harmonised data collection for NZEBs retrofit buildings in Europe

The improvement of building stock energy performance is one of the main challenges that Europe is facing. European policies are focused on reducing energy consumption in buildings to achieve the EU 2020 and 2030 goals. One of the greatest opportunities to decrease energy consumption and increase renewable production is represented by nearly zero energy buildings (NZEBs). The European Energy Efficiency Platform (E3P) is an instrument to promote energy efficiency consisting of an online platform to collect and share data and knowledge on energy efficiency topics at EU level. The importance of this tool is in the provision of a harmonised NZEBs database at EU level that can furnish a comprehensive reference guideline about NZEBs retrofit. The database collects retrofit projects implemented in both residential and non-residential buildings. The aim is to record NZEBs projects in Member States and provide an overview of the European status on retrofit buildings. This paper describes the structure of the different sections of the database as well the criteria chosen to implement the data collection at EU level. After an overview of EU energy policies and NZEBs retrofit definitions, a comparison with other available databases is given highlighting pro and cons of alternative data sets mainly characterised by a different focus and level of detail. The paper includes NZEB refurbishment case studies with variable building typologies, measures and climatic conditions, which have a relevant impact on construction technologies and energy needs. The connection with and evolution from the previous data collection tool on Green Buildings towards NZEBs retrofit is also summarised. This database will provide a useful vademecum for stakeholders, researchers, policymakers, designers and building industries that can be inspired from best cases and good practices. The data collected support good practices and information on building energy performance, interventions, savings and costs.This dataset represents a user-friendly open accessible tool to tackle the NZEBs retrofit progress in Member States.