The SmartBuilt4EU project has set up four task forces investigating issues related to smart buildings: their objective is to identify the remaining challenges and barriers to smart building deployment, and the associated research and innovation gaps that should be addressed in the near future. Task force 1 investigates how the interactions between any smart building and its users can be facilitated and improved, as a key success factor for the market uptake of smart building solutions. The topic investigated in year 2022 addressed Responsive end-user. Occupant behaviour has proven to significantly impact the energy consumption and indoor environment of buildings. The uncertainty caused by occupant behaviour accounts for a significant discrepancy between predicted and actual energy consumption, which can often reach 30%. Numerous smart building solutions have been developed with the aim of, among others, maintaining environmental indoor quality and reducing energy consumption. But comfort perception and building energy efficiency can be conflicting objectives: managing at best the related trade-offs and moving towards more energy-aware behaviours will require more interactions between occupants and the building. This will help both gather the necessary real-time data on user behaviours and building parameters and propose usable information and services to the end users towards more sustainable patterns. This white paper, therefore, aims to provide an overview of what is known and what should be further investigated to answer the following questions: What are the occupants’ expectations in terms of interaction with the building? What type of information are they interested in, through which medium, and to what end? What type of smart building functionalities can lead to actual occupants’ behaviour change? How to tackle trust issues related to data privacy and usage? In its first part, the paper proposes a brief literature review on the current state of the art to set a theoretical background and reviews the findings and ongoing developments of some key R&D projects, specific attention being paid to EC-funded projects. A brainstorming process enabled to identify some key barriers and drivers regarding responsive end-user. Based on the State of the Art and the barriers and drivers, a number of research and innovation gaps were identified including: R&D, Demo, regulation & legal framework, certification & standardisation and scaling up & industrialisation. The gaps will feed the elaboration of the Strategic Research and Innovation Agenda on smart building, together with some recommendations targeting policy makers.