Energy-efficient building retrofits must be approached from three perspectives: law regulation approach, financial incentives approach, and practice approach. The concepts of zero energy building and life cycle energy building are presented as the basis for energy retrofits. Multi-criteria boards to assess the decision-making process are reviewed, analysed, and categorised under an architectonic perspective. Some examples are presented, with different packages of measures, from deep to non-invasive energy retrofits. Passive and active energy generation systems, together with control and management strategies, are the physical elements identified with the potential to improve buildings’ energy efficiency. From a practice approach, this literature review identifies the concept of performance-based architectural design to optimise the planning and design of buildings’ energy retrofits. In addition, tools such as Building Information Modelling are described as part of optimisation processes, as they enable designers to rapidly analyse and simulate a building’s performance at the design stage.