Over the last few years, new materials have been developed which a priori, appear to improve passive energy efficiency in buildings. This article focuses on chromogenic devices that allow changing their optical properties in a reversible manner through some external stimulus. The covering of the envelopes may have different textures or colors, which determine the amount of solar radiation absorbed by the material compared to the incident radiation. In buildings with a high percentage of roof relative to façade, the surface finish plays an interesting role in the energy demand. In the present work, the influence of the application of thermochromic materials to the roofs of commercial buildings is analyzed. It has been demonstrated that the application of a thermochromic surface finish can produce savings of annual energy demand between 1% and 12% in kilowatt-hours and kilograms of CO₂ and they become more significant for construction solutions with higher transmittances values. Then, the impact of applying a thermochromic finish per day is analyzed and which transition temperature range will be the most optimal to the highest energy performance is discussed. At the same time, an assessment is made of the optimal cost; although economic investment is not currently amortized, it is a good resource for reducing energy demand in buildings.

An immediate paradigm shift is needed to transform the deep renovation market for improved building performance and expanded energy efficiency horizons. The financial, social, and sustainability challenges of the EU targets suggest research towards reliable, inter-compatible, and interoperable solutions aiming at combining different energy conservation measures. This work proposes the implementation of a lightweight Plug-and-Play (PnP) building system for façade renovation using a set-based design approach. The PnP module, based on a main structure in the form of a Light Steel Frame (LSF) and a metal-faced sandwich panel, is combined with various market-ready components. The efficient integration of these third-party products is highlighted by defining and demonstrating the design process, implementing a solution driven by the reach of a highly industrialised solution, easy to assemble and install, customizable, scalable, and adaptable to the existing buildings. With the set-based design matrix, different integration scenarios are investigated through virtual prototypes. Moreover, to facilitate the shift from design to construction of the integrated PnP module, the study proposes three prototyping levels to demonstrate the efficiency of the design integration methodology and the technical feasibility of both the various module's configurations and the overall module, exploring them through the realisation of preliminary, full-scale façade and actual environment-applied prototypes.

The revised Energy Performance of Buildings Directive and Energy Efficiency Directive aim to accelerate the energy transition of the European building stock; however, progress remains insufficient. Off-site construction (OSC) and industrialised systems, such as Plug-and-Play (PnP) systems, are considered pivotal towards more efficient renovation practices. In this study, a PnP facade for building renovation—developed in an H2020 EU-funded research project—has been analysed with the following objectives: (i) benchmarking and assessing the construction process with a PnP facade system through the data gathered in two renovation scenarios, and (ii) identifying advantages and limitations related to implementing the technology. Two buildings—an early adopter in Budapest and a demonstration case in Pamplona—have been selected as renovation scenarios to validate the implementation of the system, testing different levels of technological integration and prefabrication. Key findings reveal that the PnP system offers significant advantages, including streamlined installation processes and reduced on-site waste compared to a conventional ventilated façade. However, the need for high workers’ tolerance, sensitivity, and precision during installation, as well as coordination protocols, has been highlighted to ensure a smooth implementation. This research contributes to the body of research on OSC technologies for building renovation, offering practical insights towards developing more sustainable construction practices.