Recently, innovative and responsive technologies applied to building envelopes have drawn the attention of researchers to reduce energy consumption and improve indoor environmental quality. The main feature of these systems is to react to external environmental stimuli and adapt themselves to improve the overall building performance. The spread of these technologies has promptly led to a wide range of very different new devices that have added a further degree of complexity in the energy efficiency field. This study is part of this research topic and proposes a comparison of four different responsive technologies applied to glazed surfaces of an office model located in three different Italian cities to compare their advantages and disadvantages in different contexts. This comparison is conducted from both technological and energy points of view on the following selected technologies: i) electrochromic windows, ii) Phase Change Material windows, iii) dynamic automated external shadings, and iv) windows with variable thermal transmittance. The first part of this study focuses on the technology comparison – with reference to users’ control, building integration, cost, and maintenance – to highlight the main strengths and disadvantages of these systems. Hence, starting from an office reference model located in Brindisi, Rome, and Milan, dynamic energy analyses are conducted in EnergyPlus to compare the responsive systems with reference static envelopes obtaining as the final output the savings comparison between different technologies, exposures, and climates.