Abstract
The decarbonization of the built environment has placed the building sector at the center of climate-mitigation efforts. With almost one-third of global greenhouse-gas emissions originating from buildings, improving the energy performance of the envelope, especially of transparent façade components, is one of the most effective strategies to reduce operational energy demand. In recent decades, façade technologies have evolved from simple glazed assemblies to multi-layer, adaptive systems combining advanced glazing, ventilated cavities, shading devices, and automated controls. These innovations have increased both the performance potential and the operational complexity of façades, making their behavior more dependent on configuration and context and their performance optimization more challenging. Consequently, both design simulations and post-construction verifications face growing uncertainty, contributing to the well-known performance gap between predicted and actual building operation. Commissioning is a quality-oriented process that ensures building systems achieve the performance targets defined during design and maintain them in operation. Although international guidelines provide general frameworks, their application to façades remains limited. In Europe, the approach is fragmented, and most procedures focus on integrity tests—such as airtightness, watertightness, or visual inspections—while the actual thermal and optical behavior of the envelope is often overlooked. As façade systems become increasingly dynamic and integrated, these traditional checks are no longer sufficient to guarantee that the intended energy and comfort performance is achieved. This study develops a methodological framework for façade commissioning and continuous commissioning, with an emphasis on the thermal performance of transparent and dynamic façade systems. The research incorporates several activities:
• Conducting interviews with façade manufacturers, designers, and consultants to validate the identified research gap and collect the perspective, the opinions and the experience from experts in the field;
• Defining performance indicators appropriate for in-situ verification and simulation analysis;
• Establishing, simulating, and experimentally validating measurement methodologies for thermal and solar-thermal indicators;
• Examining the potential of continuous commissioning for the long-term performance evaluation of the façade through data-driven assessment and monitoring in a real demo-case.
The interviews revealed a shared perception that current façade commissioning practices are limited and fragmented, with performance often assumed rather than verified. While regulations ensure basic compliance, aspects such as the real thermal behavior of façades are rarely tested on site. Interviewees agreed that more systematic and continuous verification processes are needed to ensure performance and durability over time. Building on these insights, the research defined Key Performance Indicators (KPIs) to quantify thermal and solar-thermal behavior in real conditions. For the thermal domain, U value and conductance were selected for on-site measurement of transparent components. In the solar-thermal field, to address the constraints associated with the conventional Solar Heat Gain Coefficient (SHGC), which is typically defined under steady-state conditions and perpendicular irradiation, two dynamic metrics, calculated or measured over a full clear-sky day, have been introduced - Daily Integrated SHGC (INT SHGC) and Maximum Solar Gain Ratio (MSGR), capturing time-varying irradiance, orientation, and thermal inertia. Simulation campaigns conducted on both static and dynamic façades demonstrated that these indicators accurately reflect system performance according to contextual factors and dynamic operations. This facilitates the comparison of control strategies and assists in the commissioning process for adaptive façades. The methodology for evaluating thermal conductance was adapted from ISO 9869-1, originally designed for opaque walls. The same heat flux approach was applied to transparent components, with the aim of reducing measurement time from three nights to one due to their lower thermal inertia. A simulative uncertainty and sensitivity analysis identified the boundary conditions under which reliable results can be obtained. A transient model was implemented using real weather data to further assess feasibility, showing that measurement campaigns must be carefully planned according to local climatic conditions. This work contributes to defining practical protocols for commissioning transparent elements. The final part of the research focuses on continuous commissioning, demonstrated through a long-term monitoring campaign on a multi-storey ventilated façade at the EURAC Research headquarters in Bolzano, Italy. The study defined a sensor network combining temperature, humidity, air-quality, proximity, and window-position sensors to monitor cavity ventilation, surface temperatures, indoor comfort, and user interactions as well as get feedback on the systems (i.e., window opening and shading) status. The case study provides a practical foundation for continuous façade monitoring, showing the feasibility of discreet, wireless sensor networks and highlighting the organizational challenges related to data management and interpretation. The findings converge into a coherent framework linking façade design, laboratory validation, on-site testing, and long-term operation within a continuous commissioning perspective. The proposed methodology enables consistent performance evaluation from prototype to real operation, quantification of the performance gap through measurable dynamic KPIs, and integration of sensor-based monitoring for ongoing verification. Overall, the research demonstrates that extending commissioning beyond traditional integrity checks to include thermal and solar effectiveness is essential for the next generation of high performance, user-centered façades, supporting both energy-efficiency and zero-emission goals for future buildings.