Operational building performance of Double Skin Facades (DSFs) is highly sensitive on their control strategies. Due to the complexity of their operations, model-based controls could represent an opportunity to improve further the potential energy savings and occupant comfort. The present work explores the potential and applicability of rule and model-based control strategie, implemented on a facade-embedded single-board controller. This is demonstrated by means on a virtual experiment, carried out by means of a co-simulative framework implemented on the controller itself, to replicate the real world implementation. The embedded controller has different tasks, from signal processing from low-cost sensors, to performing parametric on-line simulation to feed in the control decision making algorithm, to sending the control signal to the different DSF actuators. Two different control strategies are developed for the implementation, and their performance compared by means of co-simulation on the single board controller: a) a Rule-Based Control strategy, based on ifelse rules depending on environmental conditions; b) a Model-Based Control strategy, aims at minimising the heating and cooling loads of the environment adjacent of the DSF, while maximising the autonomous Useful Daylight Illuminance. The results show that, compared to benchmark DSF configurations and control strategies, the MBC implemented on the embedded single board controller would be able to reduce total (heating, cooling and lighting) energy use between 11% and 18%, while improving useful daylight availability by 13% without introducing potential glare risk.

The building sector contributes significantly to energy consumption and greenhouse gas emissions, with many buildings being energy inefficient. In response, the European Green Deal promotes improving energy efficiency to support decarbonization goals. However, managing energy consumption and integrating data from multiple sources presents challenges, especially for large building portfolios. This study introduces a novel methodology designed to optimize energy renovation strategies, balancing technical, financial, and maintenance considerations. The methodology is implemented in CERPlan 1.0, a web-based decision-support platform that combines data on building energy performance, renovation costs, and maintenance needs. Through simulations, CERPlan 1.0 helps decision-makers prioritize retrofit interventions based on economic criteria while leveraging synergies between energy improvements and regular maintenance. Application of this methodology to real estate portfolios reveals opportunities to enhance cost-effectiveness and energy savings. The results show that integrating maintenance into renovation planning reduces payback times and allows for more comprehensive renovation strategies. The conclusions highlight CERPlan 1.0’s potential to improve decision-making, making building renovations more efficient and sustainable.

This paper presents a study of the thermo-hygrometric behaviour of a Double Skin Façade (DSF) unit. The study aims (i) at comparing currently used calculation procedures according to European and American standards (UNI EN ISO 10077, UNI EN ISO 12631:2018, ISO 15099:2003, ANSI/NFRC 100 for the thermal performance and ISO 13788:2012 (2012) for the condensation risk), and (ii) at assessing the 2D hygrothermal performance of a double skin module through a Finite Element Method (FEM)-based model. According to the current standards, a detailed characterization of thermal and fluid dynamic phenomena in closed and ventilated cavities is neglected and a simplified approach is proposed, which tends to overestimate the overall U-value of the curtain wall (U_CW) due to an incremental thermal resistance that depends on the thickness of the air gap layer and the level of ventilation. The potential risk of this simplification is that the DSF estimated design performance, whilst complying with regulatory requirements, present inconsistencies respect to the real behaviour, impacting energy, comfort, material degradation, etc. Accurate assessments could be done already during design through detailed FEM multi-physic analyses. Nevertheless, those require a specific knowledge, are cost and time-consuming. As a first step, this study focuses on comparing the normed calculation approach for the design, against a detailed FEM-based multi-physics methodology. Specifically, this couples CFD, hygrothermal and Ray Tracing physics in a tool for the calculation of thermal transmittance, g-value and relative humidity of a DSF with a customizable geometry. As a second step, given a real DSF unit that showed unforeseen phenomena of surface condensation inside the cavity during several hours in spring and autumn, the multi-physic tool has been used to evaluate the condensation risk with the current and modified DSF design, under static and time-dependent boundary conditions.