## 1 Introduction  
Passive solar facades with their primary modes of operation (Figure 1), namely, exhaust [1, 2, 3], supply [4, 5, 6, 7], indoor air curtain [8, 9, 10], and outdoor air curtain, have proven their ability to contribute toward improving the thermal efficiency of buildings when they are integrated into their envelope (Table 1). Supply-air facades are low-tech devices that can recuperate a part of the heat losses from the inside and capture solar gains to primarily heat the fresh air blown inside, thus reducing the heating load of buildings during the heating season. The studied systems can be classified into different groups according to several criteria: transparent or opaque facades, mechanically or naturally ventilated facades, facades with one or two layers of airflow, and facades with or without thermal storage. Supply-air windows are a variation of multiple-pane windows in which air is drawn in from the outside and heated within the cavity by convection, conduction, and radiation [11]. [PERSON] et al. [4] studied experimentally the thermal performance of a naturally ventilated double window with one airflow layer during the heating season. This study was carried out in a test cell in a mountainous region in central Portugal exposed to real outdoor weather conditions. It was discovered that such window systems act as efficient heat exchangers using transmission heat losses and solar radiation to preheat the ventilated air, thereby reducing domestic energy consumption. A triple-gla(Paziaud window) was investigated numerically by [PERSON] et al. [5]. Laminar forced convection was considered for the airflow in the air gaps. The authors developed models which can be implemented in building simulation codes by referring to the results obtained with the CFD code. The energy efficiency of this system was demonstrated by the calculated performance indicators. Similar research was reported by [PERSON] et al. [6]. The authors evaluated the energy performance of an airflow window via a numerical simulation and an experimental test. The air supply preheating was found to be significant, ranging from approximately 10-20 \({}^{\circ}\)C without solar radiation and during sunny periods, respectively. [PERSON] et al. [7] presented an airflow window equipped with heated glazing. The results indicated that heated air-circulation windows help reduce heating energy consumption compared to traditional double-glazed windows. Heated airflow windows can replace the conventional electric heating solutions. Another type of these envelopes is the double-skin facade (DSF). Two layers of glass and an air cavity between them (that can be equipped with Venetian blinds) constitute the DSF [16]. The DSF studied by [PERSON] et al. [17] was made up of a single outer glass layer, an air channel, and an inner layer comprising two zones: a double-glazed area at the top and an insulated panel at the base. The behavior of the ventilated facade was studied over one year under Mediterranean climatic conditions. As a result, it was proven that a well-designed facade can reduce indoor gains in summer and use enthalpy gains to reduce energy consumption in winter. From the perspective of energy demand for cooling and heating, a numerical and experimental analysis of naturally ventilated DSF with Venetian blinds showed good application in the Yangtze River area in China [16]. [PERSON] et al. [18] evaluated a double-skin facade with a thermal mass. Three different configurations were proposed: replacement of the aluminum shading device between the two panes, and replacement of the interior or the exterior pane of the classic DSF by a concrete thermal mass. The results indicated that this concept of mechanically ventilated DSF can, based on the configuration, save from 21% to 26% of energy in summer and from 41% to 59% in winter compared to conventional DSFs without a thermal mass. Figure 1: Solar facade types (inspired by [12; 13; 14; 15]). [PERSON] et al.