## 1 Introduction
### Heating load savings  
Reduction in heating energy consumption after the integration of the passive solar system into the building envelope.  
In this paper, we study a new configuration of a supply-air facade with a storage element used to preheat fresh air for winter ventilation. Two parallel panes of glass are placed in front of the exterior wall of a building in such a way as to form two air gaps. The exterior concrete wall serves as a thermal mass that can store thermal energy in the form of sensible heat. This configuration of the opaque parietodynamic solar facade makes it possible to lengthen the path traveled by the air. To our knowledge, this system has not been studied in the literature.  
To assess the complex airflow in the two cavities of the VSW, detailed numerical modeling that represents the heat, mass, and momentum transfer is needed. This type of numerical modelling can be obtained with the CFD tool, with which the detailed temperature and velocity distributions for each position in the cavities are calculated with a high degree of accuracy by solving the conservation equations for mass, momentum, and thermal energy when boundary conditions are properly specified [26]. This approach has proven its effectiveness in modeling the various heat transfer modes that are presented in such a system [5; 6]. It is also a more flexible and less expensive tool compared to physical experiments because it enables unlimited repeatability for remodeling and simulation [27]. We supposed that it would be reasonable to start with numerical simulations in this first phase of researching a unique and innovative solar wall since they allow for evaluating a wide range of different designs at a low cost. Hence, for this study, CFD was chosen as the investigation tool to examine the performance of the ventilated solar wall. However, an experimental validation will be carried out at a later time in order to provide significant added value to the numerical investigations.  
On the other hand, the solar wall model to be developed must assess the impact of this passive solar system on the energy behavior of a building over a long period of time while considering its interaction with the exterior and interior environments. The multizone approach is the method used by the majority of dynamic thermal simulation software programs for buildings, TRNSYS, EnergyPlus, ESP-r, and so on. This simple approach is based on the main assumption that each zone of the building, when assimilated to a node, is a homogeneous volume characterized by uniform state variables. In general, a node can represent a wall, a room, or even a set of rooms. A heat balancing process is carried out for each of the zones. Thus, the model dedicated to the energy simulation of the solar wall over a long period of time requires a relatively short calculation time.  
Thus, CFD models do not allow for the calculation of the dynamic regime over long periods of time (annually) with reasonable computing resources [28]. CFD simulation is a popular and effective method for steady-state performance analysis. Consequently, a fast and reliable numerical model that can be integrated into energy simulation tools is required for dynamic annual energy analysis.  
This paper is structured as follows. Section 2 describes the ventilated solar facade from this study. Section 3 provides detailed data about the mathematical (CFD) model of the ventilated solar wall, as well as an analysis and discussions to address the performance of the VSW under steady-state conditions. Section 4 describes the developed simplified model adapted to building simulation, and Section 5 contains the main research findings of this study.