## 1 Introduction
### Natural Ventilation in Historic Buildings  
In vernacular architecture, the main form of cross-ventilation that is established is between the exterior of the building and the interior courtyard. The definition of a courtyard can be considered as an enclosed area surrounded completely or partly by a building's walls and is open to the sky. This topic is scarcely discussed in the literature, with some research regarding the multiple features of courtyards [25]. However, when considering the impact on the climate, one of the most valuable outcomes of courtyards is the ability to create ideal conditions for passive cooling techniques, such as natural ventilation of rooms and buildings.  
One of the cases that could benefit most from natural ventilation with courtyards is historic buildings. Preserving the thermal comfort of historic buildings presents a unique challenge [26]. While modern structures often rely on mechanical systems for heating and cooling, many historic buildings were designed and constructed without such technology. This absence of built-in climate control systems, coupled with the increasing severity of climate change, has led to a growing need for sustainable and sensitive solutions to maintain comfortable indoor temperatures. Nevertheless, installing modern mechanical systems in historic buildings poses significant challenges. The integration of such systems often requires substantial modifications that can disrupt the building's original fabric, compromising its historical integrity and architectural character. Fortunately, natural ventilation using courtyards presents a viable alternative in these instances [27]. This approach leverages the natural forces of wind and air pressure to circulate fresh air through the building, effectively cooling and ventilating interior spaces without the need for mechanical systems. This approach could take advantage of the building's own structure to ventilate it without the need for works or modifications to the structure that could endanger the integrity of the building, as well as deteriorate its historical value. To achieve this, the airflow within the structure has been the subject of extensive research [28; 29]. Among all the studies completed, some study the airflow pattern in a given courtyard through the calculation of the pressure coefficient on the neighbour walls [12], which gives an idea of its ventilation potential. On the other hand, some studies are more general and try to identify which are the main factors altering the airflow pattern in a courtyard modifying some factors as the building height or the courtyard length, the form of the roof [30] and even including vegetation [31]. In relation to the applicability of using courtyards to enhance wind driven cross-ventilation, [PERSON] compared in his work [32] the ventilation potential in two blocks of buildings with a bi-dimensional CFD simulation between rooms which were under single-sided ventilation and rooms between two courtyards, obtaining that the air renovation level of the second ones is much bigger than that of the others. Additionally, [PERSON] [33] modelled a building with a courtyard in CFD but in this case, with a 3D geometry, also calculating the airflow across a room to study the performance of cross-ventilation. In this regard, most of the studies of cross-ventilation only calculate the air inflow in terms of wind velocity across the openings without giving more results about temperature decrease or air mass flow rate. Apart from that, research usually only calculates air ventilation through CFD simulations and does not check the relationship between that and reality.  
While wind-driven ventilation may not be suitable for every historic building, it offers a promising approach for many, particularly those with courtyards. By carefully considering the building's design and local climate conditions, architects and engineers can create effective natural ventilation systems that enhance thermal comfort, preserve cultural heritage, and contribute to a more sustainable future.