## 5 Discussion and Applicability of Results  
The European project of conditioning open spaces to recover life in the street UIA03-301-CartujaQanat of Urban Innovative Action (UIA) has generated the need to develop new techniques for conditioning open spaces in order to characterise them. One of the techniques is the heating/cooling of surfaces without the consumption of water. For that, the studied solution has been designed, tested, and characterised. Results of this study have allowed for the integration of this solution in a new open space, the project's pilot. The second stage studies the integration of the solutions studied in an open space. This space is a semi-buried open space of 750 m\({}^{2}\) (see Figure 18). The climatic control solution of this space will be used as natural technique to produce cold and hot water for intensive use in the summer and winter. Nevertheless, summer weather conditions are extreme in Seville (the hottest zone in Spain), so the space is sized to achieve thermal comfort in cooling conditions. Likewise, the systems of the pilot, even the solution, can operate in heating mode, but there will be few hours of the year in which its operation is required. The treatment proposed the generation of thermal comfort conditions and reduction of solar gains, the entry of outside air into the volume to be conditioned, and the impulsion of air, but it is impossible to achieve this without controlling the temperature of the surfaces [39]. In this aspect, the cover of the souk plays a fundamental role. The ceiling is the dominant form factor of the occupant. As it is an open space, the air near the surface will be air at an outside temperature far from the space to be conditioned. So, the convective effect of this solution is not attractive. For this reason, in the first stage of the project, it was decided to study alternatives that allow for achieving a hot or cold surface according to the needs. As a result of this work, a radiant solution adapted to the outdoors is proposed. The solution presented in this work has been modelled, tested, and characterised by building a coherent prototype. All this to achieve a high level of knowledge of the system, especially the radiant effect, to carry out the design and evaluation of the integration of the solution on the roof of said space in the second stage of the project. Currently, this project is in the execution phase. So, the real impact of the solution will be measured on-site in the future. Figure 17: Heating mode. Convective heat flux (**left**) and convective heat transfer coefficient (**right**) as a function of representative temperature difference \(LMTD_{cv}\). Figure 18: Design of climatic outdoor conditioning system by radiant surface in the open space (case of study). This space's comfort needs (summer conditions) have been obtained following the procedure described by [PERSON] et al. [40]. These can be summarised as follows: block the solar gains inside the space, achieve an air temperature lower than 29 \({}^{\circ}\)C, control relative humidity between 30% and 70%, and, above all, maintain an average radiant temperature lower than or equal to 28 \({}^{\circ}\)C. All this was calculated for conditions of 39 \({}^{\circ}\)C outside temperature, global horizontal radiation of 950 W/m\({}^{2}\), and a wind speed of 4 m/s. Now, the view factor between the occupant and the space's ceiling is greater than 50%. The rest is practically the floor and the half-buried walls. (see Figure 18). In order to guarantee an average radiant temperature of 28 \({}^{\circ}\)C, the cover must be at a temperature lower than 26 \({}^{\circ}\)C. To achieve this effect, the solution proposed in this paper should be used. In winter conditions, the comfort requirements would force the roof to maintain a temperature above 30 \({}^{\circ}\)C. As has been commented, the design of the space is done based on a summer regime.