Evaluation of the outdoor space thermal comfort in traditional mosques ofKhorasan province based on the PMV index(Case study: the Cities of Qouchan, Mashhad, Sabzevar and Tabas)

Thermal comfort has always been one of the primary goals of architectural design. Many studies have addressed indoor thermal comfort. However, less attention has been paid to outdoor thermal comfort. Outdoor spaces need to be equally emphasized because of the occurrence of daily activities in them. Open spaces play a unique role in the spatial structure of traditional Iranian architecture. Mosques are among the most important buildings in the history of Iranian architecture. With the spread of Islam in the early centuries of Hijri, many mosques were constructed in the great province of Khorasan, some of which are still standing. Most of these mosques have open spaces that are built based on the climate; therefore, they are among the best sources of modeling for contemporary architecture to achieve thermal comfort. Thus, the research questions of the present study can be expressed as follows: What is the range of thermal comfort in the open spaces of Khorasan mosques based on the PMV index? What are the optimal geometry patterns of mosque courtyards in the Khorasan region to achieve thermal comfort? In order to answer the questions, ENVI-MET4 simulation software was used.

The approach of the current study in terms of its purposes and methodology is applied research and quantitative respectively. In the first stage of the study, the form, dimensions, and proportions of the yard and the percentage of open to closed spaces of the traditional mosques of Khorasan province were analyzed through an analytical method, based on library studies. The courtyards of the traditional mosques were categorized, the patterns governing them were extracted, and thermal comfort was evaluated. Four sample cities were selected based on four different climatic zones. In the second stage, using the simulation method, the models were made on July 23rd during the summer solstice for the four cities in the ENVI-MENT 4 software. The simulation results were illustrated and analyzed in the Leonardo software, and the PMV thermal comfort index was used.

Three types of mosque courtyards in the mentioned cities were analyzed. Based on the PMV index and the comparison of plan structures, the results revealed that in Qochan City, the plan with a square geometry is close to the thermal comfort range. In Mashhad, a rectangular courtyard with an extension in the direction of the Qibla is the best option to achieve thermal comfort in open spaces. Moreover, in the city of Sabzevar, the rectangular plan perpendicular to the Qibla direction, and in the city of Tabas, the rectangular plan parallel to the Qibla direction were identified as the best models of thermal comfort.

The proportions and forms of the courtyards are square in the high foothills; rectangular in line with the Qibla in the low foothills; rectangular in the direction of the Qibla in the plains, and rectangular in the direction of the Qibla in the desert climate. Considering the joy of outdoor worship, it is necessary to design the courtyard in such a way that it can provide comfortable conditions as a subclimate, particularly during hot summer days.