Experimental field study of the integration of passive and evaporative cooling techniques with Mashrabiya in hot climates

Abstract

Mashrabiya is one of the primary features of Arab-Islamic architecture which can be found and still used in different cities around the world. It can be defined as an opening covered with wooden lattice for ventilation, daylight, privacy, and an aesthetic appeal for houses. The motivation for this work stems from the lack of existing field studies on the ventilation and thermal performance of buildings incorporated with Mashrabiya and the potential to enhance its capabilities by combining it with different passive cooling techniques. The present study aims to investigate the influence of Mashrabiya on the indoor environment in a traditional building situated in a hot climate. The case study selected for this work is the Baeshen House which is located in the heart of historic Jeddah and the area with the most traditional Mashrabiyas in Saudi Arabia. The field data of air temperature, relative humidity, globe temperature, and air velocity were collected for two similar rooms (one open Mashrabiya and one close) in the building during typical hot summer conditions when the outdoor temperature ranged between 40 and 41.6 °C in the afternoon. Different techniques of passive/evaporative cooling strategy were integrated with the Mashrabiya: thermal mass, water pots, water spray, and cloth. The results showed that the closed Mashrabiya contributed to reducing the flow of hot air into rooms during the afternoon, and the indoor temperature was maintained at 35.4–35.8 °C. Increasing the speed of airflow into the room by opening the Mashrabiya had a minimal effect during the afternoon, but it was observed that the night cooling improved. It was found that the most effective strategy was the use of wetted cloth near the inlet of the Mashrabiya (33.8 °C indoor average when the outdoor temperature was at 41.6 °C). The study demonstrated that comfortable conditions could be attained between 1 and 9 a.m. during hot summer conditions. Overall, the Mashrabiya with evaporative cooling was not able to provide comfort during the midday, and other strategies should be considered for hot summer conditions. Future work will focus on investigating different materials and strategies to enhance the performance of Mashrabiyas.