AbstractThe University of ManchesterHayder Murad KhanDoctor of Philosophy (PhD)Modelling and Thermal Optimization of Traditional Housing in a Hot Arid Area10th June 2015This thesis studies the use of night ventilation as a passive cooling strategy for a traditional courtyard house in a hot dry climate. This was done by CFD simulation of the house and its surroundings, using weather data for Baghdad. The simulation was done for a large number of scenarios in which each represented a change in one of the house elements, such as courtyard and room dimensions, and in some cases included modern technologies such as a ceiling fan. The thesis suggests that performance should be calculated with the aid of a "Night Time Effectiveness Ratio" (NTER) and time constants.The findings show that building elements can change the performance to various degrees, that the airflow patterns inside the rooms change from day to night, and that the thermal conditions during the day depend more on the intensity of solar radiation than other factors. The results show that a courtyard house can ensure the thermal comfort for its residents. However, it needs some assistance from new techniques such as fans to keep the air quality inside the house within acceptable limits.The values for NTER from initial simulations are around ten, which indicate that night ventilation is not enough for cooling the building. However, the values drop to less than one by using a small and narrow courtyard with a two-level house and a gallery around the courtyard. Also, it is necessary to have a connection between the courtyard and alleyway at ground level in the night only and to cover the courtyard during the day. The windows have the largest role in deciding the performance of night ventilation. Ideally they should be small and tall, or preferably a pair of windows separated by a vertical distance and kept closed during the day. The effects of room dimension are clearer in affecting the thermal comfort more than improving the performance of night ventilation.The research also examines the indoor air quality and suggests ways to improve it. Some of the ways are traditional like the use of a wind catcher in ventilating the courtyard and the basement, and others are more modern like using an exhaust fan. Furthermore, it suggests an algorithm to control these ways and to introduce only a limited quantity of fresh air to avoid excessive warming.Suggestions for future work are given, including tests for more elements in the courtyard house and for longer duration runs. It would also be helpful to study the use of latent heat storage (e.g. phase change material) as an additional effective thermal mass.
|Date of Award||31 Dec 2015|
- The University of Manchester
|Supervisor||Gregory Lane-Serff (Supervisor) & Jonathan Dewsbury (Supervisor)|
- Night ventilation, CFD, Passive cooling
- courtyard house, Baghdad, air quality, energy