I would like to express my thanks and gratitude to Allah, the Most Beneficent, the Most Merciful whom granted my the ability and willing to start and complete this thesis. I pray to his greatness to inspire me the right path to his content and to enable me to continuo the work started in this thesis to the benefits of my country.

The work carried out in this thesis has the support and assistance advice of many people to whom I am grateful:

• My supervisor Prof. Phillip Jones who gave my a lot of his time, advice, support and encouragement throughout the time it took me to achieve this work.

•  Mr. Don K Alexander and Mr. Simon Lannon for their support and advice during the work with HTB2 computer simulation;

• Mr. Huw Jenkins for his assistance and advice in the wind tunnel experiment;

•  Mr. Nigel Vaughan for his support and advice in the analysis of the questionnaire survey and encouragement throughout this work;

•  Dr. Peter Lewis and Dr. Mike Fedeski for their advice and support;

•  Mr. Dave Bull chief technician and facilities manager for his assistance in the field work experiments;

•  My colleagues Dr. Egal Al-Jofi and Dr. Thamar Al-Rugaib for their support, advice, encouragement and inspiration;

•  The High Commission for the Development of the City of Riyadh, Eng. Salah Al-Homod, and The Department of Monuments and Museums, Mr. Fahad Al-Hawas  for their valid support in the field work experiments and allowing me to gain access to the site to perform the experimental work;

•  Finally to my family: my wife and three children, Shahad, Abdul Rahman and Wid for their prayers and moral support.