M. Tahbaz , ÐArchitecture of ShadowsÑ ÐLiving in Deserts: Is a sustainable urban design still possible in arid and hot regions?Ñ Ghardaïa, Algeria, 9-12 December 2006. 45 Architecture of Shadows Mansoureh Tahbaz PhD. in Architecture, Professor Assistant, School of Architecture and Urban Planning, Shahid Beheshti University, Evin, Tehran, Iran Tel: 0098 21 29902871, Fax: 0098 21 22400440, Email: m-tahbaz@cc.sbu.ac.ir Abstract Clear sky and high intensity of solar energy is one of the specifics of hot climates. Producing shadow in open areas and passages is a very effective element to cool environment and reduce temperature in such conditions. For 2/3 to 3/4 periods of a year shadow is necessary in hot climates, which is the reason of innovating manifest samples of vernacular umbrageous architecture. To following this culture and to create umbrageous new architecture these questions are propounded: 1. How is it possible to distinguish shadow need periods during a year in a specific climate? 2. How is it possible to produce shadow in hot periods without being deprived of pleasant sunshine in cold periods? Using Ðshading mask of OlgyayÑ this article will introduce a method that will help architects: to determine shadow need periods according to climatic considerations, to design sunshade for hot periods and to evaluate its efficiency in a pattern year. Keywords: Thermal Comfort in Open Area, Solar Energy, Climatic Needs Calendar, Shading Mask, Sky Dome, Sun-Path Chart, Shadow Angle Protractor 1. INTRODUCTION One of the aims of climatic architecture is to prepare thermal comfort for residents. Inside buildings, it is possible to achieve thermal comfort by using HVAC systems, even with no regards to climatic considerations. But in open areas achieving thermal comfort is completely dependent on the knowledge of climatic architecture. Also microclimate of surrounding open areas will affect the climatic conditions of buildings. Considering climate in designing open areas is a great step to achieve thermal comfort inside the buildings, energy saving and preserving the environment. In hot climates, producing shadow in open areas and passages is one of the effective ways to reduce temperature and to achieve thermal comfort. It would be desired if the shadow being produced in hot periods would not deprive pleasant sunshine in cold periods. To achieve this aim it is necessary to have enough knowledge about climate of the region, human thermal comfort conditions, and location of the sun. An example will show the necessity of this knowledge: In a conference performed in Bam Citadel in April 2006, some parts of the program were performed in open spaces. For this reason a shade was constructed in Hoseinieh yard of the citadel. The shade was settled just on the top of the sitting area. In the middle of the day the appropriate shadow was created by the shade. By moving sun to the east after 2 pm. sunshine reached the chairs and audiences had to escape to the shadow of the surrounding walls. The shade in top of the sitting area had lost its efficiency. This example shows the