climatic exterior walls in residential buildings of yazd

this paper deals with evaluating the thermal behavior of exterior walls in dwellings of a particular place. today, there is a huge increase in constructing multi-storey apartment buildings and single-family houses in the city of yazd, a city with hot dry climate and a rich historical architecture in iran. unfortunately, the new methods that are used nowadays to make the envelopes of these dwellings are not suitable for the climate of the city, so they are not sustainable. the aim of this study is to evaluate the thermal properties of all types of applicable walls and recommend suitable exterior walls that are constructed of common materials in the region to improve comfort and energy conservation. the procedure of the research includes two parts: at first the climatic characteristics of yazd is studied. at the second part, to define the most suitable wall, effective thermal properties of the walls are calculated in none steady-state conditions. these properties are calculated for the walls with different types and thicknesses of common material layers in various positions. at last, a comprehensive compare between thermal properties of the different walls is done and sustainable envelopes ─exterior walls that are suitable for both cold and hot seasons in yazd─ are defined. in the result section, the types, thicknesses, and positions of the layers of the recommended walls in four directions of acceptable building orientation (that is +15 degree towards east-south) are defined, and the needed amount of mass and insulation as well as their relative positions is discussed. furthermore, sun porch as a suitable passive heating system for cold seasons is suggested in some directions.