The environmental crisis in the last 50 years has created challenging conditions for human life on earth. Consequences of mechanical and industrial life together with an ever increasing use of fossil fuels for comfort have raised serious issues in environments and resource conservation and critical disputes for the scientists. 

In architecture design, thermal comfort is one of the most important categories and providing thermal comfort for occupants of a building is one of the principal concerns in designing the living spaces. Today in our country, energy consumption level for common household appliances is relatively high compared to international standards. This High level is certainly related to different effective items and factors among which the importance of building external envelope and outer walls should not be overlooked.

This paper tries to study the effect of building external walls on transferring or wasting thermal energy through the identification and analysis of the general wall details in vernacular architecture of regions with cold climate. Accordingly, the following steps have been taken in this research:

1- The role and function of the external layer of buildings has been analyzed.

2- With a look at thermal comfort concepts, the range of thermal comfort for people in closed spaces has been studied and specified.

3. Climate and Climatic properties of the selected regions together with the relevant meteorological data have been extracted and studied. After the thorough definition of climate in these regions (which are among the cold regions in Iran) and comparing the climatic properties of such regions with range of temperature change in the thermal comfort limit, type of movement and energy transfer by building external walls has been specified. 

4. Methods of thermal energy transfer in walls, calculating process of the amount of exchanging this energy, the thermal indexes of unstable flow transfer has been studied and the required software was developed in order to reach more accuracy in calculation of thermal indexes.

5.  Specification of all common walls in the selected regions were collected including the details of walls, common local material used in buildings and properties of the outer layers.

6. Thermal indexes of buildings fabric in the selected regions were calculated and then compared with each other in relevant charts and diagrams according to their priority. 

7. With due reference to the obtained results from conducted studies and calculations, specifications and properties of common material in vernacular architecture of the region has been catagorized.

Hopefully this study can be a positive step toward better and more exact knowledge of specifications and properties of common material in vernacular building envelope in cold regions of Iran.