Since the energy consumption has become one of the crisis of modern buildings, modeling the Iranian past architecture patterns could be helpful. The shopping streets as one of the main sectors consuming energy locate near the open spaces it seems, therefore, they need more thermal comfort. However, using passive techniques, the Iranian traditional bazaars architecture solved the problems regarding thermal comfort. The present inquiry aimed at investigating thermal comfort of traditional and modern commercial buildings from the perspective of solar radiation to compare traditional structures (with traditional design and materials) with modern ones (with modern design and materials). Therefore, Vakil (traditional) and Mollasadra (modern) Bazaars (with the same orientation), located in Shiraz with a semi-arid climate, have been chosen. Vakil bazaar situated in historical context of city and Mollasadra situated in the first modern part built in 1980. A naturalistic approach was applied to investigate the relation between shadow on surfaces, shopping load and cooling needed in summer and the relation between the solar radiation on surfaces, shopping load and heating load in winter first, a number of questionnaires were used to survey 120 samples including both customers and shopkeepers to show the relation between shopping load and cooling or heating need second, Ecotect Analysis 2011 was employed to simulate surfaces with shadow and solar direct radiation in winter and summer to evaluate the relation between the surfaces received shadow and heating or cooling need. The results showed that along with a full shade in summer, the customers of Vakil Bazaar are interested to do shopping almost in all hours since there is no obtrusive solar radiation in contrast, customers of Mollasadra Street experienced a shadow from sunrise to 11:00 in summer morning thus 73.3% of customers in Mollasadra made complaints about the existing shadow since there is no shade in crowded shopping hours and points especially in summer afternoon furthermore, 93.3% of shopkeepers in Mollasadra used cooling and heating equipment which demonstrate congruently of orientation and quality in sunshades with climate. At the end, some suggestions regarding the mentioned problem in Mollasadra have been proposed.
