Lawrence Berkeley National Laboratory

The Spanish establishments in America were located in a vast territory between southernmost American continent and California. It can be considered as one of the greatest construction processes of planned cities in the history of the humanity. Although for more than three hundred years a great number of cities were constructed on very different territories and cultural atmosphere, all of them present common elements due to the existence of an urban pattern regulated by the Laws of the Indies. The basic urban layout consisted of a grid formed by parallel streets in whose center the main public space was located. The most representative buildings, the City Council, the church and the main market were constructed around this square in which the most important activities of the city took place. Different variations and proportions with respect to this model existed. In this paper the incidence of solar radiation in the original urban layout of eight cities has been studied using the software Ecotect. The obtained data have been classified as a function of the latitude of the cities. With this criterion, graphs have been made that allow us to compare the incidence of solar radiation in all the cities based on the orientation of the urban layout (45° intervals) and width-to-height ratio of the streets. The results allow us to establish criteria about the most advisable orientation and proportion of the streets according to the case.