Natural lighting is a fundamental element in the habitability of dwellings. However, it is
still difficult to calculate its effect on the façades of the buildings in detail, due to the morphological
complexity of the property itself, as well as the environment that surrounds it. This study provides
a methodological proposal that uses pre-existing open data to extrude buildings by using a GIS
procedure. Based on three selected real estate properties with different characteristics in the city of
Marbella (Spain), the hours of sunlight received by each building’s façade are calculated, taking into
account the digital land model and the digital surface model of the area. The results confirm the
usefulness of the method to measure and analyze differences in luminosity between buildings with
similar urban characteristics and their surroundings, as well as to record the differences in luminosity
between floors and the orientations of the same building at several heights. The methodological
proposal opens a path for many applications related to energy efficiency, housing conditions, and
property valuation.