COMPARATIVE STUDY OF THE OPTICAL PROPERTIES EFFECT OF THE FACADE EXTERIOR COATING ON THE BUILDING ENERGY DEMAND

Abstract

There are different technologies to optimize the use of solar energy in construction systems, with the aim of improving the building energy efficiency and also to reduce the effect of solar radiation on the exterior coatings, which in turn affects the urban areas warming. Among these technologies, chromogenic devices based on materials whose optical properties can be reversibly modified by some external stimulus have become relevant. These materials are especially interesting because they adapt to variations of solar radiation during the day and throughout the different seasons of the year. The facade coating may have different types of texture or color, which determine specific optical properties. One of these properties is the absorptance, which determines the amount of solar radiation absorbed by the material with respect to the incident radiation. The effect of the absorptance on the building energy demand will be conditioned by other parameters that also influence it, such as the climatic zone, orientation and thermal properties of the wall. In the work presented, the influence of the optical properties of three types of exterior facade coating on the building energy demand is analyzed. The materials chosen for this study are a conventional white Portland cement, a belitic cement synthesized in the laboratory by a process of low energy and low CO2 emissions and a brick representative of a brickwork wall, presenting the first two a more polished finish and clearer colors than the second. The final objective of this study is to determine the parameters that optimize the utilization of the optical properties of the studied coatings in the building energy efficiency.