Comparative analysis of technologies used in responsive building facades

Multiple factors initiated the idea of active facades in the 1960s. These factors stem from revolutionary changes in public culture, economy, technology and their impacts on architecture. The energy crisis over the decade and depletion of natural resources caused the increasing cost of fossil fuel energy as well as the growing public awareness towards crucial environmental problems such as public green/public sustainable culture and the popularity of sustainable strategic planning. On the other hand, these changes paralleled advancements in technology such as electrical control systems, computer engineering and information technology, artificial intelligence and cybernetics as well as material science. These dramatic and comprehensive changes in culture, economy, society and technology have urged architects to propose new theories of design. Cybernetic theory of architecture was one of these theories that proposed to design dynamic architecture rather than static entities. These dynamic entities in architecture and its components offer close interactions between human and environment. Buildings as one of the main consumer of fossil fuel energies with a high consumption rate of 40% per year in the United States, have been considered for sustainable strategies for energy consumption. Building envelope, as represented by relationship of interior and exterior of a building, interacts with both natural environment and building users. This interaction is responsible for more than 85% of annual heat lost in a traditional building façade. Moreover, characteristics of a traditional static façade limit energy performance in various seasonal conditions. The traditional façade limitations, which affect static façade energy performance consist of high rate of heat transmission, high rate of solar heat gain and high rate of air exchange. Furthermore, daylight and visual performance of a static façade could be improved by reducing window glare discomfort effect, decreasing high energy demand for artificial lighting, providing self-shading façade, and optimizing internal natural daylight levels. To overcome the limitations of existing traditional façades, the idea of an active façade as a systematically adapted entity has been proposed to exploit potential benefits of new technology in the design of a multifunctional and integrated façade system. An active facade can manage internal environments by modifying characteristics of a façade dynamically as well as controlling external environmental parameters. Studies have shown that these modifications can improve the performance of the active façade by 16 to 18% in comparison with the static facades. In 1962, advancement in technology enabled designers to create new responsive facades that have direct impact on performance and appearance of buildings. However, there is no clear classification about types of technology used in responsive façade designs. In this paper, the historical evolution of implemented technology in responsive façade is presented. By analyzing existing cases of facades, five main categories of implemented technology have been developed. These classifications are differentiated based on the types of sensors, actuators and control systems that are utilized. The five categories include electro-mechanical technology, information technology, advanced material technology, green technology and integrated technology. Furthermore, comparisons of these technologies and their benefits/shortcomings are discussed. Finally, an efficient integrated model is proposed, which implements positive characteristics of previous technologies. © 2017 American Society for Engineering Educatio