Integration of Electrochromic Smart Windows in Building Automation Systems

Abstract: To lower energy consumption, the building industry invests in smart solutions. These solutions usually use control and automation to both increase energy efficiency and facilitate usage, and therefore attract consumers. This paper gives a better insight into how an electrochromic (EC) window, which is a relatively new smart product, should be used to further improve the intelligence of buildings. The funding company has not yet integrated the EC windows in building automation systems (BASs). A research was realized to understand the BAS technologies available so that it is possible to decide which to use. The researched technologies were LonWorks and BACnet; both are explained and discussed in this paper. The paper goes on to conclude that LonWorks is more convenient to implement. Windows provide solar power and indoor illuminance. If there is too much sunlight indoors, the room might get too warm and people may be affected by glare. Being able to automatically control these parameters improves comfort. This paper provides equations to calculate the position of the sun to be used in simulations. Simulation procedures are also provided so it is possible to calculate the indoor illuminanceas well as the temperature; the latter is then used to estimate the energy consumption and compare EC with high efficient regular windows. These simulations show that, with illuminance controlled EC windows, the energy used to regulate the temperature to 23oC is around 2:6% less than with high efficient regular windows. A control algorithm is proposed to adjust indoor illuminance by manipulating the transmittance of the EC windows. This algorithm is then implemented on the real system. Then, to be able to manually control the windows, a website is designed so anyone with access to a web-browser and a connection to the intranet (where the windows are connected) can manipulate them.