An early design tool/method for assessing the performance of complex fenestration systems

Abstract: It is common knowledge that shading systems and solar control glasses are used to avoid glare and overheating at expenses of daylight. In Dynamic Thermal Modelling tools, there is no assessment method where the shading use is expressed when predicting the building performance. Furthermore, literature often refers to studies where complex fenestration systems are optimized for specific cases. However, there is a lack of a component-based, or room-independent tool to be used in the early-design phase in common practice which fills the gap and assesses the use of shading together with the building performance. In this perspective, an innovative tool was created to provide hints on how to predict the performance of fenestration systems in real life, and help designers when choosing the glazing and shading control. As input, location information as well as hourly radiation data, and the basic window geometry are asked. Three different shading control strategies are used, namely a solar gains threshold, incident solar radiation, and a prediction on the user’s behaviour. Following, the tool assesses the solar gains and view to the outside per control strategy, and gives as an output the hourly shading use distribution and the View Quantity Index. Some important limitations that can be defined are: the simplification in the calculation of the secondary solar transmittance that is used for the solar heat gains; and the complexity of predicting the user’s behaviour, which is combined with the direct sun beam as glare factor. The study showed how this tool assesses the performance of different glazing products combined with shading control systems and strategies, to help designing a functioning façade that fills the gap between shading systems and solar control.