Occupant perception of spectral light content variations due to glazing type and internal finish

Indoor Environmental Quality (IEQ) is a key issue in the design and renovation of any indoor building environment. It is comprised of different aspects (e.g. visual, thermal, acoustic comfort, etc.), which directly affect the building occupants' wellbeing. Studies on this topic have grown rapidly in recent years, as the time that occupants spend indoors is increasing. In this regard, indoor luminous conditions are crucial for providing sufficient task illuminance as well as to stimulate the human circadian system. Insufficient lighting conditions have been proven to be related with reduced productivity/learnability, mood swings and health disorders, thus emphasizing the necessity for further research in this field. Therefore, proper performance evaluation criteria for managing and optimizing lighting spectral composition is needed. For instance, indoor lighting conditions can be evaluated by quantity, intensity, and/or uniformity, but also by spectral content, which determines the energy conveyed and the level at which the human body is stimulated. This spectral content can vary depending on the preferred or prevalent light source, interior finishes and glazing properties generating a singular indoor lighting environment. Thus, a preliminary study on the variation of the indoor daylight spectral content is conducted using a scaled model, applying various glazing types and interior finishes. Then, daylight simulations are performed on a calibrated virtual model to evaluate the effect of various environmental conditions. Results show a considerable impact of the interior finishes as well as glazing type on the attained circadian potential of studied indoor environment.