Incorporation of therapeutic effect of daylight in the architectural design of in-patient rooms to reduce patient length of stay (LoS) in hospitals

The biological need for lighting by an individual differs from the merely visual purpose, such as viewing objects and doing work or movement. Lack of adequate daylight for biological stimulation can lead to health problems, for e.g. imbalanced circadian rhythm. The importance of daylight is vital for hospital patients who are mostly physically and/or psychologically stressed. As, many patients stay indoors for 24 hours, they might be vulnerable to the lack of daylight which is necessary for health reasons. Hence, for hospital patients, daylight can be a strong therapeutic environmental design element to ensure good health and accelerate clinical recovery. The complex relationship between daylight environment and individuals responses are not fully understood. Controversy results that are debated by the previous researchers, has made the implementation of daylighting strategies in the architectural design of hospital in-patient rooms critical, mainly for therapeutic purpose. Strong evidence needs to be established that can build confidence to both architects and policy makers to use daylight for therapeutic purpose and integration of therapeutic effect of daylight to in-patient room architecture is necessary as well. This thesis provides information to architects (with examples) for incorporation of therapeutic effect of daylight in the design of in-patient rooms to reduce patient length of stay (LoS) in hospitals. A triangulation research method was applied in this work, where theories were developed qualitatively and tested quantitatively. Literature review was carried out to establish the potential effect of daylight on patient health. Retrospective field investigations were conducted to establish the quantitative relationship between daylight intensity and patient LoS inside in-patient rooms by developing Multiple Linear Regression (MLR) models under a general hospital environment. Using the daylighting goal to enhance therapeutic benefit for hospital patients, referred from literature and verified from field investigation data, a daylight design concept (sky window configurations) was developed and evaluated by prospective simulation study, and found better compared to traditional standard hospital window configurations, in order to enhance therapeutic benefit for hospital patients. A dynamic annual Climate-Based Daylight Modelling (CBDM) method that uses RADIANCE (backward) raytracer combined with a daylight coefficient approach considering Perez all weather sky luminance model (i.e. DAYSIM), was used for simulation analysis. This thesis develops strategies for architects to incorporate therapeutic effect of daylight in the architectural design of hospital in-patient rooms, including guidelines to support architectural decisions in case of conflicting situations, and to identify the range of daylight intensities within which patient LoS is expected to be reduced. The strategies also consider the ultraviolet radiation (UVR) protections and discuss the challenges of climate change for daylight researchers for the incorporation of therapeutic effect of daylight in the design of hospital in-patient rooms. The thesis provides a contribution to knowledge by establishing strong evidence of quantitative relationship between daylight and LoS, and by presenting new architectural forms for hospital in-patient room design as one of the possible ways to incorporate therapeutic effect of daylight in the design of hospital in-patient rooms effectively. It is expected that the research will encourage and help architects and policy makers to incorporate therapeutic effect of daylight in the design of hospital in-patient rooms, efficiently.