Sustainability-Oriented Lighting Performance Assessment of Daylight and Artificial Lighting in Hospital Patient Rooms: Effects of Room Configuration, Wall Reflectance, and LED Retrofit Systems

Abstract

Lighting in hospital patient rooms supports appropriate visual conditions, patient well-being, and sustainability-oriented healthcare retrofit decisions. Although previous studies have examined daylighting or artificial-lighting systems in healthcare buildings, limited research has systematically compared practical retrofit strategies within a consistent framework while considering both illuminance quantity and spatial uniformity. This study evaluates two existing single-bed patient rooms at F & imath;rat University Hospital in Elaz & imath;& gbreve;, T & uuml;rkiye. The rooms had comparable dimensions but differed in fa & ccedil;ade orientation and window width. Three-dimensional models were developed in DIALux Evo 13, and simulations were conducted for the summer and winter solstices under clear- and overcast-sky conditions at 09:00, 12:00, and 18:00, together with an artificial-lighting-only scenario at 00:00. The scenarios included the existing lighting condition, increased wall reflectance, two LED luminaire replacement systems, and combined daylight and artificial-lighting conditions. Lighting performance was assessed using average illuminance, lighting uniformity, and daylight factor. Independent field measurements at 12 points showed close agreement with the simulations, with a mean absolute percentage error of 2.86%, an RMSE of 5.68 lx, and R2 = 0.9996. The south-facing room generally received more daylight, but higher illuminance was often accompanied by lower uniformity. Under artificial-lighting-only conditions, increasing wall reflectance raised visual-task-area illuminance by 4.2-4.9%, whereas the LED systems produced increases of 48.6-53.7% in the north-facing room and 93.8-101.2% in the south-facing room. Overall, wall-reflectance modification provided a moderate improvement, whereas LED replacement produced greater improvements in illuminance and spatial uniformity. The findings provide preliminary, context-specific guidance for sustainability-oriented hospital patient-room retrofit projects.