Daylighting Performance in Hospital Patient Rooms: Effects of Orientation and Evaluation of an Internal Light-Shelf Using DIALux Evo
DOI:
https://doi.org/10.15377/2409-9821.2026.13.11Keywords:
Daylighting, Internal light shelf, Building orientation, Lighting performance, Hospital patient rooms, Combined daylight–artificial lightingAbstract
Daylighting performance in hospital patient rooms is strongly influenced by façade orientation, seasonal conditions, and spatial light distribution, requiring orientation-sensitive assessment of daylight-control strategies. This study evaluates daylight-only and combined daylight–artificial lighting performance in comparable north- and south-facing single-patient rooms at Fırat University Hospital, Türkiye, and investigates the effect of a fixed internal light shelf. The novelty of the study lies in evaluating the same light-shelf configuration across contrasting room orientations and examining not only its effect on daylight availability and spatial uniformity but also its influence on artificial-lighting requirements under combined lighting conditions. Simulations were conducted using DIALux Evo 13 for 21 June and 21 December under clear and overcast skies at 09:00, 12:00, and 18:00. Performance was assessed using illuminance and uniformity at the work plane and visual task area, together with daylight factor and luminaire operation. The north-facing room was primarily daylight-limited, whereas the south-facing room received substantially higher but more spatially variable daylight. The investigated light shelf did not increase overall daylight availability. Under daylight-only conditions, mean work-plane illuminance decreased by 22.1% and 21.7% in the north- and south-facing rooms, respectively, while daylight factor decreased by 29.9% and 28.1%. Under combined conditions, artificial lighting partially compensated for these reductions, while mean work-plane uniformity improved by ΔU₀ = +0.015 in the north-facing room and +0.065 in the south-facing room. However, the shelf did not provide a systematic reduction in luminaire use. Overall, the investigated shelf functioned primarily as a daylight-modulation element rather than a daylight-enhancement strategy, with its practical effectiveness dependent on orientation, baseline daylight availability, and interaction with artificial lighting.
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