Simulation-based Evaluation Of Non-visual Responses To Daylight: Proof-of-concept Study Of Healthcare Re-design

Abstract

The discovery of a novel non-rod, non-cone photoreceptor in the human eye that mediates a number of effects on the brain has sparked a growing interest in incorporating these non-visual effects of light into the design process of buildings. Appropriately-timed light exposure has the potential to stabilize and improve circadian rhythms, including sleep, and has direct stimulating effects on alertness and performance. The novel photoreceptors are more sensitive to blue light than the rods and cones used for vision, and respond differently to light intensity, duration, history and timing of a light exposure. The dynamic behavior of the non-visual system provides new challenges in evaluating lighting performance of buildings. In this proof-of-concept study, a novel model that predicts the non-visual responses to light is introduced. The model is used as a part of simulation-based framework for the evaluation of daylighting performance. The evaluation includes four different light pattern generation methods used to investigate the influence of occupants' movements and activities on simulation results. The framework is applied to the re-design of a healthcare facility. The results lead to new ideas and suggestions for future re-design.

Simulations of non-image-forming effects of light in building design: A literature review

“…The duration of light exposure was either considered statically, assuming that a fixed duration of exposure of a few hours a day (1–5 hours) is enough to stimulate the NIF system, 42,44,55 or dynamically, considering that short duration light exposures are more effective than long ones, and intermittent light patterns are more effective than continuous per minute of exposure. 32,36,38,47,58,68…”

“…Spectral information was also included by performing simulations of photometric quantities and post-processing the results based on the spectral power distribution (SPD) of the light source. 35,36,38,44,47,66,[68][69][70]73,75,[80][81][82][83]85 This method disregards that the SPD that reaches the eye is modified by the spectral properties of materials, which might be a reasonable assumption in neutrally coloured spaces. For non-neutrally coloured spaces, a simplified approach was to multiply the SPD of the light sources with the spectral reflectance of the materials and use this to post-process photometric results.…”

“…The duration of light exposure was either considered statically, assuming that a fixed duration of exposure of a few hours a day (1-5 hours) is enough to stimulate the NIF system, 42,44,55 or dynamically, considering that short duration light exposures are more effective than long ones, and intermittent light patterns are more effective than continuous per minute of exposure. 32,36,38,47,58,68 In addition, the directionality of light being projected on the retina of the eye was investigated by Khademagha et al 84 that used renderings to estimate the effect of room design parameters by applying masks corresponding to the upper and lower field of view.…”

“…D65). 44,67,68,85 Other approaches were to use standard illuminants based on the window orientation of the simulated space, 48,64,66,83 differentiating between the spectrum of the direct and diffuse contribution, 70 or between overcast and clear sky conditions. 48,69 Bellia et al 45 modelled typical average SPDs for cities located in the north, centre and south of Europe based on the percentage of overcast skies in each location (close to D50 for northern locations, close to D65 for middle locations and more blue than D65 in southern locations).…”

“…Specifically, in two publications, occupants were assumed to move randomly between selected zones. 68,83 In a paper that investigated light exposure in offices, 36 occupant behaviour profiles were defined based on their role in the office. The occupant profiles determined when and how much time a person would spend at their desk, in a meeting room, or in other spaces in the office.…”