Development of Visualization System of Spatial Illuminance.

Kotani, Tomoko; Tashima, Hideki; Shikakura, Tomoaki; Takahashi, Sadao

doi:10.2150/jlve.21.2_28

Cited by 2 publications

(2 citation statements)

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“…For balancing the consuming time of calculation and accuracy of results, methods to determine mean spherical illuminance from cubic illuminance value were proposed. 42,43 The method using cubic illuminances (representing the positive and the negative x-, y-, z-axes) has a relatively high accuracy, 44 so it was adopted in this study. The mean spherical irradiance of the shortwave portion ( E sw ) at one point can be calculated with the Equation (13):…”

Section: Methodsmentioning

confidence: 99%

Simulating invisible light: a model for exploring radiant cooling’s impact on the human body using ray tracing

et al. 2022

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Radiant systems are an energy-efficient method for providing cooling to building occupants through active surfaces. To assess the impact of the radiant environment on occupants in space, we develop a ray-tracing simulation, which accounts for longwave radiation. Thermal radiation shares many characteristics with visible light, and thus is highly dependent on surface geometry. Much research effort has been dedicated to characterizing the behavior of visible light in the built environment and its impact on the human experience of space. However, longwave infrared radiation’s effect on the human perception of heat is still not well characterized or understood within the design community. In order to make the embodied effect of radiant surfaces’ geometry and configuration legible, we have developed a Mean Radiant Temperature (MRT) simulation method, which is based on a ray-tracing technique. It accounts for the detailed geometry of the human body and its surrounding environment. We use a case study of a pavilion built with an envelope consisting of active cooling panels in Singapore. Using measured data for the surrounding surface temperatures in the pavilion, we explore the impact of both the active panels and the surrounding passive elements and thermal environment on a person’s radiant heat exchange in different postures. The reflectivity and emissivity values of different surfaces are taken into account, and the ray-tracing process allows for multiple-bounce simulation. The model accounts for both longwave and shortwave radiation, and the simulation results are compared with field measurements for validation. The results are expressed both numerically and as spatial radiant-heat-maps. These show a variation of up to 11°C in MRT across the space studied. Furthermore, a digital manikin is used to assess the impact of the radiant cooling panels across the human body. The results show a 10°C variation in radiant temperature perceived by different regions of the body in one position. The findings reveal a significant heterogeneity of radiant heat transfer that current analysis methods typically overlook for both architectural space and the geometry of the human body.

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Section: Methodsmentioning

confidence: 99%

Simulating invisible light: a model for exploring radiant cooling’s impact on the human body using ray tracing

et al. 2022

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“…For the fluence rate calculation, we adopted a method parallel to that of calculating spherical illuminance. We derived the spherical illuminance from cubic illuminance, as it maintains high accuracy but is efficient on computational time 31–33 . The fluence rate,

E_{0}

, can thus be derived from the spherical illuminance at any one point defined by Equations 1–3 31 :

false| bold-italicE false| = \sqrt{E_{false(x false)}^{2} + E_{false(y false)}^{2} + E_{false(z false)}^{2}}

\sim E = \frac{\sim E_{(x)} + \sim E_{(y)} + \sim E_{(z)}}{3}

E_{0} = 4 \sim E + false| bold-italicE false|

where E ( x ), E ( y ), E ( z ) respectively, denote the irradiation vector components measured at the three principal axes, | E | is the irradiation vector magnitude, and ~ E is the symmetric components on the three axes.…”

Section: Methodsmentioning

confidence: 99%

Spatial analysis of the impact of UVGI technology in occupied rooms using ray‐tracing simulation

2021

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The use of Ultraviolet Germicidal Irradiation (UVGI) devices in the upper zones of occupied buildings has gained increased attention as one of the most effective mitigation technologies for the transmission of COVID‐19. To ensure safe and effective use of upper‐room UVGI, it is necessary to devise a simulation technique that enables engineers, designers, and users to explore the impact of different design and operational parameters. We have developed a simulation technique for calculating UV‐C fluence rate within the volume of the upper zone and planar irradiance in the lower occupied zone. Our method is based on established ray‐tracing light simulation methods adapted to the UV‐C wavelength range. We have included a case study of a typical hospital patient room. In it, we explored the impact of several design parameters: ceiling height, device location, room configuration, proportions, and surface materials. We present a spatially mapped parametric study of the UV‐C irradiance distribution in three dimensions. We found that the ceiling height and mounting height of the UVGI fixtures combined can cause the largest variation (up to 22%) in upper zone fluence rate. One of the most important findings of this study is that it is crucial to consider interreflections in the room. This is because surface reflectance is the design parameter with the largest impact on the occupant exposure in the lower zone: Applying materials with high reflectance ratio in the upper portion of the room has the highest negative impact (over 700% variation) on increasing hot spots that may receive over 6 mJ/cm2 UV dose in the lower occupied zone.

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Development of Visualization System of Spatial Illuminance.

Cited by 2 publications

References 0 publications

Simulating invisible light: a model for exploring radiant cooling’s impact on the human body using ray tracing

Simulating invisible light: a model for exploring radiant cooling’s impact on the human body using ray tracing

Spatial analysis of the impact of UVGI technology in occupied rooms using ray‐tracing simulation

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