2014 IES Street and Area Lighting Conference
September 14-17, 2014 | Nashville, TN
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Recent research in photobiology has revealed links between light and human health that are likely to have a significant effect on lighting practice. These effects should begin to be incorporated into lighting design practice and lighting recommendations.
Research attempted to link the three-dimensional light-field associated with object modeling to occupants’ subjective impressions of a space. Computer models were created for six light settings studied by Flynn. The directional nature of the light-field was quantified using an array of vector to scalar (V:S) illuminance ratios. Analysis suggests that: spaces with variation in V:S ratio are preferred to spaces that have homogeneous ratios; the combination of a lower V:S ratio coupled with low variance in the V:S ratio favors spaces that appear spacious; and impressions of clarity may be related to a combination of the V:S ratio and illuminance.
Ballast-integrated compact fluorescent lamps (BCFLs) have been used to replace incandescent lamps. Most BCFLs have electronic circuits and have been smaller and much more efficient, compared with magnetic ballasted types. Greater thermal reliability of electronic circuits is required for these new lamps. In addition, the BCFLs covered with outer globes generally have a problem of slow luminous run-up. This is strongly linked with the temperature of the amalgam. These two issues are linked from the viewpoint of heat transfer analysis. Focus here is on the heat-transfer network analysis that solves the steady-state and transient problems for BCFLs with and without outer globes. This analysis is proved to be valid for calculating the temperatures and heat flux of many kinds of BCFLs; the temperatures calculated for steady-state problems are in accord with the measured ones within less than 10 K.
An approach for numerical computation of form factor between two polygons based on dividing each polygon into triangles and subdividing each triangle into identical incremental triangles is described. The approach is applied to evaluate the double area integral of the form factor under deterministic and Monte Carlo schemes. These and other methods based on use of incremental rectangles, together with a classical Monte Carlo method, are used to obtain numerical values of form factors in four test configurations. The results of the five methods are compared and it is shown that the proposed method is simple to apply, accurate, and efficient.
For more than a decade, daylighting optical devices (DOD) using reflection, refraction and diffraction have been used in commercial buildings. Some of these systems show considerable promise for south facing facades, as they can reject or redirect sunlight and diffuse daylight. However, their daylight performance is not clearly understood. Simulation tools employing Monte Carlo forward ray tracing are now available and can used to trace rays from the source (the exterior environment) through a devise and into the building interior. Two problems remain, however. The first is the generation of a ray distribution of the exterior environment. The second problem is the representation of the resulting daylight distributions at the DOD exit surface. There would be several advantages if an exiting ray distribution could be represented as an intensity distribution in narrow angular increments in a photometric file format. We show how to generate ray representations of hemispherical luminance maps for exterior environments, introduce a method to determine intensity distributions for DODs, and discuss errors involved. Results of tests against measurements for a commercially available specular micro louver are reported.