Environmental Engineering Reference
In-Depth Information
daylighting system was not new. However, no previous system concepts had
focused on integrating electric lighting as a fundamental part of the system.
There were perceived to be major advantages with this approach. First, to have
a daylighting system achieve rapid acceptance in the architectural and lighting
design communities, there was a definite advantage to having the lighting
components look like and fit with other commonly used lighting components.
A fluorescent troffer design was the first implementation of a hybrid lighting
luminaire. Second, by integrating the daylight source and the electric light source
into the same fixture, it simplified the challenge of harmoniously blending the two
sources. With the use of a daylight harvesting sensor and dimmable fluorescent
ballasts, the fluorescent troffer design enabled the spatial and temporal unifor-
mity of the light from the luminaires to remain constant as sky conditions varied.
Although the design existed only on paper, the integrated nature of the HSL
system was emphasized in every promotional presentation to potential sponsors,
lighting designers, and architects (Fig. 5.8). The integration of the natural and
electric light into a lighting system that could be seamlessly introduced into
existing buildings greatly facilitated the early acceptance of the HSL concept.
Initial prototype development—When funding for an initial prototype
system was finally acquired, many system elements had to come together in a
very short period of time. The fundamental components for a system; collec-
tion optics, a tracking system, optical fiber, and a luminaire all had to be
selected and or developed in a period of a few months. For the HSL concept
tocontinue toreceiveacceptanceby the lightingcommunity, the firstprototype
system had to be developed using components that would achieve impressive
performance but could ultimately be manufactured as reasonably priced com-
modity items.
The selection of an off-the-shelf collection optic was one of the most critical
elements. To ensure maximum optical throughput, a high-quality glass
Fig. 5.8 Conceptual diagram of HSL system
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