Cost–benefit analysis of retrofit of high-intensity discharge factory lighting with energy-saving alternatives
Due to increased concern about overall energy costs and the appearance of efficient and inexpensive lighting system alternatives, factories and plants with high-intensity discharge (HID) lighting are forced to consider retrofit with more modern, energy-efficient lighting. The decision is complicated from an economic perspective, and there is a lack of information readily available on the topic. This study provides an analysis of the replacement by retrofit of common probe-start metal halide and high-pressure sodium industrial lighting systems. Retrofit options considered include the more recent pulse-start metal halide lamps and a range of T5 high output and T8 fluorescent lamp configurations. Recent data on lighting system pricing, labor and energy costs, and time required for tasks are reported. The results generated include savings, payback period, and net present value for many retrofit options, as well as the change in energy consumption, carbon footprint, and lumen output for each retrofit. Effects of varying rate of return and daily duration of operation are considered. Based on change in lumen output, payback period, net present value, and comparison of lighting quality, one or two options are recommended from the overall retrofit options considered. A fluorescent retrofit is recommended for each of the HID initial scenarios considered. The payback period is no more than 3 years in any recommended case. The focus of this study is on the potential energy and cost savings, and some proposed solutions may, or may not, be acceptable due to lack of illuminance uniformity.
Improving energy efficiency in lower quality commercial buildings: Simulation, retrofit optimisation and uncertainty
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Computer simulation of asymmetric arc lamp volume emitters
Various simulations of volume-based sources are explored, beginning with an overview of optical design software, the industry that utilizes it, and a procedural outline for source simulation. These simulations are explained from the simplest to most complex methodologies to date. Two basic approximations of the volume-emitter, (1) a tubular surface distribution and (2) a cylindrical volume distribution, that cannot model the asymmetry of the original emitting-volume are considered. Simulation methodologies that rely on mathematical tools are investigated. Using a CCD image of the emission and the inverse Abel transform, a 2D irradiance distribution is transformed into a 3D emitting volume. An algorithm developed to handle asymmetric volume-emitters is discussed, and the results of the simulated arc are compared to its original CCD image. In addition, the geometry of the arc source is modeled into a CAD (Computer Aided Design) program, and optical properties are assigned to its components in the optical/illumination design program. Using the most detailed emitter simulation, an assessment of the source geometry's influence on system output is made. The need for a detailed volume-emitter simulation is demonstrated through system output comparison between those utilizing the most complicated simulation and those using basic surface and volume approximations of the actual emitting-volume.