2014 IES Street and Area Lighting Conference
September 14-17, 2014 | Nashville, TN
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This article describes an empirically derived light loss curve and Total Light Loss Factor (LLFT) for sports lighting applications. An empirical model was developed by comparing the illuminance from initial design computations against measured illuminance, on a point-by- point basis, for 37 sport fields. The study was limited to lighting systems that employ 1500W metal halide lamps with a rated life of 3000 hours. The model demonstrates that values for LLFT of 0.75, 0.69, and 0.65 are representative of real-world sports lighting applications at 1200, 2100 and 3000 hours, respectively, and suggests an LLFT of 0.69 as part of the design calculations for new sports fields. This recommendation is markedly different from the common practice of using a LLFT of 0.80.
Demand-responsive buildings utilize control mechanisms to reduce their electricity use during periods of high grid-wide demand, primarily to aid utilities in maintaining grid stability. Dimming lighting is proposed as one such demand response mechanism, and several laboratory studies have explored the speed and extent of dimming that is either noticeable or acceptable to occupants. We conducted a field study to examine whether these laboratory findings could be applied in real buildings with commercial lighting control systems. The study, conducted during summer months, included an open-plan office with 330 dimmable luminaires, and a college campus with 2300 dimmable luminaires across several buildings. There were no lighting-related complaints to facilities management throughout the trials. Based on prior laboratory studies and this field study we suggest guidelines for dimming lighting as a demand response strategy.
Contemporary office buildings are frequently designed with curtain wall systems that inevitably allow enormous amounts of direct sunlight. This fact has several negative effects on the work environment and as a result, from an energy usage point of view, most of today’s curtain wall buildings use certain shading devices. Among many shading devices, perforated aluminum panels have often been used as an esthetic response to popular High-tech and Neo Modern style architecture, but their functional effectiveness has been not seriously examined. This study compared luminous environments in office buildings using illuminance and luminance values between several perforated panels and fabric roller shades, which are the most widely used shading devices. This study creates a new functional standard for perforated panels and demonstrates their value not only in style but also as a reliable shading device.
Tubular light guides are a novel technology that can achieve energy savings in windowless interiors in the core of buildings. Their design and evaluation posed a considerable challenge to illuminating engineers. The Hollow Light Guide Interior Illumination Method (HOLIGILM) provides analytical calculations of the illuminance distribution on an interior work plane as well as on the top of the interior tubular diffuser. This precise mathematically defined daylight transport takes into account both sun and sky luminance, tube size as well as cupola and inner diffuser transmittance and is derived from basic relations and backward ray-tracing procedures used in a computer program HOLIGILM 4.2 for quick calculations of interior illuminance distributions.