“Light Fidelity” (Li-Fi) is a new technology using visible light energy from LEDs to provide ubiquitous wireless access for communications in illuminated areas. With LiFi, data is transmitted by modulating the intensity of the light, which is then received by a photo-sensitive detector, and the light signal is demodulated into electronic form. This modulation […]
The causes of lighting overvoltages and how they affect public lighting installations Voltage surges have a very destructive impact on public lighting systems. They wear out LED drivers and distribution panels prematurely and increase service interruptions to street lighting. Beyond material damage to the luminaires, voltage surges caused by lightning, for example, can trigger […]
This article provides guidelines for LED selection, given a particular optical system. When choosing an LED for an application, its optical properties must first be considered. Properties such as lumen output, intensity distribution, and source size must be suited to the optical system of the application. Fig. 1: Example listing of flux bins. Brightness […]
Technological improvements have enabled LED floodlights to replace HID luminaires and to either achieve substantial energy savings or at least to match the power consumption of HID luminaires. High-mast lighting is found in almost all geographical locations in South Africa. It provides light to areas where either limited electrical reticulation is found or because […]
This article investigates how human nature influences our reaction to a new environment with respect to lighting. Research indicates a preference for directional or peripheral lighting as opposed to diffuse lighting, as the former provides the observer with environmental cognition while maintaining their involvement in the space. It is suggested that meeting these basic […]
The Edge is a multi-tenant office building in Amsterdam where the architect’s goal was to create an intuitive and productive environment for employees, and to inspire sustainable design around the world. Opened in 2015, The Edge received a 98,36% Building Research Establishment Environmental Assessment Methodology (BREEAM) rating, the highest rating ever. A key aspect […]
Glare is best described as an excessively bright light spill exposed to the line of sight of an individual, causing discomfort and/or disability to the person experiencing it. According to Rea (2000), “disability glare is the reduction in visibility caused by intense light sources in the field of view, while discomfort glare is the […]
The issues and solutions you may encounter when driving multiple LED strings from a constant current source. Many LED applications require more than one LED in a system. When multiple LEDs are used, the LEDs can be arranged in series, parallel, or series-parallel configurations. Due to regulatory requirements (especially in class II environments) there […]
This article provides a study of the thermal efficiency benefits associated with surface-mounted LEDs compared to recessed LEDs in residential applications. This study focuses on energy loss from air leakage as a result of recessed downlight ceiling cutouts; energy loss through insulation gaps required for recessed downlights, and the energy required to run the […]
An explanation of the traceability chain at the NMISA photometry and radiometry laboratory to support the South African lighting industry. The South African lighting industry requires a calibration service for light measuring instrumentation and lamps used as source standards. Examples include illuminance meters, luminance meters, photometers, colorimeters, luminous intensity lamps and luminous flux lamps. […]
