Raising the bar for lighting excellence - KZN’s first lighting laboratory
Tuesday, November 25, 2014
The Energywise Systems Lighting Laboratory in Riverhorse Valley is the first of its kind in KwaZulu-Natal and plans to be one of three accredited labs offering complete photometric, electric and thermal testing of light sources and luminaires (SABS and NMISA in Pretoria are the only other accredited testing labs in the country).
The purpose of the lab is to test the performance of various light sources, fittings and fixtures. The Energywise Systems Lighting Laboratory is equipped to create IES and LTD photometric files for lighting computer simulation as well as thermal analysis for those products exposed to challenging temperature conditions. Lab service and equipment is also available from Energywise for hire or purchase.
At a site visit and lab tour hosted by Illumination Engineering Society of South Africa (IESSA), Andre Barausse, Managing Director of Energywise said, “6 months and R2million later, we have a lab fully fitted with a 2.4m integrating sphere, Type C Goniometer, and thermal oven.”
The integrating sphere measures the amount of lumens emitted by various light sources such as compact fluorescent lights (CFLs), light emitting diodes (LEDs) and even incandescent bulbs. Powered with state of the art software, the goniometer measures candle power, colour spectrum, photopic (well lit conditions) and scotopic levels (low light conditions).
The thermal oven tests the performance of the light source at elevated temperatures. This is important for various applications where high temperatures are experienced such as above factory kilns.
For non-industry experts, it may seem excessive to invest in such a lab, however there can be large variances in performance between similar lighting products. Three of the factors which are important when selecting lighting products are lumen efficiency, energy efficiency and lighting efficacy.
Light output of a light bulb is measured in lumens. Luminaire efficiency is measured as a percentage of total lumen output. Daniel Zuczek of Energywise explains:
“If a single bulb that emits 100 lumens is placed into a luminaire and the total lumen output of the luminaire is 70 lumens, then the luminaire is 70% efficient (some light emitted from the bulb is trapped inside the luminaire housing). It is typically desirable to use high efficiency luminaires so you get as much usable light for the energy being used and energy cost being paid. Note however, that a bare bulb with only a lampholder has a high efficiency (because there is less luminaire hardware to trap the light output), but using bare bulbs is not practical for many reasons – so “light output” efficiency needs to be weighed against other factors.”
Likewise, energy efficiency is measured as a percentage of energy consumed by the luminaire compared to another luminaire. The lower the energy consumed, the more efficient the product.
Another way products vary is in their lighting efficacy. Efficacy is different from efficiency in that it measures lumens per watt (light output per energy unit). Incandescent light bulbs produce on average 10-15 lumens per watt; this is compared to fluorescent lamps, which produce approximately 80-90 lumens per watt. This can explain why there has been major drive to replace incandescent bulbs with CFLs.
Choosing the right light fittings and luminaires for a shop front for example requires an understanding of the luminaire’s lumen output, efficiency and efficacy. The Energywise Systems Lighting Laboratory can provide highly accurate measurements for this purpose.
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