Sparks Electrical News April 2019

LIGHTING

20

THE GROWTH OF HORTICULTURAL LIGHTING

A CUSTOMISED FOURWAYS MALL INSTALLATION

T he revolution in horticulture is a seismic shift that will fundamentally change how we grow plants – and it’s all down to lighting. Thanks to the properties of LED light- ing and major advances in our understanding of plants, we are now able to tune light in order to boost yield, customise plant characteristics and maintain plant health. At a basic level, hor- ticulture is relatively simple. Given the right soil, temperature, moisture, and lighting conditions, horticulturalists should be able to cultivate plants anywhere. The lighting component in this formula is much more complex than replacing natural light with an artificial light source. Plants require lights with specific spectral characteristics, including concentrations of light within the appropriate wavelength bands to facilitate plant photosyn- thesis. Green plants require greater amounts of light in blue and red wavelengths, but have other wavelength requirements between those two bands. Before the advent of LED lighting, horticulturalists were unable to generate artificial light that met all wavelength requirements for optimum plant growth. The use of LED The power consumed when converting electricity into PAR pho- tons determines the efficiency of the luminaire, and LEDs are the most energy efficient solution available. In addition to most common top lighting applications where luminaires are placed at ceiling level, LEDs can be used closer to plants because of their lower heat radiation. This allows luminaires to be installed much closer to plants to create more dense farms vertically. Mixing different colour LEDs allows better matching of the light spectra for each species and the stage of growth of the plant. With LEDs the luminaires also have a longer lifetime and lower maintenance needs. Optics, on the other hand, help focus the light/photons onto the plants, allowing either greater crop yield and shorter grow- ing cycles or reduced luminaire bill of materials (BOM) costs. Having uniform light and spectral distribution also helps to pro- duce healthier and more productive plants. Focusing light energy where it is needed gives greater photosynthetic photon flux den- sity (PPFD) with less power. The greenhouse use case for LEDs is primarily as a supple- mentary light source to the sun, although artificial lighting is increasingly vital during the colder and shorter days of winter. Cannabis also requires greenhouse-like space where plants can grow vertically. Most legal cannabis growing operations are in- doors, and require electrical fixtures as the primary light source. Where LEDs are having the greatest impact, however, is in grow- ing leafy greens and herbs that only reach heights measured in centimetres and that can be grown in layers or racks with each layer having a dedicated set of LED luminaires relatively close to the plants, again enabled by little to no heat radiated by the LEDs. The layering assists so-called urban or vertical farms to occupy relatively small growing spaces inside buildings near popula- tion centres, while optimal lighting and technology – including hydroponics – enable faster plant/harvest cycles than can be achieved outdoors.

Horticultural lighting in South Africa South African lighting manufacturer, Giantlight, is at the forefront of horticultural lighting in South Africa and has recently released two products specifically catered for this market; GrowLED Maxi and Megaledbay GrowLED. The Megaledbay GrowLED offers broad spectrum white LEDs with far red on a separate, switchable circuit with a pendant cable with a clutch for easy suspension and height adjustment. Specifications include: • Body construction: Powder-coated mild steel. Available in SS on request. • Lens type: 4 mm Polycarbonate • Supply voltage: 230 V ac 50 HZ • Total circuit load: 100 W plus 10 W when far red is activated (110 W total) • 200 W plus 20 W when far red is activated (220 W total) • Lumens: 100 W – 13 600 lumens for broad spectrum white • 200 W – 27 200 lumens for broad spectrum white • IP rating: IP 65 • Control type: Standard - no control, on or off

1-10 V control available DMX control available DALI control available • Power factor: Better than 0,97

GrowLED Maxi specifications: • Body construction: Powder-coated mild steel. Available in SS on request.

• Lens type: 4 mm Polycarbonate • Supply voltage: 230 V ac 50 HZ • Total circuit load: 408 W • 430 W – With far red • Lumens: 59 560 (Broad spectrum white) • IP rating IP 65 • Control type: Standard – no control, on or off

1-10 V control available DMX control available DALI control available • Power factor: Better than 0,97

Enquiries: www.giantlight.co.za

A s part of the ongoing refurbishment of Johannesburg’s Fourways Mall, Primary Colours has installed a very large, curved LED screen above the new food court. The combination of location, scale and the innova- tive concave design all add up to an easy win for advertisers, but installing the screen presented a number of challenges. The screen is some 19.84 m in length, and 1.536m tall, one-and-a-half times the length of a Gautrain bus. The entire installation, including the custom-made frame, weighs around a tonne. The smooth curve of the screen was made possible by using LED tiles com- prised of rubber-backed modules that can be bent to fit almost any curved surface. Each tile is held in place by magnetic strips, which means that it adapts to the curvature of the mounting surface. This proved to be a crucial attribute in the case of this new installation, as the Primary Colours team discovered that the architectural drawings of the wall did not reflect the reality they were confronted with. The curvature was not only uneven, but also quite different to what was indicated on the blueprints. Work- ing at height, and the need to install the sign at night, added to the challenges involved in this project. “This installation represents a more imaginative way of using existing technology,” explained Primary Colours directors Ashendra Singh and Grant Neill. “Whereas these DigiLED panels are manufactured flat, they can be bent to almost any concave or convex curve, making them extremely adaptable and offering greatly enhanced flexibility when it comes to choosing LED signage locations,” they added. The Fourways LED screen is made up of some 1.9 million pixels (4 960 x 384). The pixel pitch (that is, the distance from the midpoint of each pixel to the next) is 3.9 mm, with the surrounding black plastic and carefully angled hoods on each pixel contributing to the impressive colour contrast. Using a non-standard resolution, essentially three strips of video each 384 pixels high, means that significant video processing power is required to gener- ate the complex content format required. This is more than offset by the impact and clarity of the results. The food court offers the perfect combination of high footfall and a captive audience, and the display can be seen from the adjacent escalators, all three floors of the mall, and three nearby entrances. To date, this is believed to be the only large-scale, OOH variably curved LED screen in South Africa. However, as with all innovations, this one is likely to catch on soon. Primary Colours believes that curved (or pliable) LED tiles have huge potential in retail environments, whether wrapping pillars or lining suspended tubes.

Enquiries: www.primarycolours.co.za

SPARKS ELECTRICAL NEWS

APRIL 2019