Lighting in Design Q1 2019

The growth of horticultural lighting

Horticultural lighting is the industry's hottest new market, revolutionising the future of farming with technologies and innovations enabling year-round sustainable crop cultivation.

T he revolution in horticulture is a seismic shift that will fundamentally change howwe grow plants – and it’s all down to lighting.Thanks to the properties of LED lighting 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, horticulture is relatively simple. Given the right soil, temperature, moisture, and lighting conditions, horticulturalists should be able to cultivate plants anywhere. The lighting compo- nent in this formula is much more complex than replacing natural light with an artificial light source. Plants require lights with specific spectral charac- teristics, including concentrations of light within the appropriate wavelength bands to facilitate plant photosynthesis. 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.

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 differ- ent 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 growing cycles or reduced luminaire bill of materials (BOM) costs. Having uniform light and spectral distribution also helps to produce healthier and more productive plants. Focusing light energy where it is needed gives greater photosynthetic photon flux density (PPFD) with less power. The greenhouse use case for LEDs is primar- ily as a supplementary 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 opera- tions are indoors, and require electrical fixtures as the primary light source. Where LEDs are having

The use of LED The power consumed when converting electricity into PAR photons determines the efficiency of the

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LiD Q1 - 2019