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LEDs in spotlight - Greenhouse Canada<br />

LEDs in spotlight<br />

Much <strong>of</strong> the research is now focusing on the effect <strong>of</strong> different colours on crops.<br />

Written by Dr. Elly Nederh<strong>of</strong>f<br />

Lemnis LED lights with water cooling in a large-scale trial in tomatoes at Redstar (the Netherlands).<br />

Page 1 <strong>of</strong> 4<br />

Introduction: Artificial lighting in greenhouses is common practice in greenhouses in northern Europe and<br />

Canada. It’s necessary <strong>for</strong> growing crops like tomatoes and roses through winter. In the Netherlands alone,<br />

an estimated 2,000 hectares <strong>of</strong> greenhouses are lighted. The standard lamp used since the 1990s is the<br />

high-pressure sodium (HPS, SON-T-Agro). Obviously the investment and running costs <strong>of</strong> lighting are high.<br />

When LED lighting was introduced into the horticultural market in 2007, salespeople promised extremely<br />

high efficiency and exceptional yields thanks to special light colours. However, test results in the first winter<br />

season were disappointing, and so was the efficiency. In the second and third season, the results were<br />

mixed. Depending on circumstances, LEDs gave lower, equal or higher yields than HPS lamps. This was<br />

under equal light levels, expressed in micromol/m2/s. Meanwhile, several practical applications are doing<br />

really well. Important differences between LED and HPS are the spectrum (light colours) and heat delivery,<br />

as well as the price.<br />

http://www.greenhousecanada.com/content/view/2941/153/<br />

Appendix BCUC IR1 83.4.1<br />

24/09/2012

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