light planning
• Physical obstacles like AC units , fans , heating / irrigation pipes , framing , shade cloth , etc . can not only create a physical obstacle to the mounting of the luminaires , but also create shadowing on the crops below . A good light plan will always factor these obstacles into the plan to ensure that the spacing and orientation of luminaires is designed to deliver optimal light intensity uniformly across the entire surface of the crop . Another consideration that is often overlooked in a light plan is the lighting in relation to walls and walkways . The symmetric light distribution from a typical luminaire results in a lot of light being projected onto the outer walls or walkways , where it is wasted . A carefully considered light plan should include luminaires with optics that are designed to direct light only where you need it — the plant canopy . So , consider a luminaire / reflector with an asymmetric distribution for these areas .
• The type of crop will also impact the light plan significantly in terms of optimal light intensity , light distribution on the canopy , and eliciting a particular plant response . For taller crops , directing light deep within the canopy to reach the lower leaves is typically a challenge . For these types of applications , the light plan should specify a luminaire / reflector that delivers a more focussed field of illumination between zero and 45 degrees in the lower hemisphere of the distribution curve , producing uniformly deep light penetration into the canopy below . When including LED luminaires in a light plan , the crop and the desired plant response will determine the spectral recipe of the luminaire . Blue light , for example , inhibits stem elongation and can enhance leaf pigmentation , whereas red light promotes stem elongation and is essential for flowering .
• Energy and temperature considerations are also something to take into account when developing a light plan . In many applications , LED luminaires consume significantly less electrical energy than traditional lighting technologies , and also produce less heat so they can be placed closer to the plants , enabling higher light intensities without excessive heat . Oftentimes , however , two ( or more ) LED luminaires will be required in a particular application to produce the same light output as a single traditional ( 1,000W HPS ) luminaire . Growers should always do their due diligence when comparing light plans based on a variety of solutions ( traditional / LED / hybrid ) before deciding on which is the best fit for their particular application .
TIP
LOOK AT THE COST PER MICROMOLE ( μmol ) OF LIGHT DELIVERED ( BASED ON THE TOTAL NUMBER OF LUMINAIRES THAT WILL BE REQUIRED TO ACHIEVE THE REQUIRED LIGHT LEVEL IN THE SPACE ) FOR A TRUE COMPARISON .
Application example # 1 of how the dimensions of the grow facility and the crop can affect the luminaires and reflectors specified in the light plan .
In this first example , the combination of an ample ceiling height and a tall vine crop presented an ideal application for the use of P . L . Light Systems ’ NXT2 luminaires with the Beta reflector to deliver optimal , uniform light intensities to the crop , deep within the canopy . The luminaires along the walls were equipped with the Asymmetric reflector to prevent the light from being directed onto the walls where it would be wasted .
48 grow cycle