Greenhouse Canada

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Inside View: Being keen on green with LEDs… or LEEDs

March 9, 2012  By Gary Jones

As plant producers, we think of ourselves as the original green industry. Ultimately, everything we do is, or was, driven by sunlight. Photosynthesis provides energy for our plants to grow now, and millions of years ago to grow plants to become the fuels we use for heat and to power vehicles. We could argue that we’re already a truly solar-powered industry!

The Institute for Sustainable Horticulture at Kwantlen University officially opens its new bio-control research laboratory this summer. The building is expected to be LEED® Gold certified. (It will be followed by a geothermally heated research glasshouse this fall.) “The Leadership in Energy and Environmental Design (LEED) Green Building Rating System™ encourages and accelerates global adoption of sustainable green building and development practices.”1 … It is “an internationally accepted benchmark for the design, construction and operation of high performance green buildings,”1 managed in Canada by the Canadian Green Buildings Council (CaGBC).

So, if we are the original green industry, how many horticultural buildings are LEED® certified? According to the CaGBC, there were 146 LEED registered projects in Canada as at March 19, 20091. In broad agricultural terms, there’s a couple of wineries, a cheese project, the George and Kathy Dembroski Centre for Horticulture (Toronto Botanical Gardens), and maybe a couple more. But all of these are likely for office/commercial buildings, with the odd classroom and retail space. There are few conventional horticultural production buildings. Don’t we have any suitable “good news” LEED practices? Sure we do. Take energy efficiency:


Lights: Greenhouse growers have made significant efforts – particularly since 2000-01 – to reduce energy consumption. For example, LED lights have been trialled in greenhouses in several countries. These consume about 20 to 30 per cent of the energy used by conventional high pressure sodium (HPS) lights2,3, which typically only convert about 25 per cent of their electrical consumption into light energy. This reduced energy input has no significant effect on plant growth (height).2,3 Further, in consuming less energy, LEDs reduce greenhouse gas emissions at power generation source. And since specific wavelengths of light can be set into LEDs, lighting can be more natural – work by Sylvain Dub1 in Sweden suggests using more blue lights in the morning and red lights in the afternoon.4

Heat: Professor Qiang (Chong) Zhang, head of biosystems engineering at the University of Manitoba, comments that “winter greenhouse production in northern regions is generally prohibitive because of the high energy consumption in heating and lighting. We have been working on developing a solar energy greenhouse technology to solve the heating problem.”5 Combining this with new lighting techniques might advance this even faster. “LED technology will potentially solve the lighting problem.”5

Energy: It’s not news to the industry that growers are switching to waste wood for greenhouse heating. However, we could tell others about work to make exhaust gasses extremely clean, allowing capture of the CO2, so produced to increase crop photosynthesis and growth. Geothermal heat sources, anaerobic digesters and other green energy options could help horticulture meet LEED certification.

But there’s a problem. LEED is primarily designed for commercial office buildings (regulated by Part 3 of the National Buildings Code), and applies to: new construction, commercial interiors, “Core and Shell”, existing buildings, homes, and neighbourhood developments.1

What about your new packhouse or office? And with no option for a greenhouse perhaps there should be! Maybe now’s the time to get a new category of LEED certification to help set the global standard for sustainability in greenhouse systems. Want to be our champion?

1  Canadian Green Buildings Council (CaGBC):
2  Klaassen, G. et al. (2005) “LEDs – New Lighting Alternative for Greenhouses.” University of Minnesota.
3  Stevenson, R. et al, (2009) “LEDs – A light at the end of the tunnel for greenhouse growers?” Conference poster, Kwantlen University, B.C.

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