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Climate-based Annual Daylight Modelling for Greenhouses with Supplemental Electric Lighting
Recent advances in LED-based luminaire design have enabled greenhouse operators to temporally control both the photon flux density and spectral irradiance incident upon the plant canopy.
Greenhouses and Light Pollution
Supplemental electric lighting for greenhouses may be essential for extending the growing season in northern climates, but it comes with a not-so-hidden cost: environmental light pollution. The consequences of this pollution may range from irate neighbours in rural...
Ultraviolet Disinfection for Consumers
In these unfortunate times, it seems that everyone is looking for ways to help with the COVID-19 crisis. From a lighting designer’s perspective, one solution is obvious: ultraviolet radiation. We have known about the disinfectant properties of ultraviolet radiation...
Circadian Lighting – An Engineer’s Perspective
Ian Ashdown, P. Eng, FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 19/11/14. Whether you call it “circadian lighting,” “biologically effective lighting” or some other name, the principle is the same: the color and intensity of light can be used to...
Light Transmittance through Greenhouse Glazing
Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 18/10/01. Look at a greenhouse manufacturer’s product specifications and you will see that the light transmittance of single-pane clear glass is typically 88 to 91 percent....
Far-Red Lighting and the Phytochromes
Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published 18/06/04. Most LED grow lights feature blue and red LEDs whose peak wavelengths – approximately 450 nm for blue and 660 nm for red – have been chosen to coincide with the spectral...
The Science of Near-Infrared Lighting
Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 18/07/13 There is a common-sense argument being presented in the popular media that since humans evolved under sunlight, our bodies must surely make use of all the solar energy...
Melanopic Green
Ian Ashdown, P. Eng. FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 18/09/03 Numerous medical studies have shown that exposure to blue light at night suppresses the production of melatonin by the pineal gland in our brains and so disrupts our...
Solid Angles
Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 2014/07/26 Do you suffer from math anxiety? A surprising number of us do (e.g., Wigfield 1988). I would tell you the exact numbers, but you would need to understand...