From Dr Eric Belfield, Plant Growth Facility Manager at Plant Sciences:
The glasshouses in Plant Sciences are crucial for departmental research and teaching. The existing high pressure sodium (HPS) and metal halide (MH) lights in the glasshouses produce a good spectrum, but they’re energy inefficient. This is partly due to the large amount of heat they generate, which can also scorch leaves, flowers and fruit, and cause heat stress in some of the taller plants we grow such as maize and tomatoes.
Following successful multi-season testing of energy-efficient LED alternatives to HPS and MH lights, we approached the Environmental Sustainability team in 2017 to discuss replacement of 18 old-style inefficient lights with LED lights. The LED lights emit only the parts of the electromagnetic spectrum that the plants require, making them highly energy efficient. Another benefits of LED lighting is longevity, with a typical lifespan twice as long as the traditional lights. Finally, because the LED lights run at a significantly lower temperature, they are less damaging to taller plants.
In 2019 we initiated the next phase of the project, replacing a further 141 HPS and MH lights. The Environmental Sustainability team worked with the Plant Sciences department and the central Purchasing team to negotiate preferential rates on the new lights, which arrived in late January.
Each LED is around 50% more efficient than what it replaces, and the project is expected to save around £25,000 a year in lower electricity bills, paying for itself within three years as well as preventing nearly 60 tonnes of CO2 per year from being released into the environment.
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