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Problem

The Plant Growth Facility (PGF), one of the ECRP Pilot Buildings, consumes approximately £30,000 of electricity per month, with the majority of this being spent on growth room lighting.

The growth rooms create specific conditions necessary for plant growth; the humidity, light intensity and period, temperature and composition of the air are all carefully regulated. Lighting may be left on in growth rooms for long periods of time in order to simulate certain growing conditions. Most growth facilities use relatively inefficient fluorescent lamps for lighting. As the PGF houses around 4,000 fluorescent tubes, the potential to make a significant energy saving by replacing these with efficient light emitting diodes (LEDs) was identified.

Solution

Since 2012, the Department of Plant Sciences with funding from the ECRP has developed LED lighting capable of growing a wide range of plant species under controlled conditions for both research and teaching. Delivering the optimum spectrum of light at controllable intensities with even coverage has proven to be a considerable challenge.

Following extensive trials with a variety of lighting array types, plant species and metrics, lighting refits of plant growth chambers at the PGF are progressing as a rolling upgrade programme. The LED arrays are easier to calibrate and the lighting power load has now been reduced by over 60%. Further savings are also being made through a reduction in cooling demand, as LEDs produce less waste heat. Monitoring has shown that the refits made up to May 2017 are saving approximately 250,000kWh a year, reducing electricity costs by £30,000.

Trials and refits will continue and, once completed, annual departmental carbon emissions are expected to be lowered by 400 tonnes of CO2 equivalent, equivalent to £100,000 savings per year.

Elsewhere in the Department of Plant Sciences, an LED refit solution for algal incubator shakers has been developed with a lab equipment manufacturer. Fluorescent tubes inside the units have been replaced, providing better light coverage and more controllable light intensity that will last for the rest of the shakers’ lifetime. This project was completed in 2016 resulting in a 55% reduction in electricity consumption, saving £1,600 per year.

In 2017, work will extend the LED trial time, this time to provide supplementary lighting in the department’s greenhouses, potentially replacing energy-hungry incandescent fittings.

Impact

The benefits of this work are not constrained to energy and carbon savings as the research and development undertaken is leading to change in the way plants are grown and studied, not just across the University of Cambridge, but throughout the world.

The importance of this work has been recognised by a Highly Commended award in the Research & Development category at the Green Gown Awards 2015. It was also shortlisted in the Laboratory Environmental Improvement category at the S-Lab Awards 2017.