Low-temperature heating in the greenhouse complex
With the expansion of the campus heat grid, the Greenhouse Complex has been connected to heat pumps in the Huygens Building in 2022. Since heat pumps work much more efficiently when they make low-temperature CV water, the CV water temperature has been lowered from 80°C to 40°C. To ensure it still gets warm enough in the greenhouse complex, a doubling of the number of heating pipes (heating surface area) has been realised. Much of the piping that had to be laid for this purpose is circular, as the pipes from the Faculty of Science's old boiler house were given a new purpose here. The greenhouse complex can now be heated gas-free. The gas boilers are only there as back-up in case of breakdowns and extreme cold for the time being.
LED lighting also saves on cooling
Half of the time, the 182 grow lights in the greenhouses are on. The replacement of the normal grow lights with LED lighting saves 400W per bulb. The new lamps are also dimmable and can be adjusted to the amount of extra light that is needed for perfect plant growth in addition to daylight. This results in additional savings of around 20%.
In the climate chambers, the lamps are on longer and a chiller is needed to cool away the heat from the lights. Half the amount of Watts also means half the amount heat that needs to be "cooled away": this results in a bonus saving due to reduced energy consumption of the chiller. During the winter season this does not apply: the residual heat released then for cooling the climate chambers is used to heat the greenhouse complex.
Mesh in the windows
The third change results in pesticide savings: to keep overnight birds with their unwanted droppings out of the greenhouses, the windows are fitted with mesh. This not only keeps out the birds – it also means that far fewer insects enter. This has a beneficial side effect on the need for pesticides: a reduction of about 30% on an already very low pesticide consumption. Biological pesticides are mainly used; chemical control is used only in emergency situations. But because far fewer insects now enter the greenhouse complex, these situations will also occur less frequently.
Making an impact
The Greenhouse Complex is used by the Radboud Institute for Biological and Environment Sciences (RIBES), for various types of research and teaching in ecology and physiology. RIBES researchers are delighted with the sustainable improvements. "As a research institute, we contribute to a healthy world with our research mission 'Towards healthy ecosystems'. This also means that we want to minimise the environmental impact of our own activities. Additionally, the greenhouse complex is vital for our research regarding, for example, crops that can better withstand climate change, reduction of greenhouse gas emissions such as methane, and carbon storage in ecosystems," said Ivo Rieu, professor of Crop Biotechnology.
Tom van Onna, manager energy & energy transition, is also enthusiastic: "Greenhouses are energy-intensive, so saving energy here has an impact. Nice work by Diederik Hilckman and Henk-Jan Banning of Campus & Facilities and Koos Janssen and Martijn Frieling of RIBES, among others."
View energy use on campus
The effect of energy savings per building can now be followed by everyone by looking at the consumption figures on: campusenergie.nl.
The display of consumption in the Greenhouse Complex below shows the savings on electricity and gas. The gasless heating of the Greenhouse Complex still requires adjustment work and therefore the gas meter is not yet completely at zero; however, this will be achieved in time.