Control of air humidity in greenhouses can be made more energy efficient

Aarhus University is a partner in a project that can reduce energy consumption in the greenhouse industry significantly. In particular, control of air humidity can be made more energy efficient.

2018.01.24 | Janne Hansen

Managing climate and light in greenhouses means finding a balance between creating optimal conditions for the crops and a desire to keep down costs and consumption of energy and other resources. Photo: Roar Påske, AU Foto

Danish tomatoes, basil, potted roses and other green products that are grown in commercial greenhouses are facing a more energy efficient future. A research project with the participation of, among others, researchers from Aarhus University, will further develop systems to control energy consumption so the expensive consumption can be curtailed. The main emphasis in the project itGrows 2.0 will be on developing a more energy efficient system for control of air humidity. 

To optimise growth in greenhouse plants the plants need to have the right environment. This means that the grower must control heat, air, humidity and light in the greenhouse. Climate and light control in greenhouses is a balance between creating optimal conditions for the crops on the one hand and a desire to keep down costs and consumption of energy and other resources on the other hand. 

The greenhouse industry has already achieved significant energy savings with the aid of increased knowledge about plant requirements combined with improved climate control technology – to the benefit of the climate and the industry’s economy. Since 2002 energy consumption has been reduced by half and is now at about 4025 thousand gigajoules per year. The reduction was made possible by investing in energy-saving measures, including improved climate control, and by shifting towards cultivation of crops that are less heat-demanding. 

Emphasis on air humidity control

The research project itGrows 2.0 will continue to develop the energy efficiency that has already been achieved in recent years in the context of, among others, the recently completed Green Development and Demonstration Programme (GUDP) project ”Reducing energy consumption by optimized humidity control in greenhouses – REDHUM”, which was led by Aarhus University. 

One of the great challenges is control of air humidity. Too high an air humidity can reduce the plant’s uptake of nutrients and have a negative effect on plant growth, well-being and health. Control of air humidity, which can comprise up to 30 percent of the annual energy consumption, is the element that consumes the most energy in an advanced greenhouse production. It is therefore an obvious choice to work on control of it with models and IT. 

The most important source of air humidity in greenhouses is plant transpiration – their ”breathing”. The key to reducing air humidity problems is to develop robust models to describe the relation between plant transpiration and greenhouse microclimate. Part of the project will therefore concentrate on developing a model that describes transpiration. The model will be based on the latest knowledge about plant stomata, among other things.   

Previous models have focused on separate parts of the production system. In itGrows 2.0 the partners will combine knowledge and experience from the practical application of several decision support systems with research in plant physiology to create a completely new decision support system that can contribute to reducing energy consumption. The strength of the new tool will be a common database with a total mathematical greenhouse model based on research previously carried out at Aarhus University. 

The vision for the new model is to make it easier for growers to target energy control with regard to greenhouse installations and varying crops. 


Facts about the project

Name: itGrows 2.0

Budget: 12.4 million kroner

Grant from the Energy Technology Development and Demonstration Programme (EUDP): 8.7 million kroner

Duration: Three years beginning October 1, 2017

Partners: Danish Technological Institute (project leader), Aarhus University (Department of Agroecology and Department of Food Science), University of Copenhagen, ByGrowers, Hjortebjerg, HortiAdvice, NB Data and Danish Horticulture. 


For more information please contact:

Professor Carl-Otto Ottosen, Department of Food Science, email: coo@food.au.dk, telephone: +45 8715 8373, mobile: +45 2290 3105 

Senior Researcher Niels Holst, Department of Agroecology, email: niels.holst@agro.au.dk, mobile: +45 2228 3340

Agro, Food, Crops, DCA