Technical

Glass Greenhouse Technique Level


High Tech

High tech glass greenhouses contain full climate controlled (temperature by heating or cooling, humidity, recirculation air flow, sun radiation (by thermal screening systems) and computer-controlled irrigation systems (drip irrigation system (hydroponic growing), water recycling system, fertilization system). Crop systems like MGS (Multi Gully Systems to grow herbs or salads) can be part of a high-tech environment.

High tech greenhouses also have the most modern automated post-harvest systems. The scale of these greenhouses is above 40.000m2.

They are characterized by high investments costs per m2, necessity of specialized and trained staff, but also produce more harvest per m2 at higher quality levels. Normally they are built to serve he export market and the high-end local markets.
 



Medium Tech 

Medium tech greenhouses can be glass greenhouses or foil houses. The internal equipment is not that fine-tuned. The scale of these greenhouses' ranges most of the time from 5000m2 to 40.000m2. 

They are characterized by medium investment costs per m2 and the level of knowledge for running these types of enterprises is less demanding. At the other hand, production levels are lower, and it will be more difficult to reach the constant quality levels required for export markets and high-end local markets.
Low Tech

Low tech greenhouses have very simple technology. The structure is cheap (tunnel foil houses or net houses) and advanced computer-controlled systems are lacking. The scale of these tunnels' ranges from 400m2 to 5000m2.

 

Generally, these type of cultivation structures require much less investment and technical knowledge, but production levels and quality are often lower and inconsistent. However, due to careful investments, these structures can be upgraded over-time to medium technology level production units, thus enabling small farmers as well to participate in modern horticulture.

As a deliverable, KHS will produce recommendations for the essential elements for each technology, plus an indicative construction price per m2 for each and every technology, to enable potential investors to make a deliberated choice.


Energy Efficient Technologies

To reduce the energy consumption of the green house several options can be implemented:    

  • Horizontal screening system: Keeps the heated-up air in the greenhouse during the night and limits the to be heated up air volume during the night.
  • Vertical screening system: Reduces heat losses at the outside glass walls of the greenhouse
  • Ventilation system: the cheapest way to cool down air is to open up windows on the roof
  • Air recirculation: recirculating air is creating a buffer between cold and heated up air
  • CO2 reduction: By cleaning the exhaust gasses of the gas burning boiler with urea the CO2 can be used for the stimulation of the growth of the crop.
  • Warm water buffer tank: during day time the crop is in need of CO2 and for that the boiler has to run. Warm water will be stored into a warm water buffer tank and be used during night time when temperatures are low.
  • Grow gutters: by collecting the irrigation water the water can be reused. This will give a reduction on water of 30% and a reduction on fertilizers of 15%.
  • Heating at purpose: The installation of different heating system the heat will be used where it is needed.
  • Rail heating systems at the bottom.
  • Wall heating system at outside glass walls.
  • Movable grow tube heating system just above the crop.
  • Snow pipe System along the greenhouse gutters.
  • Grow lights: The use of LED light armatures and bulbs reduce the electricity consumption.
  • Irrigation ferti-unit: High level of dosing fertilizers into the irrigation water by making use of precision injection.
  • Grow lights: The use of LED light armatures and bulbs reduce the electricity consumption.
  • Drip irrigation system: Emitters opening at water pressure result in equal a uniform spreading of the water supply to the plants, which results of cause to a uniform crop


Environmentally Friendly Technologies

Technical

For the glass greenhouses, only sustainable materials are used in today’s construction. The frame of greenhouses is made of dipped galvanized steel. All glass sheets are set in aluminum profiles. The three basic materials (steel, aluminum, glass) will last forever. In the Netherlands there are facilities of 50 years old! Besides, all the above materials can be recycled and used over and over again Rain water will be collected from the roof and be reused as irrigation water. This water is normally the best water for irrigation as it contains many beneficial micro-nutrients. Re-usage of the irrigation water in the greenhouse by collecting it, filtering and treating it with UV-radiation or heat can lead to 30% saving of water on an annual basis. Zero emission of CO2: exhaust gasses to be cleaned and the purified CO2 can be used to increase the CO2 content of the glasshouse, functioning as a natural fertilizer, as CO2 and water are essential elements in the photosynthesis cycle. KSH will deliver a list of technical minimum requirements potential companies and investors should comply with, in order to qualify for building permits. These requirements will include as a minimum the above-mentioned aspects.
Agronomical

In general, there are 5 main negative components of the environmental impact of agriculture on the environment:


Limiting Farmland Expansion

In order to feed the ever-growing world population, more and food needs to be produced. Also, in order to comply with the increasing tendency of supplying vegetables and fruits on a year-round basis, farmers are obliged to move into regions marginal for agricultural production and further away from the primary markets. The use of modern greenhouse technology not only increases the production per m2, thus occupying less land, it also can be done in the close vicinity of the main markets, reducing the CO2 footprint of intercontinental transport of horticultural produce.

Preserving biodiversity

Advances in crop protection have allowed farmers to make the most of existing cropland and curb expanding acres into biodiverse areas. Approximately 35% the world’s potential crop production is lost annually due to weeds, insects, diseases and other pests. These losses would double without crop protection products, forcing farmers to cultivate more land. The use of greenhouses for food production reduce the need for crop protection. Growing on substrates reduces the need for herbicides, the use of beneficial insects limits the use of insecticides and the introduction of a perfect climate inside the greenhouse, limits the need for fungicides.

 

Reducing greenhouse gases Plant biotechnology and crop protection products have helped farmers significantly cut their greenhouse gas emissions to mitigate climate change. By working in a soilless growing environment such as a greenhouse, soil tillage is not necessarily, hence resulting in less greenhouse emission. Also because of the efficient way of heating a modern greenhouse, the flue gasses are retuned back into the greenhouse and used as a fertilizer for the crops, instead of being released into the atmosphere.

Conserving water

Water shortages are a constant threat for farming communities. Also, the quality of the after is becoming more and more an issue (contamination with heavy metals, alts etc.). With the use of water recirculation, about 30% of the irrigation water is recycled. Also, plant breeders are looking into crops and varieties tolerating higher salt contents and using less water (more crop per drop). In the AZIR a training and demo unit is foreseen, screening new varieties for low input growing options as well.

 

Protecting the soil

Up to 50,000 square kilometres of soil is lost every year to soil erosion. By growing in a closed environment in a soilless situation, this is avoided. Worldwide, about 40% of the food produced gets lost, spoiled or otherwise does not reach the final consumer on its way from field to fork. The moment a produce gets harvested, the decaying process sets in. To deliver a high-quality product, the produce should be sorted and graded as soon as possible and shipped to the consumer. In case this is not feasible, the produce should be cooled back to its most ideal keeping temperature and humidity. Several separated cooling units are needed, as not all products have the same ideal storage conditions (temperature and RH) nor can some products be stored together due to ethaline susceptibility.