Venlo glass industrial greenhouses

When a Venlo glass greenhouse is the right choice

Venlo suits large intensive operations where high light transmission, year-round use and precise microclimate control matter. The format is used in vegetable production, supplementary-light growing, flower projects and other operations that put heavy demands on the engineering systems.

The solution requires a larger initial budget than a film format, so the choice of Venlo is justified by the growing technology, the intended service life, the available energy supply and the automation requirements.

Structure, foundations and glazing

The frame and the foundations are calculated for the size of the facility, the snow and wind loads of the region and the weight of the engineering equipment. Glass covering provides high light transmission, but it also raises the requirements for the precision of the steelwork, the fixing details and the drainage.

Ventilation windows are built into the roof; their area and opening pattern are determined by calculation. Their operation is tied to an external weather station, internal sensors and the climate control system.

Service and process areas

For an industrial complex, the growing area alone is not enough. The service section determines how convenient the operation will be to run day to day.

• boiler house and heat substation
• mixing room or dosing unit for preparing nutrient solutions
• grading and packing area
• cold rooms and storage for finished produce
• stores for packaging, consumables and tools
• technical rooms for the automation, pumps and electrical equipment

Venlo engineering systems

Heating and the pipe-rail circuit

Heating is calculated from the heat losses and the growing regime. In industrial vegetable production several circuits may be used: a lower pipe-rail circuit, overhead or growth pipes, and separate circuits for the roof and the service areas. The layout has to distribute heat evenly and allow control by compartment.

The boiler house is tied into the main manifold, the pump groups and the pressure maintenance system. In vegetable technologies the pipe-rail circuit doubles as a track for process trolleys. Additional circuits are placed under the gutters or in the plant growth zone where the crop and the heating layout require it.

Ventilation, recirculation and screening

Natural ventilation through the roof vents is supplemented by recirculation fans. Screens are used for shading, for reducing overheating and for cutting heat losses in cold weather. The type of screen fabric and the number of screens are selected for the crop and the light regime.

Irrigation, fertigation and drainage

The dosing unit, the pumps, the distribution network, the drippers and the drainage collection system are designed as a single circuit. The automation doses water and nutrients according to set recipes, while the drainage is collected and, where the technology allows, returned to circulation after treatment.

Water treatment and water storage are part of the process layout as well. Stable fertigation depends on the quality of the source water, the capacity of the dosing unit, the flushing lines and the ability to collect drainage separately by climate compartment. On large facilities these decisions directly affect the stability of plant nutrition and water consumption.

CO2 and assimilation lighting

Intensive vegetable production may use CO2 dosing and supplementary lighting systems. Their capacity and operating regime are calculated from the crop, the natural light levels, the mounting height and the production schedule. These systems have a significant effect on the energy consumption of the facility and must be taken into account as early as the concept stage.

Climate computer and automation

The climate computer brings together heating, ventilation, irrigation, fertigation, screening, CO2 and supplementary lighting. It takes readings from the internal sensors and the weather station, keeps an archive of the parameters and runs coordinated scenarios for the different climate compartments.

How the engineering affects daily operation

At a Venlo complex most daily operations depend on the coordinated work of the automated systems. If heating, ventilation, screening, irrigation and lighting are designed separately, the climate computer will not be able to hold the regime properly when the weather outside changes sharply.

That is why the climate compartments, the drive operating scenarios, the priorities between heating and ventilation, the emergency algorithms and staff access for maintenance are all defined at the design stage. For an investment project this also matters for OPEX: a setup error or oversized equipment shows up in energy consumption throughout the entire service life.

Venlo versus an industrial film greenhouse: what to weigh up

What the cost of a Venlo complex depends on

What data is needed for an estimate

• crop, variety and growing technology
• target area and planned output
• region of construction and site characteristics
• operating regime: seasonal or year-round
• available gas, heat, electricity and water capacity
• requirements for irrigation, supplementary lighting, CO2 and automation
• the set of service rooms and post-harvest infrastructure
• target launch dates and possible phasing