Environmental Control Systems

Evolution, Current Systems, the Future

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What can be regulated?

• Temperature (heat/cooling systems)

• Humidity

• Supplemental Lighting

• Photoperiod (day length extension or black cloth)

• Atmospheric composition (CO2 enrichment)

• Irrigation

• Nutrient Delivery (Fertilization)

Types of Controls

• Manual

• On/off Switches

• Step Controllers

• Dedicated Microprocessors

• Computers (Integrated Control)

Manual Greenhouse Control

• Common before 1950 to have people 24/7 to monitor temperature (winter)

• Manual ventilation, heat valves

• Manual pulling of shade cloth

• Manual sun shades

• Hand watering

On/Off Switches

• Simple

• For heating and cooling based on a thermostat

• Problems with accuracy

• May still be suitable for simple season extension houses

• Many styles and manufacturers available

Step Controller

• Advancement over on/off switch

• Instead of just one option there are multiple stages possible (for example)• Stage 1 – louvered vent opens• Stage 2 – exhaust fan on opposite wall on low speed• Stage 3 – exhaust fan on opposite wall on high speed

• Not expandable• Not good for complicated temperature control

schemes• Can be difficult to ‘set up’ and ‘change’

Dedicated Microprocesssors

Computers

• Despite cost effectiveness and ease of use 85% of greenhouses still have some manual controls

• Cost 5 to 7K and up

• Very expandable

• System can grow with your operation

• Data can be easily made available to others for troubleshooting

• Integrated record keeping

IFAC TECHNICAL BOARD

AUGUST, 2003

IFAC EMERGING AREASPROJECT

CC 8: BIO & ECOLOGICAL SYSTEMS(APPLICATIONS)

Keith Godfrey (for Ewart Carson)

TC 8.1 Control and Automation in Agriculture

• “Speaking animals”Automated measurement of the responses of individual

animals to differing feeding and climate regimes so as to optimise their management

• “Speaking plants”Automated measurement of plant responses to different

treatments for the purpose of automatic control of processes in the soil-substrate-plant continuum

• Automation of harvesting and handling of cropsDevelopments required due to a lack of skilled, affordable

labour• Automation for tracking and tracing of products and

of the production conditionStage of maturity, variability, treatments etc.