This document describes a humidity control system for greenhouses. It outlines the project objectives of maintaining optimal humidity levels for plant growth. The system design uses a humidity sensor and two comparators with resistors to check voltage across the sensor and trigger actions to control humidity. The total cost is estimated at $7.76. The design is compared to commercial controllers, with advantages of a lower cost but lower resolution and measuring range. Suggestions are provided to improve the design using more accurate components and a microcontroller.

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Darwish Al-Arafati 86949
Nasr Al-Abdali 86996

2. • Introduction
• Project Overall (Problem, Specifications and
Constraints).
• Project Design and its principle.
• Sensor Specifications.
• Project and market Product Comparison.
• Conclusion
• References
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3. Project Objective:
In the greenhouse the humidity level is very important as a very
humid atmosphere may be harmful to some plants because the rate of
transpiration and evaporation is reduced in a very humid conditions,
and these plants my suffer damage from overheating unless you use
the ventilation to bring into the greenhouse cooler and drier air. On
the other hand, many tropical plants from native humid climates
require high levels of humidity for a healthy growth and will not
survive in a dry atmosphere. That is why Controlling Humidity
needed!.
Introduction:
One of the biggest challenges in maintaining a greenhouse is
humidity control. Most plants enjoy a humidity of 50 to 60
percent, and this is a challenge to manage at times. The main
goal is to avoid condensation on plants, which promotes mold
and fungus growth. Low humidity leads to leaf dehydration,
more frequent watering and pest infestation.
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4. 1 Problem Statement 2 Constraints
Economical:[ Total Cost is equal
Nearly 8$]
Humidity level in Green Environmental: No Impact
Health and Safety: It does not
Houses may affect plants
affect them.
growth.. Social and Cultural: System is
acceptable.
Performance: Fast System
Response
3 Specifications
•Performance: Accurate and It has Very Fast Response....
•Functionality: System Will check Voltage across the Sensor ,so
valid action will be done
•Operational: System can work on the environment on which
temperature lie between 10 to 60°C.
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5. How Does it work?!!
230 Vac
1k Ohms
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6. Project Cost
Component Name Cost
HS 1101 (HUMIDITY SENSOR)
4.6
2 Comparators Operational Amplifier
1.36$
2 Relays
1.4$
4 Resistors
0.4$
Total Cost 7.76$
1$≈0.385 O.R
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7. Humidity Sensor Specifications
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8. Farm Greenhouse Humidity Controller Product
Compared With Project Design
Comparison Side Project/ Greenhouse Farm Greenhouse Humidity
Humidity Controller Controller
Resolution Lower Higher
Measuring range +0.1% RH/°C +1% RH/°C
10 to 60°C -40C~+85C
Cost 8$ 35$
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9. How to Improve Design?
•Using accurate components.
•Highly Sensitive Humidity sensor.
•Using Microcontroller instead of Comparators.
•Avoid using long wires and poor cables.
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10. Conclusion:
Humidity can be controlled easily using 2 comparators with few
resistors and a sensor.45% of Humidity is perfect one for plants
growth. By means of Humidity Absorption and Air Humidifier,
Humidity is going to be controllable and being balanced to be
45% in the air.
References
-http://www.ehow.com/how_2107526_manage-humidity-greenhouse.html
-http://fogco.com/applications/greenhouse
-http://www.ryanguitars.com/NewsandEvents/Guitar_tech_tips/Humidity_Chart.htm
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