GREENHOUS MANAGEMENT GREENHOUSE STRUCTURES

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GREENHOUS MANAGEMENTGREENHOUSE STRUCTURES

• HEATING, COOLING, AND LIGHTING SYSTEMS

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Heating systems
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Types of systems and equipment

• Boilers that produce steam or hot water
• Unit heaters
• Solar energy
• Infrared heaters
• Heating cables
• Heat blankets

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Calculation of heat requirements

• Heat lost from a greenhouse depends on
• the glazing material
• the exposed surface area of house
• the inside desired temperature
• wind speed
• the condition of the house
• the outside design temperature

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Calculation of heat requirements

• The heat requirements for a greenhouse can be
  determined using the formula
• H K a (t1 - t2)
• H the heat required in Btus per hour
• K the heat transfer coefficient of glazing
  material
• a the exposed surface area
• t1 desired inside temperature in F
• t2 outside design temperature in F

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Heat transfer coefficients
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Cooling systems

• Plant growth decreases at temperatures about 90
  degrees
• Most greenhouses on sunny days are 20 degrees
  warmer than the outside temperature

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Cooling systems include

• Opening side and ridge vents
• Exhaust fans at one end and louvers at the other
  end of the greenhouse
• Swamp coolers
• Mist systems
• Fan and pad cooling

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Supplemental lighting systems

• It is used to increase photosynthesis
• It is used to combat cloudy days
• It will cause or delay flower induction

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Types of lighting

• Incandescent lights
• Fluorescent lights
• High intensity discharge lights
• high-pressure mercury
• metal halide
• low-pressure sodium
• high--pressure sodium

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Shading systems

• Reduce the temperature inside the greenhouse
• Reduce the light intensity or duration

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Types of shading materials

• Shading compound
• thinned down white latex
• applied in spring and removed in fall
• Shading clothes
• There are various degrees of shading with shade
  clothes depending on use

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Methods to control temperature, light, and
humidity

• To increase heat
• remove shading
• turn on heat
• To decrease heat
• use a cooling system
• apply a shading cloth or compound

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Methods to control temperature, light, and
humidity

• To increase light
• turn on supplemental lights
• remove shading
• clean glazing
• To decrease light
• apply shading cloth or compound

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Methods to control temperature, light, and
humidity

• To increase humidity
• turn on overhead watering system
• water the sidewalks and under benches
• To decrease humidity
• remove warn moist air and draw in cool air
• then heat the cool air to reduce relative humidity