Chapter 2

Greenhouse Heating

(draft book excerpts)

Heating is a major concern to commercial greenhouse operations. This is due primarily to the costs involved in the purchase and operation of heating equipment as well as the potentially disastrous effects of a poorly designed system can have on crop production. Although solar energy represents a significant factor in greenhouse heating, supplemental systems are a necessity for year round production. Greenhouse heater requirements depend upon the amount of heat loss from the structure. Heat loss from a greenhouse usually occurs by all three modes of heat transfer: conduction, convection and radiation. Usually many types of heat exchange occur simultaneously. The heat demand for a greenhouse is normally calculated by combining all three losses as a coefficient in a heat loss equation. Suitable energy sources include natural gas, LP gas, fuel oil, wood and electricity. The cost and availability of these sources will vary somewhat from one area to another. Convenience, investment and operating costs are all further considerations. Savings in labor could justify a more expensive heating system with automatic controls.

Click on the following topics for more information on greenhouse heating.

Topics Within This Chapter:

  • Basics of Greenhouse Heat Loss and Gain
  • Conduction
  • Convection
  • Infiltration
  • Radiation
  • Greenhouse Heating Systems
  • Greenhouse Unit Heaters
  • Types of Unit Heaters
  • Fresh-air Vents
  • Sizing Unit Heating Systems
  • Distribution of Heat
  • Polyethylene Tubing
  • Horizontal Airflow Fans (HAF)
  • Greenhouse Hot Water Heating Systems
  • Advantages/Disadvantages of Heating Plant Boilers
  • Types of Heating Plant Boilers
  • Cast Iron Boilers
  • Steel Boilers
  • Copper-fin Tube Boilers
  • Condensing Boilers
  • Location of Boiler
  • Distribution of Heat
  • Types of Pipes
  • Perimeter Heating
  • Floor Heating
  • Overhead Heating
  • Under-bench Heating
  • Bench-top Heating
  • Hot Water (Hydroponic) Unit Heaters
  • Steam Heating System
  • Greenhouse Infrared Heating Systems
  • Types of Infrared Heaters
  • Zone Heating
  • Types of Fuel for Greenhouses
  • Gaseous Fuels
  • Natural Gas
  • Propane
  • Fuel Oils
  • Alternative Fuels
  • Wood Pellets
  • Wood Chips
  • Comparing the Cost of Heating Fuels
  • Horizontal Air Flow (HAF) Fans for Greenhouses
  • Horizontal Air Flow (HAF) Fans Capacity
  • Types of Horizontal Air Flow (HAF) Fans
  • Placement of Horizontal Air Flow (HAF) Fans
  • Calculating Heat Greenhouse Heating Requirements
  • Surface Area of Greenhouse
  • Calculate Temperature Difference
  • Calculate the Total Transmission of Heat Loss
  • Allowances for Wind Speed
  • Calculating Greenhouse Air Volume
  • Calculate Heat Loss by Convection
  • Calculate Total Greenhouse Heating Requirement
  • References