The Greenhouse Airflow Calculator computes common airflow metrics for a greenhouse (see below).
INSTRUCTIONS: Choose units and enter the following:
- (FAS) Fan Airspeed
- (FD) Fan Diameter
- (ASM) Airspeed in middle of greenhouse
- (ASE) Airspeed at end of greenhouse
- (L) Greenhouse Length
- (W) Greenhouse Width
- (H) Greenhouse Height
- (iT) Inside Temperature
- (oT) Outside Temperature
Greenhouse Airflow Metrics (GAM): The calculator returns the following greenhouse metrics:
- (AFF) Airflow rate at the fan level in cubic meters per second
- (AFM) Airflow rate in the middle of the greenhouse in cubic meters per second
- (AFE) Airflow rate at the end of the greenhouse in cubic meters per second
- (ECE) Evaporative Cooling Efficiency as a percentage
NOTE: The answers can be converted to compatible units via the pull-down menu to the right of the answers.
The Math / Science
Special thanks to Dr. Dhia Alchalabi, Associate Professor of Agricultural Engineering Technology for providing the equations used in this calculator. Now in retirement, Dr. Alchalbi desires to pass his wealth of knowledge on to future generations, and we are in his debt.
A greenhouse, aka a glasshouse or a hothouse, is a building or complex in which plants are grown. A miniature greenhouse is known as a cold frame. Related to a greenhouse is a high-tunnel which is a greenhouse build over soil directly.
Greenhouse structures range in size from small sheds to industrial-sized buildings with different types of covering materials, such as a glass or plastic roof and frequently glass or plastic walls. 
A Greenhouse is designed to warm as incoming sunshine is absorbed inside the structure. Air warmed by the heat from warmed interior surfaces is retained in the building by the roof and walls. By using non-porous materials such as glass or plastic, the air that is warmed near the ground is prevented from rising indefinitely and flowing away.
Commercial glass greenhouses are often high-tech production facilities for vegetables or flowers. The glass greenhouses are filled with equipment like screening installations, heating, cooling, lighting and airflow systems and also may be automatically controlled by a computer to maximize potential growth.
vCalc's Greenhouse category (tag) contains equations and calculators pertaining to greenhouse calculations, metrics and other data.
Greenhouse and High-tunnel Calculators
- Volume of a Gabled Greenhouse: Enter the dimensions of a gabled building and compute the cubic feet volume.
- Volume of a Curved Dome Greenhouse: Enter the dimensions of an arched roofed building (see diagram) and compute the cubic feet volume.
- Volume of a Quonset Hut Greenhouse: Enter the dimensions of the Quonset Hut and compute the cubic feet volume.
- Surface Area of a Gabled Greenhouse: Enter the dimensions of a normal gabled building and compute the square feet surface area.
- Surface Area of a Curved Dome Greenhouse: Enter the dimensions of an arched roof building and compute the square feet surface area.
- Surface Area of a Quonset Hut Greenhouse: Enter the dimensions of a Quonset Hut and compute the square feet surface area.
- Bell-shaped Greenhouse Volume and Surface Area: Computes volume, surface area, floor space and height based on dimensions.
- Greenhouse Air Flow: Computes the air flow volume at the fan, middle and end of the greenhouse and the Evaporative Cooling Efficiency
- Conductive Heat Loss: Enter the surface area, the heat loss coefficient for the surface material and the maximum heat range, and the calculator will compute the BTUs per hour needed to heat the inside.