The HVAC loads - the amount of heating, cooling, and humidification or dehumidification required to maintain optimal growing conditions - depends on several factors. The primary contributing factors to HVAC system design are local climate conditions, crop requirements, and facility type and construction. An engineering analysis can be performed to determine the HVAC loads and help inform the selection of systems that would work best for a given application. The following design criteria will inform this analysis:
1. Facility location
2. Facility description (type, size, construction)
3. Crop type(s)
4. Target temperature, relative humidity, and VPD.
5. Internal sources of heat gain (lights, people, equipment, etc.)
6. Internal sources of moisture (plant transpiration, evaporation from open irrigation systems)
7. What is the construction budget
There may be other design constraints and owner requirements that are unique to each operation. They may or may not impact the size of the HVAC equipment requirements, but they will most likely affect what type of system is selected, where it is located, and how it is operated. These desirable factors include everything from maximizing energy efficiency to limiting noise, as well as system redundancy and durability.