Difference between Cannabis Cultivation-specific AHUs And Traditional Commercial AHUs

Difference between Cannabis Cultivation-specific AHUs And Traditional Commercial AHUs

1. Core Function: CO₂ Management

AHUs designed for plant cultivation:

Core Function. A CO₂ injection system and gas distributor are integrated within the enclosure.

The goal is to proactively raise indoor CO₂ concentrations to 800-1500 ppm during daytime, when photosynthesis is at its peak, significantly above atmospheric levels. This directly stimulates plant growth and increases yields by up to 30%.

The AHU and ductwork must be extremely airtight to prevent costly gas leaks.

Traditional commercial AHUs:

They introduce fresh air to dilute and expel CO₂ produced by human respiration, typically aiming to maintain indoor CO₂ concentrations below 1000 ppm to ensure occupant comfort and health.

They lack CO₂ injection capabilities.

2. Key Performance: Dehumidification

AHUs designed for plant cultivation:

Dehumidification is a vital function. Plants produce significant amounts of water through transpiration.

In addition to conventional cooling and dehumidification, a separate dehumidification system, such as a rotary dehumidifier or heat pump dehumidifier, must be integrated. Reason: Cooling coils alone cannot dehumidify at night or in weather conditions where cooling is not needed. High humidity, especially during flowering, can directly lead to catastrophic diseases such as gray mold.

Precise control of VPD is required, as it is a key physiological parameter linking humidity and plant transpiration.

Traditional commercial AHUs:

Dehumidification primarily serves as a byproduct of temperature control. The cooling coils lower the air temperature below the dew point, causing moisture to condense naturally.

In particularly humid climates or locations, pre-cooling coils may be used, but robust standalone dehumidification systems are rarely integrated.

3. Structural Design: Airtightness and Light Leakage Prevention

Growth-Specific AHUs:

Extremely airtight: Prevents CO₂ leakage and ensures efficient utilization.

100% light leakage prevention: For short-day crops like cannabis, any light leakage during the dark cycle can severely disrupt the photoperiod, resulting in non-flowering or reduced yields. All access doors and joints are designed with light seals.

Traditional commercial AHUs:

Meeting basic airtightness standards is sufficient; light leakage is not a concern.

4. Air Filtration: Protection Objectives

AHUs designed for cultivation:

Use higher-grade filters (typically F8 and above).

The primary objective is to block fungal spores, bacteria, viruses, pests, and pollen, which are the main vectors of greenhouse disease transmission.

Traditional Commercial AHUs:

A filter rated G4 to F7 is sufficient.

The primary objective is to block dust, pollen, and some allergens, ensuring human health and equipment cleanliness.

5. Materials and Durability

AHUs designed for cultivation:

They are exposed to high temperatures and high humidity for extended periods of time and may come into contact with fertilizer and pesticide vapors.

The internal frames, panels, and coils are often constructed of galvanized steel, stainless steel, or epoxy coatings for enhanced corrosion resistance.

Traditional Commercial AHUs:

For operation in relatively mild environments, standard carbon steel with a paint finish can meet most requirements.

6. Control Logic and Accuracy

AHUs designed for cultivation:

Control accuracy requirements are extremely high. Temperature fluctuations must be controlled within ±1°C, and humidity fluctuations within ±5%RH. The control logic is complex, requiring coordination of multiple subsystems, including cooling, heating, humidification, dehumidification, CO₂ injection, and internal and external circulation, to maintain a dynamically balanced, optimal growth environment.

Traditional commercial AHUs:

Control accuracy is relatively loose, determined by the user not feeling noticeable discomfort.

The logic is relatively simple, primarily responding to changes in temperature and humidity set points.