Controlled Environment Agriculture (CEA) involves precisely regulating every factor affecting indoor plant growth. These sealed cultivation facilities require sophisticated air handling. The “lung room” is a specialized, dedicated space separate from the main grow area, functioning as the central environmental control hub. Air is conditioned, purified, and enriched here before being delivered to the plants, allowing cultivators to maintain the specific atmospheric conditions necessary for optimal growth.
The Purpose of the Lung Room
The fundamental reason for creating a lung room is to isolate noisy, heat-generating environmental control machinery from the sensitive plant canopy. Placing large equipment like air conditioners and dehumidifiers directly in the grow room introduces inefficiencies and inconsistent microclimates that stress the plants. The lung room acts as a buffer, preventing direct heat and noise from interfering with the precise environment required for photosynthesis and transpiration.
This strategic separation allows for the controlled mixing and stabilization of air before it reaches the plants. Air is drawn into the lung room and treated to exact temperature and humidity specifications. Conditioning the air outside the growing space allows the facility to deliver a uniform, pre-mixed atmosphere. This ensures every plant receives the same environmental inputs, leading to more predictable and higher-quality yields and maintaining unparalleled environmental stability.
Key Environmental Management Functions
A primary function of the lung room is to ensure precise temperature and humidity stabilization before distribution. Air drawn into this space is treated by cooling and dehumidification systems, preventing localized hot or cold spots that would occur if equipment operated near the canopy. This pre-conditioning process is essential for maintaining a stable Vapor Pressure Deficit (VPD), which dictates the rate at which plants transpire and absorb nutrients.
The lung room is also the designated zone for Carbon Dioxide (\(\text{CO}_2\)) enrichment, a practice that significantly boosts photosynthetic rates in sealed environments. Compressed \(\text{CO}_2\) is injected directly into the air stream and thoroughly mixed by circulation fans. This mixing ensures the air entering the grow room has a uniform concentration, typically enriched to 1,000 to 1,200 parts per million (ppm).
The lung room assists in maintaining the necessary pressure differential within the grow space. In many CEA setups, a slightly negative pressure is maintained in the cultivation area to prevent odors and contaminants from escaping. The lung room acts as the controlled intake source, supplying a precise volume of conditioned air. This volume, when balanced against the exhaust system, helps establish and maintain the desired pressure relationship, keeping the environment sealed.
Necessary Equipment and Hardware
The lung room serves as the centralized location for all heavy-duty environmental apparatus, beginning with Heating, Ventilation, and Air Conditioning (HVAC) systems. Large industrial-grade air conditioners are installed here to handle the substantial heat load generated by high-intensity grow lights. Industrial dehumidifiers and humidifiers, often larger than units that could fit in the grow space, adjust the air’s moisture content to meet the target VPD.
\(\text{CO}_2\) storage and injection systems are housed safely within this dedicated space. This includes bulk \(\text{CO}_2\) tanks, regulators, and distribution manifolds that manage the gas flow into the air stream for uniform mixing. Concentrating this equipment simplifies maintenance and refilling logistics. It also protects the sensitive machinery from the high humidity, plant debris, and harsh light exposure present in the grow room.
High-efficiency pre-filters are mounted at the air intake points in the lung room to protect the equipment from dust and airborne pathogens. The operation of all these components is coordinated by a Master Environmental Controller. This sophisticated computer system monitors conditions in both the lung room and the grow room. The central controller allows a single operator to manage the complex interplay of temperature, humidity, and \(\text{CO}_2\) across the entire facility.
Designing Airflow and System Integration
The successful operation of a lung room depends on properly engineered airflow and physical integration with the grow room. This connection is achieved through robust ductwork, which must be correctly sized to move the massive volume of conditioned air efficiently. The design must account for the required Air Exchange Rate (ACR), which ranges from one to three air changes per hour for humidity control, up to one air change per minute for temperature control during peak cooling demands.
Practical considerations within the lung room focus heavily on minimizing the transmission of noise and vibration from the machinery. Heavy equipment is placed on vibration isolation pads, such as thick neoprene, to prevent structure-borne noise from traveling through the building. Fans and ductwork are often suspended using flexible materials like bungee cords or spring hangers. Insulated ducting is used to dampen the air-borne sound created by high-velocity air movement. These measures ensure the highly controlled environment in the grow room is not disturbed by the constant operation of the powerful conditioning equipment.