Quick answer: A vertical farm needs seven equipment systems: growing racks, LED lighting, an irrigation system (NFT, deep-water culture, ebb-and-flow or aeroponics), climate control (cooling, heating and dehumidification), CO₂ enrichment, water treatment, and sensors with a control system. The climate system is usually the hardest part to get right: almost all lighting power becomes heat, and almost all irrigation water the plants take up comes back out as humidity, so cooling and dehumidification must be sized together.
Quick answer
- Seven systems: racks, LEDs, irrigation, climate (HVAC + dehumidification), CO₂, water treatment, controls.
- The LED load sets the cooling; crop transpiration sets the dehumidification.
- Recovered condensate can return to irrigation, which is how vertical farms use so little water.
The seven equipment systems
| System | Options | What to decide |
|---|---|---|
| Racks and growing structure | Static multi-tier racks, mobile racks, towers | Tier spacing, aisle access, load rating, materials that tolerate humidity |
| Lighting | LED fixtures with crop-specific spectra | Light intensity (PPFD) and daily light integral per crop; efficacy in µmol/J; heat removal |
| Irrigation | NFT channels, deep-water culture, ebb-and-flow trays, aeroponics, drip | Crop, root health, pumps, redundancy |
| Nutrient and water treatment | Dosing, pH/EC control, filtration, UV or other disinfection | Water quality, recirculation, condensate reuse |
| Climate control | Cooling, heating, dehumidification, air circulation per tier | Temperature, humidity/VPD, air speed at the canopy |
| CO₂ | Bulk tank or generator, dosing, sensors | Enrichment level and air-tightness of the room |
| Sensors and controls | Temperature, RH, CO₂, PAR, water level, pH/EC; climate computer | Sensor per zone and tier; alarms; data logging |
Why climate control is the critical system
In a closed growing room, there is no sun and little ventilation. Two balances decide the equipment:
Heat: almost all the electricity used by LEDs, pumps and fans ends up as heat in the room. Some of it is used to evaporate water from leaves (latent heat); the rest warms the air (sensible heat).
Water: the water plants take up through their roots is released through their leaves. In a recirculating system:
crop transpiration ≈ irrigation supplied − drainage − change in stored water
That transpired water must be removed from the air, by cooling coils, dehumidifiers or both. Wageningen research on plant factories analysed this crop transpiration and energy balance in detail (WUR, Plant factories: crop transpiration and energy balance).
Worked example (illustrative)
A farm with 500 m² of canopy (five tiers of 100 m²), growing leafy greens. Assumptions for this example: crop transpiration 3 L per m² per day; LEDs at about 90 W per m² for 16 hours.
- Water to remove: 500 × 3 = 1,500 L/day, mostly during lights-on, about 80 L/h at the peak.
- Latent heat in that water: about 0.68 kWh per litre, roughly 55 kW at the peak, which the climate system removes when it condenses the water.
- LED power: 500 × 90 W ≈ 45 kW while lights are on, almost all of it becoming heat.
So the cooling and dehumidification equipment must handle tens of kilowatts and hundreds of litres a day. And the hard period is often lights-off: cooling demand falls, cooling coils stop removing water, and humidity rises unless dedicated dehumidifiers run.
Vertical farming HVAC: common layouts
| Layout | How it works | Suits | Watch |
|---|---|---|---|
| Split or packaged AC + separate dehumidifiers | AC handles heat; dehumidifiers hold humidity, including lights-off | Small and medium rooms, container farms | Coordinate controls so they don't fight |
| Chilled-water fan coils + dehumidifiers | Central chiller; fan coils per room or tier | Larger farms | Coil temperature sets how much moisture fan coils remove |
| Integrated climate units (cooling + dehumidification + reheat) | One unit controls temperature and humidity | Farms wanting one control point | Size for both lights-on and lights-off |
| Dedicated outdoor air system (DOAS) | Treats fresh air separately | Farms needing ventilation | Fresh air adds moisture and heat in summer |
Whatever the layout, check lights-off: cooling demand drops sharply while plants still transpire, so humidity control must work without the cooling load.
Dehumidification options
| Option | Fits when | Notes |
|---|---|---|
| HVAC cooling coils only | Lights-on, high cooling load | Removes water while cooling; weak at lights-off |
| Dedicated dehumidifiers in the room | Lights-off and transition periods; extra capacity | Adds heat; must be included in cooling design |
| Ducted dehumidifiers outside the room | Keeping service out of the growing area | Duct pressure, air distribution to each tier |
| Integrated HVAC with dehumidification and reheat | Large farms | Higher first cost; best control |
Size dehumidifiers at the room condition (for example 22–24 °C and 60–70 % RH), not at the 30 °C / 80 % RH rating. Our ceiling-mounted and ducted dehumidifiers (26–960 L/day) suit multi-tier rooms where floor space is used for racks. See grow room dehumidifier sizing and placement.
Air distribution between tiers
Upper tiers are often warmer and drier, lower tiers cooler and more humid. Without air delivered to each tier, the canopy in the middle of a rack can stay humid even when the room sensor looks fine. Use:
- fans or perforated ducts along each tier;
- air speed at the canopy of roughly 0.3–1.0 m/s for leafy greens (helps transpiration and reduces tipburn);
- sensors at several tier heights.
Water recovery
Condensate from cooling coils and dehumidifiers is close to the volume the crop transpires: in the example, about 1,500 L/day. Returned to the irrigation system after filtering and disinfection, it cuts fresh water use sharply. Plan the condensate collection, storage and treatment at the design stage.
Fertigation and irrigation
Fertigation combines irrigation and nutrient dosing: a mixing tank, dosing pumps for nutrient concentrates and pH adjustment, EC and pH sensors, filtration, disinfection (UV or similar), and pumps to each tier. Decide recirculation (with treatment) or drain-to-waste, and redundancy for pumps. Irrigation volume minus drainage is a good estimate of the dehumidification load.
Gas detection and safety
- CO₂ enrichment to around 800–1,200 ppm is common for leafy greens. Higher levels are a worker hazard: OSHA's permissible exposure limit for CO₂ is 5,000 ppm (8-hour average). Use CO₂ sensors with alarms at the working level, and interlock dosing with ventilation.
- Refrigerant leak detection where large charges or flammable refrigerants are used, per local codes.
- Water leak detection under racks and around tanks.
Power distribution
LED lighting is usually the largest electrical load, followed by HVAC. Plan dedicated circuits per tier or zone, distribution boards near the racks, LED driver location (heat), and backup power for controls, pumps and climate so a power cut doesn't cook or dry the crop.
Control system integration
One climate and fertigation controller, or integrated controllers, with sensors per zone and tier, alarms by phone, and data logging. Agree which device has authority over temperature, humidity and CO₂ so systems don't fight.
Maintenance and sanitation
Clean trays and channels between crops; disinfect irrigation lines; replace filters on HVAC and dehumidifiers; check sensors against a reference; clean condensate drains (biofilm); keep spare pumps and sensors.
Equipment checklist for a vertical farm
- Crop list, tier count, canopy area and growing cycle
- Light intensity and photoperiod per crop
- Irrigation type and water treatment
- Room temperature, humidity/VPD and CO₂ targets for lights-on and lights-off
- Cooling and dehumidification capacity at both periods
- Air distribution per tier
- Condensate recovery route
- Sensors, control system and alarms
- Redundancy for pumps, cooling and dehumidification
Related: lettuce and leafy greens humidity and hydroponic greenhouse humidity.
FAQ
Frequently asked questions
What equipment do you need for vertical farming?
Racks, LED lighting, a hydroponic or aeroponic irrigation system, nutrient and water treatment, climate control (cooling, heating and dehumidification), CO₂ enrichment, and sensors with a control system.
What HVAC does a vertical farm need?
Cooling sized for the LED heat, plus dehumidification sized for crop transpiration that works when lights are off; see the layouts above.
What is climate-controlled farming?
Growing crops indoors (vertical farms, container farms, grow rooms) where temperature, humidity, CO₂, light and airflow are controlled by equipment rather than the weather.
What supplies and tools does an indoor farm need besides the main systems?
Trays, growing media, seeds, nutrients, pH and EC meters, cleaning and sanitising supplies, spare filters, calibration tools for sensors, and harvest and packing equipment.
What are vertical farming units?
Self-contained growing modules or containers with racks, lights, irrigation and climate control built in; they need the same climate sizing as a room.
Why do vertical farms need dehumidifiers?
Plants release almost all the water they absorb into the air. In a closed room, that water must be removed, especially when lights are off and cooling stops.
How much water does a vertical farm use?
Far less than field growing when condensate is recovered, because the water the crop transpires is condensed and returned to irrigation.
What is the biggest energy use in a vertical farm?
Usually lighting, followed by the cooling and dehumidification that remove the heat and moisture the lights and crop produce.
Sources
- Wageningen University & Research, Plant factories: crop transpiration and energy balance.
- Frontiers in Sustainable Food Systems (2023), vertical farming review.
- US EPA, vertical farming research report.
- University of Kentucky Center for Crop Diversification, Hydroponic lettuce (air speed).
- OSHA, Carbon dioxide permissible exposure limit (29 CFR 1910.1000, Table Z-1).
