Indoor cultivation requires very tight environmental control to maximize product quality and yield. To effectively control the indoor environment, both temperature and humidity levels must be addressed. Early grow rooms had a handful of issues with dedicated A/C and dehumidification, specifically during the lights off period because they were using single-stage A/C which is sized for the lights on period. At night, it was significantly oversized–when it turned on, it would overcool the space quickly creating swings in both temperature and relative humidity (RH) that were not desirable. The all-in-one A/C-based climate systems avoid this.
The advancement of staged A/C allows the contractor to better match the lights on and off load with different capacities to minimize those swings. Learn more about the differences between all-in-one systems and dedicated cooling plus dedicated dehumidification below.
All-in-One A/C-based Climate Systems
The all-in-one system is built to provide cooling and dehumidification, ensuring optimal control when installed and sized properly. When properly sized, it requires far greater capacity than dedicated systems, leading to a higher initial investment. To balance the temperature and relative humidity of the space, the system distributes the refrigerant into multiple condensing coils. According to an independent study done by the Sacramento Municipal Utility District (SMUD), the all-in-one system is less energy efficient in dehumidification mode since the coils are designed for cooling efficiency. This means that it uses more energy per pint of water removed. All-in-one systems must be designed and configured according to the specific temperature and relative humidity requirements. Adjustments to grow conditions, watering schedules, feed rates, or plant count may require further setup. Properly designed and set up systems do provide excellent control, but at a cost in both the initial investment and operating cost of time.
Dedicated Cooling & Dedicated Dehumidification
To match both the lights on and lights off sensible load in the space, it is recommended to use multi-stage A/C allowing the system to properly match the heat load during lights on & lights off. Using dedicated systems to control both temperature and humidity ensures each system is correctly sized to manage the load it is designed for. This lowers the initial investment as the system doesn’t have to be oversized to be able to manage both the sensible and latent loads. This combination also allows for better energy efficiency and lower operating costs. The A/C can be designed for temperature control and the dehumidifiers are designed for efficient latent removal.
In most cases, the dehumidifiers will operate periodically to assist the A/C with the moisture load when the lights are on. However, they truly shine when the lights go off and the A/C stops working due to lack of heat load. That is when the dehumidifiers in a grow room perform heavy lifting to prevent counterproductive spikes in RH. Working together with staged A/C will maintain an ideal environment without overcooling for optimal plant growth, quality, and yield.
Redundancy is Key
Stakes are high in many grow facilities, due to the value of the indoor crop. Redundancy is important to reduce risk in the event of equipment failure. An all-in-one system leaves the cultivator vulnerable because if anything goes wrong, the entire system is compromised. Service from a specialist is required right away or crop damage can occur. On the flipside, by using a dedicated cooling and dedicated dehumidification systems, the cultivator is protected by the inherent redundancy in the system. A typical dedicated dehumidification system will utilize multiple dehumidifiers. If one has an issue the remaining units will simply have to work a bit harder until a swap or repair can be made. In addition, if there is an issue with the A/C system, the dehumidifiers will be able to control the RH levels while the system is being repaired.
If RH is controlled, the potential for crop damage is minimal.