Cooling and Humidification
Cooling and Humidification
At FFG we approach cooling in stages. We focus on passive cooling as our first stage by integrating our ridge vents and side vents to allow hot moist air to escape the structure passively. There is no fan on earth that can move as much air as through the convection process that naturally occurs within a properly designed greenhouse. By not having to utilize mechanical ventilation and cooling at all stages our greenhouse designs save money on operating costs as well as elongating the lifespan of fans shutters and cooling systems.
Our second stage of cooling is to close the vents and instead focus on high-pressure fogging systems and our mechanical ventilation system to cool the structure efficiently, effectively, and consistently throughout the structure’
FOGGING VS. WET WALLS
Since Forever Flowering started in 2006, we have been designing our greenhouses with high pressure fogging systems to both cool and, if necessary, add humidity in very dry areas. Through years of personal Research and Development, we found that a fogging system outperformed a wet wall in several areas: consistency, efficiency and general health of the plants.
Air entering in through a wet wall cools down and moisturizes as it passes through the wet pad created from water dripping onto and slowly descending down the pad before being pumped up again to drip or be blown into the greenhouse.
This cool, moist air passes through the greenhouse and dries out and warms up as it passes across the canopy before being exhausted out of the mechanical ventilation on the opposite side the greenhouse of the wet pad vents, having a diminishing effect and lack of consistency as it travels across the entirety of the structure.
Fogging systems have small pipes that are mounted throughout the greenhouse and have emitters that can be adjusted as needed to control quantity of fog being dispersed allowing for full control of creating consistent environments in the greenhouse regardless of where your plants are growing.
When your environmental controller triggers your cooling system to activate a wet wall the pad vent must first begin to pump water onto the pad and then, when sufficient, it will begin to blow air across the cool, wet pad and, eventually, blow over the entire crop before leaving the building.
Fog system emitters are connected to fully charged, low-pressure pipes that allow the fog to be dispersed immediately upon being triggered, reducing transition times between cooling and ventilation cycles.
A client was operating approximately 40,000 sq ft of canopy and running his wet wall 24/7 to keep the environment hospitable for his flowering plants.
He decided to put a water flow meter on the inlet of his pad vent system to determine how much water he was consuming each day to keep the pad system operational.
He measured just under 40,000 gallons of water being used each day in his cooling system.
Just under 1 gallon of water/sq ft/day to cool his 40,000 sq ft.
We were able to determine, in that same environment, had he been using a fogging system he would have used about 29,000 gallons of water, approx. 25% less water.
It is very important to keep the pad vents from growing anything unfriendly to your plants on them that may in turn be blown across the entire crop.
When growing in a soil or soil-ish medium the soil will stay moister, for longer, the closer it is to where the cool, wet air enters the greenhouse.
This can become an issue if the whole crop is watered at the same time based on the driest plants located nearest to the exit point of the dry, warm air that has just traveled the length of the structure warming up and drying out due to the solar gain of the Sun’s rays bathing down on the plants.
Molds, mildews, pests and diseases are attracted to plants that are growing in soggy, anaerobic conditions due to the medium not having an opportunity to dry out because of its proximity to the pad vent.
Nature sees the anaerobic conditions as a calling out to be decomposed and so the decomposers move in to do their job and often, as a result, the whole crop gets treated.
The wet wall was keeping the plants from needing the same amount water, consistently, and instead of solutions, band-aids are applied.
Again, a fogging system can be adjusted as needed so if a certain part of the greenhouse needs less fog due to a shadowing obstruction, or if an area needs more fog because it has a more intense location due to moving air drying it out more quickly.”