By Josh Fabian
Air movement is very important for healthy crops. The HVAC and dehumidifier systems chosen will condition the air to create an environment that will keep the plants happy in a number of ways. When these systems are not sized adequately poor growth and disease will result. At our vertical farm pilot in Glens Falls, we are growing leafy greens. We aim to keep the temperature between 60-70 degrees Fahrenheit (F). When temperatures rise above this, lettuce and other leafy greens want to bolt, or go to seed. This renders them unsaleable. With humidity, we aim to keep the ambient room humidity between 50-70 degrees F; I personally prefer staying on the lower end of this range. When humidity rises above this range, a number of pathogens can thrive that will lower the value of the crop. Also, with lower humidity faster transpiration can take place, and therefore the crop can grow quicker allowing for more crop turns per year.
To achieve these temperature setpoints, we chose powerful equipment. One factor going into this decision was the planned expansion inside of our grow room. To begin, we’ve maintained the grow room such that it’s only half full. This is a strategic reason, whereby we do not want to have to buy new equipment for expansion and run more power. My advice is that it is best to design the system for the potential full load than have to go back and retrofit everything.
Selecting A Dehumidifier
For humidity management, we chose a Quest 225 overhead unit. This unit has MERV 11 filtration, is ductable, UL and ETL listed, made in the USA, has a 5-year warranty, and can be installed overhead or on the ground. These factors make it a great choice for our vertical farm. For sizing we estimated the water being added to the crop, factored in transpiration rates, and then calculated the max pints per day that needed to be removed.
An example of a Quest 225 overhead unit
"For sizing we estimated the water being added to the crop, factored in transpiration rates, and then calculated the max pints per day that needed to be removed."
In Part II of our publication, we will expand on how we selected our Air System. You can follow more insights from our partnership with Glens Falls and others committed to the Glens Falls Vertical Farm Public Pilot here.