“Due to the larger dehumidification capacity of our units, we have been active in the larger size projects with canopy space exceeding 100,000 sq ft (~10,000 m2),” Keith Coursin, Desert Aire’s president notes. Desert Aire has been actively building systems for the vertical farming market both in the United States as well as several projects in Europe.
New dehumidifier solution for large farms
Desert Aire, a Wisconsin-based supplier of commercial dehumidifiers for indoor farms, introduces a new series of HVACD products that will use chilled water/hot water instead of direct expansion (D/X): The GreenAire™ with VPDsync™. The product comprises a complete indoor climate control system and energy-efficient air handler for very large indoor agricultural grow facilities of greater than 150,000 sq. ft. (~15.000m2) of canopy space to the indoor CEA market.
This system will allow facilities to use heat recovery chillers or natural gas chillers along with the GreenAire indoor grow air handlers to maintain space conditions. “Prior to the release of this new air handler, the cultivator did not have good choices in chilled water systems that had the correct controls for indoor farming,” Keith says.
Desert Aire took its VPDsync control logic and developed a “smart air handler” dedicated to the indoor grow application that makes a chilled water system capable of providing tight control just like its D/X based systems. The company made this decision based on requests from the engineering community to improve the controllability when using chilled water systems for indoor grow applications. Accordingly, there is an energy advantage to chillers and it is easier to move water throughout some facility layouts.
Improper air movement
“In my opinion, there remains confusion between what an HVACD system requires in air movement to function properly and what supplemental air movement is required to eliminate microclimates,” Keith notes. The supplement fans help the grow facility achieve a higher turnover rate than the HVAC unit by itself. However, according to Keith, these supplemental fans are not being installed with specific coverage in mind, and thus are not truly eliminating microclimates within some facilities.
“This is, even more, the case in vertical farms where the racking and shelving create barriers to air movement. We are finally seeing creative methods of introducing the air between the racking and shelves to ensure proper air movement throughout the facility for the elimination of microclimates, but this is the exception rather than the rule,” he adds.
The GreenAire system uses EC-type fans for self-balancing airflows using the controller’s output to set the ideal air volume to meet the cooling and/or dehumidification requirements of the grow.
A Desert Aire supervised remote start-up can be accomplished utilizing AireGuard, Desert Aire’s cloud-based access system. Growers will have the indoor climate control they need to maximize yields and improve plant quality to be competitive in the indoor agriculture market using GreenAire with VPDsync.
'Spicing up the formulas’
The company has been in the indoor grow market for over six years now, during which period they have been monitoring every installation to assist the grower in using the company’s systems. “From this data, not only have our sizing formulas changed, but we have incorporated modulating airflow and recently released our fourth generation of control logic called VPDsync,” Keith adds. This new program helps maintain the temperature and dew point (vapor pressure deficit) to a significantly tighter range over the plant's entire growth cycle.