Secure systems

2017 Ask the Experts Supplement - Ask the Experts: Structures

Jeff Warschauer of Nexus Greenhouse Systems explains the latest market offerings.

October 25, 2017

Photo courtesy of Nexus Greenhouse Systems

Greenhouse Management recently spoke with Nexus Greenhouse Systems’ Jeff Warschauer, VP, sales, about greenhouse systems.

Greenhouse Management: What are some of the newest developments in greenhouse systems?

Jeff Warschauer: Today’s greenhouses are growing much of the traditional ornamental crops we are all familiar with, wait...Cannabis you say… Ok so maybe not all crops are traditional.

And with this addition we find ourselves engineering a much more precise, high light greenhouse and greenhouse environments that also lower humidity (reducing the threat of disease pressures such as powdery mildew). These greenhouses reduce temperatures with much higher light levels and with fewer shadows while reducing the risks of insect infiltration.

GM: How do you design the perfect greenhouse environment?

JW: For 50+ years Nexus, National and RBI have been serving discriminating Institutional research clients such as Syngenta, Bayer, Monsanto, USDA, NASA and leading universities worldwide. Learning from these experts over the years have allowed our team to provide high-performance greenhouses.

We use a Nexus Vail “A-Frame” greenhouse. The Vail provides a secure environment that controls condensation drip and allows for maximum light. The Vail can offer multiple grow zones and add on an insulated all metal utility house zone. Other Vail uses can be found at

Then we provide several cooling options based on the crop(s) being grown and the greenhouse layout. Crops like basil do not like the cooler temperatures that certain leafy greens may prefer. Your greenhouse is designed specifically for your application and geographical location. We provide mechanical cooling from familiar traditional gable or side fans.

Other cooling options include traditional evaporative pad systems as well as semi-sealed, sealed greenhouse packages and special dehumidification equipment.

GM: What are semi-sealed and sealed systems, and what do they offer for growers?

JW: With semi-sealed and sealed [systems], you have many options of introducing ventilation and environmental upgrades into the structure, such as pulling or pushing air through an evaporative wet wall, chilled water coil and desiccant/Freon hybrid system. These systems then distribute cooled air and when required, heated air throughout the greenhouse via a ducted and non-ducted system.

Moving air into the greenhouse is typically via ducts usually under a bench or on the floor. With most applications we are pushing air into the greenhouse (positive pressure) and not drawing the air out (negative pressure) like more traditional cooling fans. Positive pressure brings the air below the plant.

GM: Do these systems cost more than traditional methods?

JW: It should be noted that these equipment systems and specialty greenhouses cost more both from a CapX investment as well as operational costs. Certain crops such as cannabis and leafy greens make these investments possible. Yet for other crops a more traditional cooling system may be chosen such as a wide range of “Atrium” naturally ventilated open roof houses, which are less expensive, with lower operational costs as they require little electricity to cool.

GM: What other features can a grower benefit from?

JW: Optional insect screening using anti-virus or full thrip protection can be incorporated.

Our newer Nexus Vail and RBI Venlo version structures offer the latest in diffused high light glazing systems both in glass or diffused polycarbonate. — Interviewed by Patrick Williams