The right system

Photo courtesy of Argus Controls

Picking the right environmental control system, and understanding how it will affect plant growth, is a vital decision for any grower. Below, Argus Controls Vice President and General Manager E. Michael Heaven offers his advice for picking a system, how environmental control technology has improved and more.

Greenhouse Management: What are some tips for growers to pick the right environmental control system?

E. Michael Heaven: To select the right environmental control system, growers should ensure the control system can maintain the plants at the right temperature and relative humidity at the plant canopy regardless of environmental disturbances or intentionally introduced changes to fertigation, CO2 content, etc. If the environmental controls do not anticipate a feeding/watering cycle and ramp up dehumidification in advance, the plants will be unnecessarily stressed by wide swings in the environment. Growers should ask for performance guarantees at the plant canopy.

GM: Why is good service a key when selecting an environmental control system?

EMH: If you have a crop-threatening emergency, you need to know you can reach someone 24/7 that knows your environmental controls and can support you through the emergency. You do not want to reach a building management technician that has never seen an environment with plants in it and must learn your system from scratch.

GM: How has environmental control technology improved over the last few years?

EMH: There are more plant-specific algorithms that use measurements of inputs, outputs and sensor readings to maintain your plants on the right vapor pressure deficit trajectory for optimal, stress-free growth, that model and control the plant transpiration rate and that control the ever expanding world of variable intensity and spectrum lighting. Machine-learning applications are being developed for yield optimization while balancing the economic factors including energy, labor, materials, etc. New visual tools are available on their mobile devices to see the performance of a grow operation at a glance and manipulate targets from wherever they are.

GM: What are some common mistakes growers make with their environmental control systems?

EMH: Some of the common mistakes are 1) implementing building management systems designed for people, not plants 2) designing the heating/cooling/dehumidification system for a large greenhouse/grow room without considering the impact of the plants response to various inputs 3) designing a system without an experienced grower at the design table 4) failure to use lower energy elements to control the environment (such as vents, shades, fans, light diming) before switching on more expensive cooling/heating systems 5) inadequate range of inputs to control the environment as plants grow or more plants are added (such as CO2 injection at certain light levels) 6) implementing on/off HVAC controls, instead of proportional controls, which result in environments oscillating after every disturbance 7) not using enough sensors at adequate resolution and update frequency to implement zone control throughout a large growing environment so disturbances are localized to only one zone.