Propagation/Greenhouse Management
Part 1 – 118 | Unit 1.3
F. Automated and Semi-Automated Climate Control Infrastructure
- Thermostats are the least expensive and unfortunately least accurate environmental
management tools available for automation
a) Thermostats are positioned in the greenhouse to turn heating and cooling equipment
on at pre-determined temperature thresholds, based on your climate and crop needs
b) Older thermostats, while convenient, are notoriously inaccurate and may not give
the precise control desired. Additionally, separate thermostats are required to control
heating and cooling equipment.
c) Modern thermostats, while more expensive, offer more accurate control by using digital
or electronic technology to monitor temperatures and operate environmental control
equipment
- Stage controllers offer dramatic improvement in precision of environmental control by
linking the operation of heating and cooling devices, air circulation mechanisms, and even
the deployment of energy curtains and shade cloth in the higher-end models
a) Stage controllers typically provide one or two set points to activate the heating
mechanisms in your greenhouse and three, four, or more stages of activation of the
cooling mechanisms
i. For example, as the greenhouse heats beyond a given threshold, at stage one vents
will open
ii. With continued heating, vents and fans will operate
iii. And with further heating, the pad and fan cooling system will be activated to
maintain the desired temperature
b) Stage controllers are only limited by the range of set points that activate your heating
and cooling mechanisms; higher-end models may also offer a data recording feature
- Computer directed environmental controls offer the maximum level of precision in the
total environmental control of the greenhouse
a) Computer zone controllers, with or with without a PC, links all aspects of environmental
control—temperature, air circulation, water delivery, and lighting—through a single
device, offering a high degree of flexibility and the ability to customize the system
b) Integrated computer systems, using a PC, also provide maximum control of all aspects
of environmental conditions, with the added advantage of being able to control
multiple zones or separate structures from a single device. The most sophisticated
systems offer remote access through smart phones, tablets, and laptops, as well as the
ability to receive alarm warnings whenever conditions are out of the desired range or
components are malfunctioning.
Lecture 3: Greenhouse Climate Control Systems