Upgrading greenhouse controls

Features - Environmental Issues

If your current environmental control system is not meeting your needs, an upgraded or replacement system may be one of the best investments you can make in your own future.

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Are you completely happy with the capabilities and performance of your current greenhouse environmental control system? Are you enjoying trouble-free operation with readily available and reasonably priced spare parts and good factory support? If so, you can stop reading.


Control issues
Most greenhouse managers face a range of limitations with their existing environmental controls. This may cause some to consider a control system upgrade or a full system replacement. Here are some common upgrade and replacement issues.


Age of the system
Control systems last much longer than personal computers, but they do wear out. After five to 10 years you may want to consider upgrading your system with some new calibrated sensors, newer software or firmware. You may just need to run through a complete review of your greenhouse operations, including your control system, to ensure everything is working properly. These upgrades and improvements should quickly pay for themselves through better efficiency and improved system reliability.

Control systems that are 20-25 years old may start to show increasing failure rates with limited spare parts availability and increasing replacement part costs. Like an older car, these older control systems don’t “owe” you anything and are prime candidates for replacement even if they continue to work as originally intended. If you are having difficulty purchasing parts, upgrades or expansions for your present system, you may be forced to replace the system even if you are happy with its operation.


Lightning damage and protection
Is your control system suffering from repeated lightning damage? Are you’re making expensive repairs? It may just be poor grounding or other site-specific issues or it may be a fundamental design problem with your existing controls. Consider upgrading your electrical grounding and protection systems or replace the old controls with a more lightning hardened system capable of withstanding most lightning events and transient voltage spikes.


Requirement changes
Is your control system still up to the task to handle the environmental equipment you have installed? What is lacking in your current system? What do you like most and least about it? Do newer control systems offer desirable control capabilities and management features not available with your current system?

Can your current controls vendor provide you with the level of expertise needed to properly integrate and control all your greenhouse equipment? Does the control vendor have sufficient specialized knowledge of horticultural production and production systems?

Do you need more than climate control? Do you want to move from “islands of automation” towards “integrated control”, placing all of the control, monitoring and alarm functions under a single management system?

Are you planning a significant greenhouse expansion or upgrades? If so, now is the time to consider upgrading or replacing the control system to put your operation in the best position for the new expansion.

The latest control technology typically delivers more “bang” for fewer “bucks”. Money saved using the latest technology for an expansion may partially pay for the upgrade or retrofit of existing controls. Central data recording and alarms can be very valuable, allowing “management by exception” strategies that save valuable management time and improve production efficiency.


Considering your options
Staying with what you have might be the best option, even if what you have is not perfect. It is certainly the least expensive choice in the short term. But be careful you are not losing efficiency or crop yield and quality that can cost you a lot more in the long run.

Expanding your current control system may be a less than optimal choice. However, expanding an older system is still a legitimate path, particularly if the expansion is only a small part of your entire system.

Many control vendors offer system upgrades, including software and firmware for improvements in control or usage. If your system is more than a few years old, it is more likely that you will need more significant upgrades with sensor or control hardware upgrades or replacements. If these upgrades can work within the overall structure and wiring of your current system, they will still be much less expensive than purchasing and installing a new system. They should be able to deliver “like new” results.

Consider replacing what you have with a different control system if you are unhappy with the capabilities, service or support you are receiving from your current vendor. Also consider replacing a very old system that has otherwise served you well. In this case, your old supplier should be high on your list for a new system.


What will it cost?
Costs range from a few percent of system replacement cost for software and firmware upgrades only up to 20-30 percent (or more) for more complete upgrades involving hardware and sensors. Expanding an older system often costs more than installing a newer system, so upgrade costs may be partially offset by expansion savings.

The new control system cost is only part of the total replacement cost. It must also be properly configured and commissioned for your greenhouse application. You need to install it and learn how to effectively use it. You may be able to make use of some existing cabling, panels and line voltage interfacing equipment, but there are risks with doing this. The existing equipment will likely wear out and become unreliable sooner than the new equipment.


Finding the right fit
There are good control products available in all capability ranges. Take time to understand the features and limitations of the various control company offerings. Consider the companies’ track records. Do they have a long history of good customer support? Do they have the flexibility to address your needs in a way that works best for you? Are their products reliable and their emergency response quick and effective?

If you currently own a control system, start with the features you already have and make a list of additional capabilities you would like. Take time to find out how each vendor tackles the types of control problems associated with your facility and your equipment. Some vendors may not be capable of doing some of the things you need, while others may be difficult to work with when you need to custom fit their control system to your specific needs.

Your control system should last at least 10-15 years. Make sure it is capable of meeting your future requirements over this time frame. This is difficult to do, but you should not have to commit any extra money upfront to ensure good future expansion and upgrade potential.

Try to pick a vendor that is capable of meeting your future requirements over a vendor that can just meet your current needs. But don’t spend too much time or money purchasing a system that is far beyond your current needs just because you “might” need something more in 10 years.


Looking ahead
Small, stand-alone control systems work best for smaller, simpler greenhouses. Integrated control systems should be considered as the size and/or complexity of your operation increase. Running a 100 zone greenhouse operation without central monitoring, alarming and management would be difficult, but it would also be difficult to economically justify such a system for two Quonset houses.

A properly functioning greenhouse control system costs just a few cents per square foot per year. The system has the potential to save you much more through lower energy usage and better crop production conditions leading to higher yield and quality.

Upgrading or replacing older control systems also requires a lot of planning and management commitment during the selection and implementation of a new installation. If your older system is falling behind, ask yourself if you plan to be in business five or 10 years from now? If you do, an upgraded or replacement control system may be one of the best investments you can make in your own future.


David Flood is greenhouse horticulture consultant, Flood Technical Services, (604) 414-0695; dflood@twincomm.ca. Alec Mackenzie is director research and development, Argus Control Systems Ltd., and board of director member and director of the Education Committee of National Greenhouse Manufacturers Association, (800) 667-2090; www.arguscontrols.com.