Understanding An Environmental Control System

If you are still controlling your greenhouse environment with thermostats, or even manually, energy prices warrant that these days must come to a close. The initial cost of a thermostat is very low and fits into any budget. The increased cost to have a thermostat operating your greenhouse equipment however will astound you.

The control system you choose does not have to be an expensive and complicated computer system. There are many products on the market starting at under $1,000 that will let you control your heating and cooling costs very well. The new digital controls will let you have separate day and night settings for both heating and cooling. You can utilize DIF in your plant growth program. You can even record high and low temperature readings for later recall. The payback for installing a digital environment control is realized in as little as a couple of months depending on the size of your range.

How does a greenhouse computer control the greenhouse?

The word computer can be very intimidating. Actually, “a computer” really refers to a small microprocessor chip no larger than the width of your two fingers. What the microprocessor has allowed us to do, like virtually all industries that use control methods, is to monitor many sensors at one time, and make “intelligent” decisions on what to do, and when to do it.

What should the grower look for?

The grower should look for the features that they need, the reliability that is a must, and a price that they can afford. If a grower does not have the time and the manpower to devote to a large, complicated system, then a smaller system would be in order. The reality is that some companies will stress these major, all inclusive systems. The down side is, that all growers are not ready for these. One does not need to spend tens of thousands of dollars to have reliable, efficient computer based control. If a grower is just converting over from a thermostat or a manual system, start slow. Do one range, try it out, then proceed. After all, environmental control is only one item that today’s grower has to worry about.

How can the investment pay off?

The major payoff will be in energy savings. Simply overheating a greenhouse by a single degree can cost thousands of dollars in wasted energy. With some of the algorithms available, we can adjust temperatures based on solar gain, outdoor temperature, time of day, energy demand periods, etc. For instance, on a hot water system, why fire the boiler to a very high temperature on a fairly mild evening? Labor cost would come in at number two. Obviously having a reliable machine performing these tasks instead of a compensated employee is a plus.

What happens when the power goes out?

When the power goes out, well, nothing will work unless there is a generator. Almost all of the major control systems use a memory backup. Storing all of the grower settings, as well as the operational system in something called an EEPROM. This memory is nondependent on power, or even on a battery. When the power comes back on, and proves that it is stable, everything returns to a normal start up mode. This allows the addition of equipment loads gradually.