A greenhouse, by definition, is a facility that provides controlled conditions in which plants requiring regulated climatic conditions are grown. Industrial-scale greenhouses are usually closely monitored environments, usually within a unified system.
Environment monitoring usually serves a dual purpose:
- Data Logging
- Alarm Notification
A data logger (also datalogger or data recorder) is an electronic device that records measurements, such as temperature or relative humidity, at set intervals over a period of time. Data loggers work either with a built-in instrument or sensor or via external instruments and sensors.
Needless to say, data logging is crucial in monitoring greenhouse environments. Certain industrial greenhouses are required by government institutions to be data logged. In these cases, the data logging process can and should be automated for reliability and prevention of human error.
One of the main reasons for monitoring greenhouse environments is for the purpose of risk management. In a critical environment like a greenhouse, where stability and reliability are of utmost importance, greenhouse operators need to receive alarms fast, if something goes wrong.
Remote monitoring systems are designed to control large or complex facilities. A remote or wireless monitoring solution will record data on a server and send alerts to those parties that need to be notified in case of an alarm, via text, email or phone.
There are two different types of temperature sensors:
- Contact sensors include thermocouples and thermistors that touch the object they are to measure.
- Non-contact sensors measure the thermal radiation a heat source releases to determine its temperature. Resistance Temperature Detectors (RTDs) are non-contact sensors.
An RTD is the most accurate and stable temperature sensor and is more linear than a thermocouple or thermistor. However, RTDs are the slowest and most expensive temperature sensors. Therefore, they are used in precision applications where accuracy is critical while speed and cost are less important.
A humidity sensor (or hygrometer) senses, measures and reports both moisture and air temperature. They work by detecting changes that alter electrical currents or temperature in the air.