Sensors - Hoogendoorn Growth Management

A Batenburg Techniek company

The proper combination of temperature, humidity, CO2

and growth light in your greenhouse determines the health and vigorousness of your crop. A proper balance also helps you to prevent diseases and plagues.

The Measurement Box contains sensors that measure the temperature and humidity in the air. The plastic housing protects the sensors from water and dust and against the sun’s direct rays. The Measurement Box is equipped with an integrated fan and air filter. The fan sucks in the greenhouse air, filters it and runs it along the sensors. As options, an electronic relative humidity sensor and a CO2 sensor can be installed in the Measurement Box. The values that are measured provide a good and reliable indication of the temperature and humidity in the greenhouse.

The Measurement Box

Sensors are an essential component of every process control system. Hoogendoorn has a broad range of sensors: from simple sensors to measure the temperature of water and air to advanced sensors to determine the microclimate and activity of your crop. Sensors give you complete insight into all growth factors in your greenhouse. For example, based on measured values, you know what the best time is to adjust the opening of the windows, to open or close the shades and when lighting must be turned on or off. The sensors can be completely integrated into the iSii process computer. The values that are measured by the sensors are used by the iSii software to optimize process controls.

The Hoogendoorn sensor assortment is below.

Sensors


Next to light for growing, CO2 is the most important growth factor for the crop. The right concentration of CO2

is important because too high a value can damage the crop. Good measurement of the CO2 concentration is thus essential. Depending on the measured CO2 concentration, the proper dosage of CO2 can be determined, in combination with the sun’s rays or artificial lighting.

Electronic CO2 sensor

The relative humidity (RH) of the greenhouse air is an important climate factor for the crop. The dry-wet bulb principle works with two temperature sensors and is relatively simple and reliable. Humidity can be measured from both measurements. For purposes of the wet bulb principle, the Measurement Box is equipped with a water reservoir.

Dry - wet bulb relative humidity sensor

The electronic RH sensor is an alternative for the dry-wet bulb principle and requires less maintenance, such as topping up the water reservoir. The electronic version is suitable for both inside and outside the greenhouse, making it applicable in places that are difficult to reach. This allows you to regulate the greenhouse climate even better.

Electronic RH sensor


The outside conditions such as the outside temperature, sunshine and wind have a strong influence on the greenhouse climate. For this reason, weather sensors that can record varying weather conditions precisely are necessary for proper process control. Hoogendoorn weather sensors are delivered in combination with a special weather mast. This mast can be mounted quickly and easily outside the greenhouse.

In addition, optional sensors can be installed on the weather mast for more specific measurements of the outside conditions such as outside relative humidity, Pyrgeo sensor and a precipitation intensity meter.

Weather sensors

The sun is by far the greatest heat source for the greenhouse. In addition, the sun is determinant for crop evaporation and irrigation. So the measurement of the overall sun’s rays is of great importance for the regulation of the climate. Solar radiation is measured with a Pyrano sensor, also called a Solarimeter.

Hoogendoorn supplies a Pyrano sensor that satisfies the international norms for meteorological observations. With this, you are not only certain of a reliable measurement, but you can also compare the measurement with the sunshine information of the official weather forecasts.

Sun’s rays / Pyrano sensor

The outside temperature is an important factor for the greenhouse climate. This is true when the windows are shut, but certainly when the greenhouse is being ventilated. The outside temperature sensor allows the iSii process regulation to control the heating, ventilation and energy screen controls properly. By preventing a back-and-forth between ventilation and heating, an even and energy-efficient greenhouse climate is achieved.

The sensor is set up in a special housing that ensures sufficient ventilation of the sensor. Precipitation, direct sunlight and reflection have no influence on the measurement.

Outside temperature sensor

A standard weather mast is equipped with the following sensors:• Outside temperature

• Sunshine / Pyrano sensor• Wind speed

• Wind direction• Precipitation

Various sorts of sensors are explained briefly below.


Wind speed is also a factor in determining the greenhouse climate in the operation of the air vents. The air vents deliver more effect, for example, when the wind blows hard. Data from a wind speed sensor is used in the iSii process control to optimize the regulation of the heating and the energy screens, among other things. Moreover, the measurement is important for limiting some controls at times when the wind is blowing too hard. Air vents can be closed at wind speeds at or above a certain limit, for example, to prevent storm damage to the greenhouse and the crop.

Wind speed sensor

Precipitation in the form of rain, hail or snow has a strong influence on the greenhouse climate. On the one hand due to greater heat loss, on the other hand because the ventilation windows must be closed immediately to prevent the crop getting rained on and wet. The precipitation sensor detects precipitation because the sensor surface gets wet.

The signal of precipitation/no precipitation is passed on to the iSii process computer, which then reacts to this quickly and accurately by adjusting the controls for heating and closing air vents, among other things. The sensor’s sensitivity is adjustable so that you can choose the precipitation intensity at which the controls must be turned on. The precipitation sensor has a built-in heating element that ensures that the sensor dries quickly after a rainstorm so that normal regulation of the greenhouse climate is resumed.

Precipitation sensor

For greenhouses with air vents on both sides of the peak, a distinction is made between the lee side and the windward side. Depending on the wind direction, ventilation can be opened on the lee side, the windward side or on both sides for the best effect on the greenhouse climate. In addition to ventilation controls, many other controls can be linked in the iSii process computer, such as shades and irrigation. For example, with dry winds from the east, watering can be increased as a preventive measure.

Wind direction sensor


As a supplement to the precipitation sensor that detects the presence of precipitation, it may be useful or even necessary in some cases to measure the exact amount of precipitation per unit of time. This is done to take better account of the cooling effect of the precipitation. Beyond this, lots of precipitation in a short time can cause flooding. The precipitation intensity sensor works according to an optical principle and for this reason can also be used as a snow detector.

Precipitation intensity sensor/snow detection

The Pyrgeo sensor measures long-wavelength heat radiation. This is an important factor in the energy balance of plants and in the greenhouse as a whole. Under clear skies, cooling from “reflected radiation” is much greater than under cloudy conditions. Thanks to the Pyrgeo sensor, the control of the energy screen can be adjusted in the iSii process control - for example, to accommodate less or more reflected radiation. The result is that you save precious energy and, above all, prevent undesired cooling of the crop.

Reflected radiation / Pyrgeo sensor

Outside humidity has a strong influence on the greenhouse climate. If the air vents are opened, warm, damp greenhouse air is exchanged for cooler, drier outside air. To the extent that the outside air is drier, relatively more moisture is carried off at the same ventilation speed. For plants, low RH is often a more serious stress factor than a high greenhouse temperature. For this reason, low outside RH can be a reason to ventilate less, despite the fact that the greenhouse temperature increases.

An electronic type of outside RH sensor is used as a standard. This special version is suitable for all outside conditions such as precipitation. For more information, see Electronic RH sensor.

Outside RH sensor


The range of the plant temperature with respect to the greenhouse air temperature provides important information about the condition of the crop and offers the possibility of adjusting the climate control and irrigation even better to accommodate the needs of the crop. With this, you can prevent stress from drying out, among other things.

The plant temperature sensor measures the plant temperature using infrared radiation. This allows the sensor to determine the average temperature of a given surface on the crop so that the measurement from this sensor is stable and reliable.

Plant temperature sensor

PAR (Photosynthetically Active Radiation) or growth light is that portion of the light spectrum that the plant requires for photosynthesis. This is the process in which CO2 and water are turned into glucose. With this sensor, the lighting, CO2 dosage and the shading screens can be better controlled, among other things.

PAR sensor

To provide the plants with sufficient water, the irrigation is usually coordinated with the sun’s rays and with the lighting. Solar radiation and lighting determine crop evaporation to a high degree.

The scales measure the weight of the water content of the substrate and the crop. The use of the scales allows the working method for irrigation to be improved and refined.

Scales (substrate cultivation)


Get in touch with our Hoogendoorn experts or visit our website. T: | +31 (0)10 460 80 80E: | [email protected]

www.hoogendoorn.nl

Want to know more?

In addition to the sensors supplied by Hoogendoorn, virtually every conceivable sensor can be linked to the iSii process computer. Thanks to the iSii’s advanced software, the measurement values of these sensors can be recorded not only for more insight into the process, but can also be integrated into the process control so that they contribute directly or indirectly to an optimum result.

Every conceivable sensor can be linked to the iSii process computer

Optimum irrigation in substrate cultivation is a complex process. With strong plant evaporation due to high levels of radiation from the sun, the plant must have sufficient water. In addition, the substrate must be flushed to prevent the accumulation of nutrient elements. At low evaporation rates and at night, the roots must also get enough air. Hoogendoorn developed the Aquabalance to meet this challenge. This special sensor consists of three main components: precise scales (a standard length of 3 m), a reliable drain meter and intelligent software in the iSii process computer. Since Aquabalance tracks the water uptake of the crop precisely and starts a new drip at exactly the right moment, it is in fact the plant itself that regulates the irrigation according to its own needs.

Aquabalance

Option: The Aquabalance can be extended with sensors to measure and register the EC (nutrient concentration) and pH (degree of acidity) of the drain water.

© 2012 by Hoogendoorn Growth Management. All rights reserved.

Westlandseweg 190 | 3131 HX | Vlaardingen | the NederlandsP.O. Box 108 | 3130 AC | Vlaardingen |the Nederlands

T: | +31 (0)10 460 80 80F: | +31 (0)10 460 80 00 E: | [email protected]

www.hoogendoorn.nl

Hoogendoorn Growth Management

Worldwide innovator inhorticultural automation

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Sensors - Hoogendoorn Growth Management