A temperature and humidity sensor measures the ambient temperature and relative humidity at a site, inside a building, or within an enclosure. The measurements are typically expressed in degrees Celsius (°C) and percent relative humidity (% RH). The dew point can also be calculated from these two measurements. If a surface cools to this temperature or below, water vapour may condense on it.

Temperature and Humidity Sensors at a Glance

• The sensor monitors environmental conditions in technical rooms, control cabinets, production areas, and energy systems.
• Temperature and relative humidity must be evaluated together because relative humidity depends on temperature.
• The calculated dew point helps identify potential condensation on cooler surfaces at an early stage.
• Thresholds, time delays, and hysteresis enable targeted alarms for critical environmental conditions.

How Are Temperature and Humidity Measured and the Dew Point Calculated?

A temperature and humidity sensor typically combines two sensing elements in a single device. The temperature sensing element measures the thermal conditions at the installation location. The humidity sensing element determines the relative humidity as the ratio between the existing water vapour content and the saturation level possible at the respective temperature.

The saturation vapour pressure increases as the temperature rises. Therefore, if the water vapour content remains constant, the relative humidity decreases when the air warms and increases when it cools. A humidity value should therefore not be evaluated independently of the temperature measured at the same time.

The dew point can be calculated from the temperature and relative humidity. If a surface cools to this value or below, condensation may form. This is particularly relevant in control cabinets, technical rooms, and enclosures because moisture can contribute to corrosion, insulation problems, or malfunctions of electrical components.

The measurements are transmitted to a data logger, controller, or energy management system (EMS). Depending on the sensor type, transmission may use an analogue 0–10 V or 4–20 mA signal or a digital interface such as RS-485 or Modbus. The connected system can store and visualise the measurements and compare them with operating conditions, performance data, or fault messages.

Where Are These Sensors Used in Energy Monitoring?

Temperature and humidity sensors support various monitoring tasks:

• In BESS rooms, inverter stations, and server rooms, they can indicate excessive temperatures, high humidity, or insufficient ventilation.
• In control cabinets and data logger enclosures, they help identify thermal stress and potential condensation risks.
• In production areas and warehouses, they document environmental conditions that may affect processes, products, or technical components.
• In cooling, ventilation, and heating systems, they make it possible to verify whether the intended climate control is operating effectively.

Historical measurements can also help investigate faults, performance deviations, or accelerated component ageing in relation to environmental conditions.

Measurement Quality, Alarms, and Technical Requirements

The sensor’s position significantly affects the validity of its measurements. Direct sunlight, nearby heat sources, air outlets, or poorly ventilated areas can produce values that are not representative of the entire monitored area. Sensors used outdoors therefore require suitable radiation and weather protection.

Measurement accuracy, calibration, protection rating, and the permitted temperature and humidity ranges must be suitable for the installation environment. It is also necessary to verify whether the available communication interface, supply voltage, and cable length are compatible with the sensor.

Alarm configurations should include not only upper and lower thresholds but also time delays and hysteresis. A time delay prevents alarms from being triggered by brief, non-critical fluctuations. Hysteresis defines how far the measurement must return towards its normal range before an alarm is reset.

Integration into EcoPhi Monitoring

EcoPhi can integrate temperature and humidity sensors through available analogue or digital interfaces. By default, the sensor data is used for monitoring, storage, visualisation, and alarms. The measurements can also be compared with system operating conditions, performance data, or fault messages.

Active control of ventilation, cooling, or heating can be implemented on a project-specific basis, provided that compatible actuators and control interfaces are available. The specific functionality depends on the devices used, the available interfaces, and the project requirements.

Conclusion: Reliable Monitoring of Environmental Conditions

A temperature and humidity sensor provides measurement data on the environmental conditions within an energy system or technical environment. Appropriate positioning and configuration are essential to ensure that critical changes are detected reliably and can be considered when analysing system conditions.

Frequently Asked Questions

What Does a Temperature and Humidity Sensor Measure?

The sensor measures the ambient temperature in degrees Celsius and the relative humidity as a percentage. The dew point can also be calculated from these two measurements.

Why Is the Dew Point Relevant to Energy Systems?

The dew point is the temperature at which the air becomes saturated with water vapour. If a surface reaches or falls below this value, condensation may form on it.

Where Should the Sensor Be Installed?

The installation location should be representative of the area being monitored. Direct sunlight, local heat sources, air outlets, and areas without sufficient air circulation should be avoided.

Can a Sensor Control Cooling or Ventilation Directly?

The sensor initially provides measurement data. Active control additionally requires suitable control logic, controllable actuators, and compatible interfaces.