The race to Net Zero is reshaping the way we manage our built environment. Facility managers and sustainability leads are under increasing pressure to reduce carbon footprints and optimise energy consumption. While smart lighting and temperature control have become standard in the green building playbook, there is a critical environmental variable that remains largely uncontrolled in many facilities: humidity.
Relative Humidity (RH) is often treated as a secondary concern. It is frequently seen as an issue only addressed when occupants complain of stuffiness or when damp patches appear on walls. However, from a thermodynamic perspective, water vapour is an energy carrier. Uncontrolled humidity forces HVAC systems to work significantly harder, which drives up energy usage and carbon emissions.
This guide explores how the humble humidity sensor is becoming a cornerstone of sustainable building management strategies.
The Quick Answer
Humidity sensors are a vital tool for reducing energy waste through Demand Controlled Ventilation. Moist air holds significantly more heat energy than dry air, meaning high humidity forces air conditioning systems to work harder to cool a space (latent load). Conversely, dry winter air makes rooms feel colder than they are, prompting occupants to increase heating. By monitoring real-time humidity data via IoT sensors, Building Management Systems can optimise HVAC cycles to maintain the comfort zone without over-conditioning the air. This precise control not only lowers energy bills but also prevents mould growth, protecting the building fabric and reducing the carbon footprint associated with repairs.
The Thermodynamics of Comfort and Energy
To understand the energy cost of humidity, we must look at the relationship between “Sensible Heat” (temperature) and “Latent Heat” (moisture).
The “Feels Like” Factor
Human comfort is not determined by temperature alone. It is determined by how effectively our bodies can cool themselves via evaporation, or sweating.
When humidity is high, sweat cannot evaporate efficiently. We feel hotter and stickier. In response, building operators often lower the air conditioning setpoint to 19°C or 20°C to compensate. This is incredibly energy-intensive.
By using sensors to keep humidity within the optimal range (40% to 60% RH), you can actually raise the thermostat temperature to 23°C or 24°C while maintaining the same level of occupant comfort. For every 1°C increase in setpoint, you can save approximately 3% to 5% on cooling energy.
Reducing the Latent Load
Air conditioning units do not just cool air; they dehumidify it. A significant portion of an HVAC system’s energy consumption goes toward removing moisture (latent load) before it even begins to lower the temperature (sensible load).
Without sensors, systems run on rigid schedules or simple thermostat feedback. With networked humidity sensors, the system can distinguish between a hot and dry day versus a hot and humid day. This allows it to adjust fan speeds and compressor cycles to use the minimum energy required to achieve comfort.
Protecting the Asset: The Sustainability of Longevity
A “green” building lasts. The embodied carbon involved in constructing a building is immense; therefore, preserving the building fabric is a key tenet of sustainability.
The Mould Menace
Mould and damp are silent destroyers. High humidity leads to condensation on cold bridges, such as windows and structural beams, fostering mould growth.
The carbon cost of remedying severe mould damage is high. It often requires stripping out drywall, replacing carpets, and repainting. This generates landfill waste and requires new materials (and their associated carbon emissions) to be manufactured and transported.
IoT humidity sensors act as an early warning system. They can trigger alerts when RH levels creep above 70% for sustained periods. This allows facility managers to intervene, perhaps by boosting ventilation temporarily, before condensation forms and mould spores germinate.
The IoT Advantage: Why LoRaWAN?
Historically, monitoring humidity was difficult. Wired BMS sensors are expensive to install as they require cabling to be chased into walls. They are typically located only where the thermostat is, often near a door, which rarely represents the true conditions of the room.
The revolution lies in LoRaWAN (Long Range Wide Area Network) technology.
Retrofit Ready
LoRaWAN Sensors are battery-powered and wireless. They can be deployed in minutes with no drilling or wiring. This makes them ideal for retrofitting older, energy-inefficient buildings. These are often the buildings that need green upgrades the most.
Granular Data
Because the sensors are affordable and wireless, you are not limited to one per floor. You can place them in critical “microclimates” throughout the facility.
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Near Windows: To detect condensation risks where cold glass meets warm air.
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In Ceiling Voids: To detect hidden leaks or damp from roof issues.
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In High-Density Meeting Rooms: To manage the rapid spike in humidity caused by breath when people gather.
Case Use: Smart Ventilation in Action
Consider a typical modern office building with a Variable Air Volume (VAV) ventilation system.
The Old Way: The ventilation runs at a fixed rate from 8:00 AM to 6:00 PM. On a rainy Tuesday with few staff in the office, the system brings in humid outdoor air, dehumidifies it, and pumps it into an empty room. This is energy waste.
The Concept13 Way:
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Monitor: Wireless sensors detect that the meeting room is empty via CO2 and humidity levels.
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Transmit: The data is sent via a LoRaWAN Gateway to the cloud.
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Act: The platform instructs the BMS to ramp down the ventilation dampers for that specific zone.
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Result: The main Air Handling Unit (AHU) slows down its fans. Energy is saved.
Occupant Health: The 40 to 60 Percent Sweet Spot
A green building must also be a healthy building. The “Sterling Chart” of biological contaminants shows that maintaining Relative Humidity between 40% and 60% is critical for health.
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Below 40% (Too Dry): Viruses, such as influenza and COVID-19, survive longer in dry air and travel further in aerosols. Dry air also irritates respiratory tracts, leading to higher absenteeism.
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Above 60% (Too Wet): Bacteria, dust mites, and mould thrive.
By automating humidity control, companies not only reduce energy bills but also create a healthier environment that protects workforce productivity.
Conclusion
Humidity is the invisible variable that dictates the efficiency of our heating and cooling systems. By ignoring it, we force our buildings to run inefficiently, wasting energy and shortening the lifespan of the property.
The transition to greener buildings does not always require a complete overhaul of the mechanical plant. Often, it simply requires better eyes and ears. With the deployment of simple, robust LoRaWAN humidity sensors, facility managers can visualise this invisible data. This allows them to optimise their energy usage and secure the health of both the building and its occupants.
If you are looking to retrofit your facility with smart environmental monitoring, browse our range of Smart Building Solutions or contact our technical team to discuss your LoRaWAN network requirements.
