What is thermal comfort?
Thermal comfort is a complex concept, which can vary greatly from one individual to another. It is defined as the feeling of well-being that people experience in a given space, a feeling influenced by various parameters such as temperature, humidity, air quality and insulation.
Ambient temperature. This plays an essential role in the perception of thermal comfort. On average, in winter, a temperature of between 19°C and 21°C would be ideal. This can rise to around 24°C in summer.
Wall temperature. The temperature of surfaces such as walls, floors and windows also affects the feeling of comfort. As you might expect, walls that are too cold or too hot can create an imbalance and affect comfort.
Air humidity. The relative humidity of the indoor air is another determining factor in thermal comfort. The ideal humidity level is between 40% and 60%. Any higher and you feel colder, which encourages you to turn up the heat.
Airflow. Draughts in a building or a room are something to be avoided. While they may be welcome in summer to help perspiration and cool the atmosphere, when it's cold they can cause discomfort by promoting heat exchange through convection.
Added to this is each person's metabolism and clothing, which also affect the sensation of thermal comfort.
The new RE2020 environmental regulations have made thermal comfort an important objective of the energy transition, particularly in terms of summer comfort and the fight against heat leakage.
Why seek thermal comfort?
Improving the thermal comfort of a building is not just about the comfort of the occupants. Of course, this is essential for their well-being, but other important considerations must also be taken into account:
The sustainability of buildings. Adequate thermal comfort prevents problems of humidity and temperature variations that can damage building materials and alter air quality.
Energy savings. An effective thermal comfort management system can reduce energy loss by controlling heating and cooling costs.
Reducing the ecological footprint. Optimising energy consumption helps reduce the ecological footprint, which is crucial in the current context of energy transition.
How can thermal comfort be optimised in building management systems?
Thermal comfort needs to be addressed right from the construction or renovation stage. By using the right materials for optimum insulation of the roof, floors, walls and windows, the building can guarantee a minimum level of comfort. Similarly, a well-designed ventilation system ensures healthy air and helps to regulate indoor temperature and humidity.
However, building management systems can go much further, providing sophisticated, almost personalised control of a wide range of equipment. Installing devices that continuously regulate the main elements that contribute to well-being is an investment that quickly pays for itself. It allows you to act on:
- Temperature variations linked to the sun's rays. In summer, during heatwaves, windows - even double or triple-glazed windows - can be real heat conduits. Shutters and blinds can be controlled automatically. Shuttering can be triggered when the sun hits a pane directly and the temperature rises significantly in the room concerned.
- Measuring temperatures and humidity. IoT sensors are essential for monitoring temperature and humidity levels. They can send alerts when a threshold is reached.
- Thermostats can be fitted to radiators or heating/air conditioning units. When connected, they can be activated according to the thresholds defined in the building's energy and thermal strategy.
IoT, is an effective solution for improving thermal comfort in buildings
IoT solutions such as Wattsense can be used to centralise the collection of all sensor readings continuously, produce alerts and help to manage equipment to achieve a level of thermal comfort tailored to each individual.
IoT: An Effective Solution for Improving Building Thermal Comfort
IoT solutions, such as Wattsense, enable the centralised collection of continuous sensor measurements, generate alerts, and assist in equipment management to achieve a level of thermal comfort tailored to individual needs.
How Wattsense Enhances Thermal Comfort with BMS and IoT
Optimising thermal comfort begins with a building's design or renovation, incorporating effective insulation and adequate ventilation. However, Building Management Systems (BMS) allow for far greater sophistication, offering responsive and precise control.
Wattsense integrates the power of IoT (Internet of Things) for detailed and personalised thermal comfort management:
- Precise Monitoring with IoT Sensors: Connected sensors continuously measure temperature, humidity, and air quality in each zone. This data is crucial for accurately adjusting the setpoint temperature.
- Intelligent Equipment Control: Our solution automates the management of heating, air conditioning, and ventilation systems.
- Simplified Interoperability: Wattsense centralises data from all your equipment, regardless of their protocol (BACnet, Modbus, LoRaWAN, etc.), providing you with a comprehensive overview and unified control.
- Custom Alerts and Scenarios: Configure alerts for threshold exceedances and create automation scenarios to maintain optimal thermal comfort while minimising consumption.
Open the doors to efficient building management with the Wattsense solution! Our connectivity solution enables you to optimise the performance of your buildings effectively while keeping costs under control. By allowing you to take back control of the technical equipment in your buildings, whatever their size, condition or use, you can rapidly improve energy efficiency, maintenance and occupant comfort. Ask for a demo to find out more.
What is Thermal Comfort? Definition and Building Management Strategies
In the modern built environment, the relationship between occupants and their workspace has undergone a fundamental shift. We no longer view a building as a mere shell, but as a dynamic environment that must actively support the well-being of those inside. Central to this evolution is the concept of thermal comfort.
For Facility Managers and property owners, achieving consistent thermal comfort is one of the most challenging aspects of building operations. It is a subjective state that involves complex physics, human physiology, and mechanical engineering. However, in the era of the Smart Building, new technologies are allowing us to move beyond simple thermostats toward precise, data-driven climate management.
Defining Thermal Comfort in the Context of Smart Buildings
To manage a building effectively, we must first answer a fundamental question: what is thermal comfort? According to most technical definitions, it is "that condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation." In simpler terms, it is when a person feels neither too hot nor too cold.
In a Smart Building, thermal comfort in buildings is treated as a key performance indicator (KPI). It is no longer acceptable to rely on seasonal setpoints. Instead, modern systems use IoT sensors to monitor the environment in real-time, ensuring that the HVAC system responds dynamically to changing occupancy and external weather conditions.
The HSE and ASHRAE Standards Explained
To provide a framework for engineers, several global bodies have established rigorous standards. In the UK, the Health and Safety Executive (HSE) provides guidelines ensuring that employers provide a "reasonable" temperature in the workplace. While the HSE does not mandate a specific temperature, it suggests a minimum of 16°C (or 13°C for rigorous physical work).
On a more technical level, ASHRAE Standard 55 is the international benchmark for thermal comfort in buildings. It defines the range of indoor environmental conditions that will be acceptable to a majority of occupants. ASHRAE 55 considers the interaction between environmental variables and personal factors, providing the mathematical models used by modern Building Management Systems (BMS) to automate climate control.
Why Thermal Comfort Matters for Productivity and Health
The importance of maintaining thermal comfort in buildings extends far beyond simple luxury. Research consistently shows a direct link between indoor environmental quality and human performance. When a workspace is too warm, occupants often experience lethargy and a drop in cognitive function. Conversely, an environment that is too cold can lead to distraction and physical discomfort.
Poorly managed thermal conditions are also a primary contributor to "Sick Building Syndrome." Stale air and improper humidity levels can aggravate respiratory issues and facilitate the spread of airborne pathogens. For business owners, investing in high-quality thermal management is a strategic move to reduce absenteeism and enhance the long-term health of their workforce.
The 6 Primary Factors Influencing Thermal Comfort
To understand how to control the indoor climate, one must look at the six primary factors defined by the Fanger model. These factors are split into environmental variables, which the building systems can control, and personal variables, which are specific to the occupants.
Effective thermal management requires a BMS that can ingest data related to all these factors. By using IoT sensors, facility managers can gain a holistic view of how these variables interact to create a comfortable or uncomfortable space.
Environmental Factors: Air Temperature, Radiant Temperature, Air Velocity, Humidity
The building's technical infrastructure is responsible for managing these four variables:
- Air Temperature: This is the most common metric, referring to the temperature of the air surrounding the occupant. It is what most people mean when they ask, "what is thermal comfort?"
- Mean Radiant Temperature: This refers to the heat radiating from surfaces like windows, walls, and machinery. A person sitting next to a cold window in winter may feel chilled even if the air temperature is high.
- Air Velocity: This is the speed of air moving across the occupant. Moving air can provide a cooling effect (drafts), which is beneficial in summer but detrimental in winter.
- Relative Humidity: This measures the moisture content in the air. High humidity prevents sweat evaporation, making people feel "sticky" and hotter, while low humidity can cause dry skin and throat irritation.
Personal Factors: Metabolic Rate and Clothing Insulation
The remaining two factors are human-centric and vary from person to person:
- Metabolic Rate: This is the heat produced by the human body during physical activity. Someone walking up stairs will have a much higher metabolic rate than someone sitting at a desk, requiring a cooler environment to stay comfortable.
- Clothing Insulation: Often measured in "clo" units, this is the thermal resistance provided by an occupant's outfit. A building's HVAC system must often be adjusted based on seasonal clothing trends (e.g., heavy sweaters in winter vs. light shirts in summer).
Measuring Comfort: Understanding PMV and PPD Indices
To turn subjective feelings into actionable data, engineers use two key indices: PMV and PPD. These metrics allow Facility Managers to quantify comfort levels across an entire floor or building.
PMV (Predicted Mean Vote) is an index that predicts the mean value of the votes of a large group of people on a seven-point thermal sensation scale, ranging from -3 (cold) to +3 (hot). A PMV of 0 represents the ideal "thermal neutrality."
PPD (Predicted Percentage of Dissatisfied) is a related index that establishes a quantitative prediction of the percentage of thermally dissatisfied people. Because human preference varies so widely, it is impossible to satisfy 100% of a group. Even at a PMV of 0, the PPD is usually around 5%, meaning one in twenty people will still find the environment suboptimal.
Challenges in Maintaining Thermal Comfort in Commercial Real Estate
Despite the availability of standards and metrics, maintaining thermal comfort in buildings remains a significant operational hurdle. Most commercial properties suffer from technical debt and fragmented systems that make precise control difficult to achieve.
When these challenges are left unaddressed, the result is a "comfort gap" where occupants are unhappy and energy is wasted. Overcoming these barriers is the first step toward a more sustainable and high-performing building portfolio.
The Issue with Siloed HVAC Systems
In many older buildings, the HVAC system operates as a closed loop, isolated from other building data. For example, the heating might be controlled by a legacy boiler system while the cooling is managed by independent AC units. These siloed systems often "fight" each other, with heating and cooling running simultaneously in the same zone.
Without an integrated Building Management System, there is no "single source of truth." Sensors in the room might report a need for cooling, but the central plant remains unaware. This lack of interoperability prevents the implementation of sophisticated comfort strategies and makes it impossible to calculate real-time PMV or PPD scores.
Overheating and Energy Waste
Overheating is a common problem in modern, glass-heavy architecture. Without proper management of mean radiant temperature and solar gain, buildings can become "heat traps." Traditional systems often respond by running fans and chillers at 100% capacity, which leads to massive energy waste and high operational costs.
True energy efficiency is found in the balance between comfort and consumption. If a building is over-cooled to compensate for radiant heat, the air temperature might be too low for comfort, even if the radiant temperature is high. This mismatch results in an inefficient use of resources and a poor experience for the occupant.
How to Manage Thermal Comfort with BMS and IoT Connectivity
The solution to these challenges lies in connectivity. By bridging the gap between physical machinery and digital intelligence, we can turn a "dumb" building into a responsive environment. The integration of IoT sensors and modern gateways allows for a more granular approach to climate management.
By collecting data from every corner of the facility, managers can identify precisely where comfort is lacking. This transparency allows for targeted interventions that improve performance without requiring a total overhaul of the existing HVAC system.
Collecting Data with Interoperable Sensors (LoRaWAN, MQTT)
The first step in modern comfort management is the deployment of IoT sensors. Unlike traditional wired sensors, wireless technologies like LoRaWAN allow for rapid, non-invasive installation. These sensors can be placed at desk level to measure the actual conditions experienced by the occupant, rather than relying on a single sensor in a hallway.
These sensors can track:
- Real-time air temperature and relative humidity.
- CO2 levels (as a proxy for occupancy and metabolic rate).
- Light levels and proximity to windows.
Using a protocol like MQTT, this data can be pushed to the cloud or a local supervisor, providing a continuous stream of information that forms the basis for automated control logic.
Centralizing HVAC Control via BACnet and Modbus
To act on the data collected by IoT sensors, the building's controllers must speak a common language. BACnet and Modbus are the industry standards for building automation. By unifying these protocols, Facility Managers can centralise their HVAC control.
This interoperability allows for "Demand-Controlled Ventilation" and "Dynamic Setpoint Adjustment." For example, if LoRaWAN sensors detect high occupancy in a meeting room, the system can automatically increase the air velocity and lower the temperature via the BACnet-connected air handling unit. This responsive approach is the hallmark of a truly smart building.
Optimizing Building Climate with Wattsense Solutions
Wattsense provides the technology to simplify building management and solve the complexity of thermal comfort. We remove the technical barriers to data acquisition and control, allowing you to centralise your operations and improve building performance.
Our mission is to help you save time and cut operational costs by making your building's technical assets accessible and interoperable. Whether you are an integrator, a facility manager, or a PropTech developer, Wattsense offers the infrastructure you need to master thermal comfort in buildings.
Wattsense Bridge: Unifying Local Data for Precise Monitoring
The Wattsense Bridge is our foundational solution for local data acquisition. It is the most innovative open, interoperable IoT gateway on the market. It is designed for distributors and integrators who need a reliable local bridge to connect diverse equipment to a BMS.
The Bridge allows you to:
- Collect data from LoRaWAN sensors and redirect it locally to a BMS via BACnet or Modbus.
- Manage gateway settings remotely via a cloud console.
- Ensure real-time data access for immediate on-site control and automation.
The Bridge is ideal for projects requiring a reliable link between new wireless sensors and existing wired infrastructure, enabling local automation based on real-time comfort conditions.
Tower Control: Automating HVAC for Optimal PPD Scores
For small and medium-sized buildings, Tower Control acts as a "Light BMS." It is a complete automation solution that provides a full suite of tools for monitoring, controlling, and optimizing building performance. Tower Control puts you in command of your thermal environment.
Main features include:
- Automation Scenarios: Create custom rules to optimize energy consumption and comfort based on PMV/PPD targets.
- Scheduling: Implement time-based controls for HVAC to ensure energy isn't wasted during unoccupied hours.
- Remote Alarms: Receive instant notifications for critical events, such as a boiler lockout or a sudden spike in temperature.
- Dashboards: Visualize building performance with customizable insights, making it easy to prove the ROI of your comfort strategy.
Tower Lift: Leveraging Historical Data for PropTech Analytics
Tower Lift is our IoT solution designed for those who want to leverage building data without needing direct automation capabilities. It focuses purely on efficient and secure data retrieval, providing powerful cloud connectivity for PropTechs and data-driven managers.
Through Tower Lift, you can access:
- Data Historisation: Store and access years of thermal comfort data for in-depth analysis and reporting.
- API & Webhook Integration: Seamlessly push building data to your preferred cloud platforms and Energy Management Systems.
- Scale: Ideal for residential portfolios where the primary need is to collect vast amounts of data (e.g., electricity, water, and environmental sensors) for billing, predictive maintenance, or tenant experience apps.
Wattsense is the bridge between your building and the future of IoT. By centralising your data and simplifying your connectivity, we help you turn any facility into a high-performing, comfortable, and efficient asset. Take command of your indoor environment today and experience the power of truly integrated building management.