Dear Colleagues,

In the modern era, people spend some 90% of their time inside buildings for living, working, shopping, recreation, etc. To provide thermal comfort and good indoor environment quality (IEQ), modern buildings account for about 40% of total energy consumption. To ensure the efficient use of energy in the building sectors for sustainable development, there has been a lot of R&D on developing smart buildings. A smart building consists of the physical building, its environment, information systems, and occupants. The intelligence of a building is based on its ability to know its operating status, environment, and occupants through intelligent sensing and information processing systems so that it can provide the essential intelligence, safety, good air quality, thermal comfort, and efficient energy consumption required of the modern building.

This Special Issue of Sensors, entitled Sensing in Smart Buildings, will focus on intelligent sensing and information processing techniques for smart buildings. There are a large number of challenges associated with intelligent sensing and information processing, including cost, energy efficiency, integration, low-impact spaces, easy setup, and user-friendliness. The intelligent system is the main reason why it is called a ‘smart’ building, be it a ‘smart home’, a ‘smart office’, a ‘smart mall’, or a ‘smart service’. These smart systems usually include a heating, ventilation, and air-conditioning (HVAC) system, a lighting system, a smart grid, an indoor robotic system, etc., and their associated sensors. Since occupants are important service objects, the occupant information, including the number of occupants, locations, and activities, is another critical factor for sensing in smart buildings.

Intelligent sensing and information processing capabilities of a ‘smart’ building will determine its abilities to sense and monitor the interacting environment so as to provide optimal and efficient services to its users. The sensing building environment includes observations of building indoor/outdoor temperature, humidity, radiant temperature, air velocity, pollution density, occupants and their localization, localization of pollution sources, localization of wall cracks and abnormalities, impacts on the health and wellness of occupants, etc. The environment sensing of a smart building presents a number of academic and practical challenges, which include (but are not limited to) the following issues:

• Sensor selection and placement: A smart building requires a large amount of various types of sensors. To guarantee good sensing of the building, there will be redundant sensors. How to select the right sensors and find suitable locations to place them to guarantee sensing quality and reduce the amount of sensors is a big challenge in this area.
• Occupancy estimation: The number of indoor occupants will impact the services required of the building and its intelligent systems. How to achieve a good estimation of the number of indoor occupants in a low-cost, nonintrusive way is a hot research area.
• Localization: Accurate positioning of indoor pollution sources, occupants, and indoor robotics are important factors in providing building safety and comfort, as well as services. How to localize them in a low-cost and user-friendly manner is quite challenging and has attracted increasing attention in recent years.
• Human activity estimation: The activity information can be used for intelligent control, as different activities may have different thermal preferences. Many sensors can be used for activity recognition. The biggest problems are how to select the best sensing techniques and how to design activity estimation approaches.
• Thermal comfort sensing: Human thermal comfort plays a critical role in determining the productivities of indoor occupants and in the control of HVACs. It is related to both the environmental condition and the individual features, and it is still a big challenge to estimate each individual’s (localised) thermal comfort level and the mean thermal comfort in a user-friendly way.
• Environment sensing: Indoor temperature, humidity, air velocity, and many other environmental factors are inhomogeneous and are all involved in air quality monitoring. How to estimate the full information of the indoor environment from sparse sensors is not just an academic but a useful practical issue.
• Impact on health and wellbeing: As people are living, working and spending their leisure time indoors, the building’s impacts on the physical and mental wellbeing of occupants is of great concern. How to implement intelligent sensing to aid/complement optimal building design and to monitor wellness of occupants will be highly valued in our modern society.
• Multi-agent sensing: A room or an indoor robot will have a group of sensors. A smart building includes many rooms and robots, which constitute a multi-agent system. How to apply the multi-agent systems for better sensing is an interesting problem worth pursuing.
• Fault diagnosis: Fault detection and diagnosis is of great importance for the reliability of systems in smart buildings. As the systems in smart buildings are quite complex, it is challenging to design diagnosis systems that are both accurate and robust.  

Prof. Dr. Yeng Chai Soh
Dr. Zhenghua Chen
Dr. Chaoyang Jiang
Guest Editors

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• sensor selection and placement
• occupancy estimation
• localization
• human activity estimation
• thermal comfort sensing
• environment sensing
• impact on health and wellbeing
• multi-agent sensing
• fault diagnosis