The general purpose of ventilation in buildings is to provide healthy air for breathing by both diluting the pollutants originating in the building and removing the pollutants from it. Building ventilation plays a strong role for the good health, comfort, security and productivity of inhabitants, workers and visitors. Many new challenges with energy and pollution implications have arisen, including the identification and control of contaminant sources, fast building design requirements, online demand, sustainability and climate change adaptation. This comprehensive research reference covers state of the art research starting with ventilation systems including duct network and fluid machinery, air cleaning technologies, air distribution in mechanical ventilation systems, air distribution in natural ventilation system, and heating and cooling systems. The authors then present innovating methods for the design, control and testing including system design, numerical methods, fast predictions methods, testing methods and maintenance. The book concludes with applications in industrial buildings, high-rise buildings and urban areas. Handbook of Ventilation Technology for the Built Environment is a complete guide to the field, providing invaluable information for scientists, researchers and engineers from academia and industry who are looking to broaden or update their knowledge. It is also a useful resource for policy makers, facility managers, regulators and standards bodies in the field.
Inspec keywords: indoor environment; ventilation; HVAC; buildings (structures); air quality
Other keywords: buildings (structures); indoor environment; diseases; HVAC; computational fluid dynamics; cooling; ventilation; design engineering; air quality; patient diagnosis
Subjects: Fluid mechanics and aerodynamics (mechanical engineering); General electrical engineering topics; Conference proceedings; Indoor environment; Education and training; General topics in manufacturing and production engineering; Refrigeration and cooling (energy utilisation); Engineering mechanics; Heat and thermodynamic processes (mechanical engineering); Space heating; Building structures; Air conditioning; Heating (energy utilisation)
In this chapter, we introduced the advantages and disadvantages of the COVID-19 related technologies.
A ventilation system is designed to improve indoor polluted air by introducing fresh air or by processing the indoor air to maintain the indoor air quality (IAQ) and thermal comfort at a satisfactory level that meets the standards of residential or industrial use. Looking at the development history of building ventilation, ventilation and building thermal process have changed from separation to combination; the main ventilation mode has changed from natural ventilation to mechanical ventilation. The ventilation control has changed from simple start-up and stop operation of the whole system to local or overall "on-demand" control according to the needs of control objectives.
Depending on the air pressure and air volume provided by the fan, fresh or processed outdoor air can be effectively delivered to any workplace of the building through air supply and exhaust systems; the polluted air in the building can be discharged to the outdoor or be sent to the purification devices before discharging. This type of ventilation is called mechanical ventilation. Mechanical ventilation can be divided into local ventilation and overall ventilation according to the distribution of hazardous air and the scope of the system. Local ventilation includes local supply air system and local exhaust air system. Overall ventilation comprises a total supply air system and a total exhaust air system. According to whether the fresh air is mixed with pollutants, it can be further divided into displacement ventilation and mixed ventilation.
Duct system design is an indispensable step to realize duct system from concept to practice. If the duct is designed in a building, the design process of the duct system needs to follow the following steps: First, the material, form and working pressure of the duct system should be confirmed based on production process, production safety and human needs for ventilation and air-conditioning systems. Second, the orientation and layout of the air duct should be confirmed according to the position of tuyeres. Third, relevant parameters (such as economic flow velocity and economic friction factor) should be confirmed based on factors of cost, noise and pressure to carry out the hydraulic calculation. Finally, in addition to the fan or the air-handling unit, the specification, size, thickness of air ducts, as well as relevant hoisting, sealing and reinforcement, should be selected.
The aim of this chapter is to provide an overview about the different patterns of an electrostatic air cleaner (including electret fibrous filter, IG, ESP and HEFS). The following issues are illustrated in detail: the system filtration performance (filtration efficiency, pressure loss), the electric characteristics of porous dielectric filter medium, the by-product generation, the bacteria inactivation effect by electric field and the effect of electrostatic air cleaner on indoor environment and human health. Finally, the analytical or numerical modeling of air filtration process was also summarized.
The air distribution in spaces is a major important factor for occupants' health, comfort and performance as well as for efficient energy use. In many buildings, mechanical systems are used to transport and supply clean and cooled/heated air to occupied spaces. Air distribution in such ventilated spaces in general depends on inertia and buoyancy forces, initial conditions of the supplied flow and boundary conditions in the space. Different air distribution strategies based on the mechanical systems for air transportation are used to achieve the goal of thermal comfort and air quality. One of the strategies is to mix the supplied clean air and cool/warm air with the polluted air in the space. Dilution of the supplied air with room air is the aim of mixing ventilation. Another common strategy is displacement ventilation, where a stratified flow is created using the buoyance forces of heat sources. The air quality is then generally better than with mixing ventilation.
A building should be properly ventilated to support the health of its occupants by supplying fresh air into the living space. Natural ventilation (NV) can fulfil this purpose without energy consumption. The basic strategies for NV include single-sided ventilation, cross ventilation, stack ventilation and other types. In reality, buildings combine these basic schemes leading to a very complicated airflow so that CFD techniques must be applied to analyse the air distribution. When the outdoor climate is favourable, NV can provide a potential cooling effect for the space and remove the heat and moisture released by people and equipment. The actual capacity relies on the climatic conditions and building characteristics and is constrained by the quality of the outdoor air and the urban context. The occasions for NV should be comprehensively evaluated to enhance the design and operation of ventilation strategies.
This chapter introduces variable air ventilation strategies with heating and cooling systems and evaluate the systems' energy and exergy performance in a building. The natural and HV systems have good energy-saving strategies; however, these are quite limited to use in extreme weather conditions and have to combine other mechanical systems to adapt to local conditions. Radiant heating and cooling systems with a displacement ventilation unit have lower energy consumption and better thermal comfort than the all-air system. Hybrid radiant heating and cooling system present more energy efficiency and reduce moisture condensation risk on the surface of the radiant cooling panels.
Natural ventilation is a well-established branch discipline of ventilation under the subject of heating, ventilating, and air-conditioning engineering. It can be simply classified into two categories: single-sided and cross natural. Single-sided natural ventilation is a more common ventilation strategy particularly in densely populated urban areas, while cross natural ventilation is more efficient to provide high ventilation rates. Although the advantages of natural ventilation are widely known and most people prefer operable windows with natural ventilation, its application with intentional designs is surprisingly very limited (Carrilho da Graca and Linden, 2016) and few international or national ventilation standards (ASHRAE Standard 62, 2013; WHO,2006; CIBSE, 2005) involve natural ventilation design (Liddament, 2009). One important barrier of the application of natural ventilation in buildings is that it strongly relies on the local outdoor microclimate, including particularly windspeed, air temperature, pollutant concentration, and noise level.
Ventilation system is a typical approach to supply air and construct air distribution for the desired indoor environment quality. A poorly designed ventilation system would lead to a variety of problems such as sick building syndrome, cross infections, and reduced productivity. This chapter focuses on the numerical methods for designing the ventilation system.
Accurate and rapid prediction of ventilation in built environment is highly desired for the design, construction and operation of energy-efficient, comfortable, and healthy buildings. Developing fast prediction techniques can advocate and accelerate a broader and better application of modeling tools for engineering practices, such as building emergency management, early-stage building and system design, and real-time system control and continuous optimization. This chapter first reviews and introduces the prevalent modeling techniques for built environment ranging from the simplest mixing model to the sophisticated field (computational fluid dynamics-CFD) model. The focus is put on those fast and accurate modeling methods, including zonal models, reduced-order models (ROMs), zero-equation turbulence models, coarse-grid CFD methods, and pressure-velocity decoupling algorithms. The chapter then demonstrates the application of some of these fast simulation techniques and methods for ventilation studies through several engineering and research case studies.
HVAC systems play an important role in improving air quality (Chenet al., 2018)and thermal comfort (Bluyssenet al., 2011) in the building environment and can also cause building energy waste and even air pollution problems (Kim and Yu,2018). The main reason is that the traditional HVAC system cannot be based on dynamic changes of indoor environmental parameters and nonuniform distribution characteristics to achieve optimal real-time adjustment of air supply parameters, resulting in an excessive growth of energy consumption for running the air-conditioning system (Ren and Cao, 2020). To further save energy and improve indoor air quality, this chapter introduces an HVAC online monitoring and control strategy for unsteady, nonlinear, nonuniform and real-time response to multiple environmental parameters (e.g., CO2 concentration, temperature, and humidity) to create a healthy, comfortable, and energy-efficient building environment.
Ventilation, normally characterized by outdoor and indoor, is closely associated with indoor air quality (IAQ). Indoor air pollution has a greater impact than outdoor air pollution as most of the people spend up to 90% of their time in indoor environment (Nazaroff and Goldstein, 2015; Zhang and Smith, 2003). Thus, IAQ is greatly important for the quality of human life, including the productivity (Wargocki and Wyon, 2013) and performance (Theodosiou and Ordoumpozanis, 2008), and health condition (Sundellet al., 2011). Both natural and mechanical ventilations (MVs) determine the level of indoor air pollution and air quality. However, indoor air pollution and IAQ mainly depend on outdoor ventilation or air quality especially in the buildings with both natural and MV systems (Kukadia and Palmer, 1998).
The main task of industrial ventilation is to provide good working conditions for the production process and the workers in it. For a long time, people have been keeping a pursuit and exploration for better industrial ventilation technology. On the one hand, as an old problem, the design of industrial ventilation has accompanied with the industrial revolution. On the other hand, with the constant development of the industry, the expansion of industrial building scale and the improvement of building technology, new challenges have been put forward on the industrial ventilation. What's more, since the main attention was on worker's health and safety; thus, a higher demand was set on indoor thermal conditions and air quality for these industrial occupational environments.
This chapter presents the most recent progress in high-rise building design and control methods for achieving energy efficiency and fire safety. First, basic knowledge of high-rise ventilation is introduced. Then, the challenges of designing and controlling high-rise ventilation are pointed out. State-of-the-art energy efficiency and safety research on the modeling, control, and design of high-rise ventilation is also presented. Lastly, two case studies on high-rise fire smoke control and atrium fire smoke control are introduced and discussed. Readers will come away from this chapter with an understanding of the theory of high-rise ventilation and the design challenges related to fire safety concerns, as well as a knowledge about designing safe and energy efficient high-rise ventilation systems.
Urban ventilation is important for achieving not only a circulated outdoor air, good pedestrian-level air quality, and thermal comfort, but also a good outdoor boundary condition of building indoor ventilation. In the past decades, urban ventilation has been widely investigated from different physical scales, namely, from street canyon, precinct to full city. This chapter presents studies and discussions on the street canyon and precinct scales, which are in the order of approximately 10-1,000 m.
Provides an overview of the building ventilation topics covered in the book and looks at future possible developments.