Development and Control of Stratified Micro-environments to Maximise Ventilation Performance

Description

People in industrial countries usually spend more than 90% time indoors; thus, improving indoor environmental quality is essential for occupants' health and work efficiency. It is recognised that stratified air distributions can provide better thermal comfort and indoor air quality in the breathing zone, while saving energy to a large extent. In stratified environments, air distribution is stratified along with the height of a room.However, stratified environments still have unsolved obstacles to practical engineering applications, e.g., satisfying a wide range of thermal preferences, adapting to a more flexible room layout, and applying to both heating and cooling. Therefore, to break barriers in practical application, a novel idea of using improved sidewall air supply is originated.Conventionally, differentiated preferences are looked after by adding accessory equipment on top of the existing general ventilation system, sacrificing the flexibility of room layout and increasing initial costs. While under the sidewall air supply, air with different parameters is supplied at each supply air terminal, providing different stratified micro-environments in a shared room, without adding accessory equipment but using an improved sole ventilation system. With occupants at different positions experiencing different micro-environments, a wide range of differentiated preferences are satisfied, and therefore thermal comfort is improved.Apart from thermal comfort, better performance in indoor air quality is expected because the synergy of different stratified micro-environments could maintain the strengths and minimise the shortcomings of each stratified environment. Respiratory infection risk can be reduced by flexibly designing and adjusting the stratified micro-environments of the infector and susceptible, confining the airborne fomite in certain volumes, rather than just diluting the airborne fomite concentration with the conventional method of adding more fresh air. Similarly, illnesses caused by passive sources, such as interior decoration, can also be mitigated.Despite all these advantages, ineffective indoor environment control will defeat the design purpose and waste energy. The information collected by a conventional building management system may not represent the actual condition surrounding the occupants. There is an urgent need to develop models to monitor and control the actual micro-environments around the occupants under both cooling and heating operations.In summary, this study aims to provide stratified micro-environments in a shared environment by utilising sidewall air supply, to enhance ventilation performances and save building energy consumption.