New Approach to Mitigate Traffic Noise at Public Housing Development Projects (Housing Department, Environmental Protection Department, Buildings Department)
"Hong Kong is a metropolitan with many people and vehicles. Traffic noise is unavoidable. Therefore, we began to think if we could make use of innovative technology to resolve the problem." Senior Project Officer, Environmental Protection Department, Yeung Kwok-leung, Maurice said.
"We improved the double-glazed window that was used in Hong Kong to come up with the design of this “Acoustic Window”. We made one of the “Acoustic Windows”, and conducted tests at laboratory for technical information. We also conducted researches and studies with colleagues from the Housing Department, and invited colleagues from the Buildings Department to participate in the designing of the window. Three departments collaborated in this project.
Maurice said, "At least 20 developments of the Housing Departments will adopt the acoustic windows. Of course, some of the developments have been completed and are currently occupied. What made us happy was when residents said, "We don’t have to close the windows at all. It is very cool indoors and noise has been reduced. Thank you very much!” This compliment was so heart-warming."
Hong Kong is a densely populated place. Busy city activities inevitably create noise, causing nuisance to the public, and traffic noise is often a major issue. In view of this, the Housing Department in collaboration with the Environmental Protection Department and Buildings Department has designed the acoustic windows and acoustic balconies installation in the public housing estates.
In Shun Lai House of the Yau Lai Estate, some units are facing the portal of the Eastern Harbour Crossing with heavy traffic, and in the nearby area, there are also quarries and construction sites. The Housing Department installed acoustic windows in these units to reduce noise nuisance caused to the residents.
Resident Mr. Law said, "I’ve left the acoustic windows open at night and I could hear the noisy traffic. It becomes very quiet when I closed the acoustic windows. I can sleep until dawn. I keep the acoustic windows open in the day time for good ventilation and to keep the place cool. It is environment-friendly as I don’t need to turn on the air conditioning often!" Mr Law, the resident, highly appreciates the design of the acoustic windows which reduces the traffic noise, and it is easy to take care of them. Mr Fung, who also lives in Shun Lai House, thinks that the design of the acoustic windows caters well for the needs of the residents. Another resident Mr. Fung said, "It provides an additional layer of glazing. When I hang my clothes outside, I just slide open the acoustic window. The windows on both sides can be pushed open like this."
The design of the acoustic window looks simple, but it has come a long way from design, development through to implementation. It was a collaboration project of the Housing Department, Environmental Protection Department and Buildings Department. With the use of innovative technology, and based on the concept of “people-orientation” and “sustainable development”, we successfully implemented the acoustic window.
Architect, Housing Department, Ngai Pui-yan, Jo said, "The Housing Department strives to optimise the use of our scarce land resources. In every project, we make sure that the land usage will deliver the best possible benefits. We aim to provide a good quality living environment for the residents based on the “people-oriented” design concept, and alleviating the impact of traffic noise in building design is one of our key goals.
For years, building design in Hong Kong has evolved to deal with the traffic noise impact. In 2009, the Housing Department, Environmental Protection Department and Buildings Department collaborated to develop various measures on mitigating the traffic noise impact.
Yeung Kwok-leung, Maurice said, "We came up with this simple design of a quasi double-glazed window, which has an alley between the two layers of glasses. Then we made use of the principle of sound absorption, diffraction and reflection to achieve the noise reduction effect. Based on this concept, we carried out simulations in the laboratory and obtained positive results. We then shared our findings with colleagues of the Housing Department. They agreed that it could be put to practical application."
Building Surveyor, Buildings Department, Cheng Kam-ming, Anson added, "Traditionally, noise reduction and natural ventilation belong to two different and contradictory categories. Usually noise reduction is achieved at the expense of natural ventilation, and vice versa, good natural ventilation may compromise the noise reduction effect. We hope to devise a standard compliant acoustic window design, which meets the statutory requirements for natural ventilation, achieving noise reduction effect, and has wider applications as well."
As soon as it was confirmed that the acoustic windows could be adopted to mitigate the traffic noise impact, the three departments worked together in the areas of design, exploring the choice of materials, ascertaining statutory requirements and users’ needs, etc. Our work included continuous testing in various aspects and data collection, modification and fine-tuning of the design. The idea of acoustic window was gradually turned into a reality.
Ngai Pui-yan, Jo said, "We set up an actual size mock-up flat using the acoustic windows in San Po Kong, and conducted tests in comparison with the actual flat using conventional window design to verify that the acoustic window could reduce the traffic noise impact effectively, and at the same time maintain natural air ventilation and natural lighting, as well as other factors that we needed to take into consideration."
Through collaborations and concerted efforts of departments, the acoustic windows were finally adopted in King Tai Court, which has its first occupants in 2017. As it is situated at a location impacted by heavy traffic, it was the first public housing estate fully installed with the acoustic windows. In 2018, the acoustic windows were formally introduced into the modular flat design of public housing estates.
Yeung Kwok-leung, Maurice said, "We have a range of measures for different housing estates and for units of different sitting direction. For example, we can install sound absorption material to enhance the noise reduction effect. Overall speaking, having conducted testings and on-site verifications, we find that the acoustic window can reduce noise as high as 8 decibels. In general, if traffic flow is reduced by half, noise is reduced by 3 decibels. So it produces very satisfactory results."
The design concept of acoustic window jointly developed by the Housing Department, Environmental Protection Department and Buildings Department can also be deployed to construct “Acoustic Balconies”. The combined effort of the three departments in the development of “acoustic windows”and “acoustic balconies” showcases an exemplary cross-departmental innovative collaboration. The Housing Department will continue to use the design concept of acoustic windows and acoustic balconies to optimise land resources and increase flat production.
(For more details, please visit Sevice Excellence Website)