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November 6, 2011 / mandyhyj

On Ventilation

Last week we had the reading about ventilation strategies and applications in buildings.  Kwok and Grondzik mainly talked about different ventilation strategies: cross ventilation, stack ventilation, evaporational pool, night ventilation of thermal mass, and earth cooling tubes. With the diagrams given, I had a better understanding of how each type of ventilation works.

One thing that Kwok and Grondzik mentioned in the article, which I totally agreed with is that one needs to match climate-based design strategies to the local climate and really understand the operation patterns of the building. Thinking about the buildings I’ve seen in Singapore and China, I can’t agree more that ventilation strategies meet not only the purpose of ventilation but facilitate the general function of the building as well. Here is an example that came into my mind that uses natural ventilation strategies to solve problems specifically in a local environment and also meets the function of the building.

National Library, Singapore

Architect: Ken Yeang

The national library in Singapore used a wide range of green feature; research shows that the environmental impact of this 15-story building is lower than an average office building. It adopted passive design strategies like natural ventilation, maximum daylighting, special orientation away from east-west sun, automatic sunshades at the building facades, use of rain sensors as part of the automatic irrigation system for the rooftop garden.

Among all these design strategies, I think ventilation is one of the most important aspects due to the humid tropical climate. The library is designed to create a stack ventilation effect. The diagram in Kwok and Grondzik illustrates this effect.

A workable stack height is established in the building. The first floor may be ventilated using a stack.  Outside is flushed into the building providing a cooling effect.

In the National Library, similar strategy is adopted. There is a central atrium space covered by stacks of thermal masses on top. This structure encourages airflow from outside to the interior space through the inlets, creating a cool internal civic space. Venders usually set up booth in the central plaza and various activities take place in the linking plaza space as well.

 

The design of the National Library is sustainable in a way that responds to the local environment and fits in the daily operation of the building.  The National Library that Ken Yeang designed is the biggest library in Singapore. It is not just a public library but also provides venue for other activities, like conferences, cultural performances and competitions, exhibitions, etc. The central internal streets and plaza serve as essential part of the stack effect, and also as the main area for various activities. The design also meets the basic function of the building- to provide a studying area for the public. The use of maximum daylight not only saves energy, but also creates a comfortable studying condition. The roof top gardens provide resting spaces and at the same time controls temperature and provides fresh air. Another smart passive design strategy is that the building uses rain water for the irrigation system. This system works especially well in Singapore because the climate in Singapore has a distinct and fairly long rain season. Collection of rainwater would be sufficient for garden irrigation.

[central interior streets and plaza ]

[rooftop gardens]

[daylight lit study room]

Just like Kwok and Grondzik said, good passive design strategies match strategy to the climate and responds to the patterns of building usage. And the National Library in Singapore definitely meets these requirements.

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