Monday, September 26, 2011

Cavity

The word cavity is a noun. It’s plural form is cavities. There are two meanings of it in the Merriam Webster online dictionary. One is an unfilled space within a mass; especially, a hollowed-out space. Another one is an area of decay in a tooth. This word was first known to be in use in 1541, coming from the Latin word “cavus”.

In the field of architecture, cavity means the inner space such as atriums and patios that could utilize the natural energy like solar energy, wind energy and so on to regulate the microclimate in buildings. The idea of architectural cavity first came from the principle of honeycomb briquette. If briquette been enlarged in proportion, the enlargement of its volume would exceed that of its surface. This finally affects the full burning of the briquette. By contrast, honeycomb briquette doesn't have such defect because of its well-distributed porous structure. (“Develop the Concept Briquette”, Wu Yaohua & Li Gang) Therefore, the evolution of honeycomb briquette shows that the area of interfaces between the environment and organism should be enlarged.












Media Library at Sendia, designed by Toyo Ito




I first got to know this word in a masterpiece of Toyo Ito called Media Library at Sendia. The architect designed thirteen tubes in the shape of stems or branches penetrating through floors and endowed them with functions of structure and transportation. What’s more, those tubes work as carriers of sunlight, rain, snow, wind and landscape. In this way, when people walking in the building, they could be bathed in the sunlight, feel the wind and touch the     trees and flowers.

Last year, I went to Beijing for an architectural investigation. I visited several traditional residential buildings and surprisingly found that the idea of cavity was used very well in the building layout. Those buildings are called Siheyuan, which literally means a courtyard surrounded by four buildings. The yards bring light and wind into the buildings, while the projecting eaves of verandas protect from direct sunlight. Residents like to grow plants and dig pools in the yards to make them more comfortable and beautiful. In all, those yards act as architectural cavities to regulate the microclimate in Siheyuan.















Siheyuan


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