© ArchDaily

双层幕墙是如何工作的？
How Do Double-Skin Façades Work?

由专筑网Zia，小R编译

双层幕墙是一个不言自明的定义，指由两层（通常是玻璃）组成的外墙系统，空气可以在中间空腔流动。这个空间（从20厘米到几米不等）可以起到隔绝极端温度、风和声音的作用，提高建筑物在极端温度下的热效率。Foster+Partners 的 30 St Mary Ax大楼——“小黄瓜”，则是著名的双层外墙实例。

通过中间空腔的气流可以是自然产生的，也可以是机械驱动的，两层玻璃可以包括遮阳装置。

Double skin façades: Almost a self-explanatory name for façade systems consisting of two layers, usually glass, wherein air flows through the intermediate cavity. This space (which can vary from 20 cm to a few meters) acts as insulation against extreme temperatures, winds, and sound, improving the building's thermal efficiency for both high and low temperatures. Perhaps one of the most famous examples of double-skin facades is Foster+Partners' 30 St Mary Ax Building, "The Gherkin."
The airflow through the intermediate cavity can occur naturally or be mechanically driven, and the two glass layers may include sun protection devices.


© Cemal Emden

虽然双层幕墙的概念并不新鲜，但建筑师和工程师越来越倾向于使用这种幕墙。特别是在摩天大楼的设计中，双层幕墙因其通透的立面、热舒适度和听觉舒适度、低能耗以及易实施性而备受青睐。

While the concept of double-skin façades is not new, there is a growing tendency for architects and engineers to use them. Particularly in skyscraper design, they are favored for their transparent façade, thermal and auditory comfort, reduced air conditioning costs, and elimination of the need for window-specific technologies. 


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此外，双层幕墙还能适应较冷和较热的天气。正是这种多功能性使它们变得有趣：通过微小的动作，如打开或关闭进风口或出风口或启动空气循环器，就能改变外墙的性能。

在寒冷的气候条件下，空气缓冲层可以起到阻挡热量流失的作用。空腔中被阳光加热的空气可以加热玻璃外的空间，从而减少室内对供暖系统的需求。

Additionally, double-skin façades are adaptable to cooler and warmer weather. It is this versatility that makes them so interesting: through minor modifications, such as opening or closing inlet or outlet fins or activating air circulators, the behavior of the façade is changed. 
In cold climates, the air buffer works as a barrier to heat loss. Sun-heated air contained in the cavity can heat spaces outside the glass, reducing the demand for indoor heating systems.


Cold climate. Image © ArchDaily

在炎热的气候条件下，可将空腔中的气体排出建筑物外，以减少太阳辐射热，降低制冷负荷。多余的热量会通过烟囱效应排出，空气密度的不同会产生循环运动，导致较热的空气从上方排出。当空腔中的空气温度升高时，它就会给周围环境带来微风，同时起到隔离作用，阻挡热量的吸收。

In hot climates, the cavity can be vented outside the building to mitigate solar gain and decrease the cooling load. Excess heat is drained through a process known as the chimney effect, where differences in air density create a circular motion that causes warmer air to escape. As the air temperature in the cavity rises, it is pushed out, bringing a slight breeze to the surroundings while isolating against heat gain. 


Hot climate. Image © ArchDaily


Hot climate. Image © ArchDaily

总体而言，双层幕墙的效果在很大程度上取决于外部条件（太阳辐射、外部温度等），而这些条件会直接影响内部舒适度和用户的生活质量。因此，精心的设计以应对每种情况都至关重要，需要详细了解太阳方位、环境、当地辐射、温度条件、建筑遮挡情况等。下面是双层幕墙的一些优缺点：


优点

降低制冷和供暖需求；
视线效果好，自然光线充足；
改善隔热和隔音效果；
有助于自然通风和空气更新，创造更健康的室内环境。


缺点

初始建造成本高；
占用一定的空间；
需要后期维护；
如果建筑环境发生重大变化（如被其他建筑物遮挡），双层幕墙可能无法发挥效果。

Overall, double-skin façades depend heavily on external conditions (solar radiation, external temperature, etc.) that directly influence internal comfort and user quality of life. Therefore, careful design is essential for each case, requiring detailed knowledge of solar orientation, context, local radiation, temperature conditions, building occupancy, and much more. We highlight, below, some of their benefits and disadvantages:

Benefits
Reduce cooling and heating demand;
Allow clear views and natural light;
Improve insulation, whether thermal and acoustic;
Allow natural ventilation and air renewal, creating a healthier enivronment.

Disadvantages
Much higher initial cost of construction;
Space consumption;
Maintenance demand;
It may fail to function properly if the context changes significantly (shading by other buildings, for example).


© Martin Van der Wal


© Martin Van der Wal


© Sergio Grazia


© Cemal Emden


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