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A curtain wall system is an outer covering of a building in which the outer walls are non-structural, but merely keep the weather out and the occupants in. As the curtain wall is non-structural it can be made of a lightweight material, reducing construction costs. When glass is used as the curtain wall, a great advantage is that natural light can penetrate deeper within the building. The curtain wall façade does not carry any dead load weight from the building other than its own dead load weight. The wall transfers horizontal wind loads that are incident upon it to the main building structure through connections at floors or columns of the building. A curtain wall is designed to resist air and water infiltration, sway induced by wind and seismic forces acting on the building, and its own dead load weight forces. Curtain wall systems are typically designed with extruded aluminum members, although the first curtain walls were made of steel. The aluminium frame is typically infilled with glass, which provides an architecturally pleasing building, as well as benefits such as daylighting. However, parameters related to solar gain control such as thermal comfort and visual comfort are more difficult to control when using highly glazed curtain walls. Other common infills include: stone veneer, metal panels, louvres, and operable windows or vents. Curtain walls differ from store-front systems in that they are designed to span multiple floors, and take into consideration design requirements such as: thermal expansion and contraction; building sway and movement; water diversion; and thermal efficiency for cost-effective heating, cooling, and lighting in the building. ==History== Buildings were constructed with the exterior walls of the building (bearing walls, typically masonry) supporting the load of the entire structure. The development and widespread use of structural steel and later reinforced concrete allowed relatively small columns to support large loads and the exterior walls of buildings were no longer required for structural support. The exterior walls could be non-load bearing and thus much lighter and more open than the masonry load bearing walls of the past. This gave way to increased use of glass as an exterior façade, and the modern day curtain wall was born. Early prototype versions of curtain walls may have existed in buildings of timber construction before the nineteenth century, should columns have been used to support the building rather than the walls themselves, particularly when large panels of glass infill were involved. When iron began to be used extensively in buildings in late 18th Century Britain such as at Ditherington Flax Mill, and later when buildings of wrought iron and glass such as The Crystal Palace were built, the building blocks of structural understanding were laid for the development of curtain walls. Oriel Chambers (1864) and 16 Cook Street (1866), both built in Liverpool, England, by local architect and civil engineer Peter Ellis, are characterised by their extensive use of glass in their facades. Towards the courtyards they even boasted metal framed glass curtain walls which makes them two of the world's first buildings to include this structural feature. The extensive glass walls allowed light to penetrate further into the building utilizing more floor space and reducing lighting costs in short winter months. Oriel Chambers comprises set over five floors without an elevator which had only recently been invented and was not yet widespread.〔(【引用サイトリンク】title=History )〕 An early example of an all steel curtain wall used in the classical style is the Tietz Kaufhaus Department Store, Leipzigerstrasse, Berlin built in 1901 (since demolished).〔(【引用サイトリンク】title=History )〕 Some of the first curtain walls were made with steel mullions and the plate glass was attached to the mullions with asbestos or fiberglass modified glazing compound. Eventually silicone sealants or glazing tape were substituted, using a glass mullion system. Some designs included an outer cap to hold the glass in place and to protect the integrity of the seals. The first curtain wall installed in New York City, in the Lever House building (Skidmore, Owings and Merrill, 1952), was this type of construction. Earlier modernist examples are the Bauhaus in Dessau (1926) and the Hallidie Building in San Francisco (1918). The 1970s began the widespread use of aluminum extrusions for mullions. Aluminum offers the unique advantage of being able to be easily extruded into nearly any shape required for design and aesthetic purposes. Today, the design complexity and shapes available are nearly limitless. Custom shapes can be designed and manufactured with relative ease. The Omni San Diego Hotel curtain wall in California, (Developed by JMI Realty and designed by architectural firm Hornberger and Worstell and constructed by AGA (Architectural Glass and Aluminum), is an example of a unitized curtain wall system with integrated sunshades. 〔Wausau Press Releases , ("Omni San Diego Hotel offers breathtaking Bay views through Wausau’s curtainwall" ), ''Wausau Press Releases'', Retrieved 2 October 2015〕 Similarly, sealing methods and types have evolved over the years, and as a result, today’s curtain walls are high performance systems which require little maintenance. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Curtain wall (architecture)」の詳細全文を読む スポンサード リンク
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