Curtain wall (architecture)

Glass is typically used for infill because it can reduce construction costs, provide an architecturally pleasing look, and allow natural light to penetrate deeper within the building.

However, glass also makes the effects of light on visual comfort and solar heat gain in a building more difficult to control.

Unlike storefront systems, curtain wall systems are designed to span multiple floors, taking into consideration building sway and movement and design requirements such as thermal expansion and contraction; seismic requirements; water diversion; and thermal efficiency for cost-effective heating, cooling, and interior lighting.

[citation needed] The development and widespread use of structural steel and later reinforced concrete allowed relatively small columns to support large loads.

[citation needed] 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.

Toward the courtyards they boasted metal-framed glass curtain walls, which makes them two of the world's first buildings to include this architectural feature.

[4] An early example of an all-steel curtain wall used in the classical style is the Kaufhaus Tietz [de] department store on Leipziger Straße, Berlin, built in 1901 (since demolished).

The landmarks of curtain wall design as it came to dominate construction were the very different systems used by the United Nations Headquarters and the Lever House completed in 1952.

Aluminum alloys offer the unique advantage of being able to be easily extruded into nearly any shape required for design and aesthetic purposes.

The Omni San Diego Hotel curtain wall in California, designed by architectural firm Hornberger and Worstel and developed by JMI Realty, is an example of a unitized curtain-wall system with integrated sunshades.

This allows sections of curtain wall to be fabricated in a shop, effectively reducing the time spent installing the system onsite.

Unitized curtain wall has the advantages of: speed; lower field installation costs; and quality control within an interior climate-controlled environment.

A curtain wall system must be designed to handle all loads imposed on it as well as keep air and water from penetrating the building envelope.

Seismic loads in a curtain wall system are limited to the interstory drift induced on the building during an earthquake.

In most situations, the curtain wall is able to naturally withstand seismic and wind induced building sway because of the space provided between the glazing infill and the mullion.

In tests, standard curtain wall systems are typically able to withstand up to three inches (76 mm) of relative floor movement without glass breakage or water leakage.

This means that over the span of a couple of floors, the curtain wall will expand and contract some distance, relative to its length and the temperature differential.

Incidentally, this slot also accounts for live load deflection and creep in the floor slabs of the building structure.

Accidental explosions and terrorist threats have brought on increased concern for the fragility of a curtain wall system in relation to blast loads.

As such, blast resistant curtain walls are designed to withstand such forces without compromising the interior of the building to protect its occupants.

The American Architectural Manufacturers Association (AAMA) is an industry trade group in the U.S. that has developed voluntary specifications regarding acceptable levels of air infiltration through a curtain wall.

This set up simulates a wind driven rain event on the curtain wall to check for field performance of the product and of the installation.

The depth of a given curtain wall system is usually controlled by the area moment of inertia required to keep deflection limits under the specification.

Another method of hiding spandrel areas is through shadow box construction (providing a dark enclosed space behind the transparent or translucent glass).

A louver is provided in an area where mechanical equipment located inside the building requires ventilation or fresh air to operate.

They can also serve as a means of allowing outside air to filter into the building to take advantage of favorable climatic conditions and minimize the usage of energy-consuming HVAC systems.

Factory applied fluoropolymer thermoset coatings have good resistance to environmental degradation and require only periodic cleaning.

Anodized aluminum frames cannot be "re-anodized" in place but can be cleaned and protected by proprietary clear coatings to improve appearance and durability.

Stainless steel curtain walls require no coatings, and embossed, as opposed to abrasively finished, surfaces maintain their original appearance indefinitely without cleaning or other maintenance.

Some specially textured matte stainless steel surface finishes are hydrophobic and resist airborne and rain-borne pollutants.