Glass for Transparency in Turkey’s Fashion House & Power Media Headquarters

A new headquarters for a Turkish fashion house Vakko and Power Media (Turkey’s equivalent of MTV) was built recently in Istanbul, Turkey. The construction of this structure was started on an old, abandoned and partially constructed concrete shell of a hotel. REX Architects created this building over an area of 9,100 m² (98,000 sq ft). Instead of hiding the old concrete skeleton of hotel, REX exposed it through a very thin and transparent glass façade, thus delivering their objective of creating a sustainable structure.

REX divided the construction of this structure into two structurally independent components. A ‘U-shaped' concrete skeleton (completed by a fourth side), labelled as “Ring”, was transformed into a conventional, flexible office space. At the ring’s centre, a new six-floor steel tower named ‘Showcase’, consisting of several special areas such as an auditorium, showrooms, meeting rooms and executive offices, and restrooms has been created.

Power Media Company, Turkey’s renowned music and television network at the upper floor of the skeleton’s subterranean parking incorporates a television studio, radio production facilities, and screening rooms.

The Transparent Glass façade of the building is stuffed with Glass Panes, which allow natural light to flood the interiors. At 5 feet by 10 feet, the 134 panels that wrap the building are a wafer-like 3/16th of an inch thick. Glass preferred for this building by the architects is Slumped Glass. This type of glass is repeatedly heated and cooled until it falls into a mould and assumes the mould’s form. Slumping is usually used for decoration purposes, but here it has been used for structural purposes: The glass panels feature an X-shaped impression that gives them vertical and lateral stiffness and strength. These glass panels are held in place by four simple pins at each corner.

Glass slumped with ‘X’ shape increases the glass’s strength. The thickness of the glass was thus reduced and the need for perimeter mullions was eliminated. The resulting ethereal glass “Saran Wrap” subtly reveals the Ring’s pre-existing concrete skeleton and suggests the Showcase behind. Glass panes give a clear view when viewed directly and capture light and reflections, when viewed from different angles.

The Showcase is clad in mirror-glass, cloaking the steel boxes with a mirage-like exterior, and enlivening the building’s interior to impart a kaleidoscopic effect. The slopes of the auditorium, showrooms, and meeting rooms create a circulation path that winds from the bottom upwards to the glass showcase.

Photovoltaic Glass

Photovoltaic glass is a special glass with integrated solar cells that convert solar energy into electricity. This means that the power for an entire building can be produced within the roof and façade areas. The solar cells are embedded between two glass panes and a special resin is filled between the panes, securely wrapping the solar cells on all sides. Each individual cell has two electrical connections, which are linked to other cells in the module, to form a system which generates a direct electrical current.

Need for Photovoltaic Glass

Apart from providing privacy and protection from noise and rain, other features such as thermal insulation and shading are becoming increasingly desirable. All of these functionalities can be obtained simply by installing photovoltaic glass to the shell of a building.

How does it work?

As seen in the science behind PV, a photovoltaic cell is created when a positively charged (P-type) layer of silicon is placed against a negatively charged (N-type) layer of silicon to create a diode and this diode is connected in a circuit via metal conductors on the top and bottom of the silicon sandwich. Though different types of photovoltaics vary in their structure, they generally include the following elements:

1. The cell or multiple cells are the core of the photovoltaic panel.
2. A glass cover is placed over the photovoltaic cell to protect it from the elements while allowing sunlight to pass through to the cell.
3. An additional plastic anti-reflective sheet is often used to enhance the effect of the glass cover and anti-reflective coating of the cell to block reflection.
4. A panel backing (typically plastic) and frame complete the photovoltaic panel, holding all the pieces together and protecting it from damage during installation.
   

Production

The solar cells are embedded between two glass panes, and a special resin fills between the panes, securely wrapping the solar cells on all sides. Each individual cell has two electrical photovoltaic modules (PVs).

A photovoltaic module or photovoltaic panel is a packaged interconnected assembly of photovoltaic cells, also known as solar cells. The photovoltaic module, known more commonly as the solar panel, is then used as a component in a larger photovoltaic system to offer electricity for commercial and residential applications.

Photovoltaic modules enable the active use of solar radiation by turning it into electrical energy; in addition, they can also represent a form of passive solar protection. The most well known PV products are silicon solar cells, available in three types:

1. Monocrystalline:

The monocrystalline solar cells are opaque, blue, or dark grey to black, and they have a high efficiency (14% to 16%). They are expensive because they are made from silicon crystals in a complicated manufacturing process.

2. Poly- or multicrystaffine:

The polycrystalline solar cells are mostly blue or opaque. These are cheaper because they are made from poured silicon blocks, but they have a lower efficiency (14%). Crystalline solar cells are produced as 0.4mm thick discs in sizes from 10 x 10cm to 15 x 15cm. These discs are then put together to form modules and embedded with resin in the cavity in a laminated glass unit. According to composition, the result can be either a transparent, translucent or a non-transparent module.

Light transmission through transparent and translucent modules can be set from 4% to 30% according to the choice of spacing. Special light-scattering and insulating glass elements have been developed to meet both the needs in terms of lighting and insulation as well as the desire to maintain and exploit the corporate image as protected through the façade. In the exterior laminated glass, PV cells have a 5mm gap between them. On the inside, a laminated glass with an opaque interlayer is used.

3. Amorphous:

Amorphous is a non-crystalline solar cells. Amorphous modules are transparent, can be used as window glazing in usual windows, sunspaces, they can be integrated into roofs etc. Transparent modules can be also part of energy efficient glazing, where they are used instead of usual glass.

Optimized exploitation of solar energy can be achieved by combining several thin film layers with different spectral responses. So-called tandem cells have reached up to 12% efficiency under laboratory conditions, slightly higher values seem possible. Further possibilities are offered by triple cells which consist of a succession of three thin film layers Efficiencies of 10% in production quantities are becoming realistic.

Body-tinted Glass

Body-tinted glass is normal float glass into whose melt colorants are added for tinting and solar-radiation absorption properties. This tinted glass saves energy and reduces heat penetration into buildings and gives a striking visual effect. Coloured glass is an important architectural element for the exterior appearance of façades.

Tinted glass refers to any glass that has been treated with a material such as a film or coating, which reduces its ability to transmit light. Glass can be tinted with various types of coating, which block and/or reflect different amounts and types of light, according to the needs and preferences of the consumer. Glare reduction is another important property of tinted glass. Glare

The production process of body-tinted glass is similar to that of float glass. The only variation is in the colorants mixed at the beginning with the standard raw materials. Body-tinted glass is produced when colorants and iron are introduced during the glass manufacturing process. Different additives may produce differently coloured glasses. Bronze, dark grey and green are the commonly used tints.

The end product does not affect the basic structure of the glass itself, but does enhance its performance in relation to the (solar) electromagnetic spectrum. The colour is homogenous throughout the thickness of the glass. The solar energy transmission, shading coefficient and visible light passing through the tinted glass will vary according to the colour selected.

During the float glass melt process, chemical colorants can be added which tint the colour and increase absorption from the sun. This helps minimize the solar radiation that enters a building, keeping it cool from the inside and protecting furniture from fading. As an example of the colorants used - to create a purple exterior, manganese is added, while pinks and reds can be produced from selenium.

Colorants and colors

Some of the most-used colorants and the colours they produce are listed below:

Iron – Green, brown, blue
Manganese – Purple
Chromium – Green, yellow, pink
Vanadium – Green, blue, grey
Copper – blue, green, red
Cobalt – blue, green, pink
Nickel – yellow, purple
Titanium – purple, brown
Cerium – yellow
Selenium – pink, red
Gold – Red
Cadmium-Sulphide – yellow
Carbon & Sulphur – amber, brown

Double-Glazed with High-Performance Tinted Glass

Tinted Glass is intended for universal application. Either as single or double glazing for a basic level of solar control, and even in furniture, interior design, partitions, etc. It is also the base glass for many high performance comfort glasses.

Doubly-glazed tinted glass reduces solar heat gain to below that of bronze or gray tint but has a visible transmittance closer to clear glass. High-performance or spectrally selective tinted glass products are typically light green or light blue. The tint has no effect on the U-factor but reduces solar heat gain. Doubly glazed tinted glass allows 51 percent of solar heat gain and 69 percent transmission of visible light.

Advantages

• Saves energy, controls solar heat and gives a striking visual effect
• Meets the increasing demands for light in workplaces, creates attractive interiors and gives a feeling of spaciousness
• Offers a practical, stylish alternative to traditional materials when used in screens, partitions and furniture at home or in the office
• Gives designers the freedom to create attractive modern environments that are also economical and easy to maintain
  

Body tinted glass gives the added benefit of making a building look unique and contemporary, creating a lasting impression for business HQs.
Applications

The range of available thicknesses enable glass to be used where superior strength, greater spans, reduced deflection, higher daylight transmission and enhanced noise suppression are required.

Automobiles

One of the most common applications of tinted glass is in automobile windows. Almost all cars come with tinting at the top of the windshield to reduce solar glare when the sun is low in the sky. Apart from this, the windows of several cars are tinted either at the factory or as an aftermarket add-on by the consumer, to provide privacy to the car’s occupants, as also to reduce the build-up of heat in a car while it is parked outdoors.

Dwellings

Another popular use of tinted glass is in windows of homes and commercial buildings. Residential glass tinting is much easier to do than automotive tinting. It can even be done by the homeowner himself, with some practice. Tinted glass in homes serves many practical purposes, such as limiting ultraviolet light transmission through windows, and reducing overall heat gain inside the home by reflecting solar heat energy, thereby saving the homeowner money on air-conditioning.

Commercial Buildings

Tinted glass is also used in commercial buildings. Apart from keeping the interiors cooler, it gives the outside of a building a more uniform, aesthetically pleasing appearance. Depending on the creative use of different colours of tinted glass, the building can also take on a unique and interesting appearance while being insulated from the sun at the same time.

Bullet Proof Glass

Bullet proof glass or bullet resistant glass refers to any type of glass that is built to stand up against being penetrated by bullets. Although the public uses the term ‘bullet proof glass’, generally within the industry itself it is referred to as bullet-resistant glass, because there is no feasible way to create consumer-level glass that can truly be proof against bullets.

Bullet proof glass is usually constructed using a strong but transparent material such as polycarbonate thermoplastic or by using layers of laminated glass. The desired result is a material with an appearance and light-transmitting behavior of standard glass but offers varying degrees of protection from small arms fire.

The polycarbonate layer, usually consisting of products such as Armormax, Makroclear, Cyrolon, Lexan or Tuffak, is often sandwiched between layers of regular glass. The use of plastic in the laminate provides impact-resistance, such as physical assault with a hammer, an axe, etc. The plastic provides little in the way of bullet-resistance. The glass, which is much harder than plastic, flattens the bullet and thereby prevents penetration. This type of bullet proof glass is usually 70–75 mm (2.8–3.0 in) thick.

Bullet proof glass constructed of laminated glass layers is built from glass sheets bonded together with polyvinyl butyral, polyurethane or ethylene-vinyl acetate. This type of bullet proof glass has been in regular use on combat vehicles since World War II; it is typically about 100–120 mm (3.9–4.7 in) thick and is usually extremely heavy.

Working Principle of the Bullet Resistant Glass

In the bullet proof glass, the Laminate-layers of tough plastic called polycarbonate sandwiched in between the pieces of toughened glass make the glass ten times thicker than the ordinary glass and it is very heavy. If someone fires a bullet at an ordinary piece of glass, the glass can't bend and absorb the energy. So the glass shatters and the bullet carries on through with hardly any loss of momentum. That's why ordinary glass offers no protection against bullets.

But when a bullet strikes bullet proof glass, its energy spreads out sideways through the layers. Because the energy is divided between a number of different pieces of glass and plastic, and spread over a large area, it is quickly absorbed. The bullet slows down so much that it no longer has enough energy to pierce through—or to do much damage if it does so. Although the glass panes do break, the plastic layers stop them flying apart.

Advances in bullet resistant glass have led to the invention of one-way bullet resistant glass, such as used in some bank armored cars. This glass will resist incoming small arms fire striking the outside of the glass, but will allow those on the other side of the glass, such as guards firing from inside the armored car, to fire through the glass at the exterior threat.

One-way Bullet Proof Glass

One-way bullet proof glass is usually made up of two layers, a brittle layer on the outside and a flexible one on the inside. When a bullet is fired from the outside it hits the brittle layer first, shattering an area of it. This shattering absorbs some of the bullet's kinetic energy, and spreads it on a larger area. When the slowed bullet hits the flexible layer, it is stopped. However, when a bullet is fired from the inside, it hits the flexible layer first. The bullet penetrates the flexible layer because its energy is focused on a smaller area; the brittle layer then shatters outward due to the flexing of the inner layer and does not hinder the bullet's progress.

Advancement

The field of bullet proof glass is constantly developing, and there are a number of military projects underway to create lighter-weight, more defensive forms of bullet proof glass. One of the most promising is the use of aluminum oxynitride in the outer layer, in place of a polymer layer.

U.S. military researchers are moving quickly to develop this new class of transparent armour incorporating aluminium oxynitride (Trade name: ALON) as the outside "strike plate" layer. It performs much better than traditional glass/polymer laminates. Aluminium oxynitride "glass" can't defeat threats like the .50 caliber armor piercing rounds using material that is not prohibitively heavy. This more resistant-glass that can be used in military assault vehicles and aircraft.

Applications

Bullet Resistant glasses have a wide range of applications as follows:

• Banks
• Government Buildings
• Convenience Stores
• Churches
• Schools
• Check Cashing Stores
• Liquor Stores
• Post Offices
• Jewelry Stores
• Art Galleries

Flickering Exterior of Burj Dubai

Burj Dubai – Spoken of as the tallest man-made skyscraper ever built, is under construction at Downtown and is likely to be unveiled to the world by the end of this year. At present, this structure stands at a height of 800m. This, however, is not its final dimension - which will be revealed only upon completion of construction.

The exterior cladding of Burj Dubai, developed by Emaar properties PJSC, was completed recently. The façade of this building is made up of aluminium and glass. The total weight of the aluminum used is equivalent to that of five A380 aircrafts. In May 2007, Arabian Aluminium Company in association with Hong Kong based Far East Aluminium began work on the exterior with more than 380 skilled engineers and on-site technicians.

On the whole, 24,348 cladding panels have been used over a total curtain wall of 132, 190 sq m. The last cladding panel numbered 24,348 with a weight of 750 kg. This was installed at the height of over 662m. The total 103,000 sq m of glass used in the cladding panels can cover 14 standard football pitches, while the15,500 sq m of embossed stainless steel used can cover 34 National Basketball Association specified basketball courts. The cladding material was specially made using advanced engineering techniques. Cladding includes high-performance reflective glazing, aluminium mullions and textured steel spandrels with vertical stainless steel tubular fins.

Doubly glazed and factory sealed panels of more than 18 different strength specifications and over 200 sizes have been used. The panels are of varying thicknesses and each feature two glass pieces of about 8mm to 12mm thickness, buttressed by a 12 mm spacer for strength and resilience. The length and thickness of each panel depends on the height and the location where the panel is to be fixed. Also, the strength of a panel needs to increase with an increase in altitude. Hence, panels at higher altitude are strengthened with stainless steel in addition to aluminium.

At the initial stages, 20-30 panels were installed per day. This number was eventually increased to 175 panels per day. As the altitude increased, the workforce faced grave risk; to minimize which, curtain-walling for the spire was pre-installed on the ground and then lifted to the summit as secured.

A “flickering cladding” was designed to maximize resistance to heat from the sun. This is expected to minimize load on air conditioning systems, thus improving the energy efficiency of the tower.

18 window-washing units have been built to ensure cleanliness of this huge façade. These are built using 9 track-mounted telescopic cradles, each with an extendable arm which can reach out to a distance beyond 20 meters.

The observatory deck on the 124th floor has been named “At the Top”, and will present to visitors with information on the “History and Evolution of Dubai and the Burj Dubai” and also a view of the whole city. This structure is expected to be a benchmark for high-rise developers in creating environment-friendly, sustainable and futuristic buildings.