Electrochromic Vacuum Glass

Most heat loss from within the interiors of an architectural structure is through glass windows and doors than through other components. Thus, finding ways to make glass in windows and doors more thermally insulating is important to improve the energy efficiency of a building. One of the techniques usually applied is to combine two window construction procedures — vacuum glazing and electrochromic glazing. Doing this ensures improved thermal comfort while limiting the use of auxiliary space heating and artificial light. This guarantees very low heat loss and variable light transmission, and also controls glare from day lighting.

A vacuum glazing (VG) comprises two sheets of glass that are separated by a very narrow evacuated space. An array of metal or ceramic pillars holds the sheets apart, and the edges are sealed with solder glass or indium. The interior faces of one or both glass sheets usually have a transparent, low-emittance coating. Glass windows made from vacuum glazing are much more thermally insulating than either single pane or conventional double glazed windows.

Electrochromic (EC) glazing causes glass to change its tint in response to an applied voltage change. Visible light transmittance by EC films can be varied between 8% in their coloured state and up to 80% in the bleached state by applying a 1–2V DC switching voltage.

Electrochromic vacuum glass combines EC and VG technologies. This novel glazing system combines the low-heat-loss properties of VG—a U value (heat transmittance) of less than 1Wm−2K−1—with the variable transmittance of EC glazing to control solar gain.

High densities of nodes in and around the pillars are used to represent the heat transfer. When the EC layer faces inward, glazing surface temperatures become too high for occupant comfort and result in damage to the EC VG system. The temperature difference between the two glass panes of the VG result from the high thermal resistance of the vacuum gap; the temperature difference between the panes separated by the EC layer result from the EC layer absorbing heat.

Electrochromic vacuum glass is more thermally insulating than a standard double pane window and is comparable to a good triple pane window. Windows made from Electrochromic vacuum glass improve the energy efficiency of buildings while keeping occupants thermally comfortable.

Electrochromic Glass

Electrochromic Glass, also called as electric-control curtain glass can change from opaque to clear with a flick of a switch. It provides total privacy when needed. This specified structural glass is produced with the multi-development of electronics and glass techniques.

Electrochromic glass is an energy-saving component for buildings and can change colour on command. It works by passing low-voltage electrical charges across a microscopically-thin coating on the glass surface, activating an electrochromic layer which changes colour from clear to dark. The electric current can be activated manually or by sensors which react to light intensity. Glass darkening reduces solar transmission into the building. When there is little sunlight, the glass brightens, so that the need for the artificial light is minimized.

Electrochromic glass changes light transmission properties in response to voltage and thus controls the amount of light and heat passing through. In electrochromic glass windows, the electrochromic material changes its opacity: it changes between a coloured, translucent state (usually blue) and a transparent state.

A burst of electricity is required for changing its opacity, but once the change has been effectuated, no electricity is needed for maintaining the particular shade which has been reached. Darkening occurs from the edges, moving inward, and is a slow process, ranging from many seconds to several minutes depending on glass size.

How does it work?

A thin multi-layer assembly is sandwiched between traditional pieces of glass. The two outside layers of the assembly are transparent electronic conductors. Next are a counter-electrode layer and an electrochromic layer, with an ion conductor layer in between. When a low voltage is applied across the conductors, moving ions from the counter-electrode to the electrochromic layer cause the assembly to change color. Reversing the voltage moves ions from the electrochromic layer back to the counter-electrode layer, restoring the device to its previous clear state. The glass may be programmed to absorb only part of the light spectrum, such as solar infrared.

Salient Features

When a current is supplied, it darkens and when electricity is withheld it becomes clear. Another unique aspect of this kind of glass is that it isn’t all black and white. It is able to create varying levels of light penetration, allowing total management of the sun’s power. Sometimes it takes several minutes to change shades.

Applications

Electrochromic glass provides visibility even in the darkened state and thus preserves visible contact with the outside environment. It has been used in small-scale applications such as rearview mirrors. Electrochromic technology also finds use in indoor applications, for example, for protection of objects under the glass of museum display cases and picture frame glass from the damaging effects of the UV and visible wavelengths of artificial light.

Electrochromic glass can be applied to offices, meeting rooms, hotels, villas, bathroom doors and windows, shower rooms, kitchen cabinets, glass curtain walls, technical resident conservatories and commercial buildings, as well as automobile skylights, exhibition halls, hospitals, open counters of banks, security windows of automatic machines, and so on.

Electrically Heated Glass

Electrically heated glass was first developed in World War II to prevent aircraft windshields from frosting over and obscuring visibility. Since then, this technology has been become almost universally used in aviation. It has even reached supermarket freezers, where glass doors must remain clear for customers to be able to see the merchandise.

Electrically heated glass is a laminated glass, incorporating almost invisible electrically-conductive wires. It comprises two or more sheets of glass interlaid with one or more films of polyvinyl butyral (PVB). This assembly combines comfort with safety, whilst preventing condensation. Electrically heated glass is suitable for any circumstance where there is high moisture content in the air and where the difference between the internal and external temperature may lead to condensation risk.

Production

In order to electrically heat glass, a microscopic Tin (II) Oxide coating is applied to a pane of ordinary float glass. This coating is perfectly transparent and conducts electricity. An electrical current is supplied by two busbars located on opposite sides of the glass. The electrical resistance of the Tin Oxide coating produces heat energy. This heat radiates from the glass in the form of infrared energy. The busbars are typically connected to a power control unit that regulates the flow of electricity and thus the temperature of the glass.

Electrically heated glass maintains a steady and consistent temperature across the entire surface, and heat radiates off the glass in only one direction: toward the object or area to be heated. In addition, this technology imparts beauty and elegance to glass. The glass can also be coloured or etched with designs in order to complement the appearance of a room or appliance.

Groceries

Heated glass is both visually attractive and sanitary, making it ideal for use with food in a public setting. Since the glass is perfectly transparent, deli items are in full view of the customers, and remain hot and ready to serve. Keeping meat and other food items warm improves their taste and prevents spoilage. This technology is much more efficient and effective than heat lamps, and is a definite improvement over microwaving cold food just before it is served.

Electronic Controller

An electronic controller regulates power flow to the heating components, and thus controls glass temperature. With a simple twist of the dial, the glass can assume any temperature from approximately 70oF to 350oF. An important feature of the controller is its automatic fault and glass breakage detection capability that will automatically shut down the heating circuit if there is a problem. In addition, the appliance should include a GFCI breaker to guard against ground faults and leakage currents.

Electrically heated glass windows

Electrically heated glass can also be incorporated into a double-pane Low-E architectural window unit. With the heating element applied only to the interior side, the window will radiate warmth into the room no matter what the temperature outside. This eliminates heat loss, chills, drafts, and frost problems associated with ordinary glass in cold climates. In warm weather, heated glass prevents condensation, which helps prevent mould from growing on the window sill.

Towel warmers

Electrically heated glass can also be employed in the design of towel warmers for both custom homes and hotels, replacing traditional radiator style units. The invisible thin film conductor involved in this design is even more efficient than traditional radiator-type towel warmers. These stylish towel warmers are comprised almost entirely of glass, yet the glass used in these applications is never too hot to touch, and it does not contribute noticeable amounts of heat to the room.

Glass Windows with Low-e Glass

A window is a quadrangular opening in a wall that allows light, air and sound to pass through, provided the window is not closed or sealed. Windows are usually glazed (made of glass) or constructed using an appropriate transparent or translucent material.

Low-E Coated Glass in Window Technology

Low-E coating stands for Low-emittance coating on a solid surface. It is an extremely thin, nearly invisible film of metal or metal oxide layers deposited on a window or skylight. Its primary function is to reduce U-factor by restricting radiative heat flow. The key methodology by which heat is transferred in multilayer glazing is thermal radiation from a warm sheet of glass to a cooler sheet. Covering a glass surface with a low-emittance element and placing that coating into the gap between the layers of glass impedes this radiant heat transfer significantly, thus reducing the overall flow of heat through the window.

Benefits of Low-E Glass

Low-E technology is over two decades old in the glass market. Although its benefits have been duly acknowledged, glass with low-e coating is rarely used in construction. There are several priceless advantages and cost savings that can be achieved by using low-e glass.

During the severe energy crisis the world faced during the 1970s, everyone endeavoured to minimize consumption of natural resources. In case of glass, energy was lost by way of heat loss through the glazed surface. In 1980, the commercial development of thin, transparent, low emissive coatings literally revolutionized the concept of energy savings in windows. The low-e coating, placed on the inside of the insulating glass unit, enabled the sun’s short-wave energy to enter the room and at the same time prevented internal warm air from leaving the room.

SOURCE: www.glazette.com

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 124^th 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.

ZAK GlassTech – 2009

ZAK GlassTech 2009 is one of the very effective marketing juncture for the glass industry players to display their innovative glass products and gather reputation for those products. ZAK GlassTech 2009, the 7^th edition of the event is planned to be conducted from 3-6 December 2009 at the state of art Bandra Kurla Complex (BKC), Mumbai, Maharashtra, India. ZAK Glass Tech 2009 will be really a blooming opportunity for all the glass trading fraternity. ZAK GlassTech is being successfully organized by one of the leading exhibition organizers in Asia, ZAK Trade Fair and Exhibitions Private Ltd.

ZAK GlassTech event has emerged proudly as a very largest technology trade fare in the Indian sub-continent, which gathers various kinds of buyers and exhibits under different categories. Over the past 6 editions, ZAK GlassTech exhibition grabs the visitors from different parts of India and also across the world. Number of visitors visiting the trade fair is increasing for every year. So it is expected that by this year also the amount of visitors will be increased to visit the creative and exciting glass products.

Nearly 200 companies from 25 countries will be the participants of this trade fair. Leading technologists are committed to address the technology seminars. Consultants and leading technology peoples will launch the industry workshops. Interactive sessions with the technicians for the better understanding of the new products are also scheduled. As the growth of the glass and glazing industries leads to the growth of the ZAK GlassTech and visa versa. This event is a big roof for the technology leaders and the industry leaders to meet and change their thought and ideas.

Product profile

Products profile includes architectural glass, processed glass products, toughened, tempered, laminated glass, glass and its accessories, structural glazing and curtain walls, insulating glass materials and machines, stained glasses, printings on glasses, glass robots, solar protection glasses, fire resistant glasses, active self cleaning glasses and so on.

visitors profile 

Visitor’s profile includes glass dealers, automotive dealers, glass processors, interior decorators, glass furniture manufacturers, architects, interior designers, fabricators, interior consultants, planning and construction departments, property developers, business, IT parks, hotels, malls and etc.