Low-E Glass

Low-E Glass(Low Emission Glass)

The amount of human activity happening indoors, in homes and offices, is very high. Maintaining optimal temperature indoors promotes both healthy living and healthy working. And, there is nothing better if this can be done in a sustainable and energy-efficient manner. This is where Low-E Glass has come to play such an important role.

How does it work?

How  Low-E Glass Works

How Low-E Glass Works

Sunlight or solar radiation consists of visible light, longwave (or ultraviolet) and shortwave (infrared) radiation. Low-E glass reflects back or reduces both types of radiation while allowing visible light to pass through. It also works in reverse. Indoor objects like furniture and people give off varying amounts of heat; since Low-E glass reflects heat back to it’s source, this heat is preserved within the room.

Using Low-E glass

* Low-E glass comes in high, moderate and low gain panels. High solar gain panels are great for colder climates where there is a need for heat to be preserved and reflected back into the building. Low solar gain panels reflect excess heat back into space making them ideal for hot climates. Moderate gain panels are a good fit for areas with temperature fluctuations. These panels are manufactured by applying a Low-E coating to the exterior (to keep heat out) or the interior (to keep heat in).

* High gain panels are also recommended for north and east facing windows where a larger amount of heat loss is to be expected. South and west facing windows work well with low gain panels especially during summer when there is a possibility of overheating.

Benefits of  Low-E glass

* Low-E glass helps conserve heat during winter and dissipates heat during summer, leading to lower energy consumption for heating or cooling. You save on energy bills too!

* Low-E glass provides better fading protection as well. Your furniture, carpets, curtains and wall furnishings preserve their colour for longer.

* The energy savings from installing Low-E glass considerably outweigh the energy consumed while manufacturing the glass, thus providing benefits for the larger environment as well.

Manufacture

* Hard Coating (or Pyrolytic coating): Tin oxide and other additives are deposited directly onto the glass’s surface while it is still hot resulting in a hard and durable glass.

* Soft Coating (or Sputter or Vacuum coating): This coating is applied in multiple layers of optically transparent silver sandwiched between layers of metal oxide in a vacuum chamber resulting in a high-performing glass.

* Low-E films fulfill most of the functions of Low-E glass and are cheaper but much less durable.

Since the introduction of Low-E technology in 1979, the technology has evolved to the point where Low-E has now become part of mainstream construction.

Self Cleaning Glass

Self cleaning glass is a type of glass with a surface that can keep itself clean of dirt.

Self Cleaning Glass

Development

Self cleaning glass technology has been in development since the 1990s and probably earlier; in 2001, it was Pilkington who launched the world’s first self cleaning glass, the Pilkington Activ™, followed by other major glass manufacturers. The technology has continued to evolve and the development of the first dual-coated self cleaning glass that can be toughened from stock, Saint Gobain’s SGG BIOCLEAN® COOL-LITE ST marks an important point in this evolution.

How does it work?

Self cleaning glass harnesses the natural forces of sunlight and rain to keep itself clean. A special coating applied to glass during it’s manufacture gives it the self cleaning attribute.

How Self Cleaning Glass Works
How Self Cleaning Glass Works

There are two types of self cleaning coatings available:

* Hydrophilic coating uses a thin, transparent coating of titanium oxide that is both photocatalytic and hydrophilic. Photocatalysis uses the ultra violet rays of the sun to react with organic dirt, oxidising them and breaking their adherence to the glass. Hydrophilis prevents the formation of water droplets, causing it to “sheet” on the surface of the glass and wash away the dirt particles loosened by photocatalysis.

It should be remembered that although regular cleaning is not necessary, heavy accumulations of dirt/dust and during periods of little/no rainfall, washing with clean water will keep the cleaning process going.

* Hydrophobic coating works by repelling water; this is similar to the action of Lotus leaves which exhibit a very high level of water repellency. At a microscopic level, the apparently smooth glass surface reveals “jags” or peaks/valleys which are a natural magnet for dust and grime. The hydrophobic coating covers these peaks and troughs over which water runs off picking with it the dust particles.

Applications 

Self cleaning glass is great for:

* Glass Windows

* Structural Glazing

* Greenhouses

* Glass Roofs

* Skylights

* Shopfronts

* Conservatories

* It could potentially be used for manufacturing computer, mobile and tablet screens.

Benefits

Listed below are the benefits of  self cleaning glass

* It reduces the frequency of glass cleaning and makes cleaning sessions much easier as less dirt and grime adhere to the glass.

* Standard glass cleaners use chemicals that are harmful to the environment; by minimizing the use of such cleaners, self cleaning glass contributes to environmental health.

* Cleaning expenses are reduced resulting in increased cost savings.

* It’s self cleaning action makes it ideal for hard to reach areas like roofs and canopy glazing.

* Many of the commercial self cleaning glass products available also come with solar control and noise reduction attributes. The solar control characteristic will also provide fading protection by reducing bleaching by UV rays.

Sustainable Glass for Buildings

Glass has proved to be an important ally in the development of Sustainable Construction or Green Construction, as it is alternately referred to. Glass, treated in various ways, offers benefits that are not just functional or aesthetic but also Sustainable.

Glass for Building

Sustainable Glass for Building

Glass, suitably treated, aids in enhancing the Sustainability rating of a structure in the following ways:

* It provides optimal thermal insulation, reducing heat gain inside buildings leading to lesser electricity and utility costs.

* Suitably sized and sited glass elements like windows, skylights, doors and walls provide great natural lighting without glare for the inside of the building, leading to lesser artificial lighting and associated costs.

* Glass can also filter out harmful UV (Ultraviolet) solar radiation of the B type (UVB).

* Sustainable glass is recyclable.

* Glass can also provide acoustic insulation and comfort leading to a tranquil internal environment.

* A well-planned design that uses glass extensively can lead to Sustainable structures that have significantly lesser weight.

* Sustainable Glass is also available in multiple colour and design options for pleasing aesthetics.

* Glass can also be used to generate renewable energy through solar-thermal and photovoltaic applications and wind turbine, which benefit from light weight of the reinforced glass fibres.

While the benefits are manifold, it is important to use the right kind of glass for the right place for a fit that is effective, attractive and safe.

Different Types of Sustainable Glass used in Building

There are a number of different types of Sustainable Glass in a range of patterns and tints that are used in the construction industry. Here are some of the main types:

Float or Annealed Glass: Molten glass is “floated” onto a bed of molten tin. This produces a glass that is flat and distortion- free. It is also the starting material used to produce more advanced types of glass through further processing.

Laminated Glass: This is made of two or more layers of glass with an intermediate plastic layer that holds the glass together when shattered, making it a safe product for various applications. Laminated glass is also used to protect coatings susceptible to damage.

Toughened Glass: It is produced by heating glass to above 600°C and then rapidly cooling it. Not only does it have an increased resistance to breakage, but when broken it breaks into small pieces without sharp edges making it a safe product for a wide range of applications including sliding doors, partitions and low-level windows.

Coated Glass: Coatings are applied to the glass, either during the manufacturing stage (hard coating) or after (soft coating) to endow the glass with special reflective, thermal and corrosion-resistance characteristics.

Coated Reflective Glass

“Shimmering” high-rises and “Glazed” facades are terms that indicate the role, use and popularity of glass in the construction industry. Glass fulfills both functional and aesthetic purposes and Coated Reflective Glass forms a significant portion of the glass population used in the construction industry today.

Ordinary glass acts almost like a direct transmitter of solar heat necessitating use of expensive cooling mechanisms. Reflective glass, on the other hand, absorbs and reflects a major proportion of the sun’s direct heat energy more effectively than ordinary glass or even tinted glass. The mirror like appearance of reflective glass is achieved through the application of a metallic coating during or after glass manufacture

Reflective Coating Glass

Reflective Coating Glass

Coated Reflective Glass- the basics

There are two methods of manufacturing Coated Reflective Glass:

Pyrolitic (Online / Hard Coating) Process

A coating is applied and fused into the glass while the glass is still hot in the annealing chamber, at 1200°C. The glass so produced, in addition to it’s reflective and thermal properties, is tough and durable. It can be cut, heat strengthened, toughened, laminated and bent and handled like any standard square of glass.

Vacuum (Offline / Sputter / Soft Coating) Process

Metal particles are deposited onto the glass surface by means of a chain reaction in a vacuum vessel or chamber. The coating applied by this method is soft and more inclined to damage than hard coatings. Vacuum coated glass is generally available in laminated form with the coating on the inside to protect it from damage.

In general, vacuum coated products have better SHGCs (the fraction of solar radiation admitted through the window, skylight or door) and lower ‘U’ values (a measure of heat transmission; a smaller U is better at reducing heat transfer) than pyrolytic products, which are more durable.

Other Offline techniques of manufacture include Immersion Process, Chemical Process, Foil and Screened Glazing.

Reflective coatings may also be applied to the inner glass surface of an existing window by means of an adhesive-bonded, metallic-coated plastic film. The applied films are effective at reducing solar gains but are not as durable as some types of coated glass.

Benefits of Coated Reflective Glass

* Reduces heat gain inside buildings, leading to reduced electricity and utility costs.

* Allows optimum lighting the natural way, reducing both electricity costs and artifical lighting requirements.

* Coated Reflective Glass is also available in multiple colour options to meet various design requirements.

Coated reflective glass is a major is a widely used element in Green designs today, that seek to minimize the use of non-renewable materials, maximize the use of natural resources and contribute substantially to the reuse/recycling of renewable materials. Glass, in addition to it’s above benefits, is also a recyclable resource, making it a great fit for Green construction.

Energy Efficient Glass

Glass offers more than a great view. With the advent of green architecture, glass is  increasingly being relied upon for energy savings, because of its unmatched attributes.

Energy Efficient Glass

Energy Efficient Glass

Energy efficient glass is basically architectural glass, that allows you to effectively  regulate heat and light transfer between interiors and exteriors, so as to give you more control over energy consumption.

How does it work?

How Energy Efficient Glass Works

How Energy Efficient Glass Works

When a portion of sunlight enters a space through a glass window, it heats up the space. If the glass is such, that it retains a portion of the refracted sunlight, heating up the internal space and raising the temperature, conventional heating can be made redundant. These glasses, with glazed surfaces that allow you to regulate the heat of a closed environment fall in category of energy efficient glasses.

The opposite can also be achieved, with a glass that allows lesser amount of heat to enter via sun rays, by acting as an effective shield and keeping the interior temperature cool enough to make air conditioning redundant. In both cases the glass plays a key role in energy efficiency.

Energy efficient glasses are widely applied– in cold and in warm locations.

Applications

Insulated glazing, is a type of energy efficient glazing that  is often used in situations where heat transfer needs to be tackled. With a layered construction and gaps between layers, insulated glazing allows for effective regulation of heat. Often such glazing also results in some noise reducing properties. Energy efficient glasses of this sort, find application in sound studios and industrial sites, where certain units need temperature & sound regulation.

In warmer conditions, a simple toned glass that offers just lower SHGC, can be unsuitable because of its property to absorb heat. It makes the glass hot and will radiate heat into the living space. Instead, a low E or a low emissivity coated glass can do wonders in tackling heat. Low E glazing type glasses, with special coatings that allow light but reduce solar heat  gain, are very popular in warm locations and are known to bring down consumption by 12 to 20%.

Using energy efficient glass strategically with an understanding of the local conditions can  make a huge difference to homes and work places, by not just tackling energy issues, but by also creating better conditions.

Architectural glass

Architectural Glass, is an umbrella term that refers to all glass types that are normally used in buildings and constructions. Typically glass used in windows, frame-less doors, indoor and outdoor home design elements, facades etc., come under the wide ambit of this term.

Architectural Glass

The origins of architectural glass can be traced back to the first experimental attempts made by the Egyptians, when they tried to include cast glass in their buildings. Since then, glass has come to acquire a special status in architecture, making it famous with both the conservatives and the adventurous.

Categories of Architectural Glass

Architectural Glass used today can fundamentally be divided into two broad categories for better understanding-

a) for utility purpose and b) for decorative and cosmetic purpose

A glass used in the facade of a building to protect, and give structural stability, will be very different from a crown glass piece used on a window for mere cosmetic reasons. And this, end level application of the architectural glass, is what gives it its major differences. Each glass type has its own merits and its own suitable application.

Types of architectural glasses

The Earlier Architectural Glass

  • Crown Glass

    Cast, Crown and Drawn sheet glass are one of the earliest known glass types that were used for architectural purposes. Their manufacturing processes being primitive gave them distinct attributes and made them suitable for only certain applications.

  •  The Cast glass for example, was made by pouring glass into molds, and so the end product lacked a great degree of transparency. However it was very suitable as a glass that offered the right amount of privacy.
  • Today, even though cast glasses are completely phased out, architects may choose to work with them for aesthetic reasons.

Modern architectural glasses

  • Modern Architectural Glass

    Toughened Glass, Insulated Glass,Solar Control Glass,Laminated glass and  Reflective glass are some of the glasses used in modern architecture.

  • Modern architectural glasses vary in terms of strength, thickness, opacity, color and glaze, depending on the use they are put to. A glass used as a part of the structure itself, will definitely be of a thicker dimension and stronger built, than a one used in a window.
  • Strength and reinforcement are defining features of modern architectural glasses.
  • Another aspect of modern glasses is the technology used to make it better suited for special conditions. For example, Architectural glasses meant for frame- less doors, on impact shatter into tiny individual pieces, so as to present a lesser hazard.
  • Safety type glasses are mostly used for buildings and are typically reinforced, toughened and laminated.

Going Green with Glass

A stroll through a busy business center in any of the metro cities of India will tell you how widespread the use of glass is, in today’s construction. The best looking building that attracts your attention, in all likelihood, is one that features glass heavily in its design; only you might have never stopped to ponder. From the sleekest contemporary designs to the most complex facades, glass is everywhere.

technopark      green    green-2

But why is glass so widespread in its usage? And why is it the first choice for most architects?

The fact lies in the natural properties of glass and also in what cutting edge technology has done to add to its inherent attributes. Glass has immense advantages when used strategically and the advantages go beyond the purely aesthetic reason, which is why it is popular with almost everyone: the home owner and the architect. If its benefits were merely cosmetic, then it would never have found popularity with the cost conscious Indian consumer.

Glass’s ability to offer solutions that have a deep impact on the environment and its ability to change the way a building looks and works makes it arguably the ultimate green element, for the sake of construction.

A quick look at what makes glass such an out and out green element and how glass helps us to go green  :

  • The only element that acts as an active go between the exterior and the interior. In colder places, glass lets heat come in and retains the heat within the interiors, reducing the need for heating.
  •  While in warmer places, glass can reduce the amount of heat coming in, thereby reducing the need for internal air conditioning. Imagine the contribution. No other material can play such a role.
  • Glass has the ability to offer natural light- through reflection and refraction. Through strategically placed glass panels as windows and design elements, a whole room can be lit with natural light. In fact even with just a little bit of planning the need for internal lighting can completely be eliminated.
  • Most large work environments that have put in a thought during their design benefit hugely from this manner of lighting. These green buildings have demonstrated almost zero internal artificial lighting.
  • The design wonder- Glass has the ability to completely change the look and performance of the building, when correctly used. A glass panel or arrangement can add extra room to a cramped design by simply being more open and airy.
  • Glass gives a light, open, airy feel that is very popular these days, given the high square foot cost. With limited built in area, we can use glass to give us the more area feel. This also has a direct co relation with the work environment.
  • Many small business units, in high rise buildings resort to this green trick to make the most of their available office space. Delhi’s commercial high rise buildings are a fine example of such usage of glass.

Glass is recyclable, is nontoxic and is a great tool to work with and so is definitely green. However, not all glass structures are green structures. When not carefully researched and planned, merely using glass can defeat the purpose of green architecture. A case study of buildings in Dubai, that use glass extensively in their architecture, demonstrated how they failed to achieve the green goals, for a variety of reasons. One of the key reasons was the wrong selection of the glass and the glazing.

While glass remains the most sought after green element and a definitive tool for going green, a thorough understanding of local conditions and the building’s architecture is a must, for green efforts to be successful.