Features & Articles

Windows are usually a dominant feature of a building’s exterior appearance. Their impact on visual comfort, on thermal comfort and on spaces in the interiors requiring heating and cooling, is immense. Furthermore, glass windows maximize day lighting and occupant comfort. Windows come in a number of different frames and glazing types. Improving the thermal resistance of windows and effective lighting depends greatly on frame type and type of glazing chosen for windows. Glazing is chosen, based on various factors, such as type of window fixed, window design, window orientation, climate, building design, etc. Glazing also implies the inclusion of special tints that change the colour of the glass. Types of glazing on windows: Tinted glass absorbs a large portion of the incoming solar radiation through a window, reducing the solar heat, gain, visibility and glare. Insulated window glazing refers to windows with two or more panes of glass. To insulate the window, the glass panes are spaced apart and sealed, leaving an insulating air space. This is done to lower the U-factor. Low-emissivity or low-e coatings on glass control heat transfer through windows with insulated glazing. A low-e coating is a thin, metal or metallic oxide layer deposited directly on the surface of one or more of the panes of glass. Different types of low-e coatings have been designed to allow for high, moderate or low solar gain depending on the intensity of sun’s rays in that region. Reflective coatings on window glazing or glass reduce the transmission of solar radiation, blocking more light than heat. Reflective coatings usually consist of thin, metallic layers, and come in a variety of colors.

Creating tempered glass and annealed glass involves the use of chemicals and heat to give it its characteristic properties. Tempered glass and annealed glass are basically made the same way. But their differences lie mainly in their structure, applications and more importantly in the cooling process. Structure Tempered glass is one of the hardest types of glasses. It is basically safety glass processed by controlled thermal or chemical treatments to increase its strength. The contraction of the inner layers during manufacturing induces compressive stresses in the surface of the glass, which increases its strength. On the other hand, Annealed glass is glass produced without the internal stresses of heat treatment. Strength Tempered glass is made using special heated furnaces, which heat the glass to a uniform temperature. As a result, Tempered glass has higher thermal strength and it can withstand high temperature changes. It is four to five times stronger than annealed glass Cooling process When the glass is removed from the furnace, it is cooled very quickly. This rapid cooling puts the glass surface into a state of compression while the centre core remains in tension. This produces a stronger glass. This is the reason why tempered glass is stronger. While Annealing is a process of slowly cooling glass to relieve internal stresses after it is formed. Annealed glass is thus cooled slowly, producing glass with intensity, but Tempered glass has a mechanical strength higher than annealed glass. Heat resistance Tempered glass can withstand both uneven heating and high temperatures due to its superior edge strength compared to annealed glass. Breakage When annealed glass breaks it will break or crack at the location of impact relative to the force of the impact. The broken shards can be of varying sizes. When tempered glass breaks it just shatters entirely into small pieces. This is due to the surface stress of tempered glass. Annealed glass breaks into large, jagged shards that can cause injury, therefore considered hazardous in certain architectural applications. Safety Unlike annealed glass, tempered glass breaks into small, square pieces when broken. Tempered glass is safer to use as small pieces are likely to cause less damage. They are used in places where safety is an issue. Tempered glass is valued for its safety and strength. Cutting and Drilling Tempered glass cannot be drilled, cut or altered because of its shattering quality. On the other hand Annealed glass can be drilled and cut if proper tools and procedures are used. Applications Tempered glass has various applications like industries, building, manufacturing, automotive, facades, doors and more. While annealed glass has simpler applications like windows, shop windows and display counters, facades, partitions and more. Expense Tempered glass is more expensive than annealed glass because it has to go through more processes in its creation. Annealed glass is comparatively less expensive.

With the growing need to go green in all aspects of living especially for homes there is a sudden development for Green homes in India. In the coming years, India is bound to witness an exponential growth in the housing sector. The Indian Green Building Council (IGBC) Green Homes is the first rating program developed in India, exclusively for the residential sector. The rating system describes in detail the goal and compliance options, and methodologies for credits. IGBC is the only council that has different rating programs to suit every program. All rating programs are aligned with the government goals as well as national priorities. The Rating programs focus on a holistic view and the key areas of implementation are as follows: 1. Sustainable site 2. Water efficiency 3. Energy and atmosphere 4. Material and resources 5. Indoor environmental quality These rating programs are national by choice and global in performance. National priorities and requirements may differ for different countries but the global aspects of the system of the program, addresses local requirements, as well as national concerns. This also implies that India is not inferior in any way, in keeping up to global standards. The above mentioned key requirements were already prescribed and practiced by ancient Indians. The elements of nature have always been revered by our forefathers. The reason for the green movement being a success in India is due to ancient Indians adherence to values for the finite resources on the crust of the earth and its important resources underneath. Therefore there is a blend of the old with the new in the latest developments for housing following IGBC norms. The only difference is the technological advancements in construction. Projects under IGBC (whether housing or commercial building) are marked with credit points which are based on certain factors, for it to be compliable with IGBC standards for green homes or green building. The factors are as follows: Energy performance, which is given a holistic approach. Adherence to mandatory measures for projects. Encouragement of renewable energy systems. Day lighting - different glazing factors for different spaces. Application of Rain Water Harvesting systems depending upon the climatic conditions and water table of the region Reduction in water and efficient use of the resource and aggregate water savings. Indoor air quality – a factor which would help in bringing in more comfort for the people. Rating programs need constant up gradation and this is based on the feedback from users of IGBC accredited homes and buildings. The green home committee strives to upgrade and launch the various versions of rating systems with changes in requirements. The Committee’s overall approach is, taking stringency to the next level. Raising the stringency bar or lowering it depending upon architects and end users. The next factor is implement ability. As each type of dwelling requires its own specific needs and requirements, implement ability will thus vary with requirements, with specific issues being streamlined and implemented. The committee also attempts to introduce new areas for offices and homes with onsite basic facility for the work force. Click here for the webinar

By analyzing the impact of the sun on a site, as well as the building’s location, the spatial arrangement, orientation, window placement, daylight access and other design features, the designer can take full advantage of its façade design features and increase the energy efficiency and comfort of the building. In other words Sun path analysis affects the architect’s knowledge of the suns effect on building design. The position of the sun with respect to an observer is commonly represented by two angles – altitude and azimuth. Solar azimuth is represented by the angle along the horizon of the position of sun, measured to the east or west referred to as Y. Solar altitude is the angle measured between the horizon and the position of the sun above the horizon referred to as X. Sun path diagrams are a convenient way of representing changes in the path of the Sun through the sky enabling the designer to locate the position of the sun at any time of day and at any location. The sun path and its analysis provide a summary of solar position that the designer can refer to when considering design options and shading requirements. The Sun Path Analysis is helpful in passive design features that are incorporated in buildings as a good passive design reduces heat gain thereby reducing the dependency on air-conditioning system, lighting system etc. Architecture has evolved over the years and today facades play an important role in defining the structure and form of buildings. Glass has become an eminent material for façades. Shading facades systems for solar control can resolve the challenge of receiving sufficient daylight into the building for the appropriate visual effects, without causing glare and unwanted heat gains to optimize comfort. Shading is an effective strategy to achieve thermal comfort and day light infiltration. An ideal shading strategy or device would block maximum solar radiation while still permitting daylight within. Shading largely depends on climatic conditions and orientation and nature of building, including sun path analysis.

Passive design features, if well designed reduces heat and cooling loads through energy-efficiency strategies in buildings. Elements to be considered in a building with efficient passive design features include, window placement for cross ventilation, air circulation, orientation of the building, the specific glazing type, thermal insulation, shading and materials to minimize energy use. Orientation of Building The most effective designs are based on specific understanding of a building site’s wind patterns. A primary strategy for cooling buildings in hot humid climates especially like India is to employ natural ventilation with the orientation of openings and windows in buildings in the correct direction. For tropical countries like India, for e.g. buildings should have maximum openings in the northern direction. Prevailing breezes are from the north and openings on this side make it convenient for natural breeze to flow in. The building design should enable night time temperatures to cool the building to increase comfort for its occupants. Cross Ventilation Windows and openings transmit not only sunlight but also both indoor heat and solar heat. That's why they may account for major heat losses in winter as well as major solar heat gains in summer. Passive cooling by way of cross ventilation maximizes the efficiency of the building envelope by minimizing heat gain from the external environment and facilitating heat loss by efficient movement of air. Natural ventilation can also be increased by reducing barriers to air paths through the building. Shading Shading is a strategy to achieve thermal comfort. Shading enables blocking of maximum solar radiation while still permitting day light and prevailing winds. In climates where winter heating is required, shading devices should exclude summer sun but allow full winter sun to penetrate. In climates where summer is harsh, shadings should protect the building from heat gain. It must be kept in mind that shading requirements vary according to climate and building orientation. Windows and openings would require different shading options. During the spring, fall, and cooling season, the windows should be shaded to avoid overheating, and heat gain within. While in winter the shading should enable maximum sunlight to enter. Unprotected glass is a great source of heat gain. Therefore it is essential to shade it. Shading of glass is a critical consideration in passive design. Windows and glazing are a very important component of passive design because heat loss and gain in a well insulated home occurs mostly through the windows. While choosing the right energy efficient glazing solution, the façade design needs to incorporate an understanding of the orientation of the building, location, wind and solar actions with respect to the building. Façade designing to improve passive design features is generally practiced throughout the world and has shown to produce buildings with low energy costs, reduced maintenance, and superior comfort. Passive design features, if well designed reduces heat and cooling loads through energy-efficiency strategies within interiors.

In tropical countries like India, the solar factor is a major contributor to heat gain in buildings. Thus the climatic conditions would require the use of material which would minimise heat transfer. It is essential therefore to choose the appropriate building materials that would improve the overall thermal performance of a building, making it more comfortable and consequently less energy dependant. Ideally building materials should: release unwanted heat quickly once the sun begins to set.     keep out the heat during the day     not store up the heat of the day, but release it effectively.     The main ways by which heat is transferred into the interiors of a building are by : Radiation: Heat that travels from a heat source and warms the surface on which it falls. Conduction: Heat that travels from solid objects Convection: Heat that is carried by the circulation of liquids or gases. Infiltration or air leakage in the building. Role of Glass in minimising heat transfer Glass is widely being used today as construction material as it can effectively minimise heat transfer and achieve superior indoor environmental quality while being energy efficienct. Thermal insulation glass gets its properties from a special coating on its surface which acts as a barrier to radiation, making sure the interiors of buildings are cool and comfortable. Correct glazing selection and glazing options enables high energy construction and lowers costs over time. Heat gain or heat transfer can be minimised through the correct selection and right use of glass. The benefits are as follows: Energy efficiency     Thermal comfort and ventilation     Recyclable material     Day lighting     Interior exterior blending    

Modern day architecture utilizes glass extensively in its design, structure and form. Due to constant developments in architecture, glass is now one of the most modern building materials which to a great extent influence the appearance of buildings. In recent times, glass in architecture plays an important role in optical emphases and provides numerous technical functions. Additionally glass as a material for construction fulfills the need for adequate sunlight and occupant comfort. The advantages of using glass are many and varied. Glass reduces building load     Advances in manufacturing glass have enabled glass to be effective material to reduce building load. In areas commonly used to shape with concrete are now being replaced by glass. As a material they are much lighter in weight and technically easier to install. Dimensional accuracy is possible with this material which makes it easier to fulfill the required specifications. This is also helpful in increasing construction pace. Aesthetic value     Glass has an aesthetic appeal that suits today’s requirements of aesthetic appeal with functionality, in architecture. It is also possible to obtain unique colors compared to standard construction products, which makes its structural appearance more trendy and modern. Provides a connect between interiors and exteriors     Glass makes spaces appear larger and is ideal in merging the exteriors with the interiors, in its own unique way. There is optical expanse of space increasing comfort levels for occupants. Glass offers predictable behaviors in case of earth quakes and building settlements.     The predictability of glass behavior is useful in construction as it makes it safer to use and replace in case of damage. Technological advances have facilitated the installation of the specific types of glass for specific situations. Provides natural light for interiors     A fact which is essential, natural light streaming in without constraints is the quality for which the use of glass is hugely popular. Offers fewer constrains related to shape and design     Nature of glass enables is to offer modern solutions like facades and multi block designs as there a very few constraints related to shape and design. Provides solutions for safety glazing, acoustic design etc.     Glazing solutions in design aspects, for solar protection, sound protection, heat protection and energy saving are unique qualities and benefits of glass usage. Thus glass is a multifunctional building material that can fulfill nearly any task in a modern building. Depending on the design requirements, the potential of glass is not only in increasing the thermal comfort and therefore, the quality of living, but also make a decisive contribution to the energy efficiency of buildings.

The process in which light travels through a medium without being absorbed or scattered is light transmission. Maximizing light transmission and minimizing heat transmission is an important requirement for green buildings, which is characteristic of solar control glass. When light hits upon a glass surface, some of the light is reflected, depending on the angle of incidence and the refractive indices of the glass and the source of light. The amount of light reflected and transmitted light can be calculated using formulas specific to it. Light transmission depends on heat gain inside buildings which can be optimised through high performance glass. Light transmission or LT depends on Location     Climatic conditions     Orientation     Nature of building operation     Building design - the form and layout of the building.     Building materials - the amount of mass and insulation.     The size and location of windows and shading.     Thermal properties of glazing units.     The amount of light transmitted and energy specifications are key indicators of which glazing is best for specific application. Solar energy is composed of Ultraviolet (UV), Visible and Infrared (IR) radiation. Glazing types differ in how much of it is transmitted. Visible Light Transmission Visible Light Transmission or (VLT) indicates the percentage of visible light that is transmitted through openings like the windows. Visible transmission is relatively high for clear glass and it is reduced by adding tint to the body of the glazing, or by applying a colored or reflective film or coating to the surface. Reducing visible transmission will also reduce heat gains. Therefore choosing a glazing with a lower visible transmission may be done either to achieve an architectural effect of colour or reflection or to reduce glare or heat gain through the window openings. In some applications, high visible transmission values are important to deliver as much daylight as possible like in window display. This may provide glare but the contradictory needs can be met by using different glazing options in different glasses for the same area. U Factor "U" Value is the coefficient of transmission, of heat through the materials, which compose the building's envelope. In other words it is the heat transfer through a window due to the temperature difference between the inside and outside. U factor is important whenever the inside temperature is significantly different from the outside temperature. The lower the U factor, the better the glazing is at reducing heat loss. U factor is most significant for heated buildings in cold climates since temperature difference is usually greater in winter when the outside temperatures are low. R Value The R-value is a measure of thermal resistance. The R Value is the inverse of the U factor. The higher the R value, the better the performance. The higher the R-value, the better insulated are the walls and ceilings.

Green building or sustainable building refers to a structure that is resource-efficient in its structural design and construction. In order to achieve this Green building practices take into account concerns of economy, utility, durability, and comfort. Indian Green Building Council formed by CII green building movement, works towards this goal and endeavors to make India a global leader for sustainable environment by the year 2025, especially in the housing sector. Concept of green homes is nothing new to India. Ancient Indians were well aware of the techniques of making homes green. With the advent of technological advancements, today we are able to carry forward traditional architectural excellence with modern equipment. Some of the sensitive issues and key concerns primarily related to energy concerns are: Integrating green roofs (Green roofs contribute to sustainable building development by enhancing cooling and shading effects.)     Incorporating excellent day lighting.     Installing appropriate glass for doors and windows. (Different glazing factor is required for different spaces. For eg. Living rooms and bedrooms would require less daylight while study room and kitchens would require more).     Water efficient features (Efficient water usage without wastage)     Incorporating solar water treatment plants     Onsite sewage treatment plants     Employing rainwater harvesting methods which help integrate water management systems for buildings.     Utilizing energy efficient equipment. (Efficient use of LED lamps and solar lighting systems when utilized facilitate in saving considerable amount of energy.)     Indoor air quality or effective ventilation within interiors with windows and doors placed strategically. All these above factors play a major role in enhancing the sustainable environment in buildingsand green building initiatives. Banks, convention centers, airports, residential projects, hospitals, colleges, institutions, offices, IT parks, townships and many more projects of different magnitude and scale wish to address these concerns not only in its construction, but as an ongoing process as well. In this regard IGBC accredited professional take green building initiatives forward in order to enhance green features in their projects with a holistic approach. IGBC is also an immense source of assistance to builders and architects who wish to incorporate green features in construction. Among others, significantly it is the residential sector which is taking up green initiatives in construction on a large scale. Residential sector is therefore significantly contributing to energy efficiency. Green homes bring in a lot of intangible benefits, like better air quality, good usage of water, and sunlight and more. After all a home should be a “delight to enter, serene and peaceful to live in and regrettable when leaving”. Click here to know more on IGBC green building systems and initiatives, from this Webinar.

Glass can be extensively used in furniture to lend it a contemporary and sophisticated look. It is widely used in a number of applications like kitchen countertops, wardrobes, table tops and more. Its functional and aesthetic qualities make it appropriate material for furniture. Above all, glass furniture is easily maintainable. Glass tabletops Glass tabletops are generally used to protect the surface of a table or desk. The edges are usually polished or smoothened to avoid injury due to sharp edges. Glass for tabletops comes with a specified thickness, depending upon the usage. 1/4" is the preferred thickness. If heavy objects are to be placed on it, the thickness is ½” or more. The type of glass used for table tops are usually annealed, especially on wooden tables. Tempered glass is used if the additional safety due to breakage is required. Coloured, Lacquered glass, Float glass and Patterned glass are also suited for table tops. Wardrobe glass The latest in wardrobe styles is to have Glass on wardrobes. The Glass is not necessarily mirror (though this option is also available) but glasses that make wardrobes appear elegant and exclusive. Coloured and lacquered glass used for wardrobes, can match with the colour scheme of the room. It enhances the look and feel of the space. This type of glass is highly durable. Glass in wardrobes can be easily installed, cleaned and maintained. Countertops Glass countertops are gaining in popularity among homeowners. Glass countertops for kitchens blend functionality and appearance. Patterned glass or lacquered glasses are the best options for countertops. They are scratch resistant and also highly durable. This glass is humidity resistant making it ideal for use in high humidity rooms like kitchens. Glass as a versatile material has a number of uses, in interiors enhancing functionality and aesthetic appeal.