Life cycle assessment on Glass in built environment by Ram Kumar

LIFE CYCLE ASSESSMENT ISD 5106 SUSTAINABILITY MODELS & BLUEPRINTS SUBMITTED BY RAMKUMAR (A0123482)

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Life cycle assessment study of glass in built environment 1.Objectives of undertaking Glass for LCA study Glass has been an inevitable architectural element right from very old age. Glass was used in old churches and other public structures as an aesthetic element in the form of stained glass and glass motifs. Glass was a symbol of richness and grandeur to a building. Later Glass was used in windows in the pre modernist architecture replacing wooden windows that which allowed light to pass through the internal spaces thereby avoiding the cold air and rain water coming inside. In the post modernist era the usage of glass became extensive not just for windows but for doors, partition walls, flooring, and even for staircases in some cases. The usage of glass improved from not just internal usages but also as a building facade as structural glazing, curtain wall system, even as load bearing element in few cases. However the production of glass is much more energy consuming process and results in large amount of carbon emissions as a by-product. Currently glass has been used for various commercially and industrial products which eventually lets out high amount of embodied energy in the environment. This LCA study would tell us how relevant is usage of glass in buildings and how to control the initial embodied energy and recurring embodied energy. To assess the changes resulting from design, shape and manufacturing methodology and the process. Awareness of the carbon emission produced by the material. Global movement for manufacturing companies and users to bring awareness on reduce, reuse and recycle. A way to understand the invisible complication of a product and that which paves way for new alternative solutions.

2. Property of glass and manufacturing process 2 LIFECYCLE ASSESSMENT OF GLASS IN BUILT ENVIRONMENT

Glass is a unique material that is hard, brittle typically transparent /translucent, that which is made by fusing sand(silica), soda ash, lime and gets cooled rapidly. In the process of manufacturing float glass, the energy spent on raw materials is the major cost expenditure. Silica (sand) holds the maximum weight of the the raw materials. One of the most expensive raw materials used in the production of glass is Soda ash. Even though it constitutes of 16 % of the total raw material, it takes 60% of the total cost and approximately 75% of embodied carbon di oxide in the manufacture.

3. Initial Embodied energy of glass a. On an average, the overall production of 1 tonne of packed float glass results in the emission of almost 1.25 tonnes of carbon. b. For every tonne of glass packed it produces approximately 0.32 tonnes of CO2 right from quarrying and processing of the raw materials. c. To melt the raw materials, heavy fuel oils and natural gas are used. In the process of combustion the emission is approximately 0.5 tonnes of co2 per float glass. d. Carbonated raw materials when heated decompose and emit approximately 0.2 tonnes CO2 per tonne glass. e. The energy required to heat the float glass and rapid cooling (annealing) approximately emits 0.23 tonnes of CO2 per tonne of glass at the electrical supply region.

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f. The property of the glass is enhance by the method of surface coating. This process contributes to an extra 0.7kg CO2 per m2. Every 1m2 of 5mm thick float glass weighs 8.5kg on average. g. Large piles of glasses are fused or bonded together with a thin layer of thin polymer film in between for the usage of glass in safety and security applications.

4. Environmental impacts of glass It is estimated that the manufacturing of one square meter of low-e double glazing emits 28kg of CO2. However the industrial studies shows that the energy saved by replacing one square meter of single glazing with low-e double glazing in Europe is 95 kilogram per annum, which offsets CO2 emitted during the manufacturing process after 3.5 months in use. If the basic double glazing is replaced by low-e double glazing, the offset period is typically 12months. One of the leading glass manufacturing company in Europe has alone emitted 4.8million tonnes of CO2 in the year of 2009. However many studies conducted by organisations shows the fact that more than one hundred million tonnes of CO2 emission could be avoided annually if all the buildings in Europe were equipped with advanced energy-saving glass. Out of a study involving 25 EU member states, the effect of reducing CO2 emission has been documented. CO2 emissions from buildings alone is 755milliones tonnes CO2 saved annually if all European buildings fixed with energy saving glasses is hundred million tonnes CO2 generated by European glass industry is 6 million tonnes.

5. Embodied energy of glass In general industrial terms Glass has an embodied energy of 15.80 MJ/Kg (37450 MJ/m3)

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The most common building material with less embodied energy is wood with almost 645 kilowatt hours per ton, where most of it is consumed the industrial dying and in the application of impregnation with preservatives. Therefore the green sustainable building material would be wood if the forests are maintained in a sustainable way. The next material with less embodied energy after wood is Brick 3X times to wood, 6x to concrete, 7x to plastic, 14x to glass and 25x to steel and 125x to aluminium.

So by this comparison it is understood that glass has a moderate embodied energy compared to other conventional building materials.

6. Usage of glass in built environment The glass on windows and glazing these days has lots of various uses than many people realise it. The choice of glasses is many and varied depending on the requirement and technology. Different usage of glass in built environment is as 1. Thermal insulation Glass is used as thermal insulation in parts of the colder regions of the world. Generally the hot air inside escapes through the window glazings. The thin transparent metallic coating on the inner surface does not allow the heat to escape out of the window. Also the Low_E coating on the glass lets the thermal heat to pass through the windows and warms the interior spaces. This is one of the effective ways of passive heating. 2. Solar control 5 LIFECYCLE ASSESSMENT OF GLASS IN BUILT ENVIRONMENT

This type of glass is primarily used in warmer regions where the excessive solar heat is stopped from entering the internal spaces. This is done in two ways. First method is to use the tinted coloured glass where the tint of the glass absorbs the solar heat and radiated it back to the environment and away from the building. The glass also has a thin microscopic film on the other side. Second method is to use the coated glass where the glass has transparent layer of coating to it which reflects heat right back into the environment. In the internal spaces it also reflects the unwanted glare from the evening west light. This type of glass can also be combined with various other systems like safety and security glazing, thermal insulation, noise reduction and others.

3. Safety & Security Glass is en effective material in the point of safety and security as it lets visibility and also strong to damage. To strengthen the glass quality it can either be toughened or laminated. The toughened glasses are generally less likely to breakage and even when it breaks it leaves very small fragments which is actually harmless. Laminated glass is are made so strong and it is practically impossible to break. It has got a thin layers of lamination on either side of the glass which does not let it break open even if it is damaged very badly. In some types of laminated glasses the transparent layer in sandwiched in between two glasses which is used for much more secured puposes. 4. Fire Resistance Various ranges of fire resistance glass are available with increased levels of protection. This is also measured on the basis of the defined time periods the glass can withstand such as 40,50,80, 125, 190 minutes. Fire resistance glass must undergo a series if test and compiled within the standards and has to be installed by a professional to achieve its maximum level of performance. 6 LIFECYCLE ASSESSMENT OF GLASS IN BUILT ENVIRONMENT

5. Noise control This type of glass is specially used in the dwelling units located next to a busy highway, public transit station or airport runway, busy market, etc. The acoustic property of a double glazing unit has a special internal that acts as a dampening agent that blocks the noise from the outside to the inner pane of the glass. 6. Aesthetic element Glass is also used as a decorative element in the interior spaces in kitchens, bedrooms and toilets. Since glass has a longer lifetime and also easy to maintain, it is widely used in the internal spaces. In an office space it gives a bright and fresh look and it also reflects the light and makes the room look brighter thereby reducing the amount of light energy required. 7. Self cleaning glass This type of glass has a dual functions to it that which is used on tothe sides where the window is exposed mainly by sun and the rain which gets cut down and wash away the dirt. It is activated by light, in other words it is photo catalytic in its process that breaks the dirt collected on it. The secondary function is to spread the rain water evenly over the glass. Most of the glass is water repellent (hydrophobic), letting the water to run off touching only a fraction of the surface. This coating which is self cleaning in nature prevents the droplets and allows the water to run across the entire surface washing away the dirt componenets.

7. Role of glass as an energy saving element in buildings By using advanced energy saving glasses in the buildings we can reduce the amount of energy spent in heating, cooling and artificial lighting, thereby reducing the energy consumption and associated carbon emissions. The potential for improving the energy performance of a building just by changing the single glazing with energy efficient glazing is enormous. The chart below shows the different types of glazing for the buildings in Europe. It is estimated that 100 million tonnes of CO2 could be saved by changing all the glazing to energy saving glass. 7 LIFECYCLE ASSESSMENT OF GLASS IN BUILT ENVIRONMENT

8. Types of energy saving glasses

a. Low emissivity glass (Low-E) This type of glass is specifically treated with a microscopically thin film transparent coating. This coating Reflects the heat back into the building thereby capturing the heat within the rooms and not letting it to escape through irradiation. It also reduces the heat transfer from the warm inner pane to the cooler outer pane with the layer of inert gas in between further lowering the amount of heat that escapes. This property of the glass thus reduces the demand for energy in order to heat the building. Further to this the thin microscopic film also lets in large amount of solar energy to enter the internal spaces thereby heating the room passively. LowE glazing could therefore be a net contributor of energy saving in buildings. 8 LIFECYCLE ASSESSMENT OF GLASS IN BUILT ENVIRONMENT

b. Thermal control glass This is a high performance glass which is coated product the reflects the harsh themal radiation from the run but allows the light to pass through the glass through a window or facade. Thus keeping the interior space cooler by passive cooling and also reduces the amount of artificial lighting. The solar control glass has thin invisible coating of special materials that allows the light to pass through and repels the heat radiation. This type of glasses is particularly useful in the warmer regions where it can help reduce the indoor air conditioning load and thus reducing the energy demand while maintaining a comfortable indoor environment. In addition to this the solar control glasses are mostly double glazed and therefore combine Low-E and thermal control properties giving dual benefits of maximizing thermal control properties in cooler region and solar control properties in summer.

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c. Comparison between Double & Triple glazing Basically there are no standard double glazed windows. Currently the double glazed windows are readily available in the markets with low emissivity coatings/ or Solar control coatings. Buildings can 2 .5 to 5 times more efficient when replacing the old uncoated double glazed windows or gazing systems with Low-E glazing. Triple glazing is much more efficient by reducing the u values of upto 0.7 which is almost 8.5 times more efficient than single glazing and four times more efficient than basic double glazing without insulation.

Therefore triple glazing is one of the essential component for a â&#x20AC;&#x2DC;zero energy buildingâ&#x20AC;&#x2122; which is going to become the standard for all buildings in Europe by 2020. Many of the Scandinavian countries has already standardised the usage of triple glazing and it is fast growing in usage in many parts of Germany. 10 LIFECYCLE ASSESSMENT OF GLASS IN BUILT ENVIRONMENT

The cost of triple glazing is 30% to 50% higher than the double glazing. But the U value of triple glazing is much lower than the other type of glazing. The payback period of triple glazing is almost 20 years for a typical office building. The triple glazing also with a penalty of additional embodied energy due to the extra panel of glass. Below is a comparison between three types of windows with double glazing as well as triple glazing and the embodied energy for each of the item

After 20 years of usage the recurring embodied energy of triple glazing is almost the same from the initial embodied energy whereas the carbon emission of double glazing has significantly increased. This is due to the fact that less energy is spent to achieve the comfort level in the internal spaces.

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By the above comparison it is also understood that the type of framing for the windows also matters. Using aluminium triple glazing window is almost as equal to the UPVc double glazing window in terms of embodied energy. So designer should always keep in mind the different combination of materials when designing a zero carbon emission building. Design of glazing in new constructions An energy performance building is related more to the comfort zone of the building contributed ait conditioning and artificial lighting. Therefore the energy spent in these two factors is considerably reducing by choosing the type of glazing and amount of glazing. In places which requires passive heating technique, the glazing is generally kept low due to the heal loss through glazings. But in most cases the heat gain exceeds the heat loss which energy contribution by large windows is high. I scenarios of passive cooling large glazing is always preferred due to the technology of double or triple glazing glass which repels the heat from the solar energy and allows only the light to the internal spaces thereby reducing the energy required for artificial lighting and indoor air conditioning. This becomes a gift for the Architects who like to use the large glazing in their designs and also embracing the fact that it is energy saving.

Glass beyond glazing The usage of glass in the built environment not only stops with windows and facade glazing but also in the solar energy generation. Glass is used in photovoltaic panels and thermal heat collectors. 12 LIFECYCLE ASSESSMENT OF GLASS IN BUILT ENVIRONMENT

Thermal heat collectors: This technology glass converts solar energy into heat energy which in turn generates hot water and heat generators for domestic and industrial use. Glass is used as a protective layer on top of the panel not only to prevent it from damage but also avoid the cooling of the panel. Photovoltaic panels: There are two types of glass usage in photovoltaic panels. Method 1: In this type a layer of glass is used as a protective outer layer on top of the crystalline silicon cells. Thereby transmitting the heat solar light to the interconnected photovoltaic cells underneath. Method 2: In this technology a thin transparent layer of conductive coating is applied which allows light through to the photovoltaic films underneath. This layer of coating also conducts the electricity generated from the modules.

Impact of Low-E glass in the life cycle assessment As discussed above the manufacture of glass in general is energy intensive and the carbon emission is high. For the production of 1sqm of low energy architectural glass the carbon dioxide emitted is 26kg. Annualy 95 kg od CO2 is saved by replacing the buildings with double glazing. The pay back for the glass is generated within 4 months of its usage on ideal condition. This value varies from country to country depending on the climatic conditions. Glass is basically a recyclable product and it reduces the carbon footprint almost equal to zero if it done in a sustainable way.

How is glass recycled Glass is one of the material that can be recycled completely, thus reducing the raw material input in the manufacturing of new glass. However the recycling process also has its own level of carbon emission right from dismantling, collection, distribution, cleaning, treatment before melting. In the recycle process the glass is broken into smaller cullets and is introduced into the batch mix before melting. This reduces a large amount of need for raw materials and the energy input.

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Approximately 1.3millionn tonnes of glass waste is generated in Europe alone by demolition and renovation of buildings. On an average glass contributes to 0.7% of the construction and demolition wastes. The major steps involved in the recycling of glass generated by construction and demolition are: Dismantling: The glasses which are in good condition is extracted from the building and sorted according to the types and relevance to its end usage. Cullet making: Only certain amount of glass recycled in Europe, but in many other countries there are no standardisation of dismantling and collection. Due to this process few of the glasses becomes unsuitable for recycling. 14 LIFECYCLE ASSESSMENT OF GLASS IN BUILT ENVIRONMENT

Shredding: In this process the whole building is demolished, crushed and shredded into pieces.

Recycled glass adds point in LEED Leadership in Energy and Environmental Design (LEED) has specific criterias and awards points for the usage of recycled materials in materials such as flooring tiles, carpet, soil, local materials etc. It also accounts for the materials that could be reused after the life time of the building which can be sent to the recycling plant or just used as such in a new building with very few modifications. Glass is one such building material which can be recycled and the LEED credit points gets added up due to this factor. There are green body organisations who is considering the old buildings that are poor in energy management could be converted to green building and can achieve the LEED ratings.

Pressure from the Environmentalists The trend of buildings has completely changed these days and with the advent of social media and others groups there is a strong cohesion developing among the society. Environmentalists in New York started breaking the glass of an office building by throwing stones infusing them to use energy efficiency glass rather than the old glazing which was primarily single glazed. There should be governing bodies and other committees which should monitor the energy efficiency of buildings right from the foundation to the finishes before giving approval to the projects. There also few organizations like Urban Green Council In US which is urging for a specialised energy-efficiency standards just for the exterior of the building.

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Analysis of a Glass in a single family residence in India

The project is designed for 5 people with the opening sizes of approximately 40%. The total area of the house is 220sqm.

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Outputs from ATHENA IMPACT ESTIMATOR for buildings The analysis was done by athena imapact estimator comparing three types of glazing. Single Glazing with timber frame Double Glazing with aluminium frame Triple Glazing with Hard coating aluminium frame

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The Solar access analysis generated for the model in ecotect.

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The incident solar radiation is almost the same throughout the year.

The hourly solar exposure when all the windows are single glazed.

The hourly solar exposure when all the windows are double glazed.

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HOURLY TEMPERATURES - Friday 12th January (12) Zone: Zone 1 Avg. Temperature: 13.0 C (Ground 24.4 C) Total Surface Area: 535.200 m2 (270.3% flr area). Total Exposed Area: 169.784 m2 (85.7% flr area). Total South Window: 4.680 m2 (2.4% flr area). Total Window Area: 33.350 m2 (16.8% flr area). Total Conductance (AU): 355 W/째K Total Admittance (AY): 1766 W/째K Response Factor: 4.25 HOUR INSIDE OUTSIDE TEMP.DIF (C) (C) (C) 0 13.7 10.8 2.9 1 14.1 10.6 3.5 2 14 10.3 3.7 3 13.8 9.8 4 4 13.6 9.1 4.5 5 13.4 8.6 4.8 6 13.5 8.6 4.9 7 13.5 8.6 4.9 8 14.2 8.8 5.4 9 14.9 10.6 4.3 10 15.4 12.3 3.1 11 15.7 14.1 1.6 12 15.1 15.1 0 13 15.7 16.2 -0.5 14 16.4 17.2 -0.8 15 16.6 16.8 -0.2 16 16.1 16.5 -0.4 17 15.4 16.2 -0.8 18 15.1 15.1 0 19 14.7 14.1 0.6 20 14.1 13 1.1 21 13.9 12.3 1.6 22 13.6 11.8 1.8 23 13.2 10.6 2.6

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HOURLY TEMPERATURES - Friday 12th January (12) Zone: Zone 1 Avg. Temperature: 12.0 C (Ground 24.4 C) Total Surface Area: 535.200 m2 (270.3% flr area). Total Exposed Area: 169.784 m2 (85.7% flr area). Total South Window: 4.680 m2 (2.4% flr area). Total Window Area: 33.350 m2 (16.8% flr area). Total Conductance (AU): 265 W/째K Total Admittance (AY): 1678 W/째K Response Factor: 5.11 HOUR INSIDE OUTSIDE TEMP.DIF (C) (C) (C) 0 13.2 10.8 2.4 1 13.8 10.6 3.2 2 13.7 10.3 3.4 3 13.6 9.8 3.8 4 13.5 9.1 4.4 5 13.4 8.6 4.8 6 13.4 8.6 4.8 7 13.3 8.6 4.7 8 13.5 8.8 4.7 9 13.9 10.6 3.3 10 14.2 12.3 1.9 11 14.4 14.1 0.3 12 13.9 15.1 -1.2 13 14.4 16.2 -1.8 14 14.9 17.2 -2.3 15 14.9 16.8 -1.9 16 14.8 16.5 -1.7 17 14.5 16.2 -1.7 18 14.4 15.1 -0.7 19 14.2 14.1 0.1 20 13.9 13 0.9 21 13.6 12.3 1.3 22 13.5 11.8 1.7 23 13.3 10.6 2.7

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Conclusion: Thus by doing this life cycle assessment of glazing it is evident that the usage of high performance glazing has lots of advantages than using Single glazing in buildings. Eventhough the intital cost of high performance glazing is more, the energy saving is much more in the long term. The glazing in combination with the type of window frame also accounts to the embodied energy. The carbon emission produced by using triple glazing with aluminium frame work is almost equal to the double glazing with timber framework. So as Architects and designers while designing a new building we should consider combination of materials which works with glass for fenestrations. It is also evident that the usage of high tech glazing like Triple glazing reduces the energy required for heating or cooling the building. Similarly the glass recycling should also be considered as a vital part as it can help reducing the amount of raw materials required for producing the glass therby reducing the carbon emission.

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Analysis of a Glass in a single family residence in India

The project is designed for 5 people with the opening sizes of approximately 40%. The total area of the house is 220sqm.

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The Solar access analysis generated for the model in ecotect.

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The incident solar radiation is almost the same throughout the year.

The hourly solar exposure when all the windows are single glazed.

The hourly solar exposure when all the windows are double glazed.

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Reference: measure of sustainability embodied energy.html http://www.glassforeurope.com/en/ http://www.circularecology.com/ http://www.saint-gobain-glass.com/ smart use of glass in buildings average float.ashx http://www.nsg.com/en/sustainability/glassandclimatechange/embodiedc02infloatglass http://www.glassforeurope.com/en/issues/faq.php http://www.gpi.org/recycling/glass-recycling-facts Image reference: www.gsecg.com/commercial-secondary-glazing-thermal-insu... www.valuedoors.co.uk/windows-upvc/ https://thewindowdog.com/triple-pane-vs-double-pane-windows gap.gov.tr

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