How can the glass and ceramic industry contribute to the reduction of energy demand and CO2 emissions volumeHomepage / Annual Report / Annual Report 2008 / How can the glass and ceramic industry contribute to the reduction of energy demand and CO2 emissions volume
The glass and ceramic industry belongs to energy demanding industrial branches.
Glass is melted at the temperature 1450 to 1550 °C, borosilicate glass, type 3.3, at the temperature up to 1630 °C. Therefore, the melting process is very energy demanding. The base of the glass production and the greatest energy consuming equipment is the melting aggregate. However, also processing and annealing of glass (machine drive, heating of annealing furnaces, etc.) also need energy.
In the production of china and ceramics the greatest amount of energy is consumed for products firing. As an example it is possible to adduce energy consumption of household china and sanitary ware firing. For the first household china firing in a biscuit kiln the temperature of firing is about 1000 °C, firing time is 2 to 24 hours according to the furnace type. For the second firing of household china in glost firing kiln the products are fired at about 1380 °C, firing time is 2 to 36 hours. The heat consumption is about 68 GJ/t of production, from which 70 % is energy consumed for firing. Products of sanitary ware are fired at temperatures 1220-1250 °C. Firing time is about 13 to 22 hours according to the type of product. The heat consumption is in the range 22.23 to 37.50 GJ/t of production.
At present it is not possible to expect any breakthrough in innovations in the glass and ceramic industry. Glass is melted and ceramics is fired at very high temperatures, and production technologies and raw materials for production cannot be substituted at present.
Some glass or ceramic products have, however, such properties, which can reduce the energy consumption and related CO2 emissions volume in the following industrial branches. So they can significantly contribute to the target of European Union to reduce the energy consumption by 20 % till 2020.
5.1 Influence of energy efficient glasses to the CO2 emissions reduction
About 40 % of energy in European Union is consumed in buildings.
Buildings from the point of view of requested glazing parameters can be divided to commercial buildings, office buildings, shopping centres, hotels, etc.) and residential buildings (blocks of flats, family houses, etc.). For energy saving in commercial buildings two types of glasses exist: solar control glass reducing the energy consumption used for air-conditioning, especially, in summer, and triple glazing unit minimizing heat losses in heating period. Energy saving in residential buildings is ensured by the use of double and triple glazing units. Triple glazing unit minimizes heat losses in heating period. They maximize heat profit from sun (natural energy sources) in low-energy and passive houses.
It follows from the above mentioned text that there are two requirements to glass utilization in buildings, i.e.:
“Low-E” glass (with low emissivity), reducing the energy consumption in buildings (especially heating). The emissivity refers to the ability of the glass surface to reflect heat.
“Solar Control” glass (sun-protective), reducing the necessity of air-conditioning units use. Sun control glass transmits light into interior, but an essential part of heat from sun radiation it reflects.
The greatest producer of flat glass and its applications is AGC Flat Glass Czech, a.s. the member of the AGC Group. This company is a member of the Glass for Europe – the association of flat glass producers. This association asked Dutch technical research institute TNO to carry out a study of the potential energy savings to both types of glass.
5.1.1 „Low-E“ glass
In the following figures the function of double and triple glazing units with the Low-E glass is shown in graph.
In the following graph an improvement of thermal insulating properties of glazing is shown.
The study on contributions of the Low E glass use to energy savings and reduction of CO2 emissions carried our by the technical research institute TNO for the EU 27, came out from two assumptions:
- glazing used in existing buildings or an assumed type of glazing in buildings built in the period 2008-2020;
- use of high efficient low emissivity insulating double or triple glazing units (replacement of existing glazing and new housing).
Based on these assumptions the following annual energy savings and CO2 emissions reduction in the EU 27 till 2020 are possible:
- by the use of Low-E double glazing units in all European buildings, the European Union could save: annually up to 90 mill. tonnes of CO2 emissions by 2020,
- by the use of Low-E triple glazing units in new buildings and double glazing units in existing buildings, the European Union could save: annually up to 97 mill. tonnes of CO2 emissions by 2020,
it corresponds to 21 mill. tonnes of heating oil or to the amount of energy consumed by 19 mill. inhabitants;
i.e. one third from the total emissions amount which the European Union has committed to cut at buildings operation. 95 % of these savings is created by the replacement of glazing in existing buildings.
The energy savings would be annually 975,235 TJ in the European Union, what corresponds to the reduction by 96.613 mill. tonnes of CO2 emissions. In the Czech Republic the energy savings could reach annually 26,978 TJ, what corresponds to the reduction by 2.698 mill. tonnes of CO2 emissions.
5.1.2 „Solar Control“ glass
The solar control glass allows sunlight to pass through into the interior but it reflects a large degree of the sun's heat.
In the following figure the function of the solar control glass is shown in graph.
The study on contributions of the solar control glass use to energy savings and reduction of CO2 emissions carried our by the technical research institute TNO for the EU 27, came out from the following assumptions:
- in new buildings the solar control glass will be used in all air-conditioned buildings
- replacing all non-solar control glass in existing air-conditioned buildings with solar control glass he potential savings are assumed in amount of 16 mill. tonnes of the CO2 emissions annually up to 2020, i.e. about 5 % from the total amount of emissions, which the European Union has committed to cut at buildings operation;
- assuming both above mentioned items, and further on, assuming growing use of air-conditioning units up to the level common in the USA buildings the potential annual savings are assumed in amount of 86 mill. tonnes of the CO2 emissions annually up to 2020, i.e. about 25 % from the total amount of emissions, which the EU has committed to cut at buildings operation.
By the use of the solar control glass the European Union can save annually 15 – 86 mill. tonnes of the CO2 emissions up to 2020. The greatest potential is in southern countries. The energy savings 1,170,785 TJ correspond to 86 mill. tonnes of the CO2 emissions. In the Czech Republic the volume of the CO2 emissions would reduce by 1.470 mill. tonnes and energy savings would be 15,669 TJ.
The use of high effective glazing is advantageous for everybody. It creates optimum working and living conditions for building users. It reduces excessive CO2 emissions, energy demand of buildings and operational costs.
5.2 Glass fibres
5.2.1 Thermal insulation
Thermal insulation in a form of glass fibre mats or slabs bring great energy savings. These products are used in residential, civil, industrial and agricultural buildings and technical equipments.
The only Czech producer manufacturing thermal and sound insulation from glass fibres in the form of mats and slabs (ROTAFLEX Super®) is Union Lesní Brána, a.s.
In the following example there are shown possibilities of heat saving in a family house.
The energy consumption for heating of a family house is 50 to 67 GJ/year (13,842 to 18,456 kWh/year). In the following table heat losses at heating of a family house and savings after its suitable warming up, are given.
in a family house
|reduction of heat loss
after warming up by
|windows and outer doors||30 - 35 %||x|
|peripheral walls||25 – 35 % (and more)||15 - 30 %|
|ceilings and roof||10 – 15 %||up to 10 %|
|floors||5 – 15 %||about 6 %|
It is possible to save annually about 6 to 12 GJ on heating of such house.
5.2.2 Net-like fabrics
Net-like fabrics are produced by Saint-Gobain Vertex, s.r.o.
They are manufactured from glass fibre yarns or glass fibre roving. Special types of surface treatment of fabrics make their broad use in a number of various applications possible, especially in the building industry. Outer temperature changes connected with plaster shrinkage and movement of insulation plates of warming up system, belong to potential causes of cracks and splits occurrence in the plaster surface. Therefore, net-like glass fabrics are used as a reinforcing element in certified outer contact systems. These fabrics ensure, thanks to their mechanical properties, the required strength and stability of the whole system of buildings.
5.3 Ceramic fibres
High temperature insulation products provide a broad choice of high quality solutions tailored to meet the very specific economic and operational requirements of industrial branches.
The only producer of ceramic fibres in the Czech Republic is UNIFRAX, s.r.o., the member of international UNIFRAX Group.
Individual types of fibres are shown with their properties and utilization:
- a mullite fibre product manufactured by use of a chemical process and designed to perform in temperatures up to 1600 °C (Fibermax®);
- a ceramic fibre product manufactured from alumina-silica materials and designed to perform in temperatures up to 1400 °C (Fibermax®);
- a soluble fibre product from a calcium-magnesia-silica base (Insulfrax®). Rated for performance in continuous temperatures up to 1200 °C; it meets all current and proposed European health and safety regulations for synthetic vitreous fibres;
- a soluble fibre product with a patented silica-magnesium composition solving a variety of demanding, high temperature application problems up to 1260 °C, while meeting European regulatory requirements (Insulfrax®).
High temperature insulation products have not only outstanding properties from the point of view of production technology, but they also meet requirements for energy saving.
In the ceramic industry ceramic fibre lining is used in firing kilns. Besides meeting technological requirements of producers, they help to reduce energy consumption and enable producers to meet company and legislation obligations towards environment.
In the glass industry mats designed to perform in temperatures up to 1600 °C for installation of crown of the glass furnace, are used.
In metallurgy and foundry ceramic fibre products in all types of applications, i.e. from coking to finishing plants, are used. By their low heat absorption and low heat conductivity, these products ensure thermal insulation with higher efficiency than hard refractory products. The outstanding thermal properties of ceramic fibres offer longer service life and higher energy savings.
Ceramic fibre insulation products play an important role in energy production. They have to ensure adequate thermal insulation nearby a boiler and parts of piping because of higher efficiency of energy loss reduction. They are used for instance in insulation of steam and gas turbines, steam generators and piping.
In the end there is quoted a part of an opinion of the European Economic and Social Committee (hereinafter EESC) from 15 and 16 July 2009 to the report The competitiveness of the European glass and ceramics industry, with particular reference to the EU climate and energy package:
“Glass and ceramic products are absolutely vital at this stage of the Community's development and there are not many competitive replacement materials readily available. Both sectors are exposed to competition from developing countries, which have profited from the more difficult business environment in the European Union:
In terms of renewable energy generation and energy savings, glass products, if properly recycled, outweigh the energy used and the CO2 emissions released in production. The use of these products is therefore essential in meeting European environmental objectives for housing, transportation and renewable energy over a service life which can last twenty years or more. Final disposal, after repeated recycling, is always emission free.
The EESC considers it important to address the key aspects which affect the competitiveness of the glass and ceramics sectors and to make the business environment in the European Union more supportive, as has been recommended by both sector analyses. The specifics of both sectors should be taken into account, namely: the different applications and uses and the diverse range of products; environmental benefits; levels of energy intensity; the level of concentration in the sectors, together with their regional dimension; the share of SMEs in both sectors.”
The end of quotation.