Energy saving in buildings by applying functional glass

May 05, 2013

The key is to utilize the various functions of glass

The use of glass in buildings is increasing day by day, and from composing the entire exterior with a glass curtain wall to interiors, partitions, and handrails, glass is becoming the most important element of buildings that are deeply approaching our lives. have.

In the past, the application of glass in architecture was quite limited, and at the level of simply cutting and pasting mirror products centering on the window, recently, from securing a wide view using glass, privacy protection, energy saving, image realization, board, color, etc., beautiful and unique personality It is a trend that its use is expanding to design and directing. The biggest reason for the limited application of glass in architecture is that the material called glass is easily broken and, when broken, it can cause casualties, and heat and cold air can easily flow in, which can increase energy consumption, so negative image was at the center.

However, as an eco-friendly building material, glass is increasingly being used in buildings because it has several advantages such as securing a wide view of the interior and exterior centering on the transparency of glass and creating a comfortable space for a stuffy space. If only energy is saved and design aspects and functions are given up, the building will be composed only of tight walls, and the interior space can also be closed with walls or general partitions to protect privacy.

By applying glass to all these spaces, a clean image and design are created in the building itself, and it is possible to create a clean space with various designs while protecting privacy inside, and now the living space itself is not a divided structure, but rooms, living rooms, and bathrooms. The role and function of glass at the point of being integrated into one living space is growing as much as that, making it possible to realize a more efficient and efficient emotional space in the office space.

As such, the main reason for increasing the use and use of glass in buildings is the development of functional glass that can be used in various spaces by adding functionality to glass rather than general glass. Glass with various functionalities is applied according to need in every part of life, and it makes it possible to select and apply glass conveniently for more uses. The development of technology enhances various functionalities of glass, and proper use of such functional glass is positioned as a way to reduce energy costs and increase expected effects in various spaces, starting with energy saving. By properly utilizing functional glass, it is possible to dramatically reduce the cost of energy-saving buildings in addition to the effects that can be obtained with ordinary glass, thereby improving the quality of life.

Reduce energy costs for leaks in buildings with functional glass

The most important factor of functional glass is to reduce the cost of leaking by imposing the function of glass in the space we commonly use, including energy saving.

As for the glass applied to the part where the outside air and the inside air come into contact, it is essential to secure a pleasant view, and to reduce the internal energy consumption by blocking the heat and cold air coming from the outside air to create a comfortable space. . In the reality of high-rise buildings, glass that blocks UV rays and direct solar and radiant heat from glass that prevents contamination of external glass by itself is also a way to increase the comfort of indoor space and reduce costs effectively.

In addition to this, in addition to protecting privacy, the interior divides the living space through partitions, and at the same time, a convenient life and convenience can be achieved through appropriate harmony and selection of glass with each function, from props that can realize images, memo boards, tables, and the production of various designs. In addition, it can play a role in lowering the opportunity cost that may occur externally.

The application of functional glass to all spaces made of ordinary glass makes life more prosperous and can become the biggest driving force for eco-friendly green growth that saves energy, which is the direction the building is currently advancing. With the technological development of glass, new technologies and materials, including various coating technologies, have been developed, and the architectural glass market, which has been represented by the general transparent glass market, is gradually seeking a change into the functional glass market.

Low-e glass application rate 5~10% level

A representative glass among functional materials for construction is low-e glass, which dramatically reduces heating energy by increasing the insulation effect.

The biggest feature of low-e glass is that it reflects infrared rays generated from indoors in winter and returns them indoors, and in summer, it blocks radiant heat from outdoor solar heat from entering the room, thereby improving the insulation performance of windows and doors. Thermal transmittance is a commonly used word when presenting standards for energy saving in buildings. Thermal transmittance (U Value: Uw) is the amount of heat that passes through glass due to the temperature difference between indoors and outdoors, and is widely used to predict heating energy and condensation resistance performance.

Currently, the government is implementing intensive energy-saving policies for buildings with a focus on low-carbon green growth. We are gradually lowering the thermal transmittance rate, and are in the process of enacting legislation with the goal of reaching a zero energy house in the future. Therefore, low-e glass is a glass that can lower the thermal transmittance rate of basic energy saving, and its excellence in energy saving is recognized.

When low-e glass is applied, energy is reduced by 25% compared to general double-layer glass, which can reduce heating and cooling costs. The thermal transmittance of 16mm (5mm glass + 6mm air layer + 5mm glass) is 2.8W/m2K, but the thermal transmittance of the double layer is 1.8W/mK, with 22mm (5mm glass + 12mm air layer + 5mm glass). can The lower the thermal transmittance value, the lower the energy loss through the glass. For example, when low-e glass is applied to a 32-pyeong house, an annual savings of 182,000 won can be achieved. In addition, it is the basis of green growth and green business that can save 36 million barrels of crude oil per year through energy saving of heating and cooling costs by saving resource energy and reducing oil use by saving energy for heating and cooling, thereby reducing CO2.

The domestic low-e glass application rate remained at an extremely insignificant level, less than 1% just a few years ago. It is true that low-e glass was neglected due to the lack of awareness and price increase factors. However, as eco-friendly green growth is established in Korea, most of the new buildings are using low-e glass, and the application rate is currently 5~10%. This is expected to continue to grow along with legislation.

In order to lower the thermal transmittance rate and produce energy-saving high-functional windows, the use of double-roy glass from general single-roe glass is increasing, and even triple-roy glass is gradually being applied in Korea.

Reflective glass that blocks sunlight in summer, Solar glass that blocks UV rays

In Korea, energy-saving glass is still limited to low-e glass, an insulating glass that saves heating energy, in many cases.

However, in Korea, there are four distinct seasons, and as a result of the recent acceleration of global warming, many abnormal climates occur, and abnormal high temperatures occur frequently in summer. As a result, the use of air conditioners is increasing, and it is true that the industry suffers a lot of damage as well as ordinary households due to the annual power shortage. In addition to low-e glass, which has been established as the basis of functional glass, there are reflective glass and solar glass as functional glass that reduces the cooling load in summer to take the lead in energy saving and lead a comfortable life.

Heat reflecting glass increases the reflectivity of sunlight by attaching a thin metal film to the surface of ordinary transparent glass, and reduces the cooling load of the building and has a characteristic that looks like a mirror when viewed from outside.

Reflective glass is a glass manufactured for the purpose of saving energy and has a high reflectance of visible light due to its characteristics. Due to this characteristic, it shows the effect of reducing the cooling cost by blocking the visible light of the sun. In addition, when viewed from the outside, a semi-mirror effect appears, giving the design effect of seeing the surroundings clearly. Ordinary reflective glass is manufactured by applying a special coating on the glass surface during the glass manufacturing process, and blocks more than 70% of visible light transmittance.

There are transparent and colored products. Transparent reflective glass blocks about 15% of visible light, and dark reflective glass such as silver or brown blocks about 59% of visible light, making it darker. The reason why the use of reflective glass is steadily increasing is not just the reduction of cooling costs. It is possible to form beautiful buildings with various colors, and a clear reflection image can be obtained with high visible light reflectance. From the viewpoint of emphasizing the beautiful exterior of a building, reflective glass has the characteristic of making the surrounding environment appear as it is projected on the glass, making the building more aesthetic and luxurious. In addition, the privacy protection effect is high because the inside of the building is not clearly visible from the outside. Recently, as a reflective glass, blue reflective glass has been widely applied to buildings.

In addition to reflective glass, it is possible to lower the shielding coefficient compared to general transparent glass by adding color as if tinting a car, or by using colored glass such as green and blue. However, in the same way that if only low-e glass is emphasized to capture heating energy, the cooling efficiency decreases, it is true that if only the cooling efficiency is emphasized, the heating efficiency decreases and the right to a clean view is disturbed.

In particular, excessive application of reflective glass causes a lot of damage to the surrounding environment in Korea, where rapid urbanization is progressing. This can cause glare in the surroundings through excessive reflection, which can cause various accidents and harm the aesthetics of the city, so it should be used appropriately.

Solar glass refers to glass that has superior UV protection compared to general glass, and is also called UV-cut glass. It has been applied only to glass for high-end automobiles, but recently it has been applied to glass for construction and is receiving a lot of attention. Basically, it blocks harmful UV rays, so it prevents discoloration of indoor furniture and accessories, protects health, and protects you from direct sunlight.

It also has the effect of reducing cooling costs by properly shutting off the air conditioner to maintain a uniform indoor temperature distribution. In particular, the subtle color of the solar glass makes the building look beautiful, and the visible light transmittance is adjusted to make it easier to see the outside without glare.

Self-cleaning glass that protects itself from external pollutants

In addition to energy saving, as buildings are getting taller and glass is getting larger, it often obstructs the view due to external pollution and harms the aesthetics of the building, resulting in considerable costs through periodic cleaning.

Therefore, the application of self-cleaning glass that protects itself from external pollutants is highly effective because it is easy to secure the right of view from the inside to the outside along with the aesthetics of a clean building, and it can reduce the cost of periodic cleaning.

Self-cleaning glass, also called self cleaning glass, is produced by coating TiO2 (titanium oxide), a photocatalytic material, on the glass surface. Photocatalyst refers to a substance that does not change before and after the reaction, but promotes the reaction of other substances by absorbing light. TiO2 (titanium oxide), which is often used as a photocatalytic material, reacts with the ultraviolet rays of sunlight to decompose organic matter or separate the bonds of organic matter so that it can be easily washed off by rainwater. The reason that the photocatalyst is mainly used in buildings is that by using the properties of TiO2 (titanium oxide), the self-cleaning effect of keeping the surface clean by itself can be obtained.

The dust that contaminates glass can be broadly divided into organic dust generated from organisms such as animals and plants, and inorganic dust composed of soil or minerals. In general, organic dust has a stronger binding force than inorganic dust, so it is difficult to wash off. These organic dusts can be easily removed through natural phenomena such as rain, so that the building can be kept clean. Although the coating film itself weakens the bond between the glass surface and organic dust, it maintains hydrophilicity when exposed to ultraviolet light, so water droplets flow down without condensing and can easily separate dust.

However, it is true that the application of self-cleaning glass in buildings that are being urbanized and high-rise is still insufficient. Since silicon is used to construct glass, and self-cleaning glass may be ineffective when it reacts with silicon, wet construction or special gaskets must be used. Due to these restrictions on use, market expansion is being delayed, and above all, consumers' awareness of self-cleaning glass is still not high, which is a big part.

Dimmable glass that can be used as a partition or projection screen by adjusting the transmittance

There are several functions to save energy through glass and to secure the right of view by using transparency, but when only transparency is emphasized, there is a problem of privacy protection.

Illuminated glass that can close, open, and adjust independent indoor and outdoor spaces from time to time can produce high space utilization and can perform multiple functions at the same time through various uses.

Illuminated glass is often called variable transmittance glass, and is made by processing liquid crystal into a thin film and processing it into laminated glass. Because the transmittance can be changed between transparent and opaque, it is widely applied as a general partition or projection screen. It is possible to enlarge the entire space through transparency in an independent space that is simply blocked, and it is possible to project various images, etc.

Glowing glass is not simply a concept of expanding and dividing space and protecting privacy, but also has excellent effects such as convenience and cost reduction in various spaces through more efficient space composition and use.

Solar glass that produces energy

Solar glass is a glass that produces energy on its own and makes it possible for buildings to create and use energy by itself, going beyond various functional glasses of energy saving, convenience, and cost reduction.

High-performance triple-layer glass developed by applying Low-E glass to general double-layer glass, and vacuum double-glazed glass that maximizes energy efficiency by eliminating the air layer of double-layer glass. Functional glass products are constantly being introduced.

The development of products to minimize the energy loss of products beyond the existing energy consumption efficiency rating system and the first-grade standard required for eco-friendly housing construction is steadily being carried out, and it is in line with the changes in the building glass market in the future. If triple glass and vacuum glass are highly functional glasses that minimize energy loss, then if we go to the concept of a “zero energy house” in 2020, which the government has revealed a blueprint for, as a result, it does not end at the line of reducing energy consumption, and the building directly transmits energy. It should proceed in the direction of a structure that can be produced and self-sufficient. Various countries such as Europe and Japan are continuously making these attempts, and the development of the solar glass industry is essential for building energy self-sufficiency.

The related parts and materials market is also growing together with the solar cell market. In particular, the glass market is expected to expand from $750 million in 2008 to $2.36 billion by 2013. In particular, glass materials such as glass substrates for solar cells constitute a large-scale industry including other uses. The global scale of glass for the solar cell industry is about 11.7GW as of 2009. When converted to glass area, it is about 114,523Ksqm, and when converted to weight, it is expected to be about 900kton.

In solar cells, glass is used not only as a crystalline silicon solar cell but also as a cover glass to protect various types of solar cell modules such as amorphous silicon thin film type, CIGS thin film type, and CdTe thin film type.

As for the conditions of use of cover glass, low-iron glass containing about 500 to 1000 ppm of iron is often used for construction glass, and this iron lowers the glass transmittance, which is directly related to the module efficiency of the solar cell. In the end, for efficiency, white glass with a low iron content of 150 to 200 ppm is used. In addition, there are float glass and patterned glass as cover glass for solar cells, and all of them must undergo a strengthening process before they can be used in solar cells.

An anti-reflection film is applied to the cover glass to prevent sunlight reflection. This is because the loss of sunlight due to reflection eventually lowers the conversion efficiency. Soda-lime glass, which is generally used for window glass, has a solar reflectance of 4%.

The photovoltaic industry is generally divided into PV and BIPV, and it is expected that the related laws and regulations of the building-integrated BIPV system will be gradually strengthened rather than the PV module industry. In general, BIPV integrated glass is applied through a process of manufacturing a solar module, bonding it to glass, and fitting it into a frame through processing.

Most domestic glass processing companies are focusing on processing parts rather than module production, and are equipped with strengthening facilities through continuous furnaces. Focusing on the processing part is focusing on the production of products by maintaining a cooperative relationship with the module manufacturer because the electrical part is difficult and the initial investment cost is high in the existing module production and bonding process. However, it is true that the solar glass market is still insignificant and it is experiencing many difficulties in Korea.

Currently, the demand for functional glass for construction is gradually increasing. The selection should be made as a multifunctional product through an appropriate combination of functional glass such as low-e and reflective, rather than a single item of general functional glass. Rather than simply applying low-e glass to increase insulation, it is possible to further lower energy use through various combinations such as gas injection into double-glazed glass, application of insulating spacer, triple glass, vacuum double-glazed glass, and solar double-glazed glass, and design elements and convenience Appropriate selection and use of various functional glass that combines performance and efficiency is the way for glass to change in the future construction industry.