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American Journal of Public Health Research
DOI: 10.12691/ajphr-1-1-3

The Implementation of a Tele-Homecare System with Service Oriented Architecture and HL7 Message Transmission Standard
Ching-Sung Wang

American Journal of Medical and Biological Research
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The Influence of Ethanol on Pyruvate Kinases Activity in Vivo, in Vitro, in Silico
Lelevich Sergey Vladimirovich, Khrustalev Vladislav Victorovich, Barkovsky Eugene Victorovich, Shedogubova Tatyana Aleksandrovna

American Journal of Medical Sciences and Medicine
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Clinical and Histological Features in Wegener Granulomatosis
Li Cavoli Gioacchino, Passantino Rita, Bono Luisa, Tortorici Calogera, Ferrantelli Angelo, Giammarresi Carlo, Rotolo Ugo

American Journal of Infectious Diseases and Microbiology
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The Curse of Lymphatic Filariasis: Would the Continual Use of Diethylcarbamazine Eliminate this Scourge in Papua New Guinea?
Anne Lanham, Lillian Mwanri

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Recent Advances in Material Science for Facade Systems in Contemporary Architecture: An Overview

Mohammad Arif Kamal

Architecture Section, Aligarh Muslim University, Aligarh, India

Abstract: The building facade is the main visible element of a building, acting as a boundary between the interior and the exterior environment. The facade works as an interface between the living spaces and the external climate, influencing comfort and energy efficiency. The skins of these facades are important media between the interior and exterior of a building. They not only connect between users and environments, but also play an important functional and aesthetic role. The major advancements in facade technology gives the architects and specialists the opportunity to vary the appearance of the building envelope, create an integrate grid system with all of their ideas, such as, windows, ventilation elements, glazing, aluminum features, etc. while maintaining a high level weather proofing. The objective of this paper is to identify, investigate and understand the recent innovations in the material science which have been incorporated in facades, especially in high rise buildings. In this paper, a qualitative evaluation research method is used. The research methodology comprises of case studies, visual observation and data collection. The various modern trends in the development of facade material employed in contemporary architecture around the world have been also been discussed through some examples in this paper.

Keywords: recent advances, materials, facade, contemporary architecture

Received June 11, 2020; Revised July 12, 2020; Accepted July 21, 2020

Citation: Mohammad Arif Kamal, Recent Advances in Material Science for Facade Systems in Contemporary Architecture: An Overview. American Journal of Civil Engineering and Architecture, 8 (3). 97-104. January 2020. doi:10.12691/ajcea-8-3-3

1. Introduction

The Facades are the first aesthetic feature of a building that distinguishes one building from another. A facade is generally one exterior side of a building, usually, but not always, the front. It comes from the French word facade which literally means ‘frontage’ or ‘face’. The building facade is the main visible element of a building, acting as a boundary between the interior and the exterior, working as an interface between the living spaces and the external climate, influencing comfort and energy efficiency [1]. Facade systems comprises of structural elements that provide lateral and vertical resistance to wind and other actions, and the building envelope elements that provide the weather resistance and thermal, acoustic and fire resisting properties. In current practice, in high rise buildings, the building envelope is being designed as a separation between exterior and interior environments, to provide an enclosure for comfortable indoor environment. Along with the innovation of ever-changing technologies the facade skins have been developing into an intricate but interesting multilayered system [2]. The various modern trends in the development of facade material employed in contemporary architecture around the world have been also been discussed through some examples in this paper.

2. Research Methodology

In this paper qualitative research method has been used. The systematic literature review has been explored through internet and secondary data from relevant published academic literature from journals articles and research papers. The data collection in the qualitative research are the data that comes from a number of case study examples that are described descriptively and are supported by illustrations and photographs to reinforce the arguments put forward. The basic concepts and backgrounds are investigated through literature and on-line media, observations to work for qualitative analysis conducted for different types of materials which have been used in the facades of contemporary high buildings around the world.

3. Technological Advances in Building Facade Materials

A new paradigm of facades has emerged which interact with the external environment by the integration of new materials and technologies, some with intelligent controls. Some make use of long standing passive technologies such as solar shading and thermal mass. A detailed study of these new materials and technologies of different facade systems along with case studies has been carried out to learn how these approaches can be implemented in today’s contemporary architecture. These materials have been summarized as follows:

3.1. Self-Cleaning Glass

The self-cleaning coating on glass is divided into two categories i.e. hydrophobic and hydrophilic. These two types of coating both clean themselves through the action of water, the former by rolling droplets and the latter by sheeting water that carries away dirt. Hydrophilic coatings based on titanium dioxide can chemically break down absorbed dirt in sunlight. Self-cleaning glass consist of a thin layer of photo-catalysts on its surface, which are compounds that accelerate a chemical reaction using the UV bands of sunlight. The commonly used photo-catalyst is titanium dioxide. The self-cleaning process of glass happens in two stages: The photo-catalyst stage when the glass is exposed to light, it breaks down the organic dirt particles and the hydrophilic stage when the rain washes the loose particles from the glass. This reduces the maintenance costs of the building and helps keep the glass clean. Figure 1 shows The Elbphilharmonie Concert Hall with self-cleaning glass, Hamburg, Germany.

Figure 1. The Elbphilharmonie Concert Hall with self-cleaning glass, Hamburg, Germany

3.2. Electro-Chromatic Glass

They consist of an extra layer of film, which changes its opacity when applied with an electrical voltage. The transparent electro-chromatic glass can change into a tinted glass when applied with electricity and vice versa, with the ability to remain in that state unless applied with electricity again (Figure 2). The solar heat gain reduces when the glass is tinted and it increases when it becomes clear. Therefore, it can be used according to the changing climate. It provides good shading to the building and can reduce the overall energy consumption of the building [3].

One of the most interesting buildings with Electro-chromatic glazing is the Stadtsparkasse Headquarter in Dresden, which was completed in 1999 (Figure 3). The building has a large glass area of 150 square meters on the main facade. The panels have dimensions of 90 x 170 cm. The regulation of electrochromic panels is through a computer system according to changes of some internal parameters such as temperature, light, but also the external temperature, solar radiation, presence of people or machines in operation. The activation time of the system is around 30 minutes, while the deactivation is around 45 minutes.

Figure 2. Details of functioning of Electro-chromatic glass

Figure 3. Electrochromatic glazing on the facade of Stadtsparkasse Headquarter in Dresden, Germany

3.3. Thermo-Chromic Glass

Thermochromic windows are the most advanced, yet simplest, dynamic facade window technology available and are quickly growing in popularity and being installed in many commercial, retail and residential buildings throughout the world. The thermochromic glass simply uses heat from direct sunlight to tint the windows when necessary. The more direct and intense the sunlight is on the glass the darker it will become (Figure 4). This allows the windows to drastically reduce the heat load coming into the building and because the glass transmission adapts continuously over a range of temperatures, a natural balance and maximum use of daylighting is achieved. By design, thermochromic windows help reduce glare, fading and noise, and increase safety.

Figure 4. Heat reflectance and light absorption through the Thermochromic film.

Thermochromic windows can help manage a building's changing needs for passive solar heat gain and natural daylight. All together this can lower costs associated with heating, air conditioning and artificial lighting. Thermochromic windows do not require wires, power supplies or control equipment and can be installed by glazing contractors, just like conventional windows. A clear insulated glass unit incorporating a Thermochromic laminates and Low-e coating can have a visible light transmission between 54% and 8%, a solar heat gain coefficient from 0.36 and 0.16 and a U-value of 0.24. The windows simply tint to a desirable level based on sun exposure every day of the year, any time of the day, and for any orientation on the building [4].

Figure 5. Senior Living Facility in Wyoming, Michigan uses Thermochromic glass

3.4. Fritted Glass

Fritted glass has computer controlled patterns printed on the surface. Fritted glass has application ranging from reducing solar gain; avoid glare; or simply creating a pattern, also, giving better safety and privacy. The Ryerson University student Centre at Toronto, Canada is a light, transparent designed to be energy- efficient and is an excellent example for its use of fritted glass making it resemble an ice crystal. It has a high performance facade which is triple glazed, low e-coated, fritted, and shingled (Figure 6).

Figure 6. Fritted glass on the facade of Ryerson University student Centre, Toronto, Canada

3.5. LED Facades

LED facades help create a vibrant and beautiful visual quality to both the building as well as the city. LED‘s are becoming famous as media facades, where hundreds of LED‘s can be linked together to form large screens but yet can be all controlled individually, letting images and messages come to life making shopping malls and office buildings crowd pullers. LED‘s are perfect for outdoor application as they are weather resistant. With a life of 50,000 hours, they can reduce energy and maintenance costs. The compact design allows them to be installed very close to the facade, saving energy and light emissions. The Agbar Tower by Jean Nouvel in Barcelona has 4,500 LED‘S that can be operated as computer controlled pixels, that creates moving images on the tower envelope, with as much control as the LED screen on the laptop (Figure 7). With RGB (Red Green Blue) management, the LED‘s can generate 16 million colours [5].

Figure 7. The LED facade of The Agbar Tower by Jean Nouvel in Barcelona, Spain

3.6. Composite Metal

Aluminum Composite Material (ACM) - ACM is widely known as the exterior cladding of choice on multi storey buildings because of its ability to provide complex architectural features and superior weatherproofing. It is also used for column covers, entrances, canopies and other critical design elements. ACM panels can be used in both Rain screen and barrier wall systems and also provide LEED certification value as a sustainable material. ACM panels are used widely for both new and retrofit construction, and can be field installed or as a component in prefabricated panels to provide a clean high tech look. The extra sunshade of lightweight stainless steel (with sun reflecting surface) forms a protective girth around the north and south perimeter of the office complex. In other words there is an 'eyebrow' of lightweight metal on every floor providing sun protection. It will be noted that this would counter heat when the sun is at the highest altitude between 11 am to 3 pm. The external lattice which echoes the structural system also cuts down the glare (Figure 8).

Figure 8. Composite Aluminium Panels on DMRC Metro Bhawan, New Delhi, India

3.7. Rain-Screen Cladding

Rainscreen cladding is a system designed to work with the elements of nature to protect the structure of a building from the wind and rain. It is an extra element attached to the wall to keep water from entering in as well as to prevent leakage of air, carry wind load and to offer thermal insulation. The rain-screen concept makes use of the outer layer to act a protective layer against the rain and the weatherproof inner layer blocks moisture and air from penetrating inside. Figure below shows the different forces that lead to penetration of rain into the building. They can be made of different materials such as terracotta, precast concrete, cement composite, stone, glass, metal, etc. Rutgers University Camden Graduate Student Housing in United States is one of the best example for Rain-screen cladding (Figure 9).

Figure 9. Rain-screen cladding façade in Rutgers University Camden Graduate Student Housing, USA

3.8. Nano Materials and Solar Nano Technology

The coating of the facades of tall buildings with Nano paint could reduce pollution by acting as air purifiers. Titanium oxide (TiO₂) nanoparticles in paint on exposure to ultraviolet light break down organic and inorganic pollutants that wash off in the rain. Amorphous silicon, organic and inorganic solar cells derived from nano-crystals has high solar conversion rates and so can produce electricity at a very low cost than the common silicon-based solar cells (Figure 10). These cells also have the additional characteristic that they are ultra-thin. Nanotechnology has made it possible to print tiny solar cells on very thin and flexible light retaining materials thus obviating the need to meet the cost of silicon.

Figure 10. Solar cells from nano-crystals on the façade of Sunex building, Hancock, Michigan, USA

3.9. Building Integrated Photovoltaics (BIPV)

Building Integrated Photovoltaics are photovoltaic materials used on the building envelop such as the roofs, skylights and facades of tall buildings to generate energy. The solar photovoltaic panel is integrated into the building fabric rather than a ‘tack-on’ addition and the PV panel replaces conventional building cladding materials but with the added benefit of producing renewable electricity. Photovoltaics consist of 20-40 solar cells which are joined together and embedded in a 1 x 0.5m module. The voltage obtained from each of the cells are about 0.6 volt and the energy produced depends upon the area of the cells and the solar irradiance. PV panels can be easily integrated onto the facades or placed on the roofs. The two main facades systems which can incorporate Photovoltaics are the curtain walling and rainscreen cladding. Photovoltaic modules will capture energy, but the bonus is that they can be placed on the facade to provide better sound and thermal insulation, weather resistance as well as effective solar protection [6]. They can be fixed systems or active systems. Active systems may have motorized frames or concentrators which adjust to the changing solar angles to obtain maximum output. Old buildings can be retrofitted with PV panels to give them a more appealing look. One of the best examples of installation of BIPV facade system is the New Town hall in Freiburg in Breisgau, Germany (Figure 11).

Figure 11. BIPV facade on the New Town hall in Freiburg in Breisgau, Germany

3.10. Phase Change Materials

The first reported application of PCM was back in 1940s.The main attracting feature of the PCM is that they have a greater storage capacity than that of conventional materials as they can store heat energy in a latent form. When the temperature rises, the chemical bonds break as there is a change in phase from solid to liquid. The PCM absorbs heat as the phase change process is endothermic and when the atmosphere cools down it return back to its solid phase releasing the stored heat. GlassX is an example of such PCM facades and it consists of a PCM in its core which is made up of Calcium chloride hexahydrate (CaCl2 6H2O) which is a non-toxic salt, with a melting point at room temperature. It can provide a thermal mass equivalent to that of 16‖ of concrete. The most complete model, GlassX crystal, is made up of multiple low-emissivity glass in one of whose chambers a prismatic panel is inserted that reflects solar radiation in summer (solar height> 40º) and transmits it when the sun falls below 35º in winter. The main function is carried out by a polycarbonate panel inserted in another chamber and filled with a phase change material (MCF) that, when the temperature rises above 24 or 28 ºC, melts over eight hours , absorbing up to 1185 W · h / m². When the temperature drops, at night or on cold days, the MCF crystallizes, releasing heat and therefore reducing the thermal jump. Depending on the model chosen, the U value varies between 1.1 and 0.49 W / m²K. It is marketed in a maximum format of 200 x 300 cm and 79 mm thick [7]. Facades made of this material do both the function of absorbing the solar energy and protecting it as well. A layer of salt crystals on the surface will help absorb the heat and the prismatic glass allows the radiation to pass only at the lowest angle of radiation. During summers, the solar radiation is reflected by a prismatic outer layer when the sun is at an angle higher than 40 degree. During winters, when the sun is at a lower angle lesser than 35 degrees the prismatic layer allows more solar gain. One of the recent examples is GlassX as Phase Change Materials Vocational school in Freiburg, Switzerland (Figure 12).

Figure 12. GlassX as Phase Change Materials Vocational school in Freiburg (Switzerland)

3.11. Ethylene Tetrafluoro Ethylene (ETFE)

Ethylene tetrafluoro ethylene, commonly known as ETFE is a fluoro polymer material. ETFE is a plastic derivative that is frequently used as a building material in the form of ETFE membranes. The material is characterized by high light and UV transmittance, temperature resistance and very low weight. ETFE film is a hundred times lighter than glass and allows more sunlight to pass through. As a result, it is often used for the construction of light-transmissive roofs. ETFE film is highly flame retardant and has a melting point of 270°C. This, together with the material’s self-cleaning qualities, ensures that ETFE membranes can be used in a wide range of applications. The self-cleaning function is provided by the lotus effect: The special surface structure ensures that wind and rain are sufficient to remove dirt from the ETFE skin. In addition, the copolymer is fully recyclable and available in more than 40 colors. This comes as large sheets coated with Teflon. There is a steady increase of ETFE usage in the building industry due to its built-in properties and adaptability. ETFE is a low-maintenance, recyclable and extremely lightweight material when compared to glass. ETFE has a long life of over 50 years as it is resistant to degradation by sunlight, ultraviolet (UV) light, atmospheric pollution, etc. Depending on the specific requirements it can be manufactured as single, double or triple-ply with air fillings. In single ply-form its thermal and acoustic performance is very poor and so is not suitable for façade applications. However, in the two or three- ply forms it has very good thermal properties, because the air trapped between the layers acts as an insulator [8].

ETFE does not have a tensile structure and so cannot support itself. The multi-ply sheets when filled with air forms into pillows which can adjust to the varying loads exerted by the winds. The air pressure in the pillows is maintained constant in relation to the wind force with the help of pumps. The pillows are kept supported by structures made of aluminium or steel. ETFE is fire resistant and can be easily repaired when damaged. ETFE is 100% recyclable and self-cleaning. It is a very sustainable material with low levels of CO₂ emissions due to its lightweight at the same time its carbon footprints believed to be 80 times lesser than other transparent building materials such as glass. ETFE can admit more light than glass, thereby reducing the energy costs by 30%. One prominent examples of ETFE facade is the Beijing National Aquatics Center having an area of 100,000 m² (Figure 13).

Figure 13. ETFE in facade of Beijing National Aquatics Center, Beijing, China

3.12. Polycarbonate Panels

Polycarbonate panels are transparent polycarbonate elements meeting the highest requirements and provide many possibilities of application. Polycarbonate panels are produced in several thicknesses: 40, 50 and 60 mm, in transparent, translucent, brown (smoky) colours. For larger quantities, they can be ordered in any colour. For 50mm and 60mm thick panels, an aluminium profile system with an integrated thermal break that minimizes heat loss - so-called “warm” profiles - has been developed. A huge advantage of polycarbonate panels is the simplicity of their installation. The comfort of use is also vital (easy maintenance) as well as no thermal bridges at panel joints. In walls of polycarbonate panels, hopper windows can be fitted without additional supporting structures [9]. One of the prominent examples of Polycarbonate panels is the facades of Manuel Gea Gonzalez Hospital, Mexico City (Figure 14).

Figure 14. Polycarbonate Panels on the Facade of Manuel Gea Gonzalez Hospital, Mexico City

3.13. Vacuum Insulated Panels

Vacuum Insulated layers are 5-10 times thermally more effective than layers of conventionally available insulation (Figure 15). They make use of new technology and have room for further developments, for example, incorporating them into unitary curtain walling systems. Vacuum insulated layers have good insulating properties and can be made very thin, hence they can be easily used in small tight spaces such as below the window sill or floor connections to prevent heat bridges, or by enabling thinner panels, to improve the net let table space in the gross floor plate area of a framed building. The best example of VIPs in construction is The Seitzstraße apartment block in Munich, completed in 2005 (Figure 16). The building has 20mm-thick VIPs sandwiched between the inner leaf and 80mm rendered insulation. This high-performance insulation specification provides 125m² of additional area [10].

Figure 15. Section of a thin Vacuum Insulation Panel

Figure 16. The Seitzstraße apartments with Vacuum Insulated Panels, Munich, Germany

3.14. Aerogel

Aerogels are synthetic solids that are made up of air having the lowest densities among all solids. Due to the low density, they have low thermal conductivity making them ideal for use in areas where high thermal insulation is needed. When integrated with polycarbonate sheets, they form transparent cladding materials. Aerogels have good acoustic properties with good resistance to moisture and are non-combustible. Diffused lighting into the interiors can be made possible by using silica aerogel due to its translucent nature. Sometimes known as ‘frozen smoke’, aerogel is translucent and is produced by removing the liquid from a gel, leaving behind the silica structure which is 90% air. Despite being almost weightless, aerogel holds its shape and can be used to create thin sheets of aerogel fabric. Aerogel insulation makes it extremely difficult for heat or cold to pass through and has up to four times the power of fibreglass or foam insulation [11]. One of the prominent examples of Aerosol is new building Hohlstrasse 100, Zürich (Figure 17).

Figure 17. Aerogel Facade in New building Hohlstrasse 100, Zürich

3.15. Suspended Particle Devices

SPD consists of a transparent conductive material with suspended liquid crystals laminated between layers of glass. The amount of light entering the glass can be controlled by applying a voltage. In the normal state, the liquid crystals are arranged randomly and scatters light to give it the translucent appearance. When electricity is passed through, these crystals rearrange themselves, allowing light to pass through it making them appear transparent. They are generally used indoors for privacy control and used less as building envelops [12].

3.16. Stainless Steel Panels

Stainless steel is used in all aspects of architecture, building and construction. While it has been used in this industry since the 1920’s and is not a new material, the use of stainless steel use and range of applications has been growing. Stainless steel is both aesthetic and functional, such as curtain wall and roofing. This material has been garnering plenty of attention for both aesthetic and functional for architectural curtain wall and fabric made of stainless steel. The number of different stainless steel alloys used in building and construction has expanded. The more highly alloyed molybdenum containing stainless steels are preferred because of their enhanced corrosion resistance [13]. One of the best examples of stainless steel facade is Walt Disney Concert Hall, California, Los Angeles, USA where the most of the building's exterior was designed with stainless steel with a matte finish (Figure 18).

Figure 18. Stainless Steel cladding on the facade of Walt Disney Concert Hall, Los Angeles, USA

3.17. FRP Composites

Fiber Reinforced Polymer (FRP) composites represents a family of materials combining fibers and polymers to offer excellent mechanical, thermal and insulation properties. Within the frame of engineering applications in buildings and infrastructures, FRP composites have been extensively investigated, especially in the last decade. FRP composites represent a relatively novel construction solution with several intrinsic advantageous properties, such as high strength and stiffness, reduced mass, low thermal conductivity, high corrosion and weather resistance, durability, but also the implicit feature of offsite fabrication, modular construction capacity and possibility to mould complex forms with special finishes and effects [14]. One of the best examples of FRP composite facade is the Ravel Residence at Amsterdam, The Netherlands (Figure 19). The Ravel Residence is a versatile, sustainable campus for 800 students, designed to have a positive impact on the urban environment.

Figure 19. FRP panels on the facade of Ravel Residence, Student housing

3.18. Aluminium Panels

The Aluminium facades are now commonly used on buildings all over the world. In architectural cladding there are many advantages in using aluminium over other metals. When designing and constructing buildings it’s always important to look at all possible advantages that metal can offer. There are some advantages of aluminium facade panels as compared to other materials. Aluminium facade system is lightweight and it is easier to install than for example steel facade systems. This is because aluminium is an extremely light metal, weighing a third of the weight of steel. It is resistant to weather and corrosion. The Aluminium panels are oxide coated; this coating protects the metal from corrosion and other weather effects naturally. Aluminium is very flexible, and can be easily bent and fabricate. Aluminum panels are easy to recycle. Of all the metals aluminium is the metal that is very easy to recycle without losing quality. It takes very little energy to recycle and that without loss in quality [15]. One of the best examples of Aluminum Panels is on the facade of Audi Centre, Singapore (Figure 20).

Figure 20. Aluminium Panels on the facade of Audi Centre, Singapore

3.19. Terracotta

The terracotta has been used in building construction, mostly as roof and floor tiles, since centuries. Terracotta now provides a premier architectural option used in Rain screen and ventilated exterior wall construction. Terracotta is available in varied profile shapes and earth tone colours, glazed or unglazed, to provide an architecturally appealing, energy-efficient building. Terracotta is a 100% natural material, made from clay and sand, is non-combustible and provides LEED certification value as a sustainable material. Terracotta, with its colours stabilized under a glazed finish, has an eternal durability. Terracotta is not only natural, but it also possesses incredible insulant properties that seal warmth or coolness inside buildings for longer. This reduces overall energy consumption, which is more than desirable nowadays. The most iconic building that comes to mind is The New York Times’ headquarters, designed by the renowned Renzo Piano. Nevertheless, there are plenty of other successful instances of terracotta usage at a global level [16]. There is also another example of Bund House, an office complex in Shanghai, China is a terracotta walling solution (Figure 21).

Figure 21. Terracota tiles on the facade of Bund House office complex, Shanghai, China

4. Conclusions

The facade makes up the majority of the building’s envelope separating the interior and exterior environments. Building facades are directly exposed to the external environment. Different building facades are related to varying indoor comfort and energy consumption levels. It is the single most important factor in the energy efficiency of the structure. A reasonable facade design helps reduce energy consumption and improve indoor thermal comfort [17]. A new paradigm of facades has emerged due to technological advancement in the material science and prefabrication which interact with the external environment by the integration of new technologies. Some of these facades have intelligent control system, while some use passive technologies such as solar shading, ventilation and thermal mass. Some of these materials and design strategies for facade can help in reducing the cooling and heating load on HVAC systems there by reducing the energy consumption of the structure. Future advanced facade design research is needed in order to understand sustainable design in a more comprehensive way and apply its principles to tall buildings.

References

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