Benefits of Double Skin Facades Materials - Research Paper Example

Benefits of Double Skin Facades Materials Introduction As a scientific advancement in architecture, double skin façade (DSF) acknowledges the urgent need for cost reduction in construction sector. It guarantees energy efficient system as well as aesthetics in attaining controllable variables for comfort of users. Double skin façade also allow building owner to save more as it lessen operational cost, but increases efficiency of building with regard to sustainability and environmental influences. Double skin facade should provide better transparency and offer a thermal defence for the benefit of those people working inside the buildings. The DSF certainly offers for these needs in an elegant and innovative way. This paper discusses the benefits of Double Skin Facades for the indoor surroundings in urban areas. It assesses the probable positive impact that double skin facades use can bring on the indoor surroundings. During the discussion process various literature sources and studies concerning DSF and indoor surroundings conditions will be collected and analysed. We will use qualitative research method so as to compare the concept and get a superior insight of how double skin facade function in practice. Various material used as outer skin in double skin face technology will be analysed and discussed to ascertain their benefits. In most cases, the outer layer acts as the glass outer shading device and it is not the main weather barrier. It just offers shading to the interior space. Since the external layer is not a key thermal or weather barrier, we can always use laminated glass and lessen the joint sizes. This can provide us with a taught screen effect we are in search of. The frit and coating on the glass, treated wooden blanks, aluminium or concrete shaped organic give the first layer the protection from solar radiation (about .3SHGC). The glass, wooden blanks or concrete shaped organic fins are fritted, so long as the second layer offer protection against thermal radiation. Research Objectives The study targets to compare merits of adopting various building façade finishes, particularly for office structures and its influence on the building`s energy use. The study attempts to ascertain whether double skin façade plays a significant role as far as energy saving in UAE`s office building is concerned. According to Pell, Hild, Jacob & Zaera (2010), BIM tools such as Revit, studio project and Green Building that were adopted in that study enabled a rapid visualization and modelling of dependable energy performance in conceptual stages of construction. As claimed by Schittich, Krippner, Lang, & Schittich (2012), the results revealed that double skin façade –at least for office building – was the better solution to reducing thermal radiation and providing quality light during the day. Research Outline The study will examine the technical aspects DSF technology, by inspecting the effect of materials used and answering the research questions below: a) What are the impacts of double skin façade use on the projected energy reductions? b) To what level does the local climate influence the efficiency skin materials? c) How each skin material – used in the research – does benefits the building with regard to energy reductions? d) Is there any projected energy benefit if the skin material was used across many façades? e) Which skin material is the most feasible and cost competitive to deploy in terms of economic efficiency? f) What modifications should be done so as to make the research comparative to the UAE region? Effect of double skin facade orientation on projected energy reductions Heat prevention is the main concern in desert climates as far as reducing energy use and offering comfort to occupants is concerned. Most office structures in Dubai utilize horizontal shading as a way of reducing solar gain. For instance, Abu Dhabi which is located at 24.43 kilometres north of equator, has embraced double skin façade technology. This is because the projection necessities are minimal for the south façade shading compared to the necessities for latitudes north. By simply utilizing maintenance platform and grated cleaning that is usually provided in broad air corridor double skin façades, we can reduce solar gain and achieve shading protection for double skin façade without any additional louver shades within the cavity northern locations of the equator. The west and east façades of tall buildings in particular face a greater problem since they cannot be equipped with simpler horizontal systems which are effective in the case of south facing glazing of high sun angles. Thus, if we are considering buildings in hot desert climate or north of equator, double skin façade reduces solar exposure but allow enough daylight into the building. Particularly, this is of concern for iconic tall buildings as they appear to be positioned on more isolated areas which upsurges their solar exposure. Commercial towers in big cities like Dubai appear to be positioned on smaller locations and crowded together thereby offering shading to one other, using an old-fashioned hot climate clustering method. Even though double façades of usual buffer, extract-air, and twin face types are still being built in these hot desert climates, unique double façades that uses unique materials, such as aluminium and concrete shaped organic have been developed to focus exclusively on the shading provision as the primary way of solar gain avoidance. This is normally coupled with comparatively high performing glazing within curtain wall skins so as to further limit solar gain and heat transfer into the office building. Most of the facades shading systems that use wooden blanks are inspired by the Islamic Mashrabiya`s tradition: a wooden frame screen which is used as a way of allowing some air circulation but blocking significant solar gain and offering visual privacy. This vernacular founded model for the second layer may be seen as a natural creation to modify the current type of double skin façade system. So long is the custom of mashrabiya screen and it is tolerable in the hot desert climate since it has clear views of the outside from the obscured screens. This is significant to note when evaluating the benefits of double skin façade systems which use various material to achieve the projected energy reduction target. According to Hough (2006), double skin façade systems will continue to be adopted for reasons which are hands-on and easily understood. Knaack & Klein (2009) adds that the purely energy reduction benefits of these hands-on reasons can be far more clear than the gains provided by from economic benefits. The benefits in terms of energy reduction may be a bit more tangible since they have visual or physical consequences to the users and occupants of the office buildings. As numerous buildings are getting constructed in or around noisy urban settings, double skin façade technology has been successful in controlling unwanted noise. An extra layer offered by the twin face, extract-air or buffer systems has always been effective in enhancing the buildings` acoustic performance. Many sustainable structures are turning to a natural ventilation as one way of improving the comfort of occupant and lessening the cost of energy in hot climates where temperatures are very extreme. Double skin facade systems can offer natural ventilation via strategies which offset the incapacitated air flow systems thereby reducing the overall solar gain effects that would result from overheated rays into the building. This ability to provide ventilations can also mitigate problem of air pollution – occasioned during the weather events or peak traffic hours – in the office building fitted with less closable dampers. The ventilations will also lessen the influx of urban noise to the inner spaces. Currently, natural ventilation in many commercial towers is not being used in extremely hot desert climates. There is a full reliance on mechanical cooling which has been firmly created along with its luxury expectations. That aside, the insertion of certain operable windows in commercial towers in developing nations is quite normal when compared to buildings in UAE region. Most of these desert climate regions do have considerable months where natural ventilation is perceived as being beneficial. As such, double façade technology is seen as an effective remedy in the future. Even in Western localities, double façade technology safeguards solar shading devices that would otherwise get exposed to ice, snow, rain, and wind. This permits ultimate flexibility as far as designing and deploying shading systems and operable louvers is concerned. The ultimate benefit can also be environmental protection as the system can serve to lessen the cleaning requirements, tear and wear of mechanical components, thus assisting with problem of longevity and durability. In London, the Helicon Building became one of the initial extract-air systems which its louvers being secured within the cavity. Bell & Rand (2006) notes that desert climate applications have appeared not to place operable louvers within unsealed air corridors because of issues of fine sand and dust accumulation that results in problems of cleaning. Interior blinds remain the preferred choice in assisting with shading and glare regulation and it offer occupant control. The general double skin façade types of twin face, buffer and extract-air which reflect a specific climate target consideration shave developed and could be seen in present desert climate projects situated in UAE region. In some cases this may have occasioned a hybrid tactical approach to the double façade. For others instances it was the simplification of a complex, old-fashioned approach which was expected to handle the opposing concerns of solar gain and cooling. In exceptional desert climates the design plan has emphasized on the benefit of double skin façade approach as far as achieving the desired daylight and avoiding solar gain is concerned. In some desert climate double façade technology has embraced the shading system, which is the outer layer, thereby removing the more common and additional curtain wall layer. Nonetheless, it still executes the ultimate goal of heat avoidance. Local climate impacts on the effectiveness of each skin material The climate in desert regions like Qatar and United Arab Emirates is uncommon and extreme since it is extremely humid. However, the impression and appearance if one has not visited the region would be that it is actually arid because of the lack of fresh water bodies and vegetation that are usually existing in hot-humid climates. Combined with extraordinary levels of fine sand gravels from the windy conditions in the desert, the high humidity make condensation process an issue (Almusaed, 2011, pg. 138). That is, highly chilled glazing facades that result from extreme air conditioning levels get into contact with outdoor temperatures of 45o Celsius with humidity of about 80%. When U-values of glazing units gets upsurges the dew point might be reached around the outer skin surface (aluminium, concrete shaped organic, wooden blanks or glass outer skin). This makes the blowing sand to stick to the outer skin façade, thus, limiting the overall light penetration and solar gain regardless of the material used. The thermal performance of each skin façade is adversely affected by these dust and fine sand gravels. Moreover, the maintenance and cleaning cost shoots up due to local climates. Doha Tower, for instance, uses the double skin façade which employs a static screen component as the outer skin of the system. This outer skin of the Tower of Doha has four “butterfly” aluminium components of various scales to induce the symmetrical intricacy of Islamic mashrabiya but serve as shield from the sun. Across the region, this pattern varies depending on the material orientation and respective desire for solar protection. The variation in opaqueness of the material screen (concrete shaped organic, wooden blanks or aluminium) addresses the disparity in solar avoidance needed from façade orientations. Because of its round shape, the tower needs some shading on the “north” surface as it receive daylight in the morning and evening hours. Benefits observed of each skin i. Outer skin: Aluminium Since aluminum can be painted with any color, to bring any optical effect, it is can always be painted with colors that reflect more light or retain more heat depending on the comfort of the occupants. Aluminum also has a considerable strength-to-weight ratio; a unique feature that allows architects to achieve the required energy performance specifications, but still lessen the dead weight on supporting structure of the building. This is a major benefit for roofing and cladding applications. Moreover, due to the material’s inherent stiffness and strength, aluminum curtain wall and window frames may be made very narrow, thus optimizing glazed surface and energy reduction for the given outer skin dimensions. The material also has high reflectivity: a characteristic feature which makes aluminum a highly efficient material as far as daylight management is concerned. Aluminum light channels and solar collectors can be fitted to reduce energy consumption for man-made lighting or even heating in winter. Its shading devices may be used to cut down the use of air conditioning during hot seasons. Finally, aluminum is an exceptional conductor of heat, thus, it is an effective material for exchanging heat in solar heat collectors or energy proficient ventilation systems. ii. Outer skin: treated wooden blanks A clear benefit of using treated wooden blanks in the outer skin is that its insulation is restricted within the material`s depth, so a typical treated wooden wall may be thinner compared to its masonry equivalent, say, by 50mm. The moment a considerable insulation level is attained, the amount of solar gain or heat lost due to air leaking to the surrounding from the building then gets more of a concern. Treated wooden blanks structures appear to perform well in this case since they are impenetrable and thus prevent moist air from reaching the indoor of the building. Moreover, the difference between other material facades and treated wooden blank walls is on how successfully they retain heat. People who have been in buildings of other outer skin materials will be confirm that the main heating is set on well prior to getting to the winter’s seasons to ensure comfortable indoor stay. This is because, other outer skin materials, such as concrete shaped organic inner leaf of building must first be heated before the room temperature can reach the desired level. Treated wooden blanks do not absorb heat in this manner. Because of this factor, a building enclosed by insulated wooden frame walls can heat up but then cool down almost immediately. Whether this is some desired feature or not will depend partially on the inhabitants` lifestyle and whether the building has to get heated endlessly or just at night time, as is the case in desert climates. Outer skin: Glass Numerous new building designing trends have been globally proposed due to the urge to remain environmentally friendly. Buildings outlook are no longer required to look only presentable and good but are expected do more than just that. Today’s buildings made up of glass skin have thermal protection property, are also capable of controlling the amount of light flowing through them and are also capable of electricity production as well. Thermal Insulation: Systems with double skin façade can afford greater thermal insulation property both in the summer and winter as proposed by many authors due to their outer skin. As described by Lee et al, (2000), during summer time, the warm air enclosed inside the jacket can be harnessed mechanically or naturally when it is ventilated. As the absorbed radiation from the re-radiation process is emitted into the middle jacket, a natural load then impact on the results thereby causing the air to rise, carrying with it immense supplementary heat energy. In order to guarantee proper jacket ventilation, a robust combination of the various forms of the shading devices and panes are cautiously integrated to prevent overheating of the jacket cavity and hence the internal superficial. Due to the jacket cavity opening size, width and height, the jacket cavity geometry is taken as critical, and is therefore crucial for the airflow and ensuing temperatures, that is, if ventilation of the jacket cavity is naturally. Considered again to be a great important parameter that needs to be critically examined is the positioning of the shading devices. iii. Outer skin: Concrete shaped organic Sometimes concrete tend to be elusive and is usually dressed up with several materials, to hide away the large bulk and the discrepancies of the concrete finishes, not like glass, which when used is seen clearly. The necessity of creating stream lined elegant buildings doesn’t permit for hiding and cladding the structure, but some designs entails that the concrete structure to be stream lined as well. This is visibly executed in the shell concrete structures (Pix 11). The replacement of the steel members in the concrete with the fiber glass as a result of the new technology makes the process possible to cast much stronger and thinner concrete. This particular kind of concrete do not necessarily have to solve the usual problems that are related to the deterioration of the steel reinforcement (Pix 12). The moldability feature that the concrete displays make it to be a desired medium to create built-in furniture. As a result of the new casting techniques it has been possible to create comfortable and sleek furniture which are stand alone and movable units, in contrast to bulky units (Pix 9 & 10). A part from being used in form of tiles, concrete is mostly used as cladding. The new structural systems have created optimum use of the characteristics of concrete making it possible to enable adding of vibrance, texture and colour though the mounted concrete panels. The adoption of an innovative reinforcement system and a light weight concrete mix has been a mechanism to counter the great weight that such a façade would impose. The designing of the Soccer City Stadium in Johannesburg by Boogertman, (Pix 13) Urban Edge + Partners has made use of this technology. Another innovative surface finish make use of the photolithographic techniques for the embedding of white and black or two tone images on a concrete façade. The similar technique has been adopted by De Meuron and Herzog in the Fachhochschule Eberswalde’s library (Pix 14). Advantages of applying the material across more facades According to Patterson (2011), for energy to decrease and attain thermal comfort in a building, there are parameters that should be put into consideration like noise, humility, temperature and light. Most part of the heat gain or losses in buildings comes from opening like windows. For that reason, it is clear that windows are the core element in the transfer of big amount of heat between an exterior environment and a building. Therefore, a feasible material is applied across more facades so as to maximize energy reduction. The more you apply the material on more façade, the more we achieve the projected energy reduction target. When this is observed, the solar gain coefficient can be roughly 17% which is considered to be a low CO2 committer and also interpreted as a good value (Baker, 2009, pg. 59). In the case study villa the single glazing was replaced by the double glazing with a 16mm void containing Argon instead air (Aksamija, 2013, pg. 49). The most cost competitive and feasible material The most cost competitive and feasible outer skin material is aluminium. Exceptional strength to weight ratio is one of Aluminium’s primary appeals to specifiers. It weighs lighter than steel at 2.7g/cm2 by 66% and far less susceptible to brittle fractures. Certainly when the materials are compared, Aluminium has a greater modulus of elasticity meaning that it weight ratio of 1:2 which is easily achieved. At the same time Aluminium has relatively high co-efficient of linear expansion, at 24X 10-6/’C in its pure form. The temperature induced stresses to be accommodated being enabled by the 65,500N/mm2 for 6063 alloy (materials low modulus of elasticity). In fact these are generally far lower than steel structure in comparison (M of E=21,000N/mm2). Aluminium’s load-deflection curve is illustrated graphically without a yield point and it’s continuous. In addition, when the two are compared Aluminium sections are generally deeper and thinner than equivalent steel sections to attain the necessary strength and rigidity. Moisture has no effect on Aluminium therefore it makes Aluminium windows not to stick, rot or warp. The strength, rigidity and intrinsic lightness of aluminium frames improves in door construction by typically using hollow-section extrusions and sight lines reason being that it multi-point locks and other door furniture can be fitted within the frames. Despite the reality that aluminum can be painted with any color, to bring any optical effect, it can always be painted with colors that reflect more light or retain more heat depending on the comfort of the occupants. Moreover, due to the material’s inherent stiffness and strength, aluminum curtain wall and window frames may be made very narrow, thus optimizing glazed surface and energy reduction for the given outer skin dimensions. The material also has high reflectivity: a characteristic feature which makes aluminum a highly efficient material as far as daylight management is concerned. Aluminum light channels and solar collectors can be fitted to reduce energy consumption for man-made lighting or even heating in winter. Its shading devices may be used to cut down the use of air conditioning during hot seasons. Aluminium has low maintenance cost. Most of aluminium construction products are coated and treated because it assumes a defensive layer of oxide the moment it is open to air (has a natural, built in durability). Oxidization process can be improved in one way by anodization; this improves its ability to withstand attack in aggressive environments. This process natural results in the same way silvery finish to oxidized aluminium, although it can also introduce a range of colours. Reasons being, after anodizing, the surface film remains porous, allowing it to accept colouring agents like electrolytes, pigments, metallic or organic dies. In the same way, attractive bronze, gold, black, grey are commonly achieved. Most specifiers go for electrostatically sprayed polyester powder coating for a wider choice of colour. The powder is used to provide resistance to the acidity of rainwater this is common in finishing curtains walling, cladding panels and rainwater goods. In this stage, charged paint particles which have undergone a twelve stage pre-treatment process are blown onto the extrusion and the stove at between 200 and 210’c, for 10 to 12 minutes. All this provides a high quality surface with excellent accurate colouration, film thickness and adhesion. Aluminium has the compatibility with today’s fast track construction techniques and just in time ordering that’s one of the principal’s reasons for it being able to endure and grow popular. The final outcome is earlier building occupancy and greater profit margins for the ultimate customer. Aluminium window systems, door assemblies and shop fronts present comparable on site merits, which are now being improved by fabricators computer-controlled machining rigs that can miter, countersink, grind and drill to exact tolerance enabling the easiest possible installation of ironmongery and other secondary elements. How to make the study comparative to the region of UAE Passive cooling strategies should be used to enhance thermal performance and decrease energy consumption of residential building in UAE in order to make the study comparative across UAE. To maximize the comfort and health of the building users when minimizing energy use, the passive design should be used to responds to local climate and site conditions of the same. This design can be defined as the technologies or design features adopted to decrease the temperature of buildings with no the need for power consumption thus it should take advantage of the local climate. Subsequently, the study should test the effectiveness of applying selected passive cooling strategies to enhance thermal performance and to decrease energy consumption of residential buildings in hot arid climate settings such as United Arabs Emirates and Dubai. Eight passive cooling strategies is applied in one case building that was chosen. The buildings` performance is gauged by the energy simulation software that is IES. Sun cast, part of the IES software was also used to assess solar shading performance. Energy reduction will be attained because of the two reasons, one, the minimizing of heat gaining line with applying good shading devices alongside the use of double glazing. Two, the harnessing of natural ventilation. Furthermore, green roofing proves its potential by acting as effective roof insulation. Significant findings were revealed in the study, that the total annual energy consumption of a residential building in Dubai might be decreased by 23.6% when building uses passive cooling strategies. Conclusion In summary, this paper has also discussed the benefits of Double Skin Facades for the indoor surroundings in urban areas. It has assessed the probable positive influence that double skin facades use can bring on the indoor surroundings. In our discussion, we reviewed and analysed various literature sources and studies concerning DSF and indoor surroundings conditions. Having balanced temperature yearly and access to sufficient amount of daylight is an important aspect as a good indoor air quality thus makes double skin facades beneficial for indoor environment. The benefits are not only for indoors environment in general especially when compared to conventional glass facades where they perform very well in conditions given by urban environment. In this surrounding, the risk of air pollution or noise population allow double skin façade to be structured in such a way to serve multiple purpose simultaneously and also protect the indoors surrounding from all the threats given by the outdoors setting. DFS systems, usage give the hope to attain a solution solving several problems: Consumption of energy (usage reduction) It encourages a new Architectural style gives both the energy reduction value and aesthetical value. Several combination of façade integration (skin materials and systems), can completely tweak the results of the best skin used, climate, keening in mind, skin type, orientation and skin materials. References List Aksamija, A. 2013. Sustainable Facades: Design Methods for High-performance Building Envelopes. New York: Wiley. Almusaed, A. 2011. Biophilic and bioclimatic architecture: Analytical therapy for the next generation of passive sustainable architecture. London: Springer. Architecture & sustainable development. 27th international conference on passive and low energy architecture. Vol. 1. 2011. Louvain-La-Neuve: Presses Universitaires. Baker, N. 2009. The handbook of sustainable refurbishment: Non-domestic buildings. London: Earthscan. Bell, V. B., & Rand, P. 2006. Materials for architectural design. London: Laurence King. Bragança, L., & International Conference "Portugal SB07 Sustainable Construction, Materials and Practices - Challenge of the Industry for the New Millennium". (2007). Portugal SB07 Sustainable Construction, Materials and Practices: Challenge of the Industry for the New Millennium. Amsterdam: Delft University Press. Crisinel, M., & EU COST C13. 2007. Glass & interactive building envelopes. Amsterdam: IOS Press. Hough, T. P. 2006. Trends in solar energy research. New York: Nova Science Publishers. In Dinçer, I., In Midilli, A., & In Kucuk, H. 2014. Progress in exergy, energy, and the environment. INALCO 2010, Katgerman, L., Soetens, F., Technische Hogeschool Delft., & Technische Hogeschool Eindhoven. 2010. New frontiers in light metals: Proceedings of the 11th International Aluminium Conference INALCO 2010. Amsterdam, Netherlands: IOS Press. Knaack, U., & Klein, T. 2009. The future envelope 2: Architecture, climate, skin. Amsterdam: IOS Press. Öchsner, A., Silva, L. F. M., & Altenbach, H. 2011. Materials with complex behaviour II. Berlin: Springer. Patterson, M. 2011. Structural glass facades and enclosures. Hoboken, N.J: Wiley. Pell, B., Hild, A., Jacob, S., & Zaera, A. 2010. The Articulate Surface: Ornament and Technology in Contemporary Architecture. Basel: De Gruyter. Schittich, C., Krippner, Roland., Lang, Werner., & Schittich, Christian. 2012. Building Skins. Basel: De Gruyter. Read More