- Email: [email protected]
Adaptive building envelopes of multistory buildings as an example of high performance building skins
Alexandria Engineering Journal (2019) 58, 345–352
H O S T E D BY
Alexandria University
Alexandria Engineering Journal www.elsevier.com/locate/aej www.sciencedirect.com
ORIGINAL ARTICLE
Adaptive building envelopes of multistory buildings as an example of high performance building skins Hadeer Samir Mohamed Shahin Alexandria University, Faculty of Engineering, Egypt Received 12 September 2018; revised 14 November 2018; accepted 22 November 2018 Available online 1 March 2019
KEYWORDS Adaptive envelopes; Adaptive architecture; Smart materials; Intelligent facades; Responsive facade
Abstract Recently developed generation of high-performance skins greatly leads to the emersion of innovative manufactures integrating real-time environmental response, enhanced materials, dynamic automation with built in microprocessors, wireless sensors and actuators, and designfor-manufacture techniques. This application has basically alter the thinking way of architects in the early design stages of the building with a shifting in importance from form to performance, from structure to envelope. In the field of high-performance buildings, the envelope begins to be the setting of research and development. The aim of the paper is to discuss the design of three strategies used in constructing adaptive building envelopes of multistory buildings, integrating improved energy performance and architectural innovation, in order to Control the physical environmental factors (heat, light, sounds), as well as improving occupants’ comfort. Finally, three case studies are analyzed to unveil the implementation of these strategies on constructing structures and study their effects on the building energy savings. Scope and objective: The objective of this paper is to illustrate and discuss new conceptual ways of designing adaptive building envelopes of multistory structures that respond to environmental changes in the surrounding climate of different places in the world, and how the usage of such adaptive envelopes can help reduce the energy consumption of the building. Methodology: The literature survey will first discuss the characteristics and properties of high performance facades. After that, the paper present and analyze existing examples and ideas of adaptive envelopes, gaining an overall understanding of the concept of three adaptive building envelopes. In addition, at the same time develop knowledge of the materials commonly used and how they perform. Finally, three case studies are presented to analyze the implementation of the three adaptive envelopes strategies and observe their effects on the building energy savings. Ó 2019 The Author. Published by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).
1. Introduction E-mail address: [email protected] Peer review under responsibility of Faculty of Engineering, Alexandria University.
‘‘Adaptivity” means to explicate any alteration in the surrounding environment and to respond to it. This change is characterized by dynamism. Architecture designed for a static
https://doi.org/10.1016/j.aej.2018.11.013 1110-0168 Ó 2019 The Author. Published by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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set of factors does not certainly facilitate this adaptability to alter. People observe huge changes on the sustainability front nowadays, but the paradigm for designing performance based systems has not altered. To attain the high level of climatic response, this paradigm has to change. Conventional buildings are constructed as static structures while they promote dynamic components like solar patterns and wind variation. This generates dissociation between the structure and its environment. To consider this disjunction, the necessity of entities that can cope with change, assimilating the information and learning from it. The systems are required to respond dynamically to the changes occur in climatic conditions, therefore offering better efficiency than static systems [1]. In the multistory buildings, large energy consumption is taking place due to lack of thermal comfort and low efficiencies of HVAC systems [2]. A good review was reported by Vakiloroaya et al. [3] analyzing the effect of incorporated management of shading blinds and natural ventilation on the performance of the buildings in means of energy savings and occupant comfort [4]. A whole design approach of high performance buildings, that embrace passive strategies for building skin design, has important effect on enhancing the whole building energy performance, including large scale buildings [5]. A highperformance envelope that integrates daylighting, shading, and natural ventilation systems, has the possibility to notably decrease the energy used by building operations [6]. Furthermore, building skin creates a significant component of a building visual effect and aesthetic. The design flexibility of building envelope achieves various operational and visual features, and can be vital factor that which motivate architects, clients and other stakeholders to settle for this type of high performance envelopes. To achieve these goals, addressing performance standards should take place at the same time considering the variant architectural standards at the beginning of design stages [7] (see Table 1). 2. Characteristics and properties of sustainable high performance facades High-performance facades could be described as the external building envelopes that consume the minimum amount of energy to retain a convenient indoor environmental quality,
Table 1
which improves the well-being and productivity of people inside the building [8]. Thus, sustainable envelopes considered not being simply enclosures that keep the spaces inside the building away from the outside; but vital components that generate suitable interior areas by acting in response to the building’s surrounding climate [9]. The properties of these building envelope include: (1) permit penetrating of natural light inside the building spaces; (2) stop undesired solar heat from penetrating the interior spaces; (3) stop heat transference through enhanced insulation; (4) blocking air and moisture from penetrating through the building; and (5) permitting natural ventilation to enhance the internal room temperature and air quality. These properties depend mostly on climate, in addition to the building’s operations, residence basis, orientation, and energy burden of equipment, moreover, the facade type [10]. There are basically two kinds of facades: Opaque facades, which are basically built of layers of solid materials, such as masonry, stone, precast concrete panels, metal cladding, insulation, and framing. These facades could also contain punched openings to let natural light in or operable windows. Glazed facades, for example curtain walls or storefront facades, which basically constructed with transparent or translucent glazing elements and metal framing structures [9].
3. Adaptive building envelopes These envelopes are described as a building skin, which is able to alter its properties and control the various parameters of a building skin. These changes are operated based on change in the climatic loads or changed indoor environment, so it can enhance the occupants’ comfort. The alteration could be achieved in various ways, by moving components, by the introduction of airflows or by a chemical change in a material. Altering the performance of the building skin which is dependent on the external climate and the desired internal environmental conditions is not a new idea [11]. The idea of adaptive building skin has an association with biomimicry, intelligent buildings, smart materials.
Observations and results of the three case studies. Source: Researcher.
Observations and results of case studies The Barcelona Media-ICT building An example of smart materials in adaptive building envelope Using of ETFE material, the building generates 20% less in energy consumption. This decreases the solar factor (SF) by four times, from 0.45, as accepted by the Building Code, to 0.10.
Al Bahar Towers by Aedas An example of responsive facade system in adaptive building envelope Decrease solar gain by more than 50 percent and decreases the usage of air conditioning. In addition, its capability to filter and reduce the direct solar gain to a maximum of 400 W per linear meter. It permit the usage of natural type of tinted glass, which permits more sunlight to enter the building and decreases the need for artificial lighting
Terrence Donnelly Centre for Cellular and Biomolecular Research. An example of Intelligent building skin The double fac¸ade permits natural ventilation throughout the 13 floors, enhancing air circulation, cooling and natural ventilation. In addition, the louvers placed at the fac¸ade control the penetration of sunlight, hence improving indoor environmental quality.
Adaptive building envelopes of multistory buildings
Fig. 3.1 Classification of Adaptive Building Envelope systems. Source: Researcher.
3.1. Classification of adaptive building envelope systems Adaptivity systems are mainly classified into three different categories shown in (Fig. 3.1) based on adaptivity level [12]. 3.1.1. Smart materials These are materials whose characteristics can be importantly altered in a well-managed manner by outside stimuli such as temperature, electric or magnetic fields. The use of materials that change their characteristics in reaction to heat, moisture, or light can readdress how we conceive Architecture. The main considerations in smart materials will be if the changes are reversible or irreversible. They could be as straightforward as paints which change color based on the temperature [13]. The properties of smart materials are described as: ‘‘immediacy” (real-time response), these smart substances grab designers’ attention who are targeting to improve functionality and performance simultaneously with decreasing energy use. Some of smart materials which are presented to high-performance building enclosures are: aerogel, the synthetic low-density translucent substance applied in window glazing, phase changing materials like micro-encapsulated wax, salt hydrates, thermochromics polymer films, and structure integrated photovoltaics. - Smart Thermobimetal Self-Ventilating Skin: Doris Sung, principle of DO|SU Studio Architecture and faculty member at the University of Southern California, is conducting a research to illustrate use of thermobimetals for self-supporting structure envelopes which allow their pores to open and self-ventilate without the use of external energy sources (Fig. 3.2). Laminated metals with various thermal
Fig. 3.2 Smart Thermobimetal Self- Ventilating Skin: installation of prototype and details of skin performance under different temperatures, 2010. Source: Thun. G.; Velikov, K.2013.
347 coefficients changes their shapes when introduced to temperature set points, generating tension and causing movement in the thermobimetal. When the heat source is eliminated, the bimetal get back to its first main shape. Coating two metal alloys with different coefficients of expansion together, the result is a thermobimetal that curls when heated and flattens when cooled. When an increase in the temperature occurs, this deformation allows the building skin to breathe [14]. 3.1.2. Intelligent building skin The expression ‘intelligent’ indicate a broader range of coordination and performance than ‘smart’. In a broad sense, the objective of an intelligent building skin is to maximize the systems of the building with respect to climate, energy consumption and occupant comfort. This is regularly attained by building automation and physically adaptive components such as louvers, sunshades, operable windows or smart material assemblies (Fig. 3.3). The system itself should be ‘intelligent’ and ‘emergent’; being able of learning from the set of occupant reactions taking into account future weather fluctuation and changing accordingly. Time ahead, it could be capable of learning from mistakes made in the system. With the huge number of available data streams, climatic data from the past century can be used to forecast the future weather patterns. The centralization of the building systems which have been changed by the universal communication technologies has given a enormous scope in enhancing the building intelligence [1]. In the book Intelligent Buildings, by Brian Atkin, intelligent buildings are illustrated as structures that ‘‘know” the environmental conditions in the exterior and interior of the building, then ‘‘decide” how to generate a suitable and convenient indoor environment, and that ‘‘respond” readily to occupant needs [14]. This is typically accomplished using many of sensing equipment which interact with structure control systems to maximize interior conditions, including computational protocols. Finally the envelope and HVAC systems are able to re-balance the system depending on occupant adjustments. 3.1.3. Responsive facade system The expression ‘‘responsive” is usually mentioned interchangeably with ‘‘interactive” and ‘‘adaptive”, but mostly it is used to describe, ‘‘How natural and artificial systems can interact and
Fig. 3.3 Intelligent fac¸ade of automated wood louvers with building integrated Photovoltaics create a continuous fac¸ade for TU Darmstadt’s 2007 Solar Decathlon House. Source: Thun. G.; Velikov, K.2013.
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Fig. 3.4
Responsive fac¸ade system and mechanisms. Source: Thun. G.; Velikov, K.2013.
adapt”. A responsive building envelope consists of functions and performance characteristics homogeneous to these of an ‘intelligent’ structure envelop including real-time sensing, kinetic climate-adaptive components, smart materials, automation and the occupant ability to make adjustments. However, it also has interactive aspects, such as computational algorithms which make it possible for the building system to
adjust itself and learn by time, in addition to the capability of occupants to physically handle the structure envelope components to manage environmental conditions [10]. Learning occurs in according to altering environmental conditions and occupant comfort. A responsive building skin, as a result, not only incorporates mechanisms for occupants sensing and feedback, but is also devoted to educating both the building and its inhabitants. Data is given to the building’s occupants so they can acquire knowledge of by time and adjust their actions in accordance to climate and energy load. Finally, both building and inhabitants are taking place in a continual and evolving conversation as shown in (Fig. 3.4) [14]. 4. Case studies 4.1. The Barcelona Media-ICT building (An example of smart materials in adaptive building envelope)
Fig. 4.1 Media-ICT building in Barcelona. Source: http:// rvtr.com/files/HPH.pdf.
Fig. 4.2
Criteria of selection: This case study is used to illustrate the use and performance of smart materials in adaptive building envelopes, to control solar heat gain through the facade and enhance the indoor environmental quality Fig. 4.1.
Diagrams of the way the ETFE Diaphragm worksSource : Macedo, A.2007.
Adaptive building envelopes of multistory buildings
Fig. 4.3 Al Bahar Towers by Aedas. Source: https://www. arch2o.com/al-bahr-towers-aedas.
Fig. 4.4 Islamic lattice shading device in Al Bahar Towers. Source: https://www.arch2o.com/al-bahr-towers-aedas.
349 Location: Barcelona Principal Architect: Enric Ruiz Geli, Cloud 9 Date of completion: 2011 Building Type: Cultural Center Adaptive System: Smart Material The envelope is consisting of a pillow cladding system consisting of the polymer ETFE with encased lamella fins whose pneumatic mechanisms are automatically triggered through light sensors when exposed to sunlight [14]. -ETFE (Ethylene Tetrafluoroethylene) Polymer A translucent polymer sheeting which is applied as an alternative to glass and hard plastic in some new structures. In comparison to glass, ETFE (1) permit more sunlight; (2) greater insulation; (3) costs 24 percent to 70 percent less to construct; (4) weigh 1/100 the weight of glass; and (5) has characteristics that makes it more flexible as a construction material. The ETFE layer is triggered by pneumatic mechanisms as illustrated in (Fig. 4.2) with light meter sensors which based on the presence of sunlight, it automatically and independently actuate inflation and deflation equipment in the air chambers. The light meters are independent in terms of energy production [15]. The cladding consist of three layers of substance on the facade that exposed to much sunlight. Those layers are involuntary bloated using sensors to create 2 empty chambers. The first layer of ETFE is transparent, however, the second and third layers have a reverse pattern design which, when inflated or deflated, made the facade transparent or opaque. This keeps the penetration of light and heat away during sunlight time. This is called ‘‘ETFE Diaphragm” configuration. The system can adjust the penetration of air through the facade, with suitable goals in terms of energy efficiency [15]. 4.1.1. Observations and results There is no occupants’ contribution in the system. The user has not the ability to adjust any changes made by the system.
Fig. 4.5 Detail diagram of an individual shading device, showing comparison of fully closed unit (Top) and fully opened unit (Bottom). Source: Cook, R. 2012.
350 Using 2500 m2 of ETFE material, the MEDIA-TIC building generates 20% less in energy consumption and achieves a score of 42 points of the maximum 57 points predicted by the decree on environmental standard and energy efficiency for buildings [17]. This decreases the solar factor (SF) by four times, from 0.45, as accepted by the Building Code, to 0.10 [15]. 4.2. Al Bahar towers by Aedas (An example of responsive facade system in adaptive building envelope) (Fig. 4.3) Criteria of selection: This case study is used to illustrate the execution of Responsive facade system in an adaptive building envelopes, to control solar heat gain through the facade and enhance the indoor environmental quality . Location: Abu Dhabi, UAE Architects: Aedas Type: Office building Adaptive System: Responsive facade system. The pioneering shading screen of the towers, managed by computer, operates as a curtain-wall, positioned 2 m away from the external fac¸ade of the structure in its own additional frame (Fig. 4.4). Each triangle is enclosed in micro-perforated glass fiber and adjusted to automatically respond to the motion of the sun, thus decreasing the solar gain and glare. Each of the tower compromises over 1000 individual shading devices [16]. Each unit (Fig. 4.5) includes a chain of extended PTFE (polytetrafluoroethylene) panels and is worked through a linear module which opens and closes steadily once every day, in accordance to a sequence which is previously programmed and calculated to block direct sunlight exposed to facade. The whole installing is shielded by a diversity of sensors which open the units in certain cases that conditions alter; for instance, if it’s cloudy or there are hard winds. These new parameters have resulted in higher architectural collaboration with the disciplines of mechanical and electrical engineering, computing and the physical and social sciences.
H.S.M. Shahin designers to be more specific in choosing the type of glass. It has provided them to apply more natural type of tinted glass, which permits more sunlight to enter the building and decreases the need for artificial lighting [17]. 4.3. Terrence Donnelly Centre for Cellular and Biomolecular Research. (An example of intelligent building skin in adaptive building envelope) Criteria of selection: This case study (Fig. 4.6) is applied to illustrate the use of Intelligent building skin in an adaptive building envelopes, to control sunlight radiation through the facade and enhance the indoor environmental quality. Architects: Behnisch Architekten, Stuttgart, Architects Alliance, Toronto Location: Toronto, Canada Date of completion: 2005 Type: Educational Adaptive System: Intelligent building skin.
4.2.1. Observations and results It is evaluated that the screen restrains the solar gain by more than 50 percent and decreases the usage of air conditioning. In addition, its capability to filter and reduce the direct solar gain to a maximum of 400 W per linear meter has provided the
Fig. 4.6 Terrence Donnelly. Source: https://behnisch.com/work/ projects/0135.
Fig. 4.7 (Left) Intelligent double-skin facade system of Terrence Donnelley Centre.
Adaptive building envelopes of multistory buildings The shallow plates of the lab floors optimize daylight entry and, based on needs of specific research requirements, allow for natural ventilation. Double-and triple-height gardens are placed at different points on the edges of the lab floors, giving suitable and precious meeting places for researchers, students and staff. Each facade is constructed differently to meet individual programmatic and climatic needs [18]. Since the south elevation undergoes more solar heating in Toronto, this is the reason that particular facade is one of the important aspects of the structure. This facade is more concerned with the thermal levels in each office which are exposed to the sun. Offices are designed with double-skin glass curtain wall, embedded in frames of aluminum mullions, which generates a good acoustic, solar, and thermal control. The air space between the outer envelope of monolithic glass and the internal layer of insulating glass is 2.5 feet (0.8 m), including perforated aluminum louvers to minimize solar heat obtained and redirect sunlight penetrating the building [18]. The outer envelope, include operable louvers at the top and bottom to ventilate
351 the cavity, while operable windows placed in the inner wall cause natural ventilation to the workplaces (Figs. 4.7 and 4.8) 4.3.1. Observations and results The natural ventilation at the Terence Donnelly Center is taking place through the double fac¸ade which is running through all 13 floors without partitions, and acting like a chimney it enhances the air circulation, cooling and natural ventilation, and this leads to decreasing cooling loads. In addition, perforated aluminum louvers attached to the facade enhance the natural lighting, the indoor environmental quality and decreasing building energy consumption [19]. 5. Conclusion – The high performance buildings nowadays have been optimized by various strategies and techniques in many aspects to reach the expected level of convenient performance. According to the building skin, it is inadequate to have perfectly insulated and airtight walls which handle with almost the climatic situations. Therefore, the necessity for a performance-based architecture is therefore increasing as: The adaptive building facade responds intellectually and accurately to the fluctuating climatic conditions and indoor conditions requirements, where it will utilize the existing natural energies to light, heat and ventilate the spaces and has the ability to achieve energy savings in comparison to conventional technologies, and meantime obtain maximum thermal comfort conditions. The photovoltaic costs could be decreased in the coming days, as the onsite power systems will be incorporated with the glass facade and those skins will develop into local, non-polluting energy suppliers to the building. To take into consideration, the future planning and designing of high-performance buildings is supposed to require active fac¸ade technologies, operating in intelligent coordination with HVAC and lighting systems to provide comfortable indoor environments with decreased energy use. – The huge difference, consequently, between terms ‘‘smart” and ‘‘intelligent” is that in the situation of the functionality results from essential material characteristics, meanwhile, in the latter performance is essentially managed by computation and automation. The performance aspect of intelligent skins is usually more changeable than that of smart envelopes; the performance of smart envelopes is commonly binary and more restricted in control, whereas intelligent skins usually need outer power to attain the targets. Accordingly, when execute to a whole building energy reductions, intelligent skins would perfectly be elaborated with smart substances, which are self-powering and self-actuating [14].
References
Fig. 4.8 (Right) Detailed section of Intelligent double-skin fac¸ade system. Source: Thun. G.; Velikov, K.2013.
[1] S. Edupuganti, Dynamic Shading: An Analysis, University of Washington, 2013. [2] M. Elhelw, Analysis of Energy Management for Heating, Ventilating and Air-Conditioning Systems, Faculty of Engineering, Alexandria University, 2016.
352 [3] V. Vakiloroaya, S.W. Su, Q.P. Ha, HVAC integrated control for energy saving and comfort enhancement, in: Proceedings of the 28th ISARC, Seoul, Korea, 2011, pp. 245–250. [4] F. Radwan, A. Hanafy, M. Elhelw, A. El-Sayed, Retrofitting of Existing Buildings to Achieve Better Energy-Efficiency in Commercial Building Case Study: Hospital in Egypt, Faculty of Engineering, Alexandria University, Egypt, 2016. [5] H. Sozer, Improving energy efficiency through the design of the building envelope, Build. Environ. 45 (12) (2010) 2581–2593. [6] S.B. Sadineni et al, Passive building energy savings: a review of building envelope components, Renew. Sustain. Energy Rev. 15 (2011) 3617–3631. [7] S. Medio, J. Murphy, Aesthetic Vision and Sustainability in the New York Times Building ceramic rod fac¸ade, 2008. [8] A. Aksamija, Context based design of double skin facades: climatic consideration during the design process, Perkins+Will Res. J. 1 (1) (2009) 54–69. [9] A. Aksamija, High-Performance Building Envelopes: Design Methods For Energy Efficient Facades, 2015. [10] L. Lee, S. Selkowitz, V. Bazjanac, V. Inkarokrit, C. Kohler, High-Performance Commercial Building Fac¸ades, June 2002
H.S.M. Shahin [11] H. Modin, Adaptive Building Envelopes, 2014. [12] Adaptive Building Initiative. Retrieved from http://www. adaptivebuildings.com/. [13] Al Bahar Towers Responsive Facade / Aedas. Retrieved from https://www.archdaily.com/270592/al-bahar-towers-responsivefacade-aedas. [14] G. Thun, K. Velikov, Responsive Building Envelopes: Characteristics and Evolving Paradigms, 2013. [15] Ajuntament de Barcelona, Media-Tic, With The AlmostFinished Works, Is The New Image Of Barcelona Digital, 2010 [16] R. Cook, Elbahar Tower, External Automated Shading System, 2012 [17] Al Bahar Towers, Retrieved from https://en. wikiarquitectura.com/building/al-bahar-towers/. [18] Terrence Donnelly Centre For Cellular And Biomolecular Research. Retrieved 30/8/2018 from https://www. canadianarchitect.com/features/terrence-donnelly-centre-forcellular-and-biomolecular-research/. [19] Open Concepts. Retrieved from https://www. canadianconsultingengineer.com/features/open-concepts/.
H O S T E D BY
Alexandria University
Alexandria Engineering Journal www.elsevier.com/locate/aej www.sciencedirect.com
ORIGINAL ARTICLE
Adaptive building envelopes of multistory buildings as an example of high performance building skins Hadeer Samir Mohamed Shahin Alexandria University, Faculty of Engineering, Egypt Received 12 September 2018; revised 14 November 2018; accepted 22 November 2018 Available online 1 March 2019
KEYWORDS Adaptive envelopes; Adaptive architecture; Smart materials; Intelligent facades; Responsive facade
Abstract Recently developed generation of high-performance skins greatly leads to the emersion of innovative manufactures integrating real-time environmental response, enhanced materials, dynamic automation with built in microprocessors, wireless sensors and actuators, and designfor-manufacture techniques. This application has basically alter the thinking way of architects in the early design stages of the building with a shifting in importance from form to performance, from structure to envelope. In the field of high-performance buildings, the envelope begins to be the setting of research and development. The aim of the paper is to discuss the design of three strategies used in constructing adaptive building envelopes of multistory buildings, integrating improved energy performance and architectural innovation, in order to Control the physical environmental factors (heat, light, sounds), as well as improving occupants’ comfort. Finally, three case studies are analyzed to unveil the implementation of these strategies on constructing structures and study their effects on the building energy savings. Scope and objective: The objective of this paper is to illustrate and discuss new conceptual ways of designing adaptive building envelopes of multistory structures that respond to environmental changes in the surrounding climate of different places in the world, and how the usage of such adaptive envelopes can help reduce the energy consumption of the building. Methodology: The literature survey will first discuss the characteristics and properties of high performance facades. After that, the paper present and analyze existing examples and ideas of adaptive envelopes, gaining an overall understanding of the concept of three adaptive building envelopes. In addition, at the same time develop knowledge of the materials commonly used and how they perform. Finally, three case studies are presented to analyze the implementation of the three adaptive envelopes strategies and observe their effects on the building energy savings. Ó 2019 The Author. Published by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).
1. Introduction E-mail address: [email protected] Peer review under responsibility of Faculty of Engineering, Alexandria University.
‘‘Adaptivity” means to explicate any alteration in the surrounding environment and to respond to it. This change is characterized by dynamism. Architecture designed for a static
https://doi.org/10.1016/j.aej.2018.11.013 1110-0168 Ó 2019 The Author. Published by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
346
H.S.M. Shahin
set of factors does not certainly facilitate this adaptability to alter. People observe huge changes on the sustainability front nowadays, but the paradigm for designing performance based systems has not altered. To attain the high level of climatic response, this paradigm has to change. Conventional buildings are constructed as static structures while they promote dynamic components like solar patterns and wind variation. This generates dissociation between the structure and its environment. To consider this disjunction, the necessity of entities that can cope with change, assimilating the information and learning from it. The systems are required to respond dynamically to the changes occur in climatic conditions, therefore offering better efficiency than static systems [1]. In the multistory buildings, large energy consumption is taking place due to lack of thermal comfort and low efficiencies of HVAC systems [2]. A good review was reported by Vakiloroaya et al. [3] analyzing the effect of incorporated management of shading blinds and natural ventilation on the performance of the buildings in means of energy savings and occupant comfort [4]. A whole design approach of high performance buildings, that embrace passive strategies for building skin design, has important effect on enhancing the whole building energy performance, including large scale buildings [5]. A highperformance envelope that integrates daylighting, shading, and natural ventilation systems, has the possibility to notably decrease the energy used by building operations [6]. Furthermore, building skin creates a significant component of a building visual effect and aesthetic. The design flexibility of building envelope achieves various operational and visual features, and can be vital factor that which motivate architects, clients and other stakeholders to settle for this type of high performance envelopes. To achieve these goals, addressing performance standards should take place at the same time considering the variant architectural standards at the beginning of design stages [7] (see Table 1). 2. Characteristics and properties of sustainable high performance facades High-performance facades could be described as the external building envelopes that consume the minimum amount of energy to retain a convenient indoor environmental quality,
Table 1
which improves the well-being and productivity of people inside the building [8]. Thus, sustainable envelopes considered not being simply enclosures that keep the spaces inside the building away from the outside; but vital components that generate suitable interior areas by acting in response to the building’s surrounding climate [9]. The properties of these building envelope include: (1) permit penetrating of natural light inside the building spaces; (2) stop undesired solar heat from penetrating the interior spaces; (3) stop heat transference through enhanced insulation; (4) blocking air and moisture from penetrating through the building; and (5) permitting natural ventilation to enhance the internal room temperature and air quality. These properties depend mostly on climate, in addition to the building’s operations, residence basis, orientation, and energy burden of equipment, moreover, the facade type [10]. There are basically two kinds of facades: Opaque facades, which are basically built of layers of solid materials, such as masonry, stone, precast concrete panels, metal cladding, insulation, and framing. These facades could also contain punched openings to let natural light in or operable windows. Glazed facades, for example curtain walls or storefront facades, which basically constructed with transparent or translucent glazing elements and metal framing structures [9].
3. Adaptive building envelopes These envelopes are described as a building skin, which is able to alter its properties and control the various parameters of a building skin. These changes are operated based on change in the climatic loads or changed indoor environment, so it can enhance the occupants’ comfort. The alteration could be achieved in various ways, by moving components, by the introduction of airflows or by a chemical change in a material. Altering the performance of the building skin which is dependent on the external climate and the desired internal environmental conditions is not a new idea [11]. The idea of adaptive building skin has an association with biomimicry, intelligent buildings, smart materials.
Observations and results of the three case studies. Source: Researcher.
Observations and results of case studies The Barcelona Media-ICT building An example of smart materials in adaptive building envelope Using of ETFE material, the building generates 20% less in energy consumption. This decreases the solar factor (SF) by four times, from 0.45, as accepted by the Building Code, to 0.10.
Al Bahar Towers by Aedas An example of responsive facade system in adaptive building envelope Decrease solar gain by more than 50 percent and decreases the usage of air conditioning. In addition, its capability to filter and reduce the direct solar gain to a maximum of 400 W per linear meter. It permit the usage of natural type of tinted glass, which permits more sunlight to enter the building and decreases the need for artificial lighting
Terrence Donnelly Centre for Cellular and Biomolecular Research. An example of Intelligent building skin The double fac¸ade permits natural ventilation throughout the 13 floors, enhancing air circulation, cooling and natural ventilation. In addition, the louvers placed at the fac¸ade control the penetration of sunlight, hence improving indoor environmental quality.
Adaptive building envelopes of multistory buildings
Fig. 3.1 Classification of Adaptive Building Envelope systems. Source: Researcher.
3.1. Classification of adaptive building envelope systems Adaptivity systems are mainly classified into three different categories shown in (Fig. 3.1) based on adaptivity level [12]. 3.1.1. Smart materials These are materials whose characteristics can be importantly altered in a well-managed manner by outside stimuli such as temperature, electric or magnetic fields. The use of materials that change their characteristics in reaction to heat, moisture, or light can readdress how we conceive Architecture. The main considerations in smart materials will be if the changes are reversible or irreversible. They could be as straightforward as paints which change color based on the temperature [13]. The properties of smart materials are described as: ‘‘immediacy” (real-time response), these smart substances grab designers’ attention who are targeting to improve functionality and performance simultaneously with decreasing energy use. Some of smart materials which are presented to high-performance building enclosures are: aerogel, the synthetic low-density translucent substance applied in window glazing, phase changing materials like micro-encapsulated wax, salt hydrates, thermochromics polymer films, and structure integrated photovoltaics. - Smart Thermobimetal Self-Ventilating Skin: Doris Sung, principle of DO|SU Studio Architecture and faculty member at the University of Southern California, is conducting a research to illustrate use of thermobimetals for self-supporting structure envelopes which allow their pores to open and self-ventilate without the use of external energy sources (Fig. 3.2). Laminated metals with various thermal
Fig. 3.2 Smart Thermobimetal Self- Ventilating Skin: installation of prototype and details of skin performance under different temperatures, 2010. Source: Thun. G.; Velikov, K.2013.
347 coefficients changes their shapes when introduced to temperature set points, generating tension and causing movement in the thermobimetal. When the heat source is eliminated, the bimetal get back to its first main shape. Coating two metal alloys with different coefficients of expansion together, the result is a thermobimetal that curls when heated and flattens when cooled. When an increase in the temperature occurs, this deformation allows the building skin to breathe [14]. 3.1.2. Intelligent building skin The expression ‘intelligent’ indicate a broader range of coordination and performance than ‘smart’. In a broad sense, the objective of an intelligent building skin is to maximize the systems of the building with respect to climate, energy consumption and occupant comfort. This is regularly attained by building automation and physically adaptive components such as louvers, sunshades, operable windows or smart material assemblies (Fig. 3.3). The system itself should be ‘intelligent’ and ‘emergent’; being able of learning from the set of occupant reactions taking into account future weather fluctuation and changing accordingly. Time ahead, it could be capable of learning from mistakes made in the system. With the huge number of available data streams, climatic data from the past century can be used to forecast the future weather patterns. The centralization of the building systems which have been changed by the universal communication technologies has given a enormous scope in enhancing the building intelligence [1]. In the book Intelligent Buildings, by Brian Atkin, intelligent buildings are illustrated as structures that ‘‘know” the environmental conditions in the exterior and interior of the building, then ‘‘decide” how to generate a suitable and convenient indoor environment, and that ‘‘respond” readily to occupant needs [14]. This is typically accomplished using many of sensing equipment which interact with structure control systems to maximize interior conditions, including computational protocols. Finally the envelope and HVAC systems are able to re-balance the system depending on occupant adjustments. 3.1.3. Responsive facade system The expression ‘‘responsive” is usually mentioned interchangeably with ‘‘interactive” and ‘‘adaptive”, but mostly it is used to describe, ‘‘How natural and artificial systems can interact and
Fig. 3.3 Intelligent fac¸ade of automated wood louvers with building integrated Photovoltaics create a continuous fac¸ade for TU Darmstadt’s 2007 Solar Decathlon House. Source: Thun. G.; Velikov, K.2013.
348
H.S.M. Shahin
Fig. 3.4
Responsive fac¸ade system and mechanisms. Source: Thun. G.; Velikov, K.2013.
adapt”. A responsive building envelope consists of functions and performance characteristics homogeneous to these of an ‘intelligent’ structure envelop including real-time sensing, kinetic climate-adaptive components, smart materials, automation and the occupant ability to make adjustments. However, it also has interactive aspects, such as computational algorithms which make it possible for the building system to
adjust itself and learn by time, in addition to the capability of occupants to physically handle the structure envelope components to manage environmental conditions [10]. Learning occurs in according to altering environmental conditions and occupant comfort. A responsive building skin, as a result, not only incorporates mechanisms for occupants sensing and feedback, but is also devoted to educating both the building and its inhabitants. Data is given to the building’s occupants so they can acquire knowledge of by time and adjust their actions in accordance to climate and energy load. Finally, both building and inhabitants are taking place in a continual and evolving conversation as shown in (Fig. 3.4) [14]. 4. Case studies 4.1. The Barcelona Media-ICT building (An example of smart materials in adaptive building envelope)
Fig. 4.1 Media-ICT building in Barcelona. Source: http:// rvtr.com/files/HPH.pdf.
Fig. 4.2
Criteria of selection: This case study is used to illustrate the use and performance of smart materials in adaptive building envelopes, to control solar heat gain through the facade and enhance the indoor environmental quality Fig. 4.1.
Diagrams of the way the ETFE Diaphragm worksSource : Macedo, A.2007.
Adaptive building envelopes of multistory buildings
Fig. 4.3 Al Bahar Towers by Aedas. Source: https://www. arch2o.com/al-bahr-towers-aedas.
Fig. 4.4 Islamic lattice shading device in Al Bahar Towers. Source: https://www.arch2o.com/al-bahr-towers-aedas.
349 Location: Barcelona Principal Architect: Enric Ruiz Geli, Cloud 9 Date of completion: 2011 Building Type: Cultural Center Adaptive System: Smart Material The envelope is consisting of a pillow cladding system consisting of the polymer ETFE with encased lamella fins whose pneumatic mechanisms are automatically triggered through light sensors when exposed to sunlight [14]. -ETFE (Ethylene Tetrafluoroethylene) Polymer A translucent polymer sheeting which is applied as an alternative to glass and hard plastic in some new structures. In comparison to glass, ETFE (1) permit more sunlight; (2) greater insulation; (3) costs 24 percent to 70 percent less to construct; (4) weigh 1/100 the weight of glass; and (5) has characteristics that makes it more flexible as a construction material. The ETFE layer is triggered by pneumatic mechanisms as illustrated in (Fig. 4.2) with light meter sensors which based on the presence of sunlight, it automatically and independently actuate inflation and deflation equipment in the air chambers. The light meters are independent in terms of energy production [15]. The cladding consist of three layers of substance on the facade that exposed to much sunlight. Those layers are involuntary bloated using sensors to create 2 empty chambers. The first layer of ETFE is transparent, however, the second and third layers have a reverse pattern design which, when inflated or deflated, made the facade transparent or opaque. This keeps the penetration of light and heat away during sunlight time. This is called ‘‘ETFE Diaphragm” configuration. The system can adjust the penetration of air through the facade, with suitable goals in terms of energy efficiency [15]. 4.1.1. Observations and results There is no occupants’ contribution in the system. The user has not the ability to adjust any changes made by the system.
Fig. 4.5 Detail diagram of an individual shading device, showing comparison of fully closed unit (Top) and fully opened unit (Bottom). Source: Cook, R. 2012.
350 Using 2500 m2 of ETFE material, the MEDIA-TIC building generates 20% less in energy consumption and achieves a score of 42 points of the maximum 57 points predicted by the decree on environmental standard and energy efficiency for buildings [17]. This decreases the solar factor (SF) by four times, from 0.45, as accepted by the Building Code, to 0.10 [15]. 4.2. Al Bahar towers by Aedas (An example of responsive facade system in adaptive building envelope) (Fig. 4.3) Criteria of selection: This case study is used to illustrate the execution of Responsive facade system in an adaptive building envelopes, to control solar heat gain through the facade and enhance the indoor environmental quality . Location: Abu Dhabi, UAE Architects: Aedas Type: Office building Adaptive System: Responsive facade system. The pioneering shading screen of the towers, managed by computer, operates as a curtain-wall, positioned 2 m away from the external fac¸ade of the structure in its own additional frame (Fig. 4.4). Each triangle is enclosed in micro-perforated glass fiber and adjusted to automatically respond to the motion of the sun, thus decreasing the solar gain and glare. Each of the tower compromises over 1000 individual shading devices [16]. Each unit (Fig. 4.5) includes a chain of extended PTFE (polytetrafluoroethylene) panels and is worked through a linear module which opens and closes steadily once every day, in accordance to a sequence which is previously programmed and calculated to block direct sunlight exposed to facade. The whole installing is shielded by a diversity of sensors which open the units in certain cases that conditions alter; for instance, if it’s cloudy or there are hard winds. These new parameters have resulted in higher architectural collaboration with the disciplines of mechanical and electrical engineering, computing and the physical and social sciences.
H.S.M. Shahin designers to be more specific in choosing the type of glass. It has provided them to apply more natural type of tinted glass, which permits more sunlight to enter the building and decreases the need for artificial lighting [17]. 4.3. Terrence Donnelly Centre for Cellular and Biomolecular Research. (An example of intelligent building skin in adaptive building envelope) Criteria of selection: This case study (Fig. 4.6) is applied to illustrate the use of Intelligent building skin in an adaptive building envelopes, to control sunlight radiation through the facade and enhance the indoor environmental quality. Architects: Behnisch Architekten, Stuttgart, Architects Alliance, Toronto Location: Toronto, Canada Date of completion: 2005 Type: Educational Adaptive System: Intelligent building skin.
4.2.1. Observations and results It is evaluated that the screen restrains the solar gain by more than 50 percent and decreases the usage of air conditioning. In addition, its capability to filter and reduce the direct solar gain to a maximum of 400 W per linear meter has provided the
Fig. 4.6 Terrence Donnelly. Source: https://behnisch.com/work/ projects/0135.
Fig. 4.7 (Left) Intelligent double-skin facade system of Terrence Donnelley Centre.
Adaptive building envelopes of multistory buildings The shallow plates of the lab floors optimize daylight entry and, based on needs of specific research requirements, allow for natural ventilation. Double-and triple-height gardens are placed at different points on the edges of the lab floors, giving suitable and precious meeting places for researchers, students and staff. Each facade is constructed differently to meet individual programmatic and climatic needs [18]. Since the south elevation undergoes more solar heating in Toronto, this is the reason that particular facade is one of the important aspects of the structure. This facade is more concerned with the thermal levels in each office which are exposed to the sun. Offices are designed with double-skin glass curtain wall, embedded in frames of aluminum mullions, which generates a good acoustic, solar, and thermal control. The air space between the outer envelope of monolithic glass and the internal layer of insulating glass is 2.5 feet (0.8 m), including perforated aluminum louvers to minimize solar heat obtained and redirect sunlight penetrating the building [18]. The outer envelope, include operable louvers at the top and bottom to ventilate
351 the cavity, while operable windows placed in the inner wall cause natural ventilation to the workplaces (Figs. 4.7 and 4.8) 4.3.1. Observations and results The natural ventilation at the Terence Donnelly Center is taking place through the double fac¸ade which is running through all 13 floors without partitions, and acting like a chimney it enhances the air circulation, cooling and natural ventilation, and this leads to decreasing cooling loads. In addition, perforated aluminum louvers attached to the facade enhance the natural lighting, the indoor environmental quality and decreasing building energy consumption [19]. 5. Conclusion – The high performance buildings nowadays have been optimized by various strategies and techniques in many aspects to reach the expected level of convenient performance. According to the building skin, it is inadequate to have perfectly insulated and airtight walls which handle with almost the climatic situations. Therefore, the necessity for a performance-based architecture is therefore increasing as: The adaptive building facade responds intellectually and accurately to the fluctuating climatic conditions and indoor conditions requirements, where it will utilize the existing natural energies to light, heat and ventilate the spaces and has the ability to achieve energy savings in comparison to conventional technologies, and meantime obtain maximum thermal comfort conditions. The photovoltaic costs could be decreased in the coming days, as the onsite power systems will be incorporated with the glass facade and those skins will develop into local, non-polluting energy suppliers to the building. To take into consideration, the future planning and designing of high-performance buildings is supposed to require active fac¸ade technologies, operating in intelligent coordination with HVAC and lighting systems to provide comfortable indoor environments with decreased energy use. – The huge difference, consequently, between terms ‘‘smart” and ‘‘intelligent” is that in the situation of the functionality results from essential material characteristics, meanwhile, in the latter performance is essentially managed by computation and automation. The performance aspect of intelligent skins is usually more changeable than that of smart envelopes; the performance of smart envelopes is commonly binary and more restricted in control, whereas intelligent skins usually need outer power to attain the targets. Accordingly, when execute to a whole building energy reductions, intelligent skins would perfectly be elaborated with smart substances, which are self-powering and self-actuating [14].
References
Fig. 4.8 (Right) Detailed section of Intelligent double-skin fac¸ade system. Source: Thun. G.; Velikov, K.2013.
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352 [3] V. Vakiloroaya, S.W. Su, Q.P. Ha, HVAC integrated control for energy saving and comfort enhancement, in: Proceedings of the 28th ISARC, Seoul, Korea, 2011, pp. 245–250. [4] F. Radwan, A. Hanafy, M. Elhelw, A. El-Sayed, Retrofitting of Existing Buildings to Achieve Better Energy-Efficiency in Commercial Building Case Study: Hospital in Egypt, Faculty of Engineering, Alexandria University, Egypt, 2016. [5] H. Sozer, Improving energy efficiency through the design of the building envelope, Build. Environ. 45 (12) (2010) 2581–2593. [6] S.B. Sadineni et al, Passive building energy savings: a review of building envelope components, Renew. Sustain. Energy Rev. 15 (2011) 3617–3631. [7] S. Medio, J. Murphy, Aesthetic Vision and Sustainability in the New York Times Building ceramic rod fac¸ade, 2008. [8] A. Aksamija, Context based design of double skin facades: climatic consideration during the design process, Perkins+Will Res. J. 1 (1) (2009) 54–69. [9] A. Aksamija, High-Performance Building Envelopes: Design Methods For Energy Efficient Facades, 2015. [10] L. Lee, S. Selkowitz, V. Bazjanac, V. Inkarokrit, C. Kohler, High-Performance Commercial Building Fac¸ades, June 2002
H.S.M. Shahin [11] H. Modin, Adaptive Building Envelopes, 2014. [12] Adaptive Building Initiative. Retrieved from http://www. adaptivebuildings.com/. [13] Al Bahar Towers Responsive Facade / Aedas. Retrieved from https://www.archdaily.com/270592/al-bahar-towers-responsivefacade-aedas. [14] G. Thun, K. Velikov, Responsive Building Envelopes: Characteristics and Evolving Paradigms, 2013. [15] Ajuntament de Barcelona, Media-Tic, With The AlmostFinished Works, Is The New Image Of Barcelona Digital, 2010 [16] R. Cook, Elbahar Tower, External Automated Shading System, 2012 [17] Al Bahar Towers, Retrieved from https://en. wikiarquitectura.com/building/al-bahar-towers/. [18] Terrence Donnelly Centre For Cellular And Biomolecular Research. Retrieved 30/8/2018 from https://www. canadianarchitect.com/features/terrence-donnelly-centre-forcellular-and-biomolecular-research/. [19] Open Concepts. Retrieved from https://www. canadianconsultingengineer.com/features/open-concepts/.