Analysis Framework 架構分析

In the original design process, five classic factors—detail/joint, material, object, structure, and construction—are categorized based on the classic theory of tectonics (Semper 1951; Botticher 1852; Sekler 1965; Frascari 1983; Gregotti 1983; Frascari 1983; Moneo 1988; Vallhonrat 1988; Frampton 1995 and Gao 2004). Other essential factors such as light, color, sound, temperature, ventilation, and material were suggested by Unwin, (2003) stressing the dialogue between architecture and the environment. In addition, Deplazes (2006) summarized four factors based on construction techniques—1) material, 2) boundary (such as transparent or translucent surface), 3) structure of tectonic (or non-tectonic), and 4) figuration. After rethinking the classic factors, Lim (2005) initiated a set of seven factors—namely: joint, detail, material, object, structure, construction and interaction (Semper 1951; Botticher 1852; Sekler 1965; Frascari 1983; Gregotti 1983; Frascari 1983; Moneo 1988; Vallhonrat 1988; Frampton 1995; Gao 2004;

Liu and Lim 2005). With the digital design process and new methods of assembly, some of the classic factors were insufficient to merge with digital ones. To meet contemporary needs, these factors were reorganized to be more effective. Gao (2004) proposed five digital factors including concept, manipulation, construction,

form, and space, with four additional factors—motion, information, generation, and fabrication—suggested by Liu and Lim (2005).

By merging the digital design manipulation technique with green thinking, the new method of design process is different from the original expression of digital architectural manipulation. According to the HOK Guidebook to

Sustainable Design (Mendler, Odell and Lazrus 2006), the new perspective of

sustainable design factors were proposed as site, water efficiency, energy, materials, and environmental quality such as acoustics. Another set of sustainable factors suggested by Chan (2007) are site specificity, connection with habitat (namely environmental interface), conservation of resources, and the use of building materials. In addition, Ali and Armstrong (2008) concluded that site context, environment, structure, materials, energy, water are the principal factors in the contemporary sustainable design.

In considering the operation of sustainable factors, this study addresses the key areas of structure, building form (envelope), electrical power, technical principles (ventilation, heating, cooling, lighting, etc.), environment (water, waste, energy, noise), site (microclimate, green space) and material (Trotter 1892;

Olgyay 1973; Hancock 1992; Fanchiotti 1995; Mak 1996). However, this analysis is not specifically concerned with purely sustainable mechanical issues, but rather addresses the new design process that integrates digital technology and sustainability.

An emerging concept of design framework was proposed by Liu in 2003.

In the design process, the design outcome could vary due to different design

media employed. Design process and design outcome could evolve differently in accordance with different design media (Schon and Wiggins, 1992; Liu 1996).

With the evolution of digital architecture, new design outcomes were affected by digital design media, which may also transform the design process (Zevi, 1981;

Liu 1996; Lim, 2003). This model still emphasizes strong interactions among Design outcome, Design media, and Design process (Figure 1). While being engaged in digital technologies and Green issues during the last decade, architects need to transform the basic design theories by integrating green elements and digital technologies (Schodek 2000; Kieran and Timberlake 2004;

Schodek et al. 2005; Sass and Oxman 2006).

Based on the development of Liu’s classic framework (Figure 3-11), the new design diagram was redefined as an analytical framework to cope with the changes of Digital-Green architecture (Figure 3-12). The diagram illustrates the engagement of new elements.

Figure 3-12. New Digital-Green Design Relationship Figure 3-11. Design Relationship (Liu, 2003)

According to the factor analysis of classical, digital, and sustainable fields, some of the factors, with further adjustment or re-definition, are still suitable in the new operation of the Digital-Green concept. Therefore, in response to the new needs of Digital-Green design thinking, fourteen factors, clustered in three categories, are applied in this research, as listed below.

(1) Design Process

1. Concept: The advanced digital media provide a diversity of design thinking

of more curvilinear form plus environmental sensitivity. The notion of geometrically free forms is made possible due to the emergence of digital computing, which combines structural technology, morphology and energy-efficiency.

2. CAD / Simulation: A process of computer modeling techniques make

possible the creation and analysis in an architecture design. With the digital application, a building’s structural system can be calculated with the automatic generating system, which offers several design operations in virtual forms. By simulating complex geometric models, the parametric approach and scripting interface ensure that the design options are considered in both complex form aesthetics and energy-efficiency purpose.

3. Detail: The joints connect materials, structure or components to the whole tectonics as a connectivity system. While “Detail” is defined as the formation of placing and making, where an architectural form is joined as a continuous surface that is regarded as the characteristics of a structural detail. Digital technologies provide possible locations for the generation of

connections via computer simulation. Some digital, structural techniques of morphology are employed to simplify the joint assembly. Details of a building’s digital skin formed by the Digital-Green materials are reinterpreted as the generator of construction skills.

4. Fabrication / Construction: A new method of construction and assembly

techniques use new technologies to explore more accurate processes of producing, fabricating, testing and assembling the digital components. The CAD/CAM fabrication technology of rapid-prototyping (RP), computer numeric control (CNC), and 3D scanning provide new methods of assembly to fabricate precise form.

(2) Design Media

1. Generation: Through manipulating different computer modeling processes, the form evolution and design concept are evaluated to help initiate architectural solutions for innovative forms and sustainable impacts. The automatic generating process generates freer forms through algorithms or computer generative systems with dynamic processes such as animation or morphing. Such comprehensive, digital application promises flexible modifications in meeting the needs for energy efficiency at every stage of the construction. The environmental factors of the site also function as the driving force of dynamic deformation.

2. Motion: Either virtually or physically, the manipulation of design concepts has been engaged in a variety of form evolutions with natural factors in

which a serial process of dynamic operation is deployed. The dynamic form change is influenced by environmental factors.

3. Structure: The structure can be interpreted as a system, a unit, or a concept influencing architecture tectonics that joins all elements of a building in unity. In light of the rapid development of digital technologies, new possibilities are explored in combining structural system with building surface or with new materiality. The multi-functional structure system is redefined through the making of stiff, curvilinear form via computer simulation with the spirit of energy-saving.

4. Material: The selection of the skin (surface of the building) controls solar gain, heat loss and/or other environmental factors. By merging the new technologies or computer analysis with sustainable materials, greater structural performance and more efficient surface materials could be developed. To enhance the composition of architectural construction, materials are not only chosen due to being lightweight and durable in strength, but also for a cost-effective construction.

(3) Design Method

1. Envelope: Provides efficient and functional structure that frees the form for

energy saving by the application of computer modeling systems. This is also the extended definition for Object as the architectural parts and perhaps also part of the architectural whole in the Digital-Green procedure.

2. Form: This is the direct result of responding to the requirements of both

digital and sustainable needs. Through the use of computer calculating

and modeling, the form transforms the fluidity of the exterior conditions to maximize ventilation, maintain view, or structural needs.

3. Energy: The use of computer modeling analysis and calculations to

manipulate environmental impacts, such as thermal, ventilation, air flow, natural light, etc.

4. Interaction: The relationship between site and people, green space and

architecture, or people and architecture is considered. Moreover, this also refers to the interaction between architecture and natural energy such as light, air, water, and green.

Chapter 4 C a s e S t u d i e s

4.1. Case 1: Swiss Re Headquarters

Completed by Norman Foster in 1999, this project is a 40-story office building with renowned aerodynamic form and sustainable design approach. The project analysis is based on the twelve Digital-Green design factors as follows.

(1) Design process

1. Concept

The concept of the sustainable system emerges from an energy-efficient structure which interacts with the surroundings. As shown in Figure 4-1, the design adopts a continuous triangulated skin and its diagonally braced structure for the energy-conscious enclosure, which allows for a column-free floor and entirely glazed façade for the open view and natural lighting.

The project attempts to generate a closer relationship between nature and the workplace through such a design concept .

Figure 4-1. Early Facade Sketches

2. CAD / Simulation

The project is designed with sensitive response to the sun paths, local climate, wind direction, ventilation and air temperatures. By using the digital technology, Dynamic Thermal Modeling (DTM), the energy performance of the building is initially calculated at the beginning of the design process and the computer generation results are used for the aspect of design. As shown in Figure 4-2, Foster achieved both energy efficiency and technological requirements in using the Catia process and dynamic techniques such as CFD (Computational Fluid Dynamics) programs, which simulate the virtual prototype for both building performance and appearance before the fabrication of such a complex form.

Figure 4-2. Wind Patterns Around the Aerodynamic Form

3. Detail

The project demonstrates a marriage of high-level techniques and energy-efficiency in a contemporary building well. Function-wise, the building is prided for high performance solar glass façade, ventilated floor plan, air flow entrance and lung-like lighting. Details such as triangular glass panels and light wells make up the entire spiral form, which is based on the logic

of geodesic structures and tubular frame towers. The triangulated glass panel detail on the spiral curtain wall resolve the loads and pressure from the walls and roofs.

Figure 4-3. Triangular Glass Panels and Light Wells

4. Fabrication / Construction

This design is a manipulating process with the aim of computer modeling analysis and calculating environmental impacts such as thermal, ventilation, air flow, natural light, etc. During the design process, the initial form development was affected by computer simulation for structure and energy analysis. The structural envelope of these metal and glass panels are pre-fabricated in the factory and fixed to the ‘Diagrid’ for assembling on the site. With the construction methodology of “Pre-cambering”, the mock-ups of the structural connections were constructed for simulating and calculating. Those are applied for testing the performance of the structure.

Figure 4-4. Swiss Re Headquarters under Construction

(2) Design Media:

1. Generation:

This project applies analysis software for a three-dimension model of environmental simulation. By using the computer modeling techniques, the design solutions, ranging from the conceptual stage to fabrication, are all digitally intertwined with sustainable factors. The shape of the building is also specified and automatically generated, based on the calculation of variables - heating and cooling systems, angle of the sun orientation, and airflow geographic location. During the preliminary scheme of the design process, FLUENT software simulates air flow conditions and calculates air pressure on the surface of the building, which helps to generate the overall design results.

Figure 4-5. FLUENT Software Simulation

2. Motion

The building, with its circular perimeter, ias generated by a radial plan with five degrees rotation of each floor for natural ventilation. This design effectively sustains energy such as sunlight or air flow and provides a helical appearance for the exterior. By responding to the constraints of the site and wind load, the building form is dynamically simulated with 3D software to decide its form of alteration, which appears to widen in the profile as it rises, and then slims towards its apex (see Figure 4-6).

Figure 4-6. The Parametric Nodes of the Tower's Computer Model

3. Structure

The perimeter ‘Diagrid’ structure is developed especially for constructing a large building with the need of structural efficiency. In order to support an unusual geometry like this project, triangular structures for supporting beams diagonally are created from structural steel. The ‘Diagrid’ steel structure with its triangular nodes helps support the outer weight of the overall structure and makes possible the glass exterior façade. With the support of advanced modeling software, the steel nodes used in the building frame are simulated and tested for the amount of deflection by the effects of building load and wind load.

Figure 4-7. The ‘Diagrid’ Steel Structure

4. Materials

To create a light-weight and column-free structure for the high-rise tower, the structural steel and the flat triangular glass panels are combined to construct the framework of the aerodynamic glass-walled building.

Therefore, two kinds of material systems, the framework of the skeleton and the surface for the building envelope, are presented as the main materials of the design. Full glazed and double-skinned façade with approximately five thousand glass panels comprise the exterior cladding system. Flat triangular and diamond-shape glass panels are also employed to fix to the ‘Diagrid’ structure. In the office areas, the glass materials are enhanced to reduce solar radiation; high-performance glass is used in the area of the light well for the same purpose.

Figure 4-8. The Flat Triangular Glass Panels

(3) Design Method

1. Envelope

The structural skin, helical and curved, functions as the curtain wall and major structure of the building. The envelope of the tower consists of double-glazed outer layers and a single-glazed inner screen, which function as a double-wall system. The shading devices are located in between the walls, which serve as a ventilation chimney for the whole building. The ventilated façade not only appears as the double-skin structure to reduce energy consumption, but also performs as blinds to intercept the solar gain from the outside.

Figure 4-9. Curtain Wall Details

2. Form

The shape of the building is created for reducing wind pressure. The external building form is determined by the direction of the wind and solar exposure in order to achieve natural ventilation and better thermal conditions. The project demonstrates how the spiraling form guides the

wind flow through the building and how energy is saved. Thanks to the dynamic simulation process with 3D software, multiple spiraling forms are created. Analysis of their efficiency is conducted by incorporating environmental factors (see Figure 4-10).

Figure 4-10. Key Parameters

3. Energy

The design employs the gaps of each floor to create natural ventilated shafts for double glazing effect, which directs warm air out of the building in summers and generates solar heating in winters to warm up the building.

The light wells on the façade pump, as the small lungs of the building, and allow daylight to shine through and serve as an energy-saving feature.

The wind pressure is driven through the interiors by the light wells, following the helical shape of the building. This feature minimizes the uses of air conditioning and ventilation systems. In response to various weather conditions, the double-skin façade makes the best use of heating and cooling systems and reduces the energy consumption. As Figure 4-11 shows, the radiating fingers of each floor create the atria space that

distribute fresh air as it spirals up vertically through the building and function as the building’s ‘lungs’.

Figure 4-11. The Parametric Computer Model

4. Interaction

The column-free building is resolved by the triangulated load-bearing glass on the façade, which unfolds views from the outside. Therefore, the spiral form of the project provides inside viewers with a 360-degree interaction, corresponding to outside surroundings. The building also allows a closer interaction with the natural air and sunlight flow through the light wells on the skin of the building façade.

(a) (b)

Figure 4-12. (a) Tepee-style Entrance (b) View of London from an Atrium Balcony

4.2. Case 2: Chesa Futura

The Chesa Futura is an apartment building designed by Norman Foster in 2004.

In order to design an environmentally sensitive building to reflect the natural site, the apartment on the edge of a slope emerges as a result of both advanced computer design tools and Swiss traditional construction techniques. The project analysis is based on the twelve Digital-Green design factors as follows.

(1) Design process

1. Concept

The building design is conceived via merging advanced computational technology and the ecological design of Swiss traditional fashion. In the process of exploration, the design approaches engage in computer modeling techniques and 3D model generation, where the geometrical shape/ structure, severe local weather conditions and sustainable factors are taken into consideration for tackling the challenges.

Figure 4-13. Early Facade Sketches

2. CAD / Simulation

The building form is automatically generated based on the calculation of variables -- heating and cooling systems, angle of the sun orientation, and airflow in its geographic location. At an early stage of the design process, the application of CAD software is aimed for one of the surfacing techniques - constructing the curvature. The use of Boolean subtractions helps perforate the shell-shape wall (Figure 4-14) and the logic of radial geometry provides smooth transitions to parametric relations.

Figure 4-14. The Parametric Computer Models

3. Detail

The study of the curved form is engaged in mechanical, structural and environmental analyses, in which the windows are altered to wrap around the curved façade. These chamfered windows are aimed to maximize light penetration in the internal space, which represents traditional Swiss local building technique. In the project, the Swiss traditional, velux-like, doubled-glazed windows are reinterpreted with advanced computer technology, through which panoramic views of the surroundings are

allowed and sustainable efficiency is promised, to ease the extreme weather conditions.

Figure 4-15. Doubled-glazed Windows

4. Fabrication / Construction

The advanced CAD/CAM machine of the Computational LIGNAMATIC CNC timber processing has an array of twenty tools at any angle (cut, drill, rout, bore…etc.) which allow the designer to shape a piece of laminated timber into every curvature for any unusually-shaped wooden structures (Figure 4-16). By producing the coursing lines as flat patterns, the model maker cut the timber shingles by CNC machine, and they are assembled by hand.

          

Figure 4-16. The Computational LIGNAMATIC CNC Timber Processing Machine

(2) Design Media

1. Generation

The project demonstrates the digital possibilities of cantilever structure -computer-based structural analysis modeling, innovative engineering with traditional technique, and ecological materials. By using computational, fluid dynamics analysis of ventilation and air flow pressure, the digital simulations are applied to observe individual curvatures to ensure the greatest energy efficiency.

     

Figure 4-17. Parametric Computer Models

 

2. Motion

Learning from an enduring tradition of Swiss mountain homes, the architect elevates the apartment off the ground to eleven-and-a-half feet high by eight steel piloti. The architects use 3D modeling and computer calculation to simulate the dynamic lifting of the building. The digital analysis helps test the structural stiffness during the process of automatic generation. The elevated height would keep the wooden shell from being rotted and damaged by the moisture in winter - a common situation caused by long-term exposure.

 

Figure 4-18. View of Steel Piloti

3. Structure

Though the construction site is located on the edge of a slope, the efficient superstructure is secured by the steel structural elements and two circular concrete cores (Figure 4-19). These two cores consist of an inner core for elevators and an outer core for spiralling staircase, which creates a vertical access and provides stability from the light-weight timber superstructure. The load-bearing structure of the cross-beams is supported by eight steel piloti and the outer shell perimeter of the project is protected by the edge beams. In addition, the prefabricated timber floor plates reduce the weight and allow an easier lift from the ground and simultaneously offer an integrated thermal wall to save the energy.

 

Figure 4-19. The Structural Elements

4. Material

The application of the larch shingles is chosen as a durable local resource and thermally efficient material for covering the curving surface of the

The application of the larch shingles is chosen as a durable local resource and thermally efficient material for covering the curving surface of the

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