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Solar exoskeletons – An integrated building system combining solar gain control with structural efficiency

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Abstract

We propose the use of solar exoskeletons, an integrated building system that combines material efficiency in structural load transfer with passive solar gain control. This offers an impactful way to respond to the UN climate goals, as the architecture and engineering disciplines face the challenge of delivering low carbon buildings. While reducing operational and embodied emissions is often considered independently, we can show how approaching them in tandem, through a novel building system, can offer significant savings. With large spans for maximum spatial flexibility and full glazing maximizing daylight, high-rise buildings are often suboptimal in terms of their material usage from steel frame construction and cooling demand from uncontrolled solar gains. We view solar exoskeletons as a sustainable pathway for future high-rise structures – combining solar gain control through external shading with a highly efficient structural system optimized for lateral loads in tall buildings. We present an automated workflow that combines parametric modeling of architectural elements and structural simulation with Radiance-based annual radiation simulations and an operational energy model in EnergyPlus. Evaluating embodied carbon and energy use intensity of midrise and tower buildings in timber and steel, we compare hundreds of iterations for a prototypical building in Phoenix, USA. Our results show that exoskeletons can lead to embodied and operational carbon reductions in the lateral load-resisting structural system of 37–80% and 24–48%, respectively, vis-à-vis conventional construction techniques. Adding photovoltaic modules to the external shading system can lead to net zero building solutions for the buildings investigated in this case study.

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... [12,13]), and decision-making models (e.g. [14,15]). Further literature [16][17][18] provides a comprehensive view on the assessment of key variables in diagrid structures, also in the nonlinear regime. ...
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This project is an attempt to integrate and evaluate the formal and ornamental desires of contemporary architecture with the pressing need to create designs that optimize energy and daylight performance. With increased sophistication of digital tools to assess daylight and energy in buildings, a great potential exists to optimize the performance of contemporary building façades. While pre-modern and modernist architecture have often employed light shelves, overhangs, and other passive shading techniques, such forms are not easily applied to highly articulated forms of contemporary architecture. This research study proposes a process for applying daylighting and energy analysis software to optimize the performance of a sun-shading screen based on Sculptor Erwin Hauer's design. Through an iterative analysis of the south facing screen, daylight and energy performance of an interior test space is optimized through parametrically manipulating the opening size and module depth of the screen. Results are then compared to baseline spaces with 30% and 100% Window-to-Wall ratios (WWR) to understand the screen's relative performance gains. This analysis shows that the optimized screen manages to reduce annual energy use by 35 percent and 42 percent vis-à-vis the two baseline cases.
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The topic of this paper is optimized shading and lighting systems which consist of planar fins arranged along the edges of a quad-dominant base mesh, that mesh itself covering a reference surface. Such an arrangement can be observed e.g. in the Kogod courtyard roof designed by Foster + Partners for the National Portrait Gallery in Washington DC (Fig. 1): A reference surface consisting of three vaults with curved valleys in between is panelized by a quad mesh whose faces are not planar; planar glass panels are mounted on a grid of quadrilateral fins which follow the edges of the quad mesh. In our paper we consider structures of exactly that type, whose geometry is hierarchically set up as follows: • The first element in the hierarchy is the reference surface, which may be any freeform shape. • Secondly, the reference surface is panelized by a quad-dominant mesh, which is referred to as the base mesh. • Thirdly, planar fins are arranged along the edges of the base mesh such that in each vertex the planes of fins nicely intersect in a common node axis.
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This paper reviews the existing European and UK standards, methodologies, databases and software tools for the estimation of embodied energy and carbon of buildings.While there is currently no legislation requiring the calculation of embodied energy in buildings, voluntary standards are being developed by the European Committee for Standardisation Technical Committee 350 (CEN/TC 350). Based on BS EN ISO 14040 and BS EN ISO 14044, these define a four stage process-based life cycle assessment method to calculate the embodied energy in construction, with a compulsory ‘product’ stage and optional further stages for ‘construction’, ‘use’ and ‘end of life’. A further voluntary specification for the assessment of the life-cycle greenhouse gas emissions of goods and services, PAS2050, was introduced in the UK in 2008. It too uses a process-based assessment the environmental impact of a building calculated through this method can therefore be seen as the sum of the environmental impacts of the products and processes that have created the building.Other Life Cycle Assessment methodologies have been developed in this area, including input-output (I-O) and hybrids of process and input-output. The environmental impact of a building defined by an input-output based assessment in contrast to that by a process-based method, is seen as a proportion of the total impacts of the different economic sectors which have created the building. The I-O approach therefore inherently assigns responsibility for environmental impacts to a particular industrial sector. Process-based methods are more specific to the construction product, and more accurate within the limited boundaries used. However they omit the supporting services necessary for construction, including finance, insurance, government and organisational administration and all related office buildings. While I-O assessment overcomes the problems with process assessment by considering a complete system boundary, the assumptions of homogeneity and proportionality in particular limit its use for comparison of impacts from individual products. For the purposes of designing a low embodied energy building, the I-O approach is too broad-brushed and generic to be helpful. The hybrid approaches attempt to overcome the limitations of both the process and the I-O methods.There is some existing embodied carbon and embodied energy data. However, due to the lack of current regulations and the inherent complexity and diversity of the area, the available data are varied in scope and application. There are three main sources of data:1. There are several databases which include embodied energy and carbon of standard building materials and components. Some of these are construction sector-specific, while others contain more general product data. These provide data for the ‘cradle to factory gate’ phase of the embodied energy. Manufacturers are also starting to develop their own Environmental Product Declarations (EPDs) which include this data, and several of these are publicly available.2. Both commercial and in-house software tools have been developed to calculate whole life-cycle embodied energy for buildings and infrastructure projects. This is known as ‘cradle to grave’ assessment.3. Detailed life cycle assessments of specific buildings, including housing developments and individual dwellings, have also been carried out by academic researchers.A review of the research literature shows a wide range for the calculated embodied energy. This range in reported figures is due to the use of diverse product data arrived at through different LCA methodologies, different boundaries and often for specific manufacturers, which are therefore non-comparable; different calculation methodologies for the LCA of the whole building; and different building construction and designs. Perhaps most crucially, in spite of the likelihood of an underestimation by current analysis methods, the results show that embodied energy and carbon of buildings can be a very significant absolute value, as well as an increasingly high proportion of the whole life energy and carbon.The existing databases and much of the literature provide data for the product stage (stage 1) of the process – that is for the embodied energy and carbon in the building materials. However there is less, very limited, data available for composite components such as windows, for services components and for innovative materials and products. There is also a particular shortage of data across the construction sector in the energy used and carbon emitted during transport to site (part of stage 1 in prEN 15804), stages 2 (construction), 3 (in use) and 4 (end of life). The commercial and in-house analysis tools also vary in the databases they use, in their LCA methods and in the boundaries assumed in analysis.Taking each of the missing calculations in turn, the calculation of the reduced impacts of transport to site of local construction materials will inform and support the European standard BS EN 15643 parts 3 and 4, which considers the social and economic sustainability of construction works.Some construction projects last for several years and have hundreds of workers on site carrying out energy intensive activities. The accurate prediction of energy use and carbon emissions during standard site operations for stage 2 of the life cycle is therefore a fundamental part of the calculation for whole life embodied energy. Separately the development of off-site construction systems has been heralded as a ‘sustainable’ solution; this can only be verified with the development of an accurate ‘carbon costing’ method for both on-site and off-site construction activities, enabling the accurate comparison of different techniques and materials. Furthermore there is a lack of general data on the carbon and energy savings to be made by site management operations such as reuse of subgrade rather than the import of new materials.While ongoing maintenance and repair can be considered as part of the operational energy requirements, as suggested by the Strategic Forum for Construction (SFfC) [15], the impacts of major retrofit and refurbishment works form part of stage 3 of the whole life embodied impacts of a building. A clear understanding of the service life of individual components is necessary for these to be calculated.Finally there is limited data on the energy used by demolition, reuse and recycling processes at the end of life of a building. While these may be less important for building types with a long expected lifetime such as UK housing, it is a key element of short expected lifespans such as stadia, where design approaches are often required to consider deconstruction and reuse of components.In conclusion, it is essential to measure the whole life embodied energy and carbon of buildings, as well as their operational energy and carbon emissions. The comprehensive development of a robust methodology, and a deeper understanding of its limitations, is a necessary prerequisite for this. Various initiatives to develop and collate data and tools and make them freely available are still in their infancy, and these should be encouraged by the construction industry. It is hoped that the forthcoming standardisation of EPDs should ensure that all manufacturers produce equivalent information for their products within a few years. However the diversity of products used within construction will mean that the LCA of individual buildings will remain complex.This review will guide the future development of a consistent and transparent database and software tool to calculate the embodied energy and carbon of buildings within the specific context of the UK. The research is being carried out as part of a project led by BLP Insurance, and with the support of the Technology Strategy Board and the Engineering and Physical Sciences Research Council (EPSRC).In the Climate Change Act of 2008 the UK Government pledged to reduce carbon emissions by 80% by 2050. As one step towards this, regulations are being introduced requiring all new buildings to be ‘zero carbon’ by 2019. These are defined as buildings which emit net zero carbon during their operational lifetime. However, in order to meet the 80% target it is necessary to reduce the carbon emitted during the whole life-cycle of buildings, including that emitted during the processes of construction. These elements make up the ‘embodied carbon’ of the building. While there are no regulations yet in place to restrict embodied carbon, a number of different approaches have been made. There are several existing databases of embodied carbon and embodied energy. Most provide data for the material extraction and manufacturing only, the ‘cradle to factory gate’ phase. In addition to the databases, various software tools have been developed to calculate embodied energy and carbon of individual buildings. A third source of data comes from the research literature, in which individual life cycle analyses of buildings are reported. This paper provides a comprehensive review, comparing and assessing data sources, boundaries and methodologies. The paper concludes that the wide variations in these aspects produce incomparable results. It highlights the areas where existing data is reliable, and where new data and more precise methods are needed. This comprehensive review will guide the future development of a consistent and transparent database and software tool to calculate the embodied energy and carbon of buildings.
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As a large energy-consuming part of the envelope, windows and shading system play a significant role in building savings. Once established in the primary design stage, it is difficult to make changes later, especially for high-rise buildings with large areas of glass. Moreover, strongly influenced by solar radiation, the configuration of windows and shading system conflicts with each other in terms of energy consumption and indoor comfort, the optimal configuration of windows and shading system under different climatic regions has not been well solved at yet. This paper proposes an easy-operation, useful, and efficient multi-objective optimization method, using a smart optimization algorithm NSGA-II in combination with DesignBuilder energy simulation software, especially beneficial for non-programming designers. In this research, a typical high-rise office building with a large area window has been selected as a case study. Building orientation, the configuration of windows and shading system, including materials for each layer of the double-layer window, installation angle and depth of overhangs have been taken into consideration, aiming to minimize the heating, cooling, lighting energy consumption and discomfort hours, and to find the mutual relationship between each other. A set of Pareto solutions can be obtained after optimization, and the most recommended variable parameters of windows and shading system in four cities representing severe cold climate, cold climate, hot summer and cold winter climate, and hot summer and warm winter climate can be identified, respectively. Besides, Pareto optimal solutions can give designers different scheme choices based on preferences, which are of great significance to provide guidance and suggestion for designers in the early design of buildings.
Book
This report explores the critical role buildings can play in meeting climate change ambitions, using a portfolio of clean energy solutions that exist today. It considers the investment needs and strategies to enable the buildings sector transition, and the multiple benefits that transformation would deliver, including improving the quality and affordability of energy services in buildings for billions of people. Importantly, it sets out what policy makers can do to overcome the economic and non-economic barriers to accelerate investment in low-carbon, energy-efficient solutions in the buildings sector. This ranges from traditional, yet highly effective policy tools to ambitious, innovative market-based approaches that can increase the speed and scale of investment for a sustainable buildings sector. This is the third report in a series. In 2017, the International Energy Agency (IEA) explored how a very ambitious and rapid energy transition to address climate change might look, in support of the German presidency of the G20. In 2018, the IEA provided further insights into the fundamentally important role of energy efficiency to achieve that energy transition.
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Statistical models can be used as surrogates of detailed simulation models. Their key advantage is that they are evaluated at low computational cost which can remove computational barriers in building performance simulation. This comprehensive review discusses significant publications in sustainable building design research where surrogate modelling was applied. First, we familiarize the reader with the field and begin by explaining the use of surrogate modelling for building design with regard to applications in the conceptual design stage, for sensitivity and uncertainty analysis, and for building design optimisation. This is complemented with practical instructions on the steps required to derive a surrogate model. Next, publications in the field are discussed and significant methodological findings highlighted. We have aggregated 57 studies in a comprehensive table with details on objective, sampling strategy and surrogate model type. Based on the literature major research trends are extracted and useful practical aspects outlined. As surrogate modelling may contribute to many sustainable building design problems, this review summarizes and aggregates past successes, and serves as practical guide to make surrogate modelling accessible for future researchers.
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The emerging of building information modelling provides opportunities to break through the limitations of conventional building energy modelling such as tedious model preparation, model inconsistency and costly implementation, and promotes building energy modelling into the digital building design process. The method of using building information modelling for the building energy modelling process, named building information modelling-based building energy modelling has become a prevalent and attractive topic in both the research and the industry society in recent years. This paper presents an overall review on the building design process, and applications of building information modelling and building energy modelling in the design process. It also provides an in-depth review on the development of building information modelling-based building energy modelling methods and the development of prevalent informational infrastructures. Meanwhile, this literature review provides a special consideration on the maturity of building data transformation between building information modelling and building energy modelling for building energy simulation process, from the step 1 identifying the geometry, thermal properties of buildings to the step 6 the information and components for HVAC systems. In general, the current building information modelling-based building energy modelling methods are thoroughly evaluated and the trends for future developments are outlined. It is realised that the Building Information Modelling based Building Energy Modelling is particular appropriate for the early design stage, where the most suitable and cost effective approaches for energy efficient design can be integrated into the overall building design process.
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During the recent decades it has become common to enclose large buildings with lightweight, weathertight walls that hang, like curtains, from the floor edges. The frames of these curtain walls are, usually, extruded aluminium – a material whose production is highly energy-intensive. Although means of enhancing the thermal performance of building envelopes have been scrutinized, comparatively little attention has been given to the cost and embodied energy savings that can be achieved through efficient structural design. No guidelines for efficient use of aluminium in a curtain wall have been published, and architects therefore have not known the impact that their decisions have upon the facade's material content. In this study more than 1000 unique curtain wall systems have been optimized numerically, each one to a different set of design criteria, and the results show the extent to which aluminium content is influenced by floor height, locations of supports, number of horizontal members per panel, width of the extrusions, spacing between mullions, design wind pressure, and the minimum allowable thickness of aluminium. The conditions in which the amount of metal required to construct a window wall (glazing spanning between two floors) might be less than that required for a curtain wall (an uninterrupted, multi-floor shroud), also have been explored. The results show that substantial metal savings – reductions of 40% or more – can be realized by making modest changes to the layout geometries and specifications that are in common use. The value of the corresponding construction cost reductions is significant: in the worldwide construction market, the potential savings are in billions of dollars per year. The practical steps that an architect and specifier should take in order to reduce metal content in a curtain wall are set out in a list. These savings are separate from, and in addition to, any that might be attained by optimizing the cross-sectional shapes of extrusion profiles. Unlike improvements in a facade's thermal performance, which usually require capital investment in insulating materials for returns that accrue over decades, material-efficient design methods are free to apply, and the benefits can be enjoyed immediately.
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Unlike vertical columns of traditional structure, diagrid structural systems for tall buildings have special inclined columns. Due to the inclined columns, a diagrid structural system for tall buildings produces axial force along the column direction under horizontal load, which has the advantage of resisting horizontal wind load and seismic load and gives more freedom to architectural design, so a diagrid structural system for tall buildings becomes an effective new structure style for tall and super-tall buildings. Theories and tests regarding the diagrid structural system for tall buildings have been intensely researched since the exterior tube of diagrid structural system for tall buildings was first proposed by Torroja in his seminal book. At present, studies for mechanical characteristics, joint form, theories, and tests have been systematized. This paper systematically summarizes existing research achievements of the diagrid structural system for tall buildings and confirms that the structure has larger lateral stiffness and good seismic performance. Based on the favourable performance of concrete-filled steel tubes, this paper advises the use of concrete-filled steel tube columns as the columns in diagrid structural systems for tall buildings.
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The building sector accounts for one third of the global greenhouse gas emissions, of which a substantial amount is embodied carbon from construction material production. While previous studies concentrated on analyzing the carbon emissions of low-rise buildings, they have overlooked high-rise buildings, which also have large impacts on the carbon emissions of a city. Moreover, high-rise buildings use different construction materials and structural forms, resulting in large variability in their embodied carbon estimates. Therefore, this study aims to evaluate the relationships between different design parameters and the embodied carbon in high-rise buildings. The results serve as a basis for making more environmentally-sustainable decisions when designing high-rise buildings in order to reduce the carbon emissions from the building sector. Different high-rise buildings are designed by varying the construction materials (namely reinforced concrete, structural steel and composite materials), recycled contents (steel scrap and cement substitutes), structural forms (i.e., core-frame, core-outrigger, tube-in-tube and mega-brace) and building heights. The embodied carbon values are evaluated and compared, by considering the carbon emissions from material manufacture and transportation. Given the same structural form and building height, steel buildings have 50–60% less total weight, but 25–30% more embodied carbon than composite and reinforced concrete buildings. If 80% of the steel used in buildings is recycled, the embodied carbon in steel buildings is reduced by around 60% and becomes the least among all buildings. The embodied carbon per floor area against building height follows a concave upward trend, indicating that each structural form has a suggested height range where embodied carbon is minimum. When the building height exceeds the suggested height range, the structural efficiency of the building decreases with considerable growths in material demand and embodied carbon.
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This paper examines several existing methods of static shading device design, and presents a new approach called SHADERADE. The approach is implemented as an eponymous tool based on Rhinoceros® and EnergyPlus, and offers flexible, novel techniques for assessing the thermal desirability of solar transmittance through any potential shading volume or surface. Using simulated sidelit offices located in Anchorage, Boston and Phoenix, it is shown that SHADERADE is able to consistently generate shading systems with improved thermal performance vis-à-vis existing methods. It is also shown that the approach can handle curved geometries with ease, and can effeciently manage the sizing of shading devices by identifying regions that matter most. The authors hope that these capacities will facilitate a more effective, less prescriptive approach to shading design.
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The majority of decisions in the building design process are taken in the early design stage. This delicate phase presents the greatest opportunity to obtain high performance buildings, but pertinent performance information is needed for designers to be able to deal with multidisciplinary and contrasting objectives. In the present work, an integrative approach for the early stages of building design is proposed to obtain detailed information on energy efficient envelope configurations. By means of genetic algorithms, a multi-objective search was performed with the aim of minimising the energy need for heating, cooling and lighting of a case study. The investigation was carried out for an open space office building by varying number, position, shape and type of windows and the thickness of the masonry walls. The search was performed through an implementation of the NSGA-II algorithm, which was made capable of exchanging information with the EnergyPlus building energy simulation tool. The analyses were conducted both in absence and in presence of an urban context in the climates of Palermo, Torino, Frankfurt and Oslo. In addition, a preliminary analysis on the Pareto front solutions was performed to investigate the statistical variation of the values assumed by the input variables in all the non-dominated solutions. For the analysed case study, results highlighted a small overall Window-to-Wall Ratio (WWR) of the building in all locations. Pareto front solutions were characterised by low WWR values especially in east, west and north exposed façades. The area of the south facing windows was higher compared to the other orientations and characterised by a higher variability.
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This paper deals with the environmental resources consumed to construct tall building structures; the consumption is measured by the energy required to obtain tall building structures and is expressed in terms of cradle-to-gate embodied energy. A reference structure composed of central core (made of reinforced concrete) and rigid frames (made of either reinforced concrete or steel) is considered. The reference structure is dimensioned and detailed for buildings from 20 to 70 stories; the embodied energy of each building is then estimated (total, of the components, per net rentable area). The results show that, if some design decisions are dictated by the embodied energy, the premium for height of the embodied energy is not substantial, which proves that tall building structures can be sustainable. However, a structure with the lowest weight does not imply the lowest embodied energy. The results also prove that the embodied energy depends mainly on the flooring system, and that steel consumes more embodied energy than Reinforced Concrete. Ultimately, the embodied energy is confirmed to be a viable tool to design sustainable tall buildings, and the results presented herein may address design toward minimizing the embodied energy, which means to save environmental resources.
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This paper presents a comprehensive review of all significant research applying computational optimisation to sustainable building design problems. A summary of common heuristic optimisation algorithms is given, covering direct search, evolutionary methods and other bio-inspired algorithms. The main summary table covers 74 works that focus on the application of these methods to different fields of sustainable building design. Key fields are reviewed in detail: envelope design, including constructions and form; configuration and control of building systems; renewable energy generation; and holistic optimisations of several areas simultaneously, with particular focus on residential and retrofit. Improvements to the way optimisation is applied are also covered, including platforms and frameworks, algorithmic comparisons and developments, use of meta-models and incorporation of uncertainty. Trends, including the rise of multi-objective optimisation, are analysed graphically. Likely future developments are discussed.
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An increasing number of architectural design practices harness the power of parametric design tools. The aim of these tools is to facilitate and control complex building geometries. Parametric design programs such as Grasshopper (GH) for Rhino or Generative Components popularized this approach by providing easy-to-use visual programming environments that integrate with computer-aided design (CAD) packages. A logical next step consists in connecting parametric designs to applications that evaluate non-geometric aspects such as building physics or structural performance. This brings about new opportunities of collaboration between architects and engineers in the early stages of building design. The ease of testing alternatives by tweaking a set of parameters also opens the door for the application of generic optimization algorithms. Karamba is a finite element program geared towards interactive use in the parametric design environment GH. Being a GH plug-in, it seamlessly integrates with the diverse habitat of other third party programs available for GH. These range from building physics applications to genetic optimization engines. In the author's company, Karamba is used in early-stage design, form-finding, and structural optimization. “White Noise”, a mobile exhibition pavilion for the Salzburg Biennale, serves as a case study that shows how Karamba can be used to optimize the structural performance of intricate building geometries.
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The performance-oriented design of large roof structures for semi-outdoor spaces is investigated with the aim to integrate performance evaluations in the early stages of the design process. In particular, daylight and thermal comfort are improved under large structures by exploring passive solar strategies that reduce the need for imported energy. The performance oriented, parametric design approach we developed is structured in two parts. One part uses parametric geometry to generate design alternatives, and the other part uses performance based exploration and evaluation of alternatives. We discuss how the performance based exploration is accomplished using a tool called ParaGen. The potential of the method is shown in a case study of the SolSt roof. The design process of SolSt is based on parametric variations of its curvature, the density of its modules and the geometry of its cladding, and is explored based on daylight and solar exposure of the covered space.
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Computer modeling and simulation has a relatively long history in the prediction of thermal and lighting performance in buildings. As the input requirements of such analysis are quite extensive, these areas tend to be addressed computationally only in the latter stages of the design process, usually as a validation of decisions already made. However a detailed computation of incident solar radiation requires much less detailed input and has many applications much earlier in the process. Of significant importance is its potential as a tool to drive design decision-making and as a form generator in its own right. This paper demonstrates how solar position calculations can be used to automatically generate quite complex optimised shading devices and quickly determine the solar envelope of developments given even the most stringent of overshadowing restrictions. The limitations of the precise geometric calculation of shading shape are discussed and an alternate approach to handling more complex situations using ray-tracing techniques is presented. These methodologies have been integrated into an interactive conceptual design tool called ECOTECT (http://www.ecotect.com).
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Purpose The importance of adaptability in office buildings has increased during the past years, mostly due to factors like rapid change, both in private and public organisations, new and innovative work place design and growing environmental concerns about building redundancy. Design/methodology/approach The research design of the study presented here is a comparative case study, where recently built office buildings by 11. Norwegian real estate developers are assessed with regard to 16 different adaptability measures. Findings The study shows that office buildings built by owner‐occupiers are more adaptable than office buildings built by the group who develop property for renting and management, and considerably more than the office buildings built by the group who develop property for sale to investors. A short‐term perspective on property investment, i.e. that of the group who develop property for sale to investors, does not favour adaptability concerns. A long‐term perspective as well as a use‐value perspective on property investment, i.e. that of the owner‐occupier stakeholder group, on the other hand, do favour adaptability in office buildings. Research limitations/implications Whether this research can help making buildings more adaptable, depends on whether the real estate customers, i.e. the users, they who pay for using the office building, understand the value of adaptability and are willing to pay the extra cost of adaptability. The building professions, including the real estate developers, claim that they know how to make office buildings adaptable. Originality/value The value of this paper may lie in demonstrating that this knowledge is not used in practice.
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In the present paper a genetic optimization (GO) has been carried out on an office room with a south facing window in order to design an optimal fixed shading device. Two different glazing systems have been taken into account, one standard double glass and an high performance glazing system specifically designed to prevent high sun loads. The shading device is a flat panel positioned parallel to the window and inclined by its horizontal axis. The device shades the window from direct sun penetration reducing the cooling loads in summer, but also affecting daylight and heat loads in winter limiting the sun gains, therefore the impact on the overall building energy consumption is investigated. A genetic optimization has been performed for identifying a possible geometry with the lower energy impact. Lighting loads, computed by the DAYSIM code, have been considered as inputs for the code ESP-r which drives the energy computation. The results demonstrate that electrical energy absorbed by the lighting system has to be always taken into account in designing energy efficient shading devices.
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Diagrid structural systems are emerging as structurally efficient as well as architecturally significant assemblies for tall buildings. This paper presents a simple methodology for determining preliminary member sizes. The methodology is applied to a set of building heights ranging from 20 to 60 stories, and parameters for the optimal values of the grid geometry are generated for representative design loadings. These values are shown to be useful for architects and engineers as guidelines for preliminary design. Associated architectural and constructability issues of diagrid structures are also discussed here. Copyright © 2007 John Wiley & Sons, Ltd.
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