Multi-spatial environmental performance evaluation towards integrated urban design: A procedural approach with computational simulations

Accepted Manuscript Multi-spatial environmental performance evaluation towards integrated urban design: A procedural approach with computational simulations Ali Cheshmehzangi PII:

S0959-6526(16)31315-4

DOI:

10.1016/j.jclepro.2016.08.151

Reference:

JCLP 7943

To appear in:

Journal of Cleaner Production

Received Date: 24 November 2015 Revised Date:

25 August 2016

Accepted Date: 29 August 2016

Please cite this article as: Cheshmehzangi A, Multi-spatial environmental performance evaluation towards integrated urban design: A procedural approach with computational simulations, Journal of Cleaner Production (2016), doi: 10.1016/j.jclepro.2016.08.151. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT

Multi-spatial Environmental Performance Evaluation towards Integrated Urban Design: A procedural approach with

RI PT

Computational Simulations Abstract

Urban environments are significantly important in the process of design thinking for the

SC

sectors of urban design and planning. This is often neglected or weakened in the process of [urban] design development. In this respect, we can argue in favour of integrated urban

M AN U

design which can be achieved in various ways; one of which is the use of computational tools in simulating and modelling the urban environments for the process of design development. In this study, the application of Computational Fluid Dynamics (CFD) in simulation of urban environments is examined at various scales and stages of the urban design process. A UK

TE D

case study is presented to analyse the procedure in which CFD can play an influential role to inform design. Furthermore, the study examines the practical application of CFD for

EP

integrated urban design and landscape design at micro and meso scales. Finally, this research study aims to provide a procedural model for the use of CFD tools in the process of

AC C

design development.

Key Words: Environmental Performance Evaluation; Computational Fluid Dynamics (CFD); Integrated Urban Design; Urban Environment.

1

ACCEPTED MANUSCRIPT Introduction Integrated urban design is a fundamental design method in defining comprehensive approach to contemporary urban planning and design and has been discussed briefly. So far,

RI PT

less research is undertaken in the field of integrated urban design but many examples prove application of the method in practice. The concept of integrated urban design embraces multi-layers and multi-dimensions of designing the built environment. The complex urban

SC

environment requires incorporating interlocking factors of environmental, social, economic and cultural. Although essential to the process of design, this incorporation often does not

M AN U

happen equally between the four main factors; however, possibilities of integrating them together will encourage achieving more sustainable design. Integrated urban design is also considered as part of an overall urban Sustainable Development Goal (SDG) (Jain, 2014), which through a process will develop certain indicators for better evaluation and

TE D

development of the built environment. Therefore, we can argue that the main objective of an integrated urban design is the recognition and corroboration of all imposed demands and including them in to one process of design thinking. This is significant in the sector of urban

EP

planning and design, where the simulation of urban environments can holistically inform

AC C

design thinking process at various scales. Furthermore, integrated urban design can be regarded as a modelling approach or system enabling possibilities to enhance quality of design through simulation, prediction and optimisation. As such, we have witnessed that in the last two decades, computational tools have developed significantly in integrated modelling of buildings (Galle, 1995), towards integrated planning (Chakrabarty, 2007), city information modelling or CIM (Gil et al, 2013) and formalisation of detailed city modelling (Biljecki et al, 2014). As part of many examples

2

ACCEPTED MANUSCRIPT undertaken in the field of the built environment, the application of Computational Fluid Dynamics (CFD) has proven to be an efficient and effective approach under the validation by experimental data or following the major requirements by CFD guidelines (Tominaga et al, 2008; Di Sabatino et al, 2011) and towards achieving integrated design solutions. Although

RI PT

CFD was introduced as a modelling technique to environmental design (Mochida et al, 2002; Shirasawa et al, 2003; Yoshie et al, 2005), its application in urban design and landscape planning was later recognised as an integrated modeling approach (Cheshmehzangi et al,

SC

2010; Chung and Choo, 2011). Nowadays, this approach is widely applied in practice, and

M AN U

enables landscape designer, planners and urban designers to develop multiple design options for a single project. Nonetheless, little is understood about potentials and limitations of this approach in design. This approach should not be used merely as a simulation method but rather as a design thinking process for enhancement of quality in urban design. In this

TE D

paper, these factors are discussed as part of identifying integrated thinking to urban planning, design and landscape design at various scales. As a result, in this study we argue for the use of CFD tools more than just a simple method in

EP

design, but rather as an integrated process for design application and design development.

AC C

This process needs to include various aspects and scales of urban design and landscape planning. In light of this, this research study explores the following two questions: 1- How the application of Computational Fluid Dynamics (CFD) simulation tools can lead towards a design thinking method for planners, urban landscape specialists and designers? 2- To what extend and what scales can CFD tools help us achieve an integrated urban design solutions?

3

ACCEPTED MANUSCRIPT By taking forward the argument on integrated urban design, this study evaluates the application of CFD tools at various scales of urban design and landscape planning and explores the application of such approach in practice. Previously, CFD was discussed and used as an environmental research tool and later as a design tool for the purpose of planning

RI PT

and design (Mukarami, 2006). In this paper, the aim is not only to introduce CFD in integrated urban design but is also to discuss its effectiveness as part of a design thinking process. The author aims to initiate a debate on the use of such techniques in supporting,

SC

and not completely designing, the contemporary built environment. This needs to be

M AN U

understood, modelled and applied through the integrated evaluation of urban environments to inform design thinking process. The availability of such techniques, software and tools should facilitate planners, urban landscape specialists and designers to think comprehensively and apply them effectually in order to promote integrated design solutions.

TE D

1. Integration of Computational Fluid Dynamics (CFD) in Design CFD is an effective tool for simulation and calculation of part of the environmental

EP

performance in the built environment. However, its effectiveness should not only be limited to environmental performance analysis, but rather as an analytical tool for assessing the

AC C

urban environments, particularly if existing and subject to change. In most developed contexts, the most significant change is often on landscapes and city environments (rather than on buildings) and their significance of change is often not mentioned as much; but yet seen and experienced drastically. So far, as reviewed by the literature (Li et al., 2006; Fernando et al., 2010; Blocken, 2015 ), CFD studies of the urban environments are aimed to evaluate the general wind analysis of the environments (Murakami et al, 1999; Mochida and Lun, 2008; Cheshmehzangi et al, 4

ACCEPTED MANUSCRIPT 2010; Schatzmann and Leitl, 2011; Blocken et al, 2012; Shi et al, 2015), thermal comfort (Soligo

et

al.,

1998;

Tanabe

et

al,

2002;

Vanos

et

al,

2010;

Szücs, 2013) and urban thermal environment (ReYang and Li, 2015), urban pollutant exposure evaluation (Ng and Chau, 2014), simulation of generic urban configurations

RI PT

(Ramponi et al, 2015) prediction of urban heat island circulation (Wang and Li, 2016) and urban microclimate (Toparlar et al, 2015), city ventilation and pollutant dispersion (Bady et al., 2008; Ng, 2009; Casrissimo et al, 2011; Wong et al, 2011; Hang et al., 2012; Amorim et al,

SC

2013; Blocken et al, 2013) and their implications for bioclimatic urban planning and design.

M AN U

These are often used as prediction models, or/and coupled with numerical simulations (Huang et al, 2005) and GIS (Chu et al, 2005), which are practical for design thinking development. Moreover, in studies on urban climate, there is a major focus on air quality and wind analysis of the built environment; one of which is the ‘CFD modelling of wind field

TE D

and pollutant transport in street canyons’ (Li et al, 2006), which examines the quality of wind in street canyons of the urban environment. The application of CFD for pollutant dispersion analysis is also an effective analytical approach to identifying methods of developing or

EP

altering design of the built environment (Cheshmehzangi et al, 2010). As part of such

AC C

modelling approach and assessing the effects of pollutants on health and comfort, the provided information can contribute towards development of guidelines and suggestions for policy makers (Yuan et al, 2014). In this study, CFD is used as a supporting tool and offer a holistic overview of environmental conditions in the urban environments. As a result, a combined package of solar performance and wind environment analysis (as well as overshadowing analysis studies) is considered for assessment of environmental performance in the design process. Although not completely accurate at urban scale with limitations and difficulties in measurement (Oke, 2006), the CFD 5

ACCEPTED MANUSCRIPT analysis can demonstrate, and to some extent predict, potential and possibilities of wind tunnels, comfort level (due to speed of wind) and wind directions. More accurate simulation analyses can happen at smaller scale, where detailed landscape design and planning consideration are important. CFD analyses may be a time-consuming practice at a large scale

RI PT

(i.e. macro scale or even meso scale), but in return, can offer a better understanding and evaluation of the built environment. For a design project, such approach helps to consider heights and density of buildings, allocation of open spaces and openings, green landscaping,

SC

pedestrian routes and etc. More importantly, this can help to simulate physical form and

M AN U

spatial layout of the built environment, which are studied as the part of the study. The physical form or the urban physics of the urban environment is an important part of any urban planning and design process. It is not necessarily the final product of design, but rather how it is incorporated into the process of design thinking. A successful example is the

TE D

recent study on Hong Kong’s high-density urban areas (Yuan et al, 2014), in which the researchers have developed testing scenarios of design possibilities based on the current urban form. By doing so, height and plot ratios are considered as part of the analysis. With

EP

the use of CFD, designers can determine height and form of the buildings. This is particularly

AC C

effective for smaller urban design and planning projects in dense urban environments. This improvement in design is a successful method for preparation of various design scenarios for a single design, before consideration of any detailed design that includes detailed landscape design, architectural elements, façades, urban furniture, and public place/open space. On the other hand, the spatial layout and configuration of the built environment are vital to achieving successful landscape planning and urban design. The application of CFD, as a quantitative method, is to undertake ventilation assessment of the urban layouts (Lin et al,

6

ACCEPTED MANUSCRIPT 2014). An example of such case is a proposed integrated urban design approach for masterplan of the Central Business District (CBD) in Cao Feidian Eco-city, North-East of China (Cheshmehzangi et al, 2010), in which the researchers have applied CFD analyses to make decisions on types and locations of the open spaces (such as parks), the types of green

RI PT

landscaping (plantation, surfacing, etc.), and public places (such as squares). Such approach enables landscape and urban designers to further develop an overall strategy for spatial layout of the built environment. As part of design thinking process, this is crucial to suggest a

SC

set of design scenarios, including various possibilities of urban permeability and spatial

M AN U

strategies.

At urban scale, the use of CFD is effective not only as an environmental assessment tool but as a predictive method to climatic conditions. The analysis of the environment in urban design is an integrated approach to understand and identify landscaping, uses, layouts and

TE D

patterns of the urban environment. Furthermore, we can argue that the practical application of CFD with the integration of other simulation tools is a breakthrough in enhancing the role of environmental assessment in landscape planning and urban design. This integration is

EP

aimed to change the traditional integration of multiple dimensions in design, and by taking

AC C

that forward, move towards a more complicated model of design thinking. 1.1 Framework and Application In both theory and practice, achieving an integrated urban design is a major challenge. Nevertheless, the application of integrated urban design is effective in achieving higher standards and qualities in design. As a result, this study aims to express the value of integrated urban design in practice. Through a case study analysis, the application of CFD

7

ACCEPTED MANUSCRIPT and its integration in urban design is discussed as a method towards decision making in the urban design process. (Figure 1)

RI PT

CFD is an effective simulation tool to model and analyse and test possibilities or scenarios for design solutions. Yet, its application in urban design should be planned in a more holistic

SC

framework (figure 1). For this study, application of CFD is proposed at three different phases of the design process. For each phase, the undertaken modelling and testing can be

M AN U

separated from other phases of the design process.

In phase one, computational tools are proposed for pre-design environmental assessment of the selected urban area. This is prior to design development and is concurrent with the overall site analysis of the selected urban area (i.e. for an urban design or landscape

TE D

planning project). The analysed information from environmental assessment can be integrated in to the process of design thinking. As previously discussed, the environmental

EP

assessment includes a comprehensive package of solar performance, wind environment analysis and overshadowing analysis. For specific cases, pollutant dispersion can be

AC C

considered as part of the environmental assessment (Cheshmehzangi et al, 2010). Furthermore, phase two represents initial stage of urban design after the site analysis, where an initial masterplan is developed. The application of computational tools (such as, CFD) is a modelling approach to test and develop design scenarios that are part of one design strategy/process. This is also considered as a prediction tool (Yoshie et al, 2005; Mochida and Lun, 2008) to cross-evaluate between various potential scenarios of planning and design. In this process, it is also aimed to optimise (where needed) and improve the

8

ACCEPTED MANUSCRIPT design process. By doing so, we can move from macro-scale to meso-scale in landscape planning and urban design. In this phase, computational tools have different applications compared to the first phase. In this part of design process, detailed urban design can benefit from the use of computational tools, which in practice, it is feasible to develop multiple

RI PT

design scenarios and analyse them against each other. This enables designers to undertake further assessment of the overall design process before finalisation of design. It also provides a more analytical and critical approach to the process of design development.

SC

Finally in phase three, a detailed urban design is expected to benefit from computational

M AN U

tools and modelling at both meso and micro scales of design. In this phase, application of the computational tools can vary from public place design and positioning of entrances, to landscape design and features and façade design. All can be considered as part of an

TE D

integrated urban design.

2. Application of CFD Tools in Urban Planning and Design Process

EP

For this study and based on the proposed framework, computational tools (particularly CFD) are applied for environmental assessment at macro scale, design testing, development and

AC C

refinement at meso scale and detailed integrated urban design at micro scale. These are suggested to develop a design thinking process for an integrated urban design (as in the above proposed framework). A UK-based urban design project is presented to discuss and analyse the practical application of CFD at three scales of macro, meso and micro.

2.1 Application at Macro Scale for Integrated Urban Design

9

ACCEPTED MANUSCRIPT The pre-design level for environmental assessment can almost be considered as the environmental performance part of the site analysis for an urban design or a landscape planning project. At macro scale, this approach determines outdoor climatic conditions, city ventilation opportunities, and thermal comfort. Through a graphical interface, 3D

RI PT

visualisation of wind and solar exposure can be assessed. For higher density urban environments, overshadowing analysis can support better verification of building heights and density (Yang and Li, 2015). The wind analysis provides a comprehensive assessment of

SC

the wind characteristics, including, wind direction (seasonal and regular), wind speed, mean

M AN U

pressure factor and turbulence intensity (such as vortex due to the built environment). On the other hand, the solar analysis provides a clear understanding of insolation analysis, environmental requirements (e.g. topographical and landscape) and spatial analysis based on the analysis of the built environment and its impacts on open spaces (such as squares and

TE D

pedestrian routes).

In this phase, a thorough assessment of the environmental performance can provide essential climatic data, which enables designer to have a better consideration of the

EP

environment as part of the urban design. At a later stage of design development, this

AC C

assessment can support social, morphological and functional dimensions of urban design. Therefore, the application of CFD at macro scale is a decision making tool prior to design development, which is also a new analytical interface for landscape planning and urban design projects. This includes a variety of beneficial data from environmental analysis of the selected site. Furthermore, any pro-design application of CFD tools at macro scale should only demonstrate the reflection of design, based on the new environmental performance analysis.

10

ACCEPTED MANUSCRIPT

2.2 Application at Meso Scale for Integrated Urban Design At meso scale, application of CFD tools is considered as a major testing tool for design

RI PT

development. At this scale, the simulation can occur with a three-dimensional base of the selected area, providing both plan and sectional drawings of the site. In this approach, the physicality of the developed built environment is tested and assessed based on the new

M AN U

overshadowing analysis can also take place if required.

SC

environmental conditions (i.e. wind and solar analyses). Similar to macro scale assessment,

The CFD application at meso scale needs to be considered as part of design process, enabling planners and designers to consider possible design solutions based on same environmental circumstance/condition. A more detailed graphical interface promotes a more

TE D

comprehensive understanding of the environmental and climatic conditions of the site.

As part of this testing and optimising phase, the simulation of the environment supports

EP

strategic development of open spaces layout, public place design, building forms (i.e. urban

AC C

physics) and activities. This approach is not only to focus on outdoor spaces but also to consider how we can minimise the negative impact of buildings on the outdoor spaces. For instance, if based on the simulation study, one identifies a possible vortex or overshadowing problem, the building forms or/and heights can be readapted before any further development of design. A successful model of such application is to use the simulation analysis at various sections of a selected site, where we can identify negative and positive impacts of the proposed design on the existing and the surrounding areas.

11

ACCEPTED MANUSCRIPT (Figure 2)

(Figure 3)

RI PT

In figures 2 and 3 above, both insolation analysis and general wind analysis help to simulate and then identify possible solar and wind exposure for a courtyard design in a larger landscape planning or urban design project. The simulation is undertaken based on a

SC

simplified three-dimensional base of the project, enabling designers to have a better

M AN U

understanding of the physicality and spatiality of the proposed built environment. Further modification can occur by further testing of the site, based on multiple design scenarios (if needed). This can then lead towards improvement and refinement of the proposed design. Finally, this approach is an enabling tool for urban designers to better visualise and assess

TE D

the environmental performance of their proposed design.

EP

2.3 Application at Micro Scale for Integrated Urban Design At micro Scale, the final application of CFD tools supports further integration of

AC C

environmental simulation/analyses with the final design. After refinement of design at two previous scales, the final design can develop in to detailed design stage. This is particularly important for the identification of size and shape of open spaces, what urban furniture or landscaping is required, where the furniture or landscaping will be positioned and how the proposed open space can help to shape social activities of the site. For urban landscaping detailed design, the CFD tools enable designers to integrate both quantitative and qualitative data and to provide a more in-depth perspective on the relationship between 12

ACCEPTED MANUSCRIPT environmental and social dimensions of design. Figure 4 below demonstrates the use of CFD tools in the process of detailed design for a semi-open courtyard in an urban context. In this respect, the consideration of activities, circulation and land-uses are developed and

RI PT

designed on the basis of the environmental analysis of the area. (Figure 4)

SC

As part of an urban design project, and in addition to public place design or urban landscaping of a particular design, the application of CFD at micro scale can also relate to

M AN U

building design or layout. This application enables designers to come up with detailed design scenarios that can help a better decision making on final proposed design. This includes detailed analysis of insolation analysis for new building façades (figure 5), wind analysis for the forms of proposed buildings, and overshadowing analysis for the heights of new

TE D

buildings and their impact on the existing surrounding areas. The simulation analysis of the physicality of built environment and its environmental performance is an integrated model

EP

to urban design. This approach encourages urban designers, and also architects, to propose a more informative detailed design. A quantitative platform such as, data of environmental

AC C

performance, to existing qualitative platform of design thinking is a valuable asset for development of a multi-layered detailed design of any project. (Figure 5)

The benefits of micro scale insolation analysis vary from public place design (or design consideration) to detailed façade design suggestions (figure 5). A seasonal insolation analysis of a building façade provides a better understanding of what façade and how much of it is

13

ACCEPTED MANUSCRIPT required for better heating or cooling in respect to the conditions of the urban context. This could go even further with simulation of materials, detailed design and building layouts, which is slightly out of scope of landscape planners and urban designers. Nevertheless, with the application of CFD tools, urban design can provide a comprehensive package to the

RI PT

conditions of the context, such as, the impact of surrounding buildings/context on the proposed building/area and how further design and planning should or could be considered on the basis of data from the environmental performance of the site. Similarly, for micro

SC

scale wind analysis, planners and designers can come up with suggestions for possibilities

M AN U

and locations of outdoor activities, entrances to buildings, pedestrian flows (Shi et al, 2015) and façade-to-space interaction nodes (e.g. seating for cafes, etc.). This analytical approach is an enabling tool to better understand outdoor comfort and activities. This can help urban designers to consider possibilities for utilisation of urban canyons or the need to avoid them;

TE D

where seating is required rather than open spaces; where we need more trees and what types of green landscaping can be proposed. Finally, for micro scale overshadowing analysis, a pre-construction simulation of the proposed and existing buildings/areas can demonstrate

EP

possibilities or even requirements of shading in the built environment. This is particularly

AC C

effective for design projects in dense urban environments. Regardless of scale of the project, application of CFD tools at micro scale is essential for integrated urban design. Furthermore, it is important to note that all micro scale simulation analyses are beneficial only if to be collective as a combined analysis of environmental performance and then integrated in to the urban design thinking process.

3. Result Analysis and Discussions

14

ACCEPTED MANUSCRIPT Through the suggested framework for application of computational tools and design process, this paper has examined three stages for application of CFD tools in the process of urban design. The analytical study of macro, meso and micro scales highlights the application and effectiveness of CFD tools for an integrated urban design. This expresses an overview of how

RI PT

one type of computational tool (i.e. CFD) can have different, and yet influential, applications in the process of an urban design project. In macro to micro scales, CFD can be used as an analytical tool for the environmental performance and conditions of the urban context to

SC

simulation of air quality in urban micro environments (McAlpine and Ruby, 2004); all of

M AN U

which are important in achieving an integrated urban design model.

In the past two decades, the application of computational simulation tools in urban design has grown popularity amongst planners, designers and researchers of urban climate and environmental studies. Although it is mostly used in environmental design, CFD tools have

TE D

also gained popularity in practice. In urban design, the potential of such application is not fully incorporated as part of design development and design thinking process. It is mainly used as a testing and modelling tool. Therefore, this study has investigated the use of CFD

AC C

EP

simulation studies to suggest comprehensive approaches to integrated urban design.

3.1 From Computational Simulation to Design: Implementation in Urban Design Practice This study proposes for a procedural model for the use of CFD tools in the process of design development, from the pre-design stage to the final stage of integrated urban design (figure 6). Such approach can relate to promotion of a better engagement of ‘appropriate metrics for performance assessment of the built environment’ (Zhang et al, 2015), some of which that can be proposed for multi-spatial environmental performance evaluation, ‘urban 15

ACCEPTED MANUSCRIPT sustainability agenda’ (Maclaren, 1996), as well as ‘regenerative sustainability paradigm’ (du Plessis, 2012). In this respect, this paper contributes towards a holistic consideration of environmental performance in the built environment from a multi-spatial level perspective; i.e. from large urban environment scale to façade design optimisation. This step-by-step

RI PT

procedural approach is proposed to undertake CFD simulation studies at various stages of design development. The studied project in this paper demonstrates the applications of CFD simulations at three levels of macro, meso and micro in one project, proving the fact that

SC

such techniques can be utilised at multiple levels for an integrated design thinking process.

M AN U

In this study, CFD tools are applied at three stages of an urban design project. This does not include the typical application of CFD for remodelling of buildings or simulation of environmental conditions alone. The proposed design process demonstrates potentials for the use of computational simulation tools in urban design and landscape planning. Such

TE D

implementation in urban design practice requires careful and comprehensive understanding and evaluation of the urban context. As a result, it is essential to identify key aspects for the practical application of CFD simulation in urban design; one of which is a knowledge-based

EP

decision making attribute of CFD tools (Yuan et al, 2014) that is examined as part of this

AC C

study. This would require careful data collection, data analysis and interpretation of data for application and decision making in design (Yuan et al, 2014). Therefore, in order to achieve an integrated urban design, one should consider a thorough process of design development Furthermore, the application of CFD simulation is suggested for further development of a procedural model that can embrace the three stages of: 1- ‘pre-design’; 2- ‘design development process’; and 3- ‘integrated urban design’ (figure 6). For the pre-design stage, CFD simulation should develop an information modelling platform, enabling planners and

16

ACCEPTED MANUSCRIPT designers to better assess and interpret the information based on environmental conditions of the urban context. In cases of larger masterplan, landscape planning and urban design projects, this approach should be used to collect and interpret city-level environmental data that are essential as part of the project’s site analysis. In the stage of design development

RI PT

process, the expected procedure is the initial masterplan that is developed, tested and refined for detailed design and consideration. This leads the process to achieving integrated

M AN U

(Figure 6)

SC

urban design that includes meso scale design refinement and micro scale detailed design.

TE D

Based on the proposed procedural model and analysis of the application of CFD simulation tools in urban design, we can argue for a design thinking method that is potentially comprehensive if integrated with other aspects of design thinking process. Although this

EP

study has scrutinised the extent and scales in which CFD tools can be applied in practice, there remain limitations for the application of such tools for design development process.

AC C

The most common known limitation is the lack of social consideration or even integration through the use of computational simulation and modelling. However, this only applies if the interpreted data are not integrated with the process of overall planning and design. In this respect, this study has, to some extent, responded to this major limitation by undertaking an integrated approach to the use of CFD simulation tools in urban design. For more complicated cases, the integrated approach can further develop by increasing the number of parameters for modelling and design. The other limitation is regarding the data accuracy of

17

ACCEPTED MANUSCRIPT CFD simulation studies at larger scales, such as macro scale of urban environments. For instance, in denser urban environments it is often more difficult to validate the simulation data for the wind analysis. Similarly for solar performance simulation, macro scale analysis is often not accurate but is rather indicative for an overall understanding of pre-design urban

RI PT

conditions. Finally, the time consuming process of CFD simulations may discourage the use of such method in practice. However, in the process of data analysis and data interpretation, it is important to consider the information modelling platform to urban design. In addition

SC

this, the effect from coupling CFD with other tools (such as GIS), is proven to be a successful

and urban design practices.

TE D

4. Conclusions

M AN U

approach in strengthening the prediction and modelling techniques for landscape planning

This study focuses on the application of CFD simulation tools to inform planning and design process. With an emphasis on integrated urban design, this study expresses an overview on

EP

how the collected data from CFD simulations should be analysed, interpreted and utilised as

AC C

a design thinking process. A framework is provided for application of computational tools and the urban design process at three sequential phases of design development. These are studied in three scales of macro, meso and micro urban environments. A UK case study is used to discuss the validity of the framework and respond to application of CFD tools in the process of urban planning and design. Furthermore, based on the studied urban design case, a procedural model is proposed for the use of CFD tools in the process of design development. This includes three stages of predesign, design development process and the final stage of integrated urban design, 18

ACCEPTED MANUSCRIPT demonstrating the possibilities to undertake CFD simulations as part of a design thinking process. In all three stages of design development, the application of CFD simulation tools, interpretation of data and their integration in to design, conclude the effectiveness and practicality of such approach in design development. The analysis results specify that an

RI PT

integration of prediction and evaluations from CFD simulations in each scale of macro, meso and micro could be influential to how we may consider practical design solutions, alterations

SC

and refinements.

Finally, this study concludes that the data collected and analysed from CFD simulation in

M AN U

urban planning and design, can help to develop an information modelling platform for robust decision making in design. This analytical process needs to be validated and implemented as part of achieving an integrated urban design. Based on the study, the application of CFD tools can enable planners and designers to have an enhanced

TE D

consideration of environmental assessment in design thinking and how such approach can become a design decision making tool for the purpose of integrated solutions to complicated design scenarios. A multi-layered approach to practical application of CFD simulation tools

EP

emphasise the role of available technologies and computational tools at various scales to

AC C

achieve an integrated urban design.

References

Amorim, J.H., Rodrigues, V., Tavares, R., Valente, J. and Borrego, C. (2013) CFD modelling of the aerodynamic effect of trees on urban air pollution dispersion, Science of The Total Environment, Volumes 461–462, pp. 541–551

19

ACCEPTED MANUSCRIPT Bady M, Kato S, and Huang H. (2008) Towards the application of indoor ventilation efficiency indices to evaluate the air quality of urban areas. Building and Environment, 43, pp. 1991-2004. Biljecki, F. , Ledoux, H. Stoter, J. and Zhao, J. (2014) Formalisation of the Level of Detail in 3D City Modelling, Computers, Environment and Urban Systems, 48, pp. 1

15.

RI PT

Blocken, B., Janssen, W. D. and Hood, T. V. (2012) CFD simulation for pedestrian wind comfort and wind safety in urban areas: General decision framework and case study for the Eindhoven University campus, Environmental Modelling & Software, Volume 30, pp. 15–34.

SC

Blocken, B. (2014) 50 years of Computational Wind Engineering: Past, present and future, Journal of Wind Eng Ind Aerodyn, 129, pp. 69-102.

M AN U

Blocken, B., Hooff, T. and Janssen W. (2013) Pedestrian wind comfort around buildings: Comparison of wind comfort criteria based on whole-flow field data for a complex case study, Building and Environment, 59, pp. 547–562.

Carissimo, B., Franke, J., Hellsten, A. and Schlunzen, H. (2011) The COST 732 Best Practice Guideline

TE D

for CFD simulation of flows in the urban environment: a summary, International Journal of Environment and Pollution, 44 (1–4), pp. 419–427.

Chakrabarty, B. K. (2007) Computer-aided design in urban development and management—A

473-494.

EP

software for integrated planning and design by optimization, Building and Environment, Vol. 42, pp.

AC C

Cheshmehzangi, A., Zhu, Y. and Li, B. (2010) Integrated Urban Design Approach: Sustainability for Urban Design, in proceedings for ICRM 2010, 5th International Conference for Responsive Manufacturing in China, January 2010. Chu, A. K. M., Kwok, R. C. W. and Yu, K. N. (2005) Study of pollution dispersion in urban areas using Computational Fluid Dynamics (CFD) and Geographic Information System (GIS), Environmental Modelling & Software, Volume 20, Issue 3, pp. 273–277. Chung, D. H. J. and Choo, M. L. (2011) Computational Fluid Dynamics for Urban Design: The Prospects for Greater Integration, International Journal of Architectural Computing, Vol. 9, No. 1, pp. 33-54. 20

ACCEPTED MANUSCRIPT Di Sabatino, S, Buccolieri, R, Olesen, HR, Ketzel, M, Berkowicz, R, Franke, J, Schatzmann, M, Schlunzen, KH, Leitl, B, Britter, R, Borrego, C, Costa, AM, Trini Castelli, A, Reisin, TG, Hellsten, A, Saloranta, J, Moussiopoulos, N, Barmpas, F, Brzozowski, K, Goricsan, I, Balczo, M, Bartzis, JG, Efthimiou, G, Santiago, JL, Martilli, A, Piringer, M, Baumann-Stanzer, K, Hirtl, M, Baklanov, AA,

RI PT

Nuterman, RB, Starchenko (2011) AV. COST 732 in practice: the MUST model evaluation exercise. International Journal of Environmental Pollution, 44(1/2/3/4), pp. 403-418.

du Plessis, C. (2012) Towards a regenerative paradigm for the built environment, Building Research

SC

and Information, 40 (1), pp. 7–22.

Fernando HJS, Zajic D, Di Sabatino S, Dimitrova R, Hedquist B, Dallman A. (2010) Flow, turbulence,

M AN U

and pollutant dispersion in urban atmospheres. Phys Fluids; 22(5), 051301.

Galle, P. (1995) Towards Integrated, “Intelligent”, and Compliant Computer Modelling of Buildings, Automation in Construction, 4, pp. 189-211.

Gil, J., Duarte, J. P., and Beirao, J. (2013) The Backbone of City Information Modelling (CIM): Spatial

TE D

Data Models and Tools for Urban Design, in Pedagogy meets Big Data and BIM Conference, at the Bartlett, UCL, London, June 2013.

Hang J. and Li Y. (2011) Age of air and air exchange efficiency in high-rise urban areas. Atmos Environ,

EP

45(31), pp. 5572-5585.

Hang J, Li Y, Sandberg M, Buccolieri R, Di Sabatino S. (2012) The influence of building height

AC C

variability on pollutant dispersion and pedestrian ventilation in idealized high-rise urban areas, Building and Environment, 56, pp. 346-360. Hu T. and Yoshie R. (2013) Indices to evaluate ventilation efficiency in newly-built urban area at pedestrian level, Journal of Wind Eng Ind Aerodyn, 112, pp. 39-51. Huang, H., Ooka, R. and Kato, S. (2005) Urban thermal environment measurements and numerical simulation for an actual complex urban area covering a large district heating and cooling system in summer, Atmospheric Environment, Volume 39, Issue 34, pp. 6362–6375.

21

ACCEPTED MANUSCRIPT Jain, A. (2014) Integrated Urban Design and Planning for Inclusive Public Space and City-Region Connectivity and Region, Published at SDG Communities, UrbanSDG Section. Li, X. X., Liu, C. H., Leung, D. Y. C. and Lam, K. M. (2006) Recent progress in CFD modelling of wind field and pollutant transport in street canyons, Atmosphere Environment, Vol 40, pp. 5640-58.

RI PT

Lin, M., Hang, J., Li, Y., Lou, Z. and Sandberg, M. (2014) Quantitative Ventilation Assessments of Idealized Urban Canopy Layers with Various Urban Layouts and the Same Building Packing Density, Building and Environment, Vol. 79, pp. 152-167.

SC

Maclaren, V. W. (1996) Urban sustainability reporting, Journal of the American planning association, 62(2), pp. 184-202.

M AN U

McAlpine, J. D. and Ruby, M. (2004) Using CFD to Study Air Quality in Urban Microenvironments, in Zannetti, P. (2004) (ed.) Environmental Sciences and Environmental Computing: Vol. II, Published by The EnviroComp Institute.

Mochida, A., Tominaga, Y., Murakami, S., Yoshie, R., Ishihara, T., Ooka, R. (2002). Comparison of

TE D

various k-εmodel and DSM applied to flow around a high-rise building - report on AIJ cooperative project for CFD prediction of wind environment, Wind and Structures, 5, No.2-4, pp. 227-244. Mochida, A. and Lun, I. Y. F. (2008) Prediction of wind environment and thermal comfort at

EP

pedestrian level in urban area, Journal of Wind Engineering and Industrial Aerodynamics Volume 96, Issues 10–11, pp. 1498–1527.

AC C

Murakami, S., Ooka, R., Mochida, A., Yoshida, S. and Kim, S. (1999) CFD analysis of wind climate from human scale to urban scale, Journal of Wind Engineering and Industrial Aerodynamics, Volume 81, Issues 1–3, May 1999, Pages 57–81. Murakami, S. (2006) Environmental Design of Outdoor Climate Based on CFD, Fluid Dynamics Research, Vol. 38, pp. 108-126. Ng E. (2009) Policies and technical guidelines for urban planning of high-density cities - air ventilation assessment (AVA) of Hong Kong. Building and Environment, 44(7), pp. 1478-1488.

22

ACCEPTED MANUSCRIPT Ng W. and Chau C. (2014) A modelling investigation of the impact of street and building configurations on personal air pollutant exposure in isolated deep urban canyons, Sci Total Environ, 468-469, pp. 429-48. Oke, T. R., (2006) Initial guidance to obtain representative meteorological observations at urban sites,

RI PT

World Meteorological Organization, pp. 21-22. Ramponi, R., Blocken, B., de Coo, L. B., and Janssen, W. D. (2015) CFD simulation of outdoor

ventilation of generic urban configurations with different urban densities and equal and unequal

SC

street widths, Building and Environment, Volume 92, pp. 152–166

Schatzmann, M. and Leitl, B. (2011) Issues with validation of urban flow and dispersion CFD models,

M AN U

Journal of Wind Engineering and Industrial Aerodynamics, Volume 99, Issue 4, pp. 169–186. Shi, X., Zhu, Y., Duan, J., Shao, R. and Wang, J. (2015) Assessment of pedestrian wind environment in urban planning design, Landscape and Urban Planning, Volume 140, pp. 17–28 Shirasawa, T., Tominaga, T., Yoshie, R., Mochida, A., Yoshino, H., Kataoka, H., Nozu, T. (2003)

TE D

Development of CFD method for predicting wind environment around a high-rise building Part2 : The cross comparison of CFD results using various k- models for the flowfield around a building model with 4:4:1 shape, AIJ Journal of Technology and Design, No.18, pp. 169-174.

EP

Soligo, M., Irwin, P., Williams, C. and Schuyler, G. (1998) A comprehensive assessment of pedestrian comfort including thermal effects, Journal of Wind Engineering and Industrial Aerodynamics, 77–78,

AC C

pp. 753–766.

Szücs, A. (2013) Wind comfort in a public urban space – case study within Dublin Docklands, Frontiers of Architectural Research, 2 (1), pp. 50–66. Tanabe S, Kobayashi K, Nakano J, Ozeki Y, Konishi M (2002) Evaluation of thermal comfort using combined multi-node thermoregulation (65MN) and radiation models and computational fluid dynamics (CFD), Energy Build, 34(6), pp. 637–646.

23

ACCEPTED MANUSCRIPT Tominaga Y, Mochida A, Yoshie R, Kataoka H, Nozu T, Yoshikawa M, et al. (2008) AIJ guidelines for practical applications of CFD to pedestrian wind environment around buildings. J Wind Eng Ind Aerodyn, 96, pp. 1749-1761. Toparlar, Y., Blocken, B., Vos, P., van Heijst, G. J. F., Janssen, W. D., van Hooff, T., Montazeri, H. and

RI PT

Timmermans, H. J. P. (2015) CFD simulation and validation of urban microclimate: A case study for Bergpolder Zuid, Rotterdam, Building and Environment, Special Issue: Climate adaptation in cities, Volume 83, pp. 79–90

SC

Vanos, J. K., Warland, J. S., Gillespie, T. J. and Kenny, N. A. (2010) Review of the physiology of human thermal comfort while exercising in urban landscapes and implications for bioclimatic design,

M AN U

International Journal of Biometeorology, Volume 54, Issue 4, pp. 319-334.

Wang, X. and Li, Y. (2016) Predicting urban heat island circulation using CFD, Building and Environment, Vol. 99, pp. 82–97

Wong, N. H., Jasuf, S. K. and Tan, C. L. (2011) Integrated urban microclimate assessment method as a

Issue 4, pp. 386–389.

TE D

sustainable urban development and urban design tool, Landscape and Urban Planning, Volume 100,

Yang X.Y. and Li Y.G. (2015) The impact of building density and building height heterogeneity on

EP

average urban albedo and street surface temperature, Building and Environment, 90, pp. 146-156. Yoshie, R., Mochida, A., Tominaga, Y., Kataoka, H., Harimoto, K., Nozu, T., Shirasawa, T. (2005)

AC C

Cooperative project for CFD prediction of pedestrian wind environment in the Architectural Institute of Japan, Journal of Wind Engineering and Industrial Aerodynamics, Volume 95, Issues 9-11, pp. 1551-1578.

Yuan, C., Ng E. and Norford, L.K. (2014) Improving air quality in high-density cities by understanding the relationship between air pollutant dispersion and urban morphologies, Building and Environment, 71, pp. 245-258.

24

ACCEPTED MANUSCRIPT Zhang, X., Skitmore, M., De Jong, M., Huisingh, D., & Gray, M. (2015) Regenerative sustainability for the built environment-from vision to reality: an introductory chapter. Journal of Cleaner Production,

AC C

EP

TE D

M AN U

SC

RI PT

109, pp. 1-10.

25

ACCEPTED MANUSCRIPT

Urban Design Process

Application of computational tools (such as, CFD)

Phase 2

Testing design scenarios, optimisation and improvement of design process

M AN U

SC

RI PT

Phase 1

Environmental assessment and integration in to the overall analysis

Final Integration and detailed design stage

TE D

Phase 3

AC C

EP

Figure 1 – Framework for application of computational tools and the urban design process

Figure 2 – Insolation analysis of a selected courtyard for an urban design project, Nottingham, UK.

1

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

Figure 3 – General wind analysis of a selected courtyard for an urban design project, Nottingham, UK.

Figure 4 – A multi-layered design process and application of CFD tools for detailed urban design at micro scale, Nottingham, UK.

2

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

Figure 5 – An example of the application of insolation analysis for façade design of two buildings in an urban design project, Nottingham, UK.

3

ACCEPTED MANUSCRIPT

Strategy for the initial masterplan and design

Integrated urban design at meso scale

RI PT

Urban design site analysis

Refine masterplan and design at macro scale

Test for further assessment and refinement with the use of computational tools

M AN U

Environmental assessment by computational tools

3- INTEGRATED URBAN DESIGN

2- PROCESS OF URBAN DESIGN

SC

1- PRE-DESIGN

Detailed design at micro scale

AC C

EP

TE D

Figure 6 – A procedural model for the use of CFD tools in the process of design development, from the pre-design stage to the final stage of integrated urban design (Note: dotted arrows indicate process within a single stage and non-dotted arrows indicate process between the stages)

4

ACCEPTED MANUSCRIPT

Holistic Environmental Performance Evaluation towards

RI PT

Sustainability and Integrated Urban Design

Highlights

SC


The study examines the practical application of CFD for integrated urban design;
The study provides a procedural model for the use of CFD tools in the process of design

AC C

EP

TE D

M AN U

development;
The study discusses the limitations of CFD in urban context;
The study argues the role of simulation techniques, computational tools and available technologies in achieving better design and planning of the urban environments.

1