Integrated Urban Micro Climate Assessment Method as a Sustainable Urban Development and Urban Design Tool

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  This article appeared in a journal published by Elsevier. The attachedcopy is furnished to the author for internal non-commercial researchand education use, including for instruction at the authors institutionand sharing with colleagues.Other uses, including reproduction and distribution, or selling orlicensing copies, or posting to personal, institutional or third partywebsites are prohibited.In most cases authors are permitted to post their version of thearticle (e.g. in Word or Tex form) to their personal website orinstitutional repository. Authors requiring further informationregarding Elsevier’s archiving and manuscript policies areencouraged to visit:  Author's personal copy Landscape and Urban Planning 100 (2011) 386–389 Contents lists available atScienceDirect Landscape and Urban Planning journal Integrated urban microclimate assessment method as a sustainable urbandevelopment and urban design tool Nyuk Hien Wong a , ∗ , Steve Kardinal Jusuf  b , Chun Liang Tan b a Department of Building, National University of Singapore, Singapore b Center for Sustainable Asian Cities, National University of Singapore, Singapore a r t i c l e i n f o Article history: Available online 3 March 2011 Keywords: IntegrationUrban climate researchSustainable urban developmentUrban design tool a b s t r a c t Inthepastdecades,urbanheatisland(UHI)phenomenoninthecityanditscorrespondingissuesinclud-ing the mitigation methods have become the main research topics in the area of urban climatology.Researchershaveconductedvariousinvestigationsandmeasurementsintheurbanenvironment.Predic-tion models such as impact mitigation strategies, urban air temperature predictions, improved weatherforecastingandairqualityforecastinghavebeendevelopedasaresult.Withthecurrentissueofsustain-ableurbandevelopmentinthecities,urbanplannersarebeginningtolookintodifferentaspectsofurbanclimatic parameters and incorporate them as the design parameters. However, it is rather difficult forthe planners to attempt to design without engaging the urban climate scientists. Presently, Geographi-cal Information System (GIS) is a platform commonly used in various geographical related research andapplications, including those relating to urban climate research, as it can be used to analyze differenturbanclimaticparameters.Althoughitis,byallstandards,anappropriateurbandesigntool,urbanplan-ners tend not to embrace this technology. This paper shall present an idea to overcome this challengeby means of developing a user friendly urban design platform that takes after GIS. This paper will alsodiscuss the plan for advancement of the urban design tool from the current situation to the future. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Urban populations have grown significantly over the past twocenturies, from 3% in 1800 to 14% in 1900 and 47% in 2000.Based on a United Nations estimate, 61% of world’s population(up to 5 billion people) will live in urban areas by year 2030(Oke, 1987). Given this trend, the Urban Heat Island (UHI) hasbecome a global phenomenon as cities attempt to accommo-date increasing demand for housing, commercial development,recreation space, and other uses which in turn increases theenergy consumption of buildings, alters urban climatology, mod-ifies urban wind patterns, and increases the concentration of airpollutants.Urban climate researchers have made UHI and its mitigationstrategies the main research focus in recent decades. Several stud-ies acknowledge the influence of urban form on thermal comfort,urbantemperature,andtheurbanheatislandintensity.Asaresultof UHI studies, numerous prediction models have been developedfor evaluating the effectiveness of impact mitigation strategies, ∗ Corresponding author. E-mail addresses: Wong), Jusuf). predicting urban air temperature, and forecasting weather and airquality.Currently, UHI study methods are categorized as multi-scalephenomena and include observational approaches such as fieldmeasurement,thermalremotesensing,andsmall-scalemodelling;and computer simulations where energy balance modelling andcomputer fluid dynamics (CFD) are commonly used (Mirzaei andHahighat, 2010). As a result, more than 30 urban land surface pre-diction models have been developed with different approaches(Grimmondetal.,2010).Thesemodelsvaryfromsimplerepresen-tation of urban environment to a 3D geometry of buildings withvarying heights and material characteristics. In order to make useof these prediction models, users have to key in different parame-ters, which usually confine the urban climate knowledge domain,for example, anthropogenic fluxes and turbulent latent heat.Current priorities placed on sustainable urban developmenthave encouraged urban planners to examine the various parame-tersofurbanclimatemodellingandincorporatethemintoplanningand design efforts. But while they may understand the importanceof interactions between urban morphology and urban microcli-mate condition, they lack basic knowledge of urban climatology.Engagingurbanclimatescientiststoconductassessmentsandpro-videfeedbackhashelpedinformdesignandplanningefforts,buttodatethedesignprocesshasbeenlargelydecoupledfromtheimpact 0169-2046/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.landurbplan.2011.02.012  Author's personal copy N.H. Wong et al. / Landscape and Urban Planning  100 (2011) 386–389 387 assessment and analysis process. Urban climate scientists need toimprove communication with the urban planners, architects andengineers(Yow,2007),Mills(2006)proposedaconceptualmethod that puts urban climatology knowledge at the center of designprocess with different scales; buildings, building groups and set-tlement.Geographical Information Systems (GIS) provide a commonplatform for various geographically related research and applica-tions issues, including those relating to urban climate research. Assuch, GIS can be used to analyze different urban climatic param-eters, for example, urban climatic mapping technique. However,GIS is still lacking in its capability as a user-friendly urban designand planning tool. This paper presents a means to overcome thischallengethroughdevelopmentofauserfriendlyurbandesigntoolfor climate assessment built on a GIS platform. The Screening Toolof Estate Environment and Evaluation (STEVE) will be one of theexamplesusedforthediscussion.Thispaperalsodiscussestheplanfor advancement of the urban design tool from the current situa-tion to the future, in parallel with more mature design tools at thebuilding level, such as the Building Information Modelling (BIM). 2. Current urban climate analysis tools and methods 2.1. Nation/city-wide level climatic mapping  Among the various UHI study methods mentioned above, theurban climatic mapping method (UC-Map) has been found to bevery useful for urban planning purpose since it integrates vari-ousurbanclimaticparameterswithurbanplanningconsiderations.While this method has been used in Germany since early 1980s,its wider adoption by other cities has been slow because plan-ning and urban climate research arises out of different knowledgedomains. Meteorologists know little about the planning require-ments that consider urban climate factors, while urban plannershave little understanding of the types of climate data that can beprovided for their planning purpose (Matzarakis, 2005). The map-pingmethodcompilesmeteorological,landuse,buildingfootprint,topography, and vegetation information; analyzes their effects onthermal load and thermal comfort; and spatially classifies thermalimpacts into several categories (CUHK, 2008). Map results showthattheinteractionbetweenurbanstructuresandclimatebecomesmoreprominentwhenthecityisnotlocatedinaflatterrain.Urbanventilationorwindpathswithinthecitywillalsochangeaccordingto the topographic condition. Therefore, it is not only the land useand the urban structures that are considered in the map, but alsothe topography and its influence on urban and rural ventilation. 2.2. Estate level climatic mapping  Urbanclimaticmappingattheestate(neighbourhood)levelpro-vides a more detail climatic condition, i.e., urban air temperature,ascomparedtoanurbanclimaticmapatthecitylevel,asitusuallyhas the scale of 1:5000–1:100,000 with the resolution of 100mgrid. Known as a temperature map, its methodology was devel-oped based on the findings that urban air temperatures are closelyrelatedtolanduses(Jusufetal.,2007),whichinturnarerelatedtourban morphology characteristics, such as sky view factors, green-erycondition,thermalmassofthebuiltenvironment,andbuildingmaterials (Jusuf and Wong, 2009). While urban planners are notabletomodifytheoverallclimatecondition,theycanmodifyurbanmorphology conditions. With the temperature map, planners areable to analyze the impacts of their design to the environment.The Screening Tool for Estate Environment Evaluation (STEVE)was developed with the motivation to bridge urban climaticresearch findings, especially air temperature prediction models,with urban planning and design efforts. STEVE is a web-basedapplication that is specific to an estate and it calculates the T  min , T  avg and T  max of a point of interest for the existing condition andfuture condition (proposed master plan) of an estate. With STEVE,urban planners are able to calculate the predicted air temperatureeasily based on their designs and do some design changes whenthey encounter hotspots. Therefore, urban planners do not needto engage scientist to assess their designs and thus can expeditethe design process without compromising the emphasis on thesustainable urban design. 3. Prospects for an urban climatic analysis tool To develop a sustainable city, it is not sufficient to focus onlyon green building designs. Sustainable designs must be looked aton a wider scale. The prospect of an effective urban climatic anal-ysis tool lies on how to analyze the interaction between buildingsandtheirsurroundingenvironmentsasanintegratedurbandesignprocess. This interaction cannot be separated from the geographi-calcontext,inwhichGIShasthestrongestcapability.Dangermond(2009)uses the term GeoDesign, which brings geographic analysisinto the design process, where initial design sketches are instantlyvetted for suitability against a myriad of database layers describ-ing a variety of physical and social factors for the spatial extentoftheproject.Theadvancementoftheurbanclimaticanalysistoolfromthecurrentsituationtothefuturecanbecategorizedintofourparts, which are shown inFig. 1and are explained in the followingsections. 3.1. Integration of 3D modelling with the GIS simulation platform The current GIS platform can be considered as two or two-and-a-halfdimensioninsteadofthreedimensioninterface,wherethe X  and Y  coordinates are displayed as graphics and the Z  coordinatesarestoredastheattributesoftheobjects,suchasmapsandterrainmodels. As compared to the computer-aided design (CAD) and/orbuildinginformationmodelling(BIM)software,bothhavedifferentfunctions, have their own strengths, and work at different scales.The CAD and BIM tools are mainly used in the Architecture Engi-neering and Construction (AEC), while GIS is meant for geospatialanalysis.The integration between these two platforms is the next direc-tion. There should be integration between the geographic dataand spatial modelling into the design process. The main chal-lenge is at the information workflows or data interoperability of the two domains. Interchangeable data formats among various 3Dmodelling approaches becomes critical. The Industry FoundationClasses (IFC) has established a standard for it. However, the build-ingmodelinCAD/BIMisusuallynotgeo-referencedtothelocationwhere the building sits. It will be beneficial if in the early stageof the design process contextual information is included as part of the building design, such as terrain, surrounding buildings, roads,utilities, and environmental issues. A building often relates to theothersurroundingbuildingsintermsofdesignandoperationwhichmight include the design of inter-building tunnels or skywalks orconnectionofotherinfrastructure.Inclusionofgeospatialreferenc-ing systems in BIM will facilitate the integration of multiple BIMmodels for precise design. 3.2. Integration of different climate data into an integratedsimulation platform The urban boundary layer microclimatic condition is verydynamic and complex, either due to the macro climatic conditionsor urban morphology conditions. Any urban morphology changes  Author's personal copy 388 N.H. Wong et al. / Landscape and Urban Planning  100 (2011) 386–389 Fig. 1. Workflow concept of the integrated Geographical Information System (GIS)-based urban environment assessment tool. in an area will result in a change in the surrounding air temper-ature, air movement pattern and solar radiation exposure. Theseparameters are currently obtained from different simulation soft-ware,forexample,airtemperaturebySTEVEinGISplatform,windpatternbyComputationalFluidDynamics(CFD)andsolarradiationexposure by Ecotect.Ideally,inthecontextofsustainableurbandevelopment,urbanplanners should analyze these parameters all together and obtainthe optimum results during the master planning process. Integra-tion of different simulations result into a common platform ordevelopingsimulationmodelsinacommonplatformbecomescrit-ical. By doing this, the problem of segregation between differentclimatic data will be resolved.The goal is to generate an Urban Thermal Comfort map wheretemperature, wind and solar radiation exposure layers are ana-lyzed together inside the GIS platform. Planners can then analyzeexpected comfort levels and make changes in the design at thelocations where it is uncomfortable. Meanwhile, the 3D cumula-tive building facades solar insolation layer will be integrated withtheearliersimulatedtemperature,simulatedwind,inhabitantdata,and land use data to develop an urban potential cooling energyconsumption map. Finally, the Urban Thermal Comfort map andthe urban potential energy consumption map will create an urbanliveability index. 3.3. Integration of the simulation platform with the web server asa collaborative design tool The integration of 3D CAD/BIM modelling with GIS platformexplained in Section3.1will be optimal if it can be done through awebserversincedesigningacompletecitymasterplanisacollabo-rativeandmultidisciplinarytask.Thiseffortissimilartotheideainthe SEMPER-II (S2) project (Lam et al., 2006), which developed anInternet-based building design and performance simulation envi-ronment, but at building scale as compared to a neighbourhood orcity scale. The challenge now is even greater than the S2 project,because there must be a web services architecture integrating theworkflows and information resources of CAD/BIM with GIS. TheOpen Geospatial Consortium (OGC) is currently looking into thisaspect (Cote, 2007). Once the interoperability between platformshas been established through a web service, the city scale simula-tionwillthenbedevelopedwithinthiswebservice.Urbanplannerswill be able to obtain relevant planning information, for example,fromgovernmentagenciesorgeo-engineers,throughthiswebser-viceandproceedseamlesslywithplanning,impactassessment,anddesign submission. 3.4. Integration between real time urban climate data and thesimulation platform as a boundary condition of the simulationscenarios The real urban boundary layer climate data can be consideredas non-existent since most of the meteorological data of a city isgatheredattheairportlocatedoutsideofthecity.Usingthismeteo-rologicaldataastheboundaryconditionofasimulationstudyatthecity center may lead to an incorrect prediction result. Researchersusually conduct a field measurement for a certain period of timeif the time permits, otherwise, it will just be an instantaneousmeasurement before running the simulation study. However, thismethod will no longer be sufficient if the simulation is needed aspart of the design process and its iterations.With the issue of sustainable development and climate change,itistheurbanregulatorybodiesthatareencouragedtoinvestinanurban climate measurement network integrated with, for exam-ple, traffic cameras, and make the data available to the public.Over a long period of time, this urban climate data will be usefulin various ways, not only for the immediate information of city’smicroclimate condition to the public, but also for research andpolicy making, such as for the study of the microclimate changesof a city. The simulation platform will then be connected to thereal-time urban climate data through a web service and users willbe able to select the nearest station as their boundary conditioninputs.
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