Quantitative ventilation assessments of idealized urban canopy layers with various urban layouts and the same building packing density

This paper investigates urban canopy layers (UCL) ventilation under neutral atmospheric condition with the same building area density (λp=0.25) and frontal area density (λf=0.25) but various urban sizes, building height variations, overall urban forms and wind directions. Turbulent airflows are first predicted by CFD simulations with standard k-ε model evaluated by wind tunnel data. Then air change rates per hour (ACH) and canopy purging flow rate (PFR) are numerically analyzed to quantify the rate of air exchange and the net ventilation capacity induced by mean flows and turbulence. With a parallel approaching wind (θ=0o), the velocity ratio first decreases in the adjustment region, followed by the fully-developed region where the flow reaches a balance. Although the flow quantities macroscopically keep constant, however ACH decreases and overall UCL ventilation becomes worse if urban size rises from 390m to 5km. Theoretically if urban size is infinite, ACH may reach a minimum value depending on local roof ventilation, and it rises from 1.7 to 7.5 if the standard deviation of building height variations increases (0% to 83.3%). Overall UCL ventilation capacity (PFR) with a square overall urban form (Lx=Ly=390m) is better as θ=0o than oblique winds (θ=15o, 30o, 45o), and it exceeds that of a staggered urban form under all wind directions (θ=0o to 45o), but is less than that of a rectangular urban form (Lx=570m, Ly=270m) under most wind directions (θ=30o to 90o). Further investigations are still required to quantify the net ventilation efficiency induced by mean flows and turbulence.

Sunlit fractions on urban facets: impact of spatial resolution and approach

The extent of the surface area sunlit is critical for radiative energy exchanges and therefore for a wide range of applications that require urban land surface models (ULSM), ranging from human comfort to weather forecasting. Here a computational demanding shadow casting algorithm is used to assess the capability of a simple single-layer urban canopy model, which assumes an infinitely long rotating canyon (ILC), to reproduce sunlit areas on roof and roads over central London. Results indicate that the sunlit roads areas are well-represented but somewhat smaller using an ILC, while sunlit roofs areas are consistently larger, especially for dense urban areas. The largest deviations from real world sunlit areas are found for roofs during mornings and evenings. Indications that sunlit fractions on walls are overestimated using an ILC during mornings and evenings are found. The implications of these errors are dependent on the application targeted. For example, (independent of albedo) ULSMs used in numerical weather prediction applying ILC representation of the urban form will overestimate outgoing shortwave radiation from roofs due to the overestimation of sunlit fraction of the roofs. Complications of deriving height to width ratios from real world data are also discussed.

Urban sustainability and market typologies : lessons from Tabriz Bazaar

The market is an essential component of urban form. Contemporary shopping malls can benefit from the inherent efficiencies of traditional markets. This paper addresses the development of sustainable models of market typologies based on a specific case study, the Bazaar of Tabriz in Iran.

As one of the biggest historical covered markets in the world (Moradi and Nassabi 2007), it remains an effective trading centre in the city. What are the lessons that make Tabriz a sustainable urban typology and what lessons can we draw from its spatial and operational structure?

To address this question, the paper presents two analytical studies of the urban and building morphology of Tabriz. First, the paper presents an analysis of the urban and social structure of the market based on Lynchian analysis. Second, it provides an analysis of the thermal, ventilation and lighting principles used in the buildings of the market and how they respond to the extreme climatic conditions of north-west Iran.

Rainfall and snow in one side and hot summers in the other, give the buildings in the city really critical performance in terms of life span during the years of operation.

The main target in this case study, is to illuminate the urban typological clarifications in the Bazaar of Tabriz, which wilt elucidate how parallel links between urban morphology (land cover) and urban typology (land use) in a defined urban planning can form a sustainable urban space. Moreover, how the case of this study can be an energy efficient complex with its own urban morphology.

The lessons of Tabriz for the development of contemporary markets are summarised in the paper and need to be addressed at two scales, namely the urban scale and the scale of the building.

Urban sprawl and energy use for transportation in the largest Brazilian cities

A study of the relationships between the amount of energy consumed for transportation purposes and a few selected variables related to urban form and socioeconomic characteristics of some of the largest Brazilian cities is conducted in this work. The studied cities include all 27 state capitals regardless of their size and population and 184 urban areas each with more than 20,000 inhabitants located in the state of São Paulo. Two different techniques were applied for data analyses: a more traditional regression analysis approach and artificial neural networks. In general, the results found in the analyses conducted here support the assumption that urban sprawl increases the energy use for transportation. In the case of the 27 state capitals, the analysis indicated that two spatial variables have a strong impact on the energy consumed for urban transportation: urban density and the ratio between the longest distances in the east-west and north-south directions. In the case of the 184 urbanized areas we also reached a similar conclusion. In that case, however, income and employment level apparently have a stronger influence on the amount of energy consumed. The results of the present study stress the importance of physical planning in developing country cities in order to reduce energy use for transportation. © 2007 International Energy Initiative, Inc.

Analysis of the Technical Efficiency of Urban Bus Services in Spain Based on SBM Models

During the first decade of the new millennium, fueled by the economic development in Spain, urban bus services were extended. Since the years 2008 and 2009, the root of the economic crisis, the improvement of these services is at risk due to economic problems. In this paper, the technical efficiency of the main urban bus companies in Spain during the 2004–2009 period are studied using SBM (slack-based measures) models and by establishing the slacks in the services' production inputs. The influence of a series of exogenous variables on the operation of the different services is also analyzed. It is concluded that only the 24% of the case studies are efficient, and some urban form variables can explain part of the inefficiency. The methodology used allows studying the inefficiency in a disaggregated way that other DEA (data envelopment analysis) models do not.

Sustainable Australia : containing travel in master planned estates

Low density suburban development and excessive use of automobiles are associated with serious urban and environmental problems. These problems include traffic congestion, longer commuting times, high automobile dependency, air and water pollution, and increased depletion of natural resources. Master planned development suggests itself as a possible palliative for the ills of low density and high travel. The following study examines the patterns and dynamics of movement in a selection of master planned estates in Australia. The study develops new approaches for assessing the containment of travel within planned development. Its key aim is to clarify and map the relationships between trip generation and urban form and structure. The initial conceptual framework of the paper is developed in a review of literature related to urban form and travel behaviour. These concepts are tested empirically in a pilot study of suburban travel activity in master planned estates. A geographical information systems methodology is used to determine regional journey-to-work patterns and travel containment rates. Factors that influence selfcontainment patterns are estimated with a regression model. This research is a useful preliminary examination of travel self-containment in Australian master planned estates.

Research Monograph: The role of community and lifestyle in the making of a knowledge city

Our brief is to investigate the role of community and lifestyle in the making of a globally successful knowledge city region. Our approach is essentially pragmatic. We start by broadly examining knowledge-based urban development from a number of different perspectives. The first view is historical. In this context knowledge work and knowledge workers are seen as vital parts of a new emergent mode of production reliant on the continual production of abstract knowledge. We briefly develop this perspective to encompass the work of Richard Florida who has, notedly, claimed: “Wherever talent goes, innovation, creativity, and economic growth are sure to follow.” Our next perspective examines concepts of knowledge and modes of its production to discover knowledge is not an unchanging object but a human activity that changes in form and content through history. The suggestion emerges that not only is the production of contemporary ‘knowledge’ organised in a specific (and new) manner but also the output of this networked production is a particular type of knowledge (i.e. techné). The third perspective locates knowledge production and its workers in the contemporary urban context. As such, it co-ordinates the knowledge city in the increasingly global structure of cities and develops a typology of different groups of knowledge workers in their preferred urban environment(s). We see emerging here a distinctive geography of knowledge production. It is an urban phenomenon. There is, in short, something about the nature of cities that knowledge workers find particularly attractive. In the next, essentially anthropological, perspective we start to explore the needs and desires of the individual knowledge worker. Beyond the needs basic to any modern human household an attempt is made to deduce, from a base understanding of knowledge work as mental labour, the compensatory cultural needs of the knowledge worker when not at work - and the expression of these needs in the urban fabric. Our final perspective consists of two case studies. In a review of the experiences of Austin, Texas and Singapore’s one-north precinct we collect empirical data on, respectively, a knowledge city that has sustained itself for over 50 years and an urban precinct newly launched into the global market for knowledge work and knowledge workers. Interwoven The Role of Community and Lifestyle in the Making of a Knowledge City Urban Research Program 8 through all perspectives, in the form of apposite citation, is that of ‘expert opinion’ gathered in a rudimentary poll of academic and industry sources. This opinion appears in text boxes while details of the survey can be found in Appendix A. In the conclusion of the report we interpret the wide range of evidence gathered above in a policy frame. It is our hope this report will leave the reader with a clearer picture of the decisive organisational, infrastructural, aesthetic and social dimensions of a knowledge precinct.

Research Monograph : Sustainable Australia : Containing travel in master planned estates

Low density suburban development and excessive use of automobiles are associated with serious urban and environmental problems. These problems include traffic congestion, longer commuting times, high automobile dependency, air and water pollution, and increased depletion of natural resources. Master planned development suggests itself as a possible palliative for the ills of low density and high travel. The following study examines the patterns and dynamics of movement in a selection of master planned estates in Australia. The study develops new approaches for assessing the containment of travel within planned development. Its key aim is to clarify and map the relationships between trip generation and urban form and structure. The initial conceptual framework of the report is developed in a review of literature related to urban form and travel behaviour. These concepts are tested empirically in a pilot study of suburban travel activity in master planned estates. A geographical information systems (GIS) methodology is used to determine regional journey-to-work patterns and travel containment rates. Factors that influence self-containment patterns are estimated with a regression model. The key research findings of the pilot study are: - There is a strong relation between urban structural form and patterns of trip generation; - The travel self-containment of Australian master planned estates is lower than the scholarly literature implies would occur if appropriate planning principles to achieve sustainable urban travel were followed; - Proximity to the central business district, income level and education status are positively correlated with travel containment; - Master planned estates depend more on local and regional centres for employment than on the central business district; - The service sector is the major employer in and around master planned estates. It tends to provide part-time and casual employment rather than full-time employment; - Travel self-containment is negative correlated with car dependency. Master planned estates with less car dependent residents, and with good access to public transport, appear to be more self-contained and, consequently, more sustainable than the norm. This research is a useful preliminary examination of travel self-containment in Australian master planned estates. It by no means exhausts the subject. In future research we hope to further assess sustainable travel patterns with more detailed spatial analysis.

Members abroad - Australia - Brisbane and the Gold Coast

Brisbane's sub-tropical climate, vegetation and urban history as a British settlement, endow the region with many characteristics that are familiar in KwaZulu-Natal. Brisbane settlement, firstly as a penal conlony to accommodate the hardiest criminals dispatched from Sydney, was established in 1825 on a wide river, several kilometers upstream from Moreton Bay with the Pacific Ocean beyond. The penal colony was short lived and was soon opened up to free settlement in 1842. The growth of the fledgling town was characterized by brick warehouse and service buildings to the port that was established on its riverbanks, resembling those of the old Point Road area in Durban. Government and administration buildings heralded Brisbane as the captial city of the State of Queensland, annexed from New South Wales in 1859. Morphological studies reveal that Brisbane had reached its first zenith around 1930 as a commerical city of four and five storey buildings. The urban form remained stagnant until the post-1960's building boom and the developments from this period on, consolidated land amalgamations largely ignoring the urban characteristics of the established city. Public space was poorly observed, resulting in a city that had turned its back on the river. It is only in recent times that the currency of good urban design, under the custodial direction of the City Council, has fostered a re-engagemed urban realm that, enabled by the recent building boom, has delivered high quality urban environments

Members abroad - Australia : Paul Sanders

I have been an academic since joining the University of Natal in 1998 and, following a period as a visiting lecturer in Brisbane in 2001, I joined the staff at QUT on an ongoing basis in 2003. I was appointed as Architecture Co-ordinator in 2006, and this role involves the leadership of the architectur discipline of 17 full time academics. I am currently enrolled in a PhD course in the field of urban morphology. This research proposes a theory on the relevance of mapping the evolutionary aspects of historical urban form to develop a measure for evaluating architecural elements and deriving parameters for new buildings. My participation in a QUT design team contributed to a recent successful invited competition bid for an Urban Transit Centre in Hangzhou, China. The Centre will include retail, business, entertainment, residential and service components at the heart of the Binjiang district on the 11.5ha core area with 32ha surrounding urban design precinct. The project has received the approval to commence and is to be implemented over the next three years!

The rediscovery of traditional urbanism at Melrose Arch

Contemporary urban form, particularly in the cities of South Africa, lacks distinction and quality. The majority of developments are conceived as private and dislocated initiatives, surveiled enclaves with gated access being the only conduit to the outside world. Any concern for a positive contribution to the matrix of public activity is seldom a consideration. The urban form responds to the perception that traffic systems are paramount to the successful flux of the city in satisfying the escalating demands of vehicular movement. In contrast many of the urban centres around the world, the great historical centres of Europe, Americas and the Sub-Continent are admired and considered the ultimate models in urban experience. The colonnades, bazaars and boulevards hosting an abundance of street activity are the characteristics of such centres and are symptomatic of a city growth based on pedestrian movement patterns, an urbanism supportative of human interaction and exchange, a form which has nurtured the existence of a public realm. Through the understanding of the principles of traditional urbanism we may learn that the modernist paradigm of a contemporary suburbia has resulted in disconnected and separate land uses with isolated districts where a reliance on the car is essential rather than optional.

A planning support system for airport city development

Many airports around the world are diversifying their land use strategies to integrate non-aeronautical development. These airports embrace the “airport city” concept to develop a wide range of commercial and light industrial land uses to support airport revenues. The consequences of this changing urban form are profound for both airport and municipal planners alike and present numerous challenges with regard to integration of airport and regional planning. While several tools exist for regional planning and airport operational planning, no holistic airport landside and regional planning tool exist. What is required is a planning support system that can integrate the sometimes conflicting stakeholder interests into one common goal for the airport and the surrounding region. This paper presents a planning support system and evaluates its application to a case study involving Brisbane Airport and the South East Queensland region in Australia.

Australian landscape lineages

Stephen Krog has pointed out that landscape architecture has an ill-studied Modernist history, and further suggested that landscape architecture is too theoretically bereft to have a considered theoretical Post-Modernism anyway. The projects that make up the Sunburnt exhibition all emerge from practitioners who were educated during the Post-Modern period in Australia, roughly the 10 years between 1985 and 1995 - a period corresponding to the Australian Bicentennial celebrations in 1988. This essay will quickly trace lineages of education, office experience and ideas through the projects and practices during that period. In common with theories of Post-Modernism in architecture propounded at the time, many of the projects exhibit an interest in pluralistic views of places, cultures and issues, including engaging contextual relationships with places, and involving urban form. These designers were interested in form at a time when it was regarded as incidental rather than important.