Mobile Urban Micrometeorological Monitoring (MUMiM)

To understand the urban environment from a meteorological perspective in order to design better and more sustainable neighbourhoods, an open-source and low-cost meteorological device was developed and tested at the Ecole Polytechnique Fédérale de Lausanne (EPFL). The results underlined, for example, strong temperature gradients on the campus, particularly in built-up areas with a high density of artificial surfaces. Additionally, the outdoor human comfort was evaluated for multiple locations around the campus, underlying the impact of the urban surfaces as well as the city interface and the greening design. Such studies can be seen as crucial to provide information to stakeholders in the evaluation of their planning strategies either for mitigation (such as decrease of the urban heat island effect or greenhouse gas emissions) or for the adaptation (such as improvement of outdoor spaces to face future heat waves).

Concevoir à grande échelle

Mathieu Louis Pierre Mercuriali

Large-scale design - Mobility interface models and urban transformation strategies This research project is based on the hypothesis that the urban transformations generated by mobility interfaces constitute a key component of successful sustainable urban development. Effectively visioning and understanding these multimodal interchange hubs must therefore become a major strategic objective, in order to conceive an urban model that is compact - and networked and intelligent. With this aim in mind, this research aims to propose innovative strategies for transforming these communication interfaces into central reference points within the contemporary metropolitan landscape. Projects of this kind have already been designed and realised in most major European cities during the second half of the 20th century. These designs, characterised by their complexity and scale, formed the starting point of the major railway stations in today's cities, incorporating different forms of mobility over the course of time. Today they appear not just detached from their urban contexts - the very contexts in which they are embedded - but also unable to meet the current demand for functional mixity and communication effectively. They are undergoing obsolescence and finding it difficult to adapt to the paradigm shifts that have intervened - socially, economically and spatially. At a time when the city can no longer be conceived exclusively in terms of ex-nihilo construction, but must be viewed in terms of transforming an existing built fabric, what future can be proposed for these existing transport interfaces? What strategies can be developed to anchor them in their surrounding urban context? What capacity do they have for hosting new activities, new public and private spaces? Finally, what forms is it possible to imagine for this kind of design? Three hypotheses emerge: the development of mobility interfaces has generated specific architectural and urban forms correlating to the evolution of mobility forms themselves; the transformation and obsolescence phases of mobility interfaces offer potentials for metropolitan regeneration; and the process of producing a complex design calls for articulation and interrelation between different architectural and urban scales. To verify these hypotheses, the first part of this thesis is focused on the comprehension and analysis of these multimodal hubs, based on a review of architectural and urban theories that address the issue of how major urban projects relate to transport infrastructures. This is followed by close analysis of a series of relevant case studies within the Paris metropolitan area. The second part of the thesis proposes design tools to generate new urban and architectural design processes, derived from a process of design-based research. The final part of the thesis aims to demonstrate that this type of intervention is a design project with its own specific scale and complexity: between large building and urban fragment.

EPFL2015

An urban ecohydrological model to quantify the effect of vegetation on urban climate and hydrology (UT&C v1.0)

Paolo Burlando, Matthias Roth

Increasing urbanization is likely to intensify the urban heat island effect, decrease outdoor thermal comfort, and enhance runoff generation in cities. Urban green spaces are often proposed as a mitigation strategy to counteract these adverse effects, and many recent developments of urban climate models focus on the inclusion of green and blue infrastructure to inform urban planning. However, many models still lack the ability to account for different plant types and oversimplify the interactions between the built environment, vegetation, and hydrology. In this study, we present an urban ecohydrological model, Urban Tethys-Chloris (UT&C), that combines principles of ecosystem modelling with an urban canopy scheme accounting for the biophysical and ecophysiological characteristics of roof vegetation, ground vegetation, and urban trees. UT&C is a fully coupled energy and water balance model that calculates 2 m air temperature, 2 m humidity, and surface temperatures based on the infinite urban canyon approach. It further calculates the urban hydrological fluxes in the absence of snow, including transpiration as a function of plant photosynthesis. Hence, UT&C accounts for the effects of different plant types on the urban climate and hydrology, as well as the effects of the urban environment on plant well-being and performance. UT&C performs well when compared against energy flux measurements of eddy-covariance towers located in three cities in different climates (Singapore, Melbourne, and Phoenix). A sensitivity analysis, performed as a proof of concept for the city of Singapore, shows a mean decrease in 2 m air temperature of 1.1 ∘C for fully grass-covered ground, 0.2 ∘C for high values of leaf area index (LAI), and 0.3 ∘C for high values of Vc,max (an expression of photosynthetic capacity). These reductions in temperature were combined with a simultaneous increase in relative humidity by 6.5 %, 2.1 %, and 1.6 %, for fully grass-covered ground, high values of LAI, and high values of Vc,max, respectively. Furthermore, the increase of pervious vegetated ground is able to significantly reduce surface runoff.

2020

An urban ecohydrological model to quantify the effect of vegetation on urban climate and hydrology (UT&C v1.0)

Paolo Burlando, Matthias Roth

2020

Concevoir à grande échelle

Mathieu Louis Pierre Mercuriali

EPFL2015