Défense de thèse

A methodology for cost-optimal zero-energy lightweight construction for roof stacking

Nous avons le plaisir de vous convier à la défense de thèse de Monsieur Mohamed Amer. Celle-ci se déroulera le vendredi 15 novembre à 14h, au local R7 (Institut Montefiore).

Cette thèse, réalisée sous la direction du prof. Shady Attia s'intitule "A methodology for cost-optimal zero-energy lightweight construction for roof stacking".



Roof stacking is the added structure over the rooftop of an existing building to create one or more stories of living space. Thus, roof stacking represents a sustainable approach towards urban densification and a feasible mean to overcome the challenge of accommodating increasing populations in cities. However, several challenges are associated with roof stacking, which differs from those of conventional or “stick” buildings. Unfortunately, until now, roof stacking has not been given a significant importance as a research topic within the scientific communities. Accordingly, this research aims to provide a leadership to support the decision making on roof stacking construction, and to accelerate the transformation towards cost-effective and zero-energy housing in Europe. In order to achieve this aim, this research addresses this topic from a generic, yet comprehensive perspective.

First a methodology has been established to facilitate the decision making on urban densification through roof stacking. The methodology adopts a systematic approach on three consecutive levels: urban, engineering, and social. Several criteria are identified to assess and map the roof stacking potential in terms of location and number of added floors, where Brussels Capital Region has been taken as a case study, on both urban and building scales.

A conceptual framework of a multidisciplinary decision making for selecting off-site prefabricated constructional system for roof stacking has been developed. The multidisciplinary approach includes each of safety, logistics, cost, time, environmental impact, and quality of construction as major criteria in the decision making process. This section includes a classification for roof stacking construction methods based on an exhaustive investigation of more than 136 roof stacking projects built during the last 20 years. Afterwards, a list of 37 sustainable criteria, on which the decision making on roof stacking takes place, have been identified based on sustainability triple bottom line, i.e. environmental, economic, and social. Those criteria have been identified based on intensive review of literature, individual interviews, and pilot surveys. A questionnaire has been design and distributed to architects, as active stakeholders, in addition to researchers from the field of building and construction.

At the final stage, this research develops a methodology that supports the decision making process for cost-optimal zero energy lightweight construction, by the means of a novel approach, namely Multi-Objective Parametric Analysis (MOPA). This methodology is composed of three consecutive steps: modelling setup, parametric simulation, and ends up with evaluation and selection. The methodology has been applied on a simulated and calibrated case study in Brussels, where the results show that it is possible to achieve optimum measures without the need for optimization algorithms, which fosters the transparency and repeatability to the developed methodology. The multi-level approach in this thesis aligns and strengths the common practices of the decision-making process.

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