Teses de doutoramento

Indoor walls and ceilings are often coated with plasters. Due to the large surface in contact with indoor air, the plasters can passively contribute to moisture regulation and pollutant removal. The work presented intends to better understand this contribution, while enhancing, when possible, the plasters formulations for the purpose. The first step was to analyze the hygroscopic response of traditional and modern binder-based plasters. To do so, a first study was run to quantify the relative humidity fluctuations indoor. Then, the methods fitting the most the real indoor microclimates were selected for testing. The campaign was run along with bibliographic research, to match laboratory results with those ones present in literature. The compatibility with the preexisting materials and products and the eco-efficiency of the plasters are two parameters that were kept in mind during the work. According to that, clay and gypsum based plastering mortars were selected as the most promising materials. Both, in fact, are present in traditional architecture, besides being suitable solutions for new construction, and have low embodied energy. However, while the clay-based plasters showed a high hygroscopic behavior, the gypsum-based ones showed a lower one. For this reason, the latter was modified through the addition of biomass and the clay-based plasters were kept as a benchmark along the study. The plant selected for the scope is Acacia dealbata, an invasive species that plays a role in the spread of wood fires in Portugal. The biowaste addition was aimed at enhancing the moisture buffering of gypsum-based plasters without jeopardizing other properties or their carbon footprint. Good results were obtained, increasing the moisture buffering ability of the gypsum plaster up to double, even if still lower than the clay-based ones. The ozone reactivity and primary and secondary emission rates (VOCs) of the innovative gypsum-based plaster and the clay-based ones were also analyzed. The ozone removal ability of the gypsum-based plaster was improved by the biomass addition, the primary emissions increased a little, but the secondary ones were very low. Clay-based plasters overall confirmed their low emissions and ozone removal activity.

Exposure to weathering conditions requires selecting and applying solutions with appropriate durability to preserve façades without the need for frequent extensive rehabilitation actions. The consequent heat gain from solar radiation exposure accelerates the degradation of the most exposed façade layer, reducing their service life. An attractive solution to mitigate this overheating is the incorporation of functional nanomaterials in the façades finishing coatings, which reflect a part of the solar radiation in the near-infrared region. This solution may have an even higher influence on dark-coloured coatings, whose use has been increasing by architects and final consumers. To design more energy-efficient buildings, applying thermal insulation systems, such as External Thermal Insulation Composite Systems (ETICS), is necessary. These systems experience significant surface temperature fluctuations (amplified by the dark colour application), causing dimensional variations and naturally leading to cracking.Therefore, this Doctoral Thesis proposes a strategy combining these two façade solutions: dark-coloured finishing coatings applied on ETICS, aiming to improve solar reflectance and reduce the surface temperature. The study focused on developing new dark-coloured formulations with reflective nanomaterials, without excessively changing the visual aesthetics. A systematic study of their intrinsic properties was performed to understand and predict the nanomaterials' behaviour and ability to reflect or absorb. Subsequently, a commercial TiO2 Rutile and a newly developed nanocomposite, combining two nanomaterials, were included in a dark-coloured commercial finishing coating for ETICS and the surface properties were evaluated. The thermo-optical properties revealed an overall total reflectance increase for the two samples (15% and 20%) compared to only 12% of the non-modified finishing coating, providing a similar visual aesthetic. The reflectance improvement observed with the incorporation of nanomaterials certainly impacted the surface temperature, as the modified finishing coatings showed better performance and durability, as evidenced in the accelerated ageing test as thermal oscillations responsible for fractures are reduced.From these results, this strategy could emerge as a promising solution for low-cost dark reflective coatings that can be easily applied on building façades

This research aims at developing a comprehensive approach for assessing the energy use and efficiency in wastewater systems, considering the water-energy-greenhouse gas (W-E-G) emissions nexus supported by methods and tools, such as a tailored energy balance and a performance assessment system (PAS). This approach is aligned with continuous improvement principles and allows carrying out the diagnosis of energy efficiency in wastewater systems supporting the building of a portfolio of energy use improvement measures responding to strategic objectives and attending to the systems

A presente tese tem como objetivo melhorar a gestão dos sistemas de distribuição de água através da utilização de métodos probabilísticos e estatísticos para analisar os dados de contadores inteligentes. Assim, é proposta uma metodologia para avaliação da incerteza em medições de caudal dinâmicas, baseada apenas nas próprias medições, no método de bootstrap por blocos e no ajustamento de um modelo adequado aos dados em estudo. De seguida, é desenvolvida uma metodologia de amostragem probabilística estratificada dos clientes para identificação de uma amostra representativa onde deverão ser instalados contadores inteligentes, sendo os estratos definidos pelos grupos obtidos numa análise de clusters baseada em dados de faturação. É ainda apresentada uma metodologia para a decomposição¸ de séries temporais de caudal em consumo autorizado, consumo não autorizado, roturas e perdas, utilizando técnicas de suavização de séries temporais e análise do espetro singular (singular sprectum analysis). Por último, são testados alguns métodos robustos e de analise funcional para deteção de valores anómalos em series temporais de caudal.

Os efeitos das alterações climáticas aumentaram a necessidade de investigar a capacidade da vegetação em atenuar a força das ondas, nas zonas costeiras. Apoiando-se em modelação física, analítica e numérica da propagação de ondas sobre vegetação, este estudo teve como objetivos: i) analisar a diferença na dissipação de ondas sobre campos de vegetação rígida e flexível, ii) caracterizar o movimento de vegetação flexível, iii) estimar o coeficiente de arrasto de vegetação rígida e vegetação flexível, e iv) analisar a influência da flexibilidade (movimentoda vegetação) e da força de inércia no coeficiente de arrasto.

Drinking water storage tanks are essential components of water supply systems to store water, to level off pressure in networks and to meet emergency storage. They are also frequent sources of deterioration of drinking water quality and safety owing to inadequate tank design and operation. Mostly, existing tanks design, dimensions and operation do not account for water mixing and renewal.

Nature-Based Solutions (NBS) are crucial to achieving the goals of the United Nations Agenda 2030 for sustainable development and other global agendas, such as the Paris Agreement on Climate Change. In the last decade, the NBS umbrella concept has become more relevant intending to contribute to urban resilience and to address the climate change challenges. NBS are living solutions inspired by nature that use or mimic natural processes intending to face several societal challenges, from the perspective of resource-efficient use and the promotion of economic and environmental benefits. Currently, cities are encouraged to understand and measure the NBS contribution to identify adequate strategies for enhancing resilience and prioritize investments accordingly. The objective of the present thesis is to promote and enhance the NBS implementation in cities, focused on solutions for stormwater management and control. Based on the analysis of their contribution to urban resilience, the potential to meet environmental, social, and economic challenges and to adapt across diverse urban scales and contexts is demonstrated. In this sense, a Resilience Assessment Framework (RAF) to assess the NBS contribution to urban resilience was developed. This framework aims to assess the NBS contribution to urban resilience. Moreover, a Guidance for the RAF application in cities with different resilience maturity was developed, which involved the RAF validation by seven cities (from a national and international context), that participated voluntarily in this phase. In this context, the developed RAF is comprehensive and multidimensional. It is driven by the definition of objectives, criteria, and metrics, according to the proposed structure for assessing the water supply and wastewater system service performance in the framework of the ISO 24500 standards of the International Organization for Standardization. For an oriented assessment of the criteria, qualitative and quantitative metrics were defined, considering data from different sources and complexity. Reference values were also identified and metrics' classifications were defined. In this classification, each answer is associated with a resilience development level, intending to assess the NBS contribution to urban resilience on a normalized scale. To support the RAF application to cities with different resilience maturity (in terms of resilience and available information), three analysis degrees (essential, complementary, and comprehensive) and a set of metrics were proposed, which are pre-defined in the guidance for the RAF application. To support the selection of the analysis degree more adequate to any city, a structure to characterize the city's profile was developed. This complementary profile also supports the interpretation of the RAF results, both at the city and at the level of specific NBS. To conclude, the application of the RAF essential analysis degree to the seven participating cities, with different challenges regarding urban resilience and NBS, and of the comprehensive analysis degree (complete RAF) to Porto´s urban area, through an assemble assessment at the city and NBS levels, were presented.

Over the past two decades, performance assessment (PA) has been one of the areas show-ing the greatest advancement in the water sector. PA aims to measure effectiveness and/or efficiency of an activity or process using performance metrics, supporting the decision-making process and the continuous improvement of water utilities. Despite the potential benefits, few projects, and initiatives on PA have been undertaken regarding storm water systems (SWS). The present thesis aims to develop a performance assessment framework (PAF), applicable to both conventional SWS and sustainable urban drainage systems (SUDS), objective driven and focused on systems

Infrastructure asset management (IAM) has been increasingly becoming a key topic in the mind-set shift of the water sector managers and policy makers, allowing to assist in the operational, tactical and strategic decision-making in urban water infrastructures. Nevertheless, IAM implementation by the water utilities is still far from needed and not widespread, due to several challenges and constraints, mainly associated with limited human, technological and financial resources. The current research aims at enhancing urban water infrastructure asset management through an integrated decision-making approach, that includes novel methodologies for condition assessment, service life prediction and cost modelling. This approach can be applied at three assessment levels

Transportation infrastructures are vital to our society. These infrastructures naturally tend to deteriorate over time. A set of activities is then required to manage existing assets in accordance with sound management principles. These activities are usually integrated into systems that manage infrastructures according to technical, social and economic aspects. This research aims to examine the potential of applying machine learning techniques to current transportation infrastructure management systems. Machine learning is an application of artificial intelligence enabling systems to automatically learn and improve from experience (data), arriving at solutions not explicitly programmed. Powered by algorithms that can learn from data, machine learning leads to efficient and effective systems that improve over time. Over the last few years, the application of machine learning has transformed several industries and could do so for transportation infrastructure as well.To achieve the research objectives, a set of studies was performed. Each of these studies had a specific objective, the set of which can be expressed as follows: to define combined performance indicators for pavement condition assessment using machine learning; to develop machine learning models for pavement performance prediction; to formulate machine learning solutions to overcome pavement data issues, such as missing data; to integrate machine learning techniques into decision support systems for pavement maintenance management. Together these studies explored the development of machine learning applications for solving some standard pavement management problems, providing insights into the application of machine learning to transportation infrastructure management systems. The studies successfully demonstrated the potential of machine learning applications for pavement management systems. It showed that machine learning is applicable to various transportation asset management problems, such as condition assessment, performance prediction, and decision support, and that it is able to outperform some of the analytical techniques currently used. Overall, this research work finds that machine learning is a promising tool for transportation infrastructure management systems.