Enhancing building performance : a Bayesian network model to support facility management

Premi Extraordinari de Doctorat, promoció 2018-2019. Àmbit d’Enginyeria Civil i AmbientalThe performance of existing buildings is receiving increased concern due to the need to renovate the aging building stock and provide better quality of life for end users. The conservation state of buildings and the indoor environment conditions have been related to occupants’ well-being, health, and productivity. At the same time, there is a need for more sustainable buildings with reduced energy consumption. Most challenges encountered during the analysis of the performance of existing buildings are associated with the complex relationships among the causal factors involved. The performance of a building is influenced by several factors (e.g., environmental agents, occupant behavior, operation, maintenance), which also generate uncertainties when predicting it. Most previous studies that investigate methods to assess a building’s performance do not consider the uncertainty and are often based on linear models. Although different stakeholders’ requirements regarding building performance coexist, few studies centered on the implications of these requirements. Previous studies tend to be highly specific on indicators related to a particular performance aspect, overlooking potential trade-offs that may occur between them. Therefore, a holistic and integrated approach to manage the performance of existing buildings has not been explored. Facility managers need an efficient approach to deal with uncertainty, to manage risks, and systematically identify, analyze, evaluate and mitigate factors that may impact the building performance. Taking into account the aforementioned aspects, the aim of this thesis is to devise a Bayesian network (BN) model to holistically manage the operational performance of buildings and support facility management. The proposed model consists of an integrated probabilistic approach to assess the performance of existing buildings, considering three categories: safety and elements working properly, health and comfort, and energy efficiency. The model also provides an understanding of the causality chain between multiple factors and indicators regarding building performance. The understanding of the relationships between building condition, end user comfort and building energy efficiency, supports facility managers to unwind a causal explanation for the performance results in a reasoning process. The proposed model is tested and validated using sensitivity analysis and data from existing buildings. A set of model applications are discussed, including the assessment of a building’s performance holistically, the identification of causal factors, the prediction of building performance through renovation and retrofit scenarios, and the prioritization of maintenance actions. Case studies also allow to illustrate the applicability of the model for ensuring that its interactions and outcomes are feasible. Scenario analyses provide a basis for a deeper understanding of the potential responses of the model, helping facility managers to optimize operation strategies of buildings in order to enhance its performance. The results of this thesis also include data collection methods for the inputs of the proposed BN model. A building inspection system is proposed to evaluate the technical performance of buildings, a text-mining approach is developed to analyze maintenance requests of end users, and a questionnaire is formulated to collect end-user satisfaction regarding building comfort. To conclude, this work proposes the use of Building Information Modeling (BIM) to store and access building information, which are typically disperse and not standardized in existing buildings.Actualmente, el desempeño de los edificios existentes es de gran interés debido a la necesidad de renovar el stock de edificios antiguos, proporcionando así una mejor calidad de vida a los usuarios finales. El estado de conservación de los edificios y las condiciones ambientales interiores se relacionan con el bienestar, la salud y la productividad de los ocupantes. Al mismo tiempo, existe la necesidad de edificios más sostenibles con un menor consumo energético. El desempeño de un edificio se ve afectado por varios factores (p.ej., agentes ambientales, comportamiento de los ocupantes, operación, mantenimiento, etc.). La mayoría de estos aspectos y causas muestran complejas relaciones, y consecuentemente existe una gran incertidumbre para predecirlo. Sin embargo, las investigaciones anteriores no contemplan estas relaciones causales y, a menudo, se basan en modelos lineales. Aunque el desempeño de los edificios se debe abordar teniendo en cuenta los requisitos de las diferentes partes interesadas, pocos estudios se centran en este enfoque. Los estudios anteriores tienden a analizar aspectos particulares del desempeño, ignorando las posibles relaciones que pueden ocurrir entre ellos. Los gestores de edificios deben abordar eficientemente la incertidumbre, gestionar los riesgos e identificar, analizar, evaluar y mitigar sistemáticamente los factores que pueden afectar el desempeño del edificio. Teniendo en cuenta los aspectos comentados anteriormente, el objetivo de esta tesis es desarrollar un modelo de red bayesiana (BN) para gestionar holísticamente el desempeño operativo de los edificios y apoyar su gestión. El modelo propuesto consiste en un enfoque probabilístico para evaluar el desempeño de los edificios existentes, considerando tres categorías: seguridad y funcionalidad, salud y confort, y eficiencia energética. El modelo también proporciona una interpretación de la cadena de causalidad entre los múltiples factores e indicadores relacionados con el desempeño del edificio. El análisis de las relaciones entre los diferentes aspectos del desempeño de los edificios (estado de conservación del edificio, el confort del usuario final y la eficiencia energética del edificio) va a permitir explicar y entender sus factores causales y va a posibilitar mejorar la gestión de estos edificios. La verificación del modelo propuesto se lleva a cabo mediante análisis de sensibilidad y datos de edificios existentes. Las aplicaciones del modelo incluyen: la evaluación del desempeño de edificios de forma integrada; la identificación de factores causales; la predicción del desempeño de los edificios a través de escenarios de renovación y modernización; y la priorización de las acciones de mantenimiento. La implementación del modelo en diversos casos de estudio permite ilustrar su aplicabilidad y validar su uso. Los resultados de esta tesis también incluyen métodos de recogida de datos para las variables del modelo propuesto. De hecho, se propone un sistema de inspección de edificios para evaluar el desempeño técnico de los edificios, se desarrolla un sistema de text mining para analizar las solicitudes de mantenimiento de los usuarios finales y se formula un cuestionario para recoger la satisfacción de los usuarios finales en relación a los espacios de los edificios en los que interactúan. Para concluir, este trabajo propone el uso del Building Information Modeling (BIM) para almacenar y acceder a la información necesaria para el modelo.Postprint (published version

Impact of service life on the environmental performance of buildings

The environmental performance assessment of the building and construction sector has been in discussion due to the increasing demand of facilities and its impact on the environment. The life cycle studies carried out over the last decade have mostly used an approximate life span of a building without considering the building component replacement requirements and their service life. This limitation results in unreliable outcomes and a huge volume of materials going to landfill. This study was performed to develop a relationship between the service life of a building and building components, and their impact on environmental performance. Twelve building combinations were modelled by considering two types of roof frames, two types of wall and three types of footings. A reference building of a 50-year service life was used in comparisons. Firstly, the service life of the building and building components and the replacement intervals of building components during active service life were estimated. The environmental life cycle assessment (ELCA) was carried out for all the buildings and results are presented on a yearly basis in order to study the impact of service life. The region-specific impact categories of cumulative energy demand, greenhouse gas emissions, water consumption and land use are used to assess the environmental performance of buildings. The analysis shows that the environmental performance of buildings is affected by the service life of a building and the replacement intervals of building components

Building information modeling for facility managers

A Decision Support System (DSS) can help facility managers to improve building performance, occupants’ comfort, and energy efficiency during the Operation and Maintenance (O&M) phase. These DSSs are normally data-intensive and have specific data requirements. Building Information Modeling (BIM) has the potential to advance and transform facilities O&M by providing facility managers with a digitalized virtual environment that allows them to retrieve, analyze, and process such data. However, the implementation of BIM in O&M phases is still limited. The majority of issues in the BIM-O&M context lie in the interoperability between different software that requires different data structures and formats. In a BIM environment, there are issues associated with extracting, storing, managing, integrating, and disseminating data so that interoperability is assured. Considering the aforementioned aspects, the aim of this thesis is to enable interoperability between BIM models and the DSSs for building performance aspects such as building condition, maintenance, and occupants’ comfort. This integration automatizes the data transfer process which can assist Facility Management (FM) team in properly establishing the necessary measurements to moderate the negative consequences on buildings and thereby improve their performance and occupants’ comfort. The approach can also provide FM teams with an effective platform for data visualization in a user-friendly manner that can assist in integrating digital insights into FM decision-making processes and converting them into positive strategic actions. The proposed approach is validated in existing software as a case study. It is possible to demonstrate the applicability of this approach by ensuring that its interactions and outcomes are feasible using case studies. Case studies also identify how much the task efficiencies are in comparison with the manual method, helping facility managers to optimize operation strategies of buildings in order to enhance their performance. Verification tests are also performed on the information exported from a software program. The results demonstrate an efficiency increase in high-quality FM data collection for different kinds of DSS, reducing the time and effort that the FM team spends on searching for information and entering data. A Dynamo script is designed to allow administrators to include as much information as they wish in BIM models. Moreover, a novel approach is proposed to create a new category in BIM to assist public and business administrations with managing assets efficiently. In addition, building performance aspects can also be analyzed using the proposed method of integrating occupants' feedback into BIM models. By implementing the proposed approach, FM teams are able to correctly establish measurements which can be applied to mitigate the negative effects on buildings, thus improving their performance and enhancing their occupants’ comfort. Besides, the proposed approach enables BIM to be a more useful tool for visualization by using the most appropriate charts and formatting.Un Sistema de Soporte de decisiones (SSD) puede ayudar a los gestores de edificios a mejorar su rendimiento, su eficiencia energética y el confort de sus ocupantes. Para el buen funcionamiento de los SSD se requieren muchos datos. El Building Information Modeling (BIM) permite mejorar la gestión de las operaciones y el mantenimiento de los edificios al proporcionar un entorno virtual digitalizado que permite recuperar, analizar y procesar los datos requeridos por los SSD. Sin embargo, la implementación de BIM en las fases de Operación y Mantenimimento (O&M) aún es escasa. La mayoría de los problemas en el contexto de BIM-O&M radican en la interoperabilidad entre diferentes programas que requieren diferentes estructuras y formatos de datos. En un entorno BIM, existen problemas asociados a la extracción, el almacenamiento, la gestión, la integración y la difusión de datos para garantizar la interoperabilidad. Teniendo en cuenta los aspectos antes mencionados, el objetivo de esta tesis es facilitar la interoperabilidad entre los modelos BIM y los SSD relacionados con el rendimiento de los edificios, su estado de conservación y el confort de los ocupantes. Esta integración automatiza el proceso de transferencia de datos que puede ayudar a los gestores de edificios a establecer correctamente las medidas necesarias para mejorar su rendimiento y el confort de sus ocupantes. Esta integración también va a proporcionar a los gestores de edificios una plataforma eficaz para la visualización de datos de una manera fácil de usar que puede ayudar a integrar resultados de los SSD y convertirlos en acciones estratégicas. Para demostrar la aplicabilidad y la eficiencia de este integración, ésta se valida a través de casos de estudio. También se realizan pruebas de verificación sobre la información exportada en los diferentes sistemas. Los resultados demuestran un aumento de la eficiencia en la recopilación de datos de alta calidad para diferentes tipos de DSS, lo que reduce el tiempo y el esfuerzo que los gestores de edificios dedican a buscar información e introducir datos en la diferentes aplicaciones. Un script de Dynamo está diseñado para permitir que los gestores incluyan tanta información como deseen en los modelos BIM. Además, se propone un enfoque novedoso para crear una nueva categoría en BIM para ayudar a las administraciones públicas y empresariales a gestionar los activos de manera eficiente. Además, los aspectos del rendimiento del edificio también se pueden analizar utilizando el método propuesto de integrar los comentarios de los ocupantes en los modelos BIM. Al implementar el enfoque propuesto, los gestores de edificios pueden establecer correctamente las medidas que se pueden aplicar para mitigar los efectos negativos en los edificios, mejorando así su rendimiento y el confort de sus ocupantes. Además, la integración propuesta permite que BIM sea una herramienta más útil para la visualización mediante el uso de los gráficos y las opciones de formato más apropiados, guiando a la toma de decisiones para gestionar los edificiosPostprint (published version

Ammonia emission prediction for dairy cattle housing from reaction kinetic modeling to the barn scale

One way to estimate ammonia emission rates from naturally ventilated housing systems is to scale-up mechanistic modeling results. However, obtaining the relevant data to set initial and boundary conditions adequately is usually very challenging and for a whole barn barely possible. This study has investigated the potential of coupling different mechanistic modeling approaches towards an overarching barn scale ammonia emission model, which might permit ammonia emission projections for naturally ventilated housing systems with minimal measurement efforts. To this end, we combined an ammonia volatilization model for shallow urine or slurry puddles with a dynamic mechanistic model of digestion and excretion of nitrogen, an empirical model to estimate urination volumes, semi-empirical models for pH and temperature dynamics of the puddles and a mechanistic air flow model. The ammonia volatilization model was integrated with a time step of one second over a period of twenty-four hours, while the relevant boundary conditions were updated on an hourly base (determined by the other mentioned submodels). Projections and uncertainties of the approach were investigated for a farm case with about ten months of on-farm measurements in a naturally ventilated dairy cattle building with scraped solid floor in Northern Germany. The results showed that the nested model was in general capable to reproduce the long-term emission trend and variability, while the short-term variability was damped compared with the emission measurements. A sensitivity study indicated that particularly a refinement of the submodules for urine puddle alkalizing, urination volume and urea concentration distributions as well as for local near-surface wind speeds have a great potential to further improve the overall model accuracy. The cleaning efficiency of the scraper has turned out to be a crucial and sensitive parameter in the modeling, which so far has been described insufficiently by measurements or modeling approaches

Applying safe flooring in housing environments related to the independent elderly : evaluating suitability flooring technology to absorb impact in the event of a fall

Aplicat embargament des de la data de defensa fins el dia 3/6/2022This research has been developed with the intention of investigating a different generation of pavements. Most of the current pavements have the same basic standard characteristics and this ensures that living conditions are comfortable, safe, and pleasant for the majority of citizens. But a small group of pavements is designed with a specific purpose: to reduce injuries related to people's falls to the ground; They are called CF (compliant flooring in English). A detailed study of CF flooring systems is warranted to assess their usability for vulnerable groups such as the elderly. This study is structured in six chapters. The first chapter has dealt mainly with bibliographic studies and statistical data consulted on official and international websites. This section evaluates the importance of the increase in the elderly population, life expectancy, and threats to the safety and health of the elderly, especially, and their secondary effects. The scope of the research has been carried out internationally, in Europe and within Spain, and finally, specifically for Catalonia. The second chapter presents a brief overview of the interior flooring, specifically considering its comfort and safety during use. The importance and direct relationship between the sole of the foot and the gait mechanism with respect to the type of pavement have been verified. Many factors that influence this have been investigated, such as the physics and biomechanics of the body when walking, the kinematics of falls, and the dynamics of impact. In addition, a general description of the behavior of materials for use in pavements has been made to better understand the behavior of CF systems. In addition, the most suitable strategies to cope with falls and reduce injuries are discussed. Examining other products with appreciable energy-absorbing and shock-reducing capabilities has been helpful in the proposed pre-designs, all of which have been made based on numerical analysis and related standards. The third chapter is already dedicated to the study of technology and research on the most suitable CF systems; studies from academic, commercial, and architecture departments, in general, are included. In this section, some standard tests related to the various selected materials are developed and several examples of similar products are studied. The fourth chapter includes field research (on-site) and analysis of case studies. Several notable flooring companies around the world were contacted by mail, specifically examining those products whose manufacturers claimed to be shock absorbers. This part of the investigation was slowed down by the delay in shipments. Once they arrived, a real environment was sought where they could obtain the opinion of the elderly and the personnel assigned to their care. All the practice tests were carried out in a residence for the elderly in Barcelona for about two months, focusing on the study of the current pavements of the center and the current derived problems related to users.This entire process was completed by interviewing users and caregivers with predefined questionnaires. It should be noted that this allowed us to contrast the quantitative characteristics of the study in combination with the elements of qualitative research. Chapter Five deals with the results, discussions, suggestions for installation and improvement of pavement safety in risk areas. Simulations were also carried out on a possible base structure of the pavements with the finite element method (FEM). Chapter six presents guidelines for future developments. The author further investigated the materials and their structure and is presented them as a basis for future technical developments.The author considers that, with more detailed studies, it would be possible to use as CF system other materials, either natural or recycled based on agricultural products, which would increase the diversity of the CF system offer and promote more sustainable architectureEsta investigación se ha desarrollado con la intención de investigar una generación diferente de pavimentos. La mayoría de los actuales pavimentos tienen las mismas características básicas estándar y ello garantiza que las condiciones de vida sean cómodas, seguras y agradables para la mayoría de los ciudadanos. Pero un grupo reducido de pavimentos está diseñado con un propósito específico: reducir las lesiones relacionadas con las caídas al suelo de las personas; son los denominados CF (compliant flooring en inglés). Un estudio detallado de los sistemas de pavimentos CF está justificado para evaluar su posibilidad de uso para grupos vulnerables como los ancianos. Este estudio se estructura en seis capítulos. En el primer capítulo se han abordado principalmente los estudios bibliográficos y datos estadísticos consultados en sitios web oficiales e internacionales. En esta sección se evalúa la importancia del aumento de la población anciana. El ámbito de la investigación se ha realizado a nivel internacional, en Europa y dentro de España, y finalmente, específicamente para Cataluña. El segundo capítulo se presenta una breve panorámica del pavimento interior. Se ha constatado la importancia y relación directa entre la planta del pie y el mecanismo de andar con respecto al tipo de pavimento. Se han investigado muchos factores que influyen en ello. Además, se ha realizado una descripción general del comportamiento de los materiales al uso en pavimentos para comprender mejor el comportamiento de los sistemas de CF. Además, se discuten las estrategias más idóneas para hacer frente a las caídas y reducir las lesiones. Examinar otros productos con apreciables capacidades de amortiguación de energía y reducción de impactos ha sido de gran ayuda en los prediseños propuestos, todos los cuales se han realizado sobre la base de análisis numérico y los estándares relacionados. El tercer capítulo está dedicado ya al estudio de la tecnología y la investigación sobre los sistemas de C más idóneos; se incluyen estudios procedentes de departamentos académicos, comerciales y de arquitectura en general. En esta sección se desarrollan algunas pruebas estándar relacionadas con los diversos materiales seleccionados y se estudian varios ejemplos de productos similares. El cuarto capítulo incluye investigación de campo (in situ) y análisis de estudios de casos. Se contactó por correo con varias empresas notables de pavimentos en todo el mundo, y se examinaron específicamente aquellos productos cuyos fabricantes afirmaban ser amortiguadores. Esta parte de la investigación se vio ralentizada por la demora en los envíos. Una vez llegados se buscó un ámbito real donde poder recabar la opinión de las personas mayores y del personal adscrito a su cuidado. Todas las pruebas prácticas se realizaron en una residencia de ancianos de Barcelona durante unos dos meses, centrándose en el estudio de los actuales pavimentos del centro y los problemas actuales derivados relacionados con los usuarios. Todo este proceso se completó mediante entrevistas a usuarios y cuidadores con cuestionarios predefinidos. El Capítulo Cinco se refiere a los resultados, discusiones, sugerencias para la instalación y mejora de la seguridad del pavimento en áreas de riesgo. También se realizaron simulaciones sobre una posible estructura base de los pavimentos con el método elemento finito (FEM). El capítulo seis presenta directrices para desarrollos futuros. El autor investigó más a fondo sobre los materiales y su estructura, y se presenta como una base para desarrollos técnicos futuros. El autor considera que, con estudios más detallados, sería posible utilizar como CF otros materiales, bien naturales o reciclados a base de productos agrícolas, lo cual aumentaría la diversidad de la oferta de CF y fomentaría la arquitectura más sostenible.Postprint (published version