The cost of design, construction and maintenance of facilities is on continual rise. The demand is to construct facilities which have been designed by apply life cycle costing principles. These principles have already given strong decision making power to the manufacturing industry. The need to satisfy the environmental sustainability requirements, improve operational effectiveness of buildings and apply value engineering principles has increased the dependency on life cycle costing analysis. The objective is to obtain economically viable solutions by analyzing the alternatives during the design of a building. Though the LCCA process is able to give the desired results, it does have some problems which have stood as hindrances to the more widespread use of the LCCA concept and method. The literature study has highlighted that the problem areas are the lack of frameworks or mechanisms for collecting and storing data and the complexity of LCCA exercise, which involves the analysis of a thousand of building elements and a number of construction-type options and maintenance activities for each building element at detailed design stages. Building Information Modeling has been able to repeatedly answer the questions raised by the AEC industry. The aim of this study is to identify the areas where BIM can be effectively applied to the LCCA process and become a part of the workflow. In this study, initially four LCCA case studies are read and evaluated from the point of view of understanding the method in which the life cycle costing principles have been applied. The purpose, the type alternatives examined, the process of analysis, the type of software used and the results are understood. An attempt has been carried out to understand the workflow of the LCCA process. There is a confidence that Building Information Modeling is capable of handling changes during the design, construction and maintenance phases of the project. Since applying changes to any kind of information of the building during LCC analysis forms the core, it has become necessary to use computer building models for examining these changes. The building modeling softwares are enumerated. The case studies have highlighted that the evaluation of the alternatives are primarily to achieve energy efficient solutions for the buildings. Applying these solutions involves high initial costs. The return on investment is the means by which these solutions become viable to the owners of the facilities. This is where the LCCA has been applied. Two of the important cost elements of the LCC analysis are initial costs and the operating costs of the building. The collaboration of these modeling tools with other estimating software where the initial costs of the building can be generated is studied. The functions of the quantity take-off tools and estimating tools along with the interoperability between these tools are analyzed. The operating costs are generated from the software that focuses on sustainability. And the currently used tools for performing the calculations of the life cycle costing analysis are also observed. The objective is to identify if the currently available BIM tools and software can help in obtaining LCCA results and are able to offset the hindrances of the process. Therefore, the software are studied from the point of view of ease of handling data and the type of data that can be generated. Possible BIM workflows are suggested depending on the functions of the software and the relationship between them. The study has aimed at taking a snapshot the current tools available which can aid the LCCA process. The research is of significance to the construction industry as it forms a precursor to the application of Building Information Modeling to the LCCA process as it shows that it has the capacity of overcoming the obstacles for life cycle costing. This opens a window to the possibility of applying BIM to LCCA and furthering this study.

The supply chains of military engines are linked by the repair loop, the foreign military sale loop and the procurement loop. Based on the discipline of the performance based logistics, fleet readiness and the low life cycle cost are the key performance requirement. To response the budget constraint from increasing the investment of defensive weapon systems because of the rising of the uncertain tension situation on the both sides of the Taiwan Strait, it is necessary to have good supply chain management. However most of the managers often ignore the side effects and sequelae caused by their actions to persue the success of their strategy resulting from the complicated dynamic relationship between the strategic actions and inbound logistic process of the engine supply chains. When the managers misinterpret the feedback information with the side effects and sequelae, improper strategy planning will be made and fail to make your goals as expectancy. System dynamics can be used as the solution for unlinear, multi-variables and complicated dynamic problems of engine logistic management because of its systematic, dynamic point of view characteristics. The research approach adopts the system dynamics and tries to construct a model with the data which carry on the case study. By the expansion of the supply chain management and life cycle cost, the model was carried on the setting-up, simulation, test and analyzing of the system dynamics and will be a mechanism of decision making. Besides, through the interactive simulation of the test between performance index and system variables, the key performance indexes were found out. At the same time some strategy should be revised based on the result of simulation. Because strategy is based on the logic of cause and effect, the correct strategy map can only be built after the test with the system dynamic model. Study the conclusion: (1) The consequence of the action plan implememtation for engine maintenance management strategy with the system dynamics test can be refered as the reference for policy planning and adjustment of the strategy. (2) Construct the mechanism of spares requirement controling to eliminate the Bullwhip effect. (3) The cost effectiveness of CIP( Component Improvement Program) and RDE( Repair Development Engineering) depends on the timing and cost of implementation. Those can be validated through the interactive simulation of the test. (4) Built up the strategy map with the extension of balanced scorecard for military engine maintenance management. It is benefitted to utilize the business dynamics and strategy map with key performance index as the outcome for decision making to improve the operating performance of corporation. Lastly, to address the research result that in meaning on of managing, study limitation and the suggestion with follow-on research.

Eighty percent of the 780 million people worldwide that access water from an unimproved source live in rural areas. In rural areas, water systems are often managed by community based organizations and many of these systems do not provide service at the designed levels. The Sustainability Analysis Tool developed in Chapter 2 can inform decision making, characterize specific needs of rural communities in the management of their water systems, and identify weaknesses in training regimes or support mechanisms. The framework was tested on 61 statistically representative geographically stratified sample communities with rural water systems in the Dominican Republic. The results demonstrated the impact that long term support by outside groups to support community management activities can improve sustainability indicators, including financial sustainability which is a significant issue throughout the world. When analyzing the financial sustainability of water systems, it is important to consider all life-cycle costs including the expenditures made by households. Chapter 3 analyzes financial and economic expenditures on water services in 9 rural and peri-urban communities in Burkina Faso. Data from household and water point surveys were used to determine: socio-economic status, financial and economic expenditures, and service levels received by each household. In Burkina Faso recurrent financial and economic expenditures on water service ranged between US$5 and US$9.5 per person per year, with cumulative costs approximately US$19.5 per person per year. The average expenditures on water in Burkina Faso were well above the affordability threshold used by World Bank demonstrating the need to improve subsidies in the water sector. The sustainability of water supply systems and the ability to ensure the health benefits of these systems is also influenced by the deficiencies in sanitation infrastructure. Unimproved sanitation can be a source of water contamination and a risk factor in water related disease. Furthermore, the effective management of community water supply infrastructure is not a sufficient condition for ensuring water quality and eliminating health risks to consumers. As a result water treatment technologies, such as ceramic water filters (CWFs), implemented and managed at the household level and combined with safe storage practices are proposed as a means of reducing these risks. The performance of CWFs in laboratory settings has differed significantly from field studies with regard to microbial treatment efficacy and also hydraulic efficiency. Chapter 4 presents a 14 month field study of two locally manufactured CWFs conducted in a rural community in the Dominican Republic. Each of the 59 households in the community received one filter. The CWFs in this study performed poorly with regard to water quality and hydraulic performance. Focus group meetings and household survey suggests that flow rate is a major issue for user acceptability. To address the user concerns Chapter 5 presents two mathematical models for improving the hydraulic performance for the frustum and paraboloid designs. The models can be used to predict how changes in user behavior or filter geometry affects the volume of water produced and therefore can be used as tools to help optimize filter performance.

Historiskt sett har den Svenska värmemarknaden dominerats av fjärrvärmen som i princip varit det enda kostnadseffektiva alternativet där det funnits tillgängligt. På senare tid har dock spelreglerna börjat på att förändras, bland annat på grund av värmepumparnas intåg, en förändrad energipolitik och ökade kundkrav – vilket har lett till en mer konkurrensutsatt marknad. Denna studie syftar till att både kvantitativt och kvalitativt analysera fjärrvärmens konkurrenskraft jämfört med alternativa uppvärmningstekniker, med fokus på segmenten flerbostadshus, övriga- samt offentliga lokaler. Efter en inledande marknadsundersökning bedömdes värmepumpar i kombination med el eller fjärrvärme, samt pellets i kombination med RME, kunna vara konkurrenskraftiga med fjärrvärme. Därefter beräknades livscykelkostnaden för dessa värmesystem för en generell fastighet som en funktion av dess energibehov och utnyttjningstid, samt för ett antal typanvändare. Dessa typanvändare identifierades genom att analysera förbrukningsstatistik från Vattenfall. Vidare genomfördes flera intervjuer med branschexperter parallellt med att en enkät sammanställdes som riktade sig till energi- och klimatrådgivare i Sverige. Enkäten syftade till att få en nulägesbeskrivning av fastighetsägares syn på värmemarknaden och på så sätt bidra till den kvalitativa analysdelen. Resultatet visar att det rent kostnadsmässigt är små skillnader mellan fjärrvärme och övriga alternativ givet de antaganden som författarna anser är rimliga. För ett typiskt flerbostadshus är fjärrvärme mer fördelaktigt men för en typisk övrig eller offentlig lokal är bergvärme ett marginellt bättre alternativ. Frånluftsvärmepump med fjärrvärme är i båda fallen en billig lösning. Dock visar känslighetsanalysen att det kan skilja med mer än en faktor 2,5 i livscykelkostnad för samtliga alternativ beroende på vilka antaganden som görs. Således är valet av värmesystem ur fastighetsägarens perspektiv nära kopplat till riskbedömning, vad denne tror om framtiden och vilken relation de har till nuvarande värmeleverantör. För alla fastighetsägare är säker och problemfri drift den viktigaste parametern utöver kostnaden. Det finns även en ovisshet kring framtida prishöjningar av både el- och fjärrvärme, vilket leder till osäkra kalkyler. Därför kan förtroendet och relationen med nuvarande värmeleverantör vara avgörande vid en beslutssituation. En hög investeringskostnad är också en tydlig barriär - parallellt som investeringen ofta konkurrerar med andra energi- och fastighetsåtgärder om samma budget. Miljöfrågan är viktig för offentliga lokaler och kan vara det även för övriga lokaler, men är sällan av stor betydelse för flerbostadshus. Sammanfattningsvis är det svårt att avgöra vilket alternativ som är mest konkurrenskraftigt i dagsläget. Flera faktorer spelar in och livscykelkostnaden kan variera kraftigt mellan bästa och sämsta fall för uppvärmningsalternativen. Emellertid indikerar denna studie att en effektbaserad prismodell leder till att fjärrvärmen stärker sin konkurrenssituation bland flerbostadshus men blir mer utsatt i segmenten offentliga respektive övriga lokaler. Särskilt i det senare är bergvärmepumpar ett växande hot. För att bibehålla sin konkurrenskraft är det viktigt att fjärrvärmeleverantörerna är transparenta och tydliga i kommunikationen mot sina kunder, framförallt när det gäller prisutvecklingen. På sikt kan affärsmodellen och erbjudandet behöva innafatta mer än bara värmeleveransen, exempelvis stöd vid energieffektivisering, miljöcertifierad värme samt ett komforterbjudande. / Historically, the Swedish heat market has been dominated by district heating, which basically has been the only cost effective option where it’s available. Lately, however, the situation has begun to change, partly because of the increased efficiency of heat pumps, but also due to changes in energy policies and increased customer demands - which has led to a more competitive heating market. This study aims to quantitatively and qualitatively analyze the competitiveness of district heating compared to alternative heating technologies, focusing on three segments; apartment buildings, public facilities and other premises. After an initial market analysis, heat pumps in combination with electricity or district heating as peak load, as well as pellets in combination with RME, were identified as the most competitive alternatives to district heating. The estimated life cycle cost of the heating systems was then calculated for a number of facilities, as a function of its energy needs and utilization time. These facilities were chosen based on consumption statistics from Vattenfall. Furthermore, several interviews with industry experts were conducted, in parallel with an inquiry that was addressed to energy and climate advisers in Sweden. The survey aimed to get an up-to-date status report of property owners' views on the heat market and thus contribute to the qualitative analysis. The result shows, given the assumptions that the authors find reasonable, that there are minor differences between district heating and its competition if viewed from a cost perspective only. For a typical apartment building, district heating is slightly more beneficial, but for a typical public facility/other premise geothermal heat is a marginally cheaper option. Exhaust air heat pump with district heating as peak load is in both cases a cost effective option. However, the sensitivity analysis shows that the life cycle cost can differ by more than a factor of 2,5 for all heating systems depending on what assumptions are made. Hence, the choice of heating system is from the property owner's perspective closely related to perceived risk and the extent to which trust towards the heat supplier exists. Effortless and reliable operations appear to be the most important factor besides costs for all customer types. Also, there is uncertainity about future price development among all segments, which can lead to impaired calculations. Thus, the customers’ trust for the existing heat distributor, as well as the relationship between them, may fundamentally affect the choice of heating system. A high investment cost is a crucial barrier since it carries a higher risk while also competing with other efficiency measures about the same budget. Public facility owners are keen about the environmental aspects while this question is of less importance for apartment buildings owners. It may be of importance for other premise owners depending on the owner. In summary, it’s difficult to determine the most competitive heating system since the cost effectiveness for all heating systems can vary a lot depending on the assumptions. However, this study indicates that a power based price model will strengthen the competitiveness for district heating among apartment buildings. Among public facilities and other premises it will become more vulnerable to other heating technologies, especially to geological heat pumps. To stay competitive it’s important for district heating distributors to be transparent and clear in the communication with their customers, particularly in regards of price development. In the long term it may be necessary to include more than district heating in their offer, for example support in energy efficiency measures, an environmentally certified heat supply or an offer of guaranteed indoor- comfort.

In recent years, infrastructure renewal has been a focus of attention in North America and around the world. Municipal and federal authorities are increasingly recognizing the need for life cycle cost analysis of infrastructure projects in order to facilitate proper prioritization and budgeting of maintenance operations. Several reports have highlighted the need to increase budgets with the goal of overcoming the backlog in maintaining infrastructure facilities. This situation is apparent in the case of bridge networks, which are considered vital links in the road network infrastructure. Because of harsh environments and increasing traffic volumes, bridges are deteriorating rapidly, rendering the task of managing this important asset a complex endeavour. While several bridge management systems (BMS) have been developed at the commercial and research level, they still have serious drawbacks, particularly in integrating bridge-level and network-level decisions, and handling extremely large optimization problems. To overcome these problems, this study presents an innovative bridge management framework that considers network-level and bridge-level decisions. The initial formulation of the proposed framework was limited to bridge deck management. The model has unique aspects: a deterioration model that uses optimized Markov chain matrices, a life cycle cost analysis that considers different repair strategies along the planning horizon, and a system that considers constraints, such as budget limits and desirable improvement in network condition. To optimize repair decisions for large networks that mathematical programming optimization are incapable of handling, four state-of-the art evolutionary algorithms are used: Genetic algorithms, shuffled frog leaping, particle swarm, and ant colony. These algorithms have been used to experiment on different problem sizes and formulations in order to determine the best optimization setup for further developments. Based on the experiments using the framework for the bridge deck, an expanded framework is presented that considers multiple bridge elements (ME-BMS) in a much larger formulation that can include thousands of bridges. Experiments were carried out in order to examine the framework???s performance on different numbers of bridges so that system parameters could be set to minimize the degradation in the system performance with the increase in numbers of bridges. The practicality of the ME-BMS was enhanced by the incorporation of two additional models: a user cost model that estimates the benefits gained in terms of the user cost after the repair decisions are implemented, and a work zone user cost model that minimizes user cost in work zones by deciding the optimal work zone strategy (nighttime shifts, weekend shifts, and continuous closure), also, decides on the best traffic control plan that suits the bridge configuration. To verify the ability of the developed ME-BMS to optimize repair decisions on both the network and project levels, a case study obtained from a transportation municipality was employed. Comparisons between the decisions provided by the ME-BMS and the municipality policy for making decisions indicated that the ME-BMS has great potential for optimizing repair decisions for bridge networks and for structuring the planning of the maintenance of transportation systems, thus leading to cost savings and more efficient sustainability of the transportation infrastructure.

Operations and maintenance (O&M) activities represent a significant share of the expenses during the lifetime of offshore wind farms. When compared to onshore wind farms, O&M costs are increased for the offshore case, as specialized vessels, weather windows and rough conditions mean more failures, downtime (decreasing availability), spare parts, and man-hours.This study comprises an analysis of the available O&M data from a selected offshore wind farm. The results and conclusions from this investigation could then be used to evaluate possible reliability improvements and compare options for the maintenance strategies, as well as to ponder the convenience of warranty periods and O&M agreements between wind farm operators and wind turbine manufacturers or O&M service providers.The life-cycle cost (LCC) concept is utilized in the analysis of the wind farm survey for this thesis. LCC analysis could be the starting point to make decisions regarding specific wind turbine models, as selecting the turbines with the lowest initial cost may not be necessarily the scenario which also costs the least amount of money when taking into consideration the whole life cycle. It may also be a great tool to forecast future operational incomes and expenses of offshore wind farms.

The study described in this thesis investigates how the implementation of raised floor system (RFS) for the fitout of office buildings can be promoted in the Australian construction industry. It essentially achieves this goal through justifying the RFS fitout advantages, improving industry practitioners' awareness of the innovative technology, and identifying the barriers hindering RFS application, and exploring integrated approaches to overcome these barriers. Due to increasing levels of technological, environmental and organizational changes in office buildings, the traditional office building fitout method cannot deliver flexible services economically and in a timely manner. RFS is highlighted for its superior underfloor distribution technologies and ability to promote healthy workplace environments and organizational flexibilities. Despite the many benefits RFS may bring, this innovative technology has not been widely used. Therefore, for countries with potential growth in the office building market, including Australia, how to make this state-of-the-art fitout technology more acceptable is of great importance. To encourage the RFS implementation in office buildings, the research set up five objectives: (1) to justify the RFS advantages for office building fitout compared with traditional fitout method; (2) to identify and present appropriate specifications of RFS products and applications in order to improve industry practitioners' awareness on RFS fitout; (3) to identify and seek potential solutions to barriers hindering RFS fitout implementation; (4) to integrate the barriers and their solutions into RFS project delivery using constructability study; and (5) to formulate guidelines for RFS fitout implementation in office buildings in the Australian construction industry. A comprehensive research methodology consisting of questionnaire, semi-structured interview, site observations, focus groups, life cycle cost (LCC) comparison, and constructability study was structured to support the exploratory research. With a combined qualitative and quantitative data analysis method, the questionnaire and interview surveys revealed the low level recognition of RFS within the industry, and identified 20 significant influence factors (SIFs) and 15 real problems associated with RFS fitout implementation. The site observations and focus groups validated the survey findings and justified the RFS fitout advantages. Then, the LCC comparison established a model and verified the LCC benefits of RFS fitout through a case study. The final discussion on the SIFs, real problems and their solutions uncovered 36 project level critical factors pertaining to RFS fitout design, construction, operation and maintenance. A constructability study was employed to integrate these key factors into RFS fitout project delivery, such as construction knowledge inputs, team skills, and RFS fitout programs. More importantly, five key issues with significant influences were revealed. Further investigation of these key issues led to a framework for the constructability implementation, a contracting strategy with nominated specialist contractors under CM/GC, and a process-based conceptual model for the selection of RFS products. Based on these findings, a set of guidelines for the RFS fitout implementation in office buildings was formulated as a contribution to practice. Questionnaires were again used to invite comments on the key issues and guidelines, and the results proved the validity of the research outcomes.

abstract: Building Envelope includes walls, roofs and openings, which react to the outdoor environmental condition. Today, with the increasing use of glass in building envelope, the energy usage of the buildings is increasing, especially in the offices and commercial buildings. Use of right glass type and control triggers helps to optimize the energy use, by tradeoff between optical and thermal properties. The part of the research looks at the different control triggers and its range that governs the use of electrochromic glass to regulate the energy usage in building. All different control trigger that can be possibly used for regulating the clear and tint state of glass were analyzed with most appropriate range. Its range was triggered such that 80% time of the glass is trigger between the ranges. The other building parameters like window wall ratio and orientations were also investigated. The other half of the research study looks into the feasibility of using the Electrochromic windows, as it is ought to be the main factor governing the market usage of Electrochromic windows and to investigate the possible ways to make it feasible. Different LCC parameters were studied to make it market feasible product. This study shows that installing this technology with most appropriate trigger range can reduce annual building energy consumption from 6-8% but still cost of the technology is 3 times the ASHRAE glass, which results in 70-90 years of payback. This study concludes that south orientation saves up to 3-5% of energy and 4-6% of cooling tons while north orientation gives negligible saving using EC glass. LCC parameters show that there is relative change in increasing the net saving for different parameters but none except 50% of the present glass cost is the possible option where significant change is observed. / Dissertation/Thesis / M.S.D. Architecture 2012

This research investigated using a life cycle environmental and economic approach to evaluate IX technology for small potable water systems, allowing for the identification and development of process and design improvements that reduce environmental impacts and costs. The main goals were to evaluate conventional IX in terms of life cycle environmental and economic sustainability, develop a method for improving designs of IX systems from a environmental and economic sustainability standpoint, evaluate potential design improvements, and make the research findings accessible to water professionals through user-friendly tools and frameworks that take into account their feedback. This research provides an understanding, from the perspective of life cycle environmental impacts and costs, of the tradeoffs between various reactor designs of IX, the effects of scale, key contributors to impact and cost, design trends that improve sustainability, and how combined cation anion exchange compares to conventional IX. Furthermore, tools were developed that can be used to identify design choices that improve sustainability of IX systems. These tools were made into a user-friendly format to better bridge the gap between research and practice.

Cada vez más, las empresas de transporte de viajeros se encuentran enmarcadas por un reto financiero para su supervivencia en un mundo globalizado, y están en busca de una gestión eficiente para optimizar los costes de explotación de las flotas. El principal objetivo es obtener el mínimo coste por kilómetro recorrido de los autobuses durante toda su vida útil, pero sin olvidar la influencia de la edad y del kilometraje sobre los vehículos. Desde un punto de vista puramente económico, es evidente que se obtengan los costes de operación y mantenimiento más bajos en los primeros años de trabajo de los vehículos. Pero cuando se consideran otros tipos de costes, como la compra del vehículo, impuestos, subvenciones o incentivos fiscales, y la necesidad de sustitución por nuevos vehículos dotados de innovaciones tecnológicas en conformidad con las exigentes normas de sostenibilidad y sus altos costes, la optimización económica es un reto para los operadores. Así, la determinación del momento óptimo de reemplazo es una tarea cada vez más dependiente de la disponibilidad, fiabilidad y precisión de los datos que se manejen, debido a la incertidumbre en la predicción de algunos valores y costes, tales como los futuros precios del combustible, costes de mantenimiento y la tasa de utilización. Teniendo en cuenta que este proceso ocurre a nivel global en diferentes sectores, existen diferentes modelos y herramientas de gestión que permiten encontrar al menos una solución para el problema de reemplazo. En este trabajo se han planteado dos modelos clásicos aplicados en problemáticas similares, para adaptarlos a la resolución del caso de flotas de transporte urbano de dos países diferentes, España y Brasil, propiciando así un análisis bajo condiciones y entornos distintos. Con el acceso a los datos reales de las flotas, fue desarrollada e implementada la metodología combinada entre la herramienta gerencial Life Cycle Cost y el modelo matemático de Simulación Monte Carlo, mediante la realización de un análisis estocástico, considerando tanto la edad y el kilometraje promedio anual. El estudio ha demostrado que la inclusión de las variables aleatorias en el proceso de determinación de la edad óptima de cambio, junto con la mejor tasa de utilización de los vehículos en función del kilometraje medio, aporta ventajas al proceso de reemplazo convencional, al permitir una perspectiva más confiable de los futuros escenarios, mediante el análisis probabilístico dependiente de las variables económicas y técnicas. Los resultados obtenidos apuntan hacia la eficiencia del modelo, y que podrá ser utilizado de forma satisfactoria en otros estudios comparativos en flotas de transporte urbano. / The passenger transport companies have been increasingly challenged by financial restrictions for their survival in a globalised world and they are searching out an efficient management to optimise the exploitation costs of the fleets. The main objective is not only reaching the lowest average cost per mile of the buses during their lives, but also reaching such aim considering the influence of the age and mileage over the vehicles. From an economic point of view, it is evident that the operational and maintenance costs must be lower at the first working years of the vehicle. However, when other types of costs are taken into consideration, such as the purchasing price, taxes, subsidies or tax incentives, the need of the replacement for new vehicles endowed with technologic innovations in accordance with sustainable rules and their high costs, the economic optimisation becomes a challenge for the managers. Likewise, the determination of the optimum replacement moment is a more and more dependent task on the availability, reliability and precision of the data in use due to the uncertainty and unreliability when predicting some values and costs, such as future fuel prices, maintenance costs and bus use rate. In view of this process happens at a global level over different sectors of the economy, there are several models and tools of management that leads to a solution to the replacement problem. In this study, two classic modules were applied in similar conditions, however, some changes were required to adapt them for the resolution in two urban transport fleet in two different countries, Spain and Brazil, generating an analysis under different conditions and environments though. Using the access of real date from the two fleets, a methodology was developed combining the Life Cycle Cost tool and the mathematical model of Monte Carlo Simulation, by performing a stochastic analysis considering both age and average annual mileage for optimum vehicle replacement. This study has demonstrated that the inclusion of random variables into the determination process of optimum replacement age together with the best mileage of the vehicle in function of average mileage improve the conventional replacement process since it creates a more reliable perfective on future successes through probabilistic analysis dependent on economic and technical variables. The results suggest that the model is effective, and it could be used satisfactorily in other comparative studies about urban transport fleet. / Cada vegada més, les empreses de transport de viatgers es troben majors reptes financers per a la seva supervivència en un món globalitzat, i estan a la recerca d'una gestió eficient per optimitzar els costos d'explotació de les flotes. El principal objectiu és obtenir el mínim cost per quilòmetre recorregut dels autobusos durant tota la seva vida útil, però sense oblidar la influència de l'edat i del quilometratge sobre els vehicles. Des d'un punt de vista purament econòmic, és evident que s'obti els costos d'operació i manteniment més baixos en els primers anys de treball dels vehicles. Però quan es consideren altres tipus de costos, com la compra del vehicle, impostos, subvencions o incentius fiscals, i la necessitat de substitució per nous vehicles dotats d'innovacions tecnològiques en conformitat amb les exigents normes de sostenibilitat i els seus alts costos, l'optimització econòmica és un repte per als operadors. Així, la determinació del moment òptim de reemplaçament és una tasca cada vegada més dependent de la disponibilitat, fiabilitat i precisió de les dades que es manegen, a causa de la incertesa en la predicció d'alguns valors i costos, com ara els futurs preus del combustible, costos de manteniment i la taxa d'utilització. Tenint en compte que aquest procés ocorre a nivell global a diferents sectors, hi ha diferents models i eines de gestió que permeten trobar almenys una solució per al problema de reemplaçament. En aquest treball s'han plantejat dos models clàssics aplicats en problemàtiques similars, per adaptar-los a la resolució del cas de flotes de transport urbà de dos països diferents, Espanya i el Brasil, propiciant així una anàlisi sota condicions i entorns diferents. Amb l'accés a les dades reals de les flotes, va ser desenvolupada i implementada la metodologia combinada entre l'eina gerencial Life Cycle Cost i el model matemàtic de simulació Monte Carlo, mitjançant la realització d'una anàlisi estocàstica, considerant tant l'edat com la mitjana de quilometratge anual. L'estudi ha demostrat que la inclusió de les variables aleatòries en el procés de determinació de l'edat òptima de canvi, juntament amb la millor taxa d'utilització dels vehicles en funció del quilometratge mitjà, aporta avantatges al procés de reemplaçament convencional, en permetre una perspectiva més fiable dels futurs escenaris, mitjançant l'anàlisi probabilístic depenent de les variables econòmiques i tècniques. Els resultats obtinguts apunten cap a l'eficiència del model, i que podrà ser utilitzat de forma satisfactòria en altres estudis comparatius en flotes de transport urbà. / Sá Riechi, JLD. (2018). Desarrollo de un modelo para la optimización del reemplazo de vehículos para una flota de transporte urbano de pasajeros [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/99567 / TESIS