Architectural design and construction costs, tools towards territorial sustainability

This paper is presented in CIB: Management and Innovation Sustainable Built Environment 2011, as the study and analysis of the residential model of a rural area from the Iberian Peninsula, specifically applied to the case of the province of Cáceres, in the autonomous region of Extremadura, in Spain. To this end, from a database made up of building projects whose real costs are known, it is intended to establish the links of the different parameters studied through the corresponding functions of statistical analysis. One of the main objectives of this process is constituted by the possibility of establishing those design variables of higher economic importance, so as to keep an economic control of these parameters, generally geometrical and typological, from the very start of the project. And, in general, a higher optimization of resources in the construction of dwellings in the rural environment from their design is intended.

Desarrollo de un modelo de predimensionado de costes de construcción en el proyecto arquitectónico

El objetivo de la presente investigación es el desarrollo de un modelo de cálculo rápido, eficiente y preciso, para la estimación de los costes finales de construcción, en las fases preliminares del proyecto arquitectónico. Se trata de una herramienta a utilizar durante el proceso de elaboración de estudios previos, anteproyecto y proyecto básico, no siendo por tanto preciso para calcular el “predimensionado de costes” disponer de la total definición grafica y literal del proyecto. Se parte de la hipótesis de que en la aplicación práctica del modelo no se producirán desviaciones superiores al 10 % sobre el coste final de la obra proyectada. Para ello se formulan en el modelo de predimensionado cinco niveles de estimación de costes, de menor a mayor definición conceptual y gráfica del proyecto arquitectónico. Los cinco niveles de cálculo son: dos que toman como referencia los valores “exógenos” de venta de las viviendas (promoción inicial y promoción básica) y tres basados en cálculos de costes “endógenos” de la obra proyectada (estudios previos, anteproyecto y proyecto básico). El primer nivel de estimación de carácter “exógeno” (nivel .1), se calcula en base a la valoración de mercado de la promoción inmobiliaria y a su porcentaje de repercusión de suelo sobre el valor de venta de las viviendas. El quinto nivel de valoración, también de carácter “exógeno” (nivel .5), se calcula a partir del contraste entre el valor externo básico de mercado, los costes de construcción y los gastos de promoción estimados de la obra proyectada. Este contraste entre la “repercusión del coste de construcción” y el valor de mercado, supone una innovación respecto a los modelos de predimensionado de costes existentes, como proceso metodológico de verificación y validación extrínseca, de la precisión y validez de las estimaciones resultantes de la aplicación práctica del modelo, que se denomina Pcr.5n (Predimensionado costes de referencia con .5niveles de cálculo según fase de definición proyectual / ideación arquitectónica). Los otros tres niveles de predimensionado de costes de construcción “endógenos”, se estiman mediante cálculos analíticos internos por unidades de obra y cálculos sintéticos por sistemas constructivos y espacios funcionales, lo que se lleva a cabo en las etapas iniciales del proyecto correspondientes a estudios previos (nivel .2), anteproyecto (nivel .3) y proyecto básico (nivel .4). Estos cálculos teóricos internos son finalmente evaluados y validados mediante la aplicación práctica del modelo en obras de edificación residencial, de las que se conocen sus costes reales de liquidación final de obra. Según va evolucionando y se incrementa el nivel de definición y desarrollo del proyecto, desde los estudios previos hasta el proyecto básico, el cálculo se va perfeccionando en su nivel de eficiencia y precisión de la estimación, según la metodología aplicada: [aproximaciones sucesivas en intervalos finitos], siendo la hipótesis básica como anteriormente se ha avanzado, lograr una desviación máxima de una décima parte en el cálculo estimativo del predimensionado del coste real de obra. El cálculo del coste de ejecución material de la obra, se desarrolla en base a parámetros cúbicos funcionales “tridimensionales” del espacio proyectado y parámetros métricos constructivos “bidimensionales” de la envolvente exterior de cubierta/fachada y de la huella del edificio sobre el terreno. Los costes funcionales y constructivos se ponderan en cada fase del proceso de cálculo con sus parámetros “temáticos/específicos” de gestión (Pg), proyecto (Pp) y ejecución (Pe) de la concreta obra presupuestada, para finalmente estimar el coste de construcción por contrata, como resultado de incrementar al coste de ejecución material el porcentaje correspondiente al parámetro temático/especifico de la obra proyectada. El modelo de predimensionado de costes de construcción Pcr.5n, será una herramienta de gran interés y utilidad en el ámbito profesional, para la estimación del coste correspondiente al Proyecto Básico previsto en el marco técnico y legal de aplicación. Según el Anejo I del Código Técnico de la Edificación (CTE), es de obligado cumplimiento que el proyecto básico contenga una “Valoración aproximada de la ejecución material de la obra proyectada por capítulos”, es decir , que el Proyecto Básico ha de contener al menos un “presupuesto aproximado”, por capítulos, oficios ó tecnologías. El referido cálculo aproximado del presupuesto en el Proyecto Básico, necesariamente se ha de realizar mediante la técnica del predimensionado de costes, dado que en esta fase del proyecto arquitectónico aún no se dispone de cálculos de estructura, planos de acondicionamiento e instalaciones, ni de la resolución constructiva de la envolvente, por cuanto no se han desarrollado las especificaciones propias del posterior proyecto de ejecución. Esta estimación aproximada del coste de la obra, es sencilla de calcular mediante la aplicación práctica del modelo desarrollado, y ello tanto para estudiantes como para profesionales del sector de la construcción. Como se contiene y justifica en el presente trabajo, la aplicación práctica del modelo para el cálculo de costes en las fases preliminares del proyecto, es rápida y certera, siendo de sencilla aplicación tanto en vivienda unifamiliar (aisladas y pareadas), como en viviendas colectivas (bloques y manzanas). También, el modelo es de aplicación en el ámbito de la valoración inmobiliaria, tasaciones, análisis de viabilidad económica de promociones inmobiliarias, estimación de costes de obras terminadas y en general, cuando no se dispone del proyecto de ejecución y sea preciso calcular los costes de construcción de las obras proyectadas. Además, el modelo puede ser de aplicación para el chequeo de presupuestos calculados por el método analítico tradicional (estado de mediciones pormenorizadas por sus precios unitarios y costes descompuestos), tanto en obras de iniciativa privada como en obras promovidas por las Administraciones Públicas. Por último, como líneas abiertas a futuras investigaciones, el modelo de “predimensionado costes de referencia 5 niveles de cálculo”, se podría adaptar y aplicar para otros usos y tipologías diferentes a la residencial, como edificios de equipamientos y dotaciones públicas, valoración de edificios históricos, obras de urbanización interior y exterior de parcela, proyectos de parques y jardines, etc….. Estas lineas de investigación suponen trabajos paralelos al aquí desarrollado, y que a modo de avance parcial se recogen en las comunicaciones presentadas en los Congresos internacionales Scieconf/Junio 2013, Rics‐Cobra/Septiembre 2013 y en el IV Congreso nacional de patología en la edificación‐Ucam/Abril 2014. ABSTRACT The aim of this research is to develop a fast, efficient and accurate calculation model to estimate the final costs of construction, during the preliminary stages of the architectural project. It is a tool to be used during the preliminary study process, drafting and basic project. It is not therefore necessary to have the exact, graphic definition of the project in order to be able to calculate the cost‐scaling. It is assumed that no deviation 10% higher than the final cost of the projected work will occur during the implementation. To that purpose five levels of cost estimation are formulated in the scaling model, from a lower to a higher conceptual and graphic definition of the architectural project. The five calculation levels are: two that take as point of reference the ”exogenous” values of house sales (initial development and basic development), and three based on calculation of endogenous costs (preliminary study, drafting and basic project). The first ”exogenous” estimation level (level.1) is calculated over the market valuation of real estate development and the proportion the cost of land has over the value of the houses. The fifth level of valuation, also an ”exogenous” one (level.5) is calculated from the contrast between the basic external market value, the construction costs, and the estimated development costs of the projected work. This contrast between the ”repercussions of construction costs” and the market value is an innovation regarding the existing cost‐scaling models, as a methodological process of extrinsic verification and validation, of the accuracy and validity of the estimations obtained from the implementation of the model, which is called Pcr.5n (reference cost‐scaling with .5calculation levels according to the stage of project definition/ architectural conceptualization) The other three levels of “endogenous” construction cost‐scaling are estimated from internal analytical calculations by project units and synthetic calculations by construction systems and functional spaces. This is performed during the initial stages of the project corresponding to preliminary study process (level.2), drafting (level.3) and basic project (level.4). These theoretical internal calculations are finally evaluated and validated via implementation of the model in residential buildings, whose real costs on final payment of the works are known. As the level of definition and development of the project evolves, from preliminary study to basic project, the calculation improves in its level of efficiency and estimation accuracy, following the applied methodology: [successive approximations at finite intervals]. The basic hypothesis as above has been made, achieving a maximum deviation of one tenth, in the estimated calculation of the true cost of predimensioning work. The cost calculation for material execution of the works is developed from functional “three‐dimensional” cubic parameters for the planned space and constructive “two dimensional” metric parameters for the surface that envelopes around the facade and the building’s footprint on the plot. The functional and building costs are analyzed at every stage of the process of calculation with “thematic/specific” parameters of management (Pg), project (Pp) and execution (Pe) of the estimated work in question, and finally the cost of contractual construction is estimated, as a consequence of increasing the cost of material execution with the percentage pertaining to the thematic/specific parameter of the projected work. The construction cost‐scaling Pcr.5n model will be a useful tool of great interest in the professional field to estimate the cost of the Basic Project as prescribed in the technical and legal framework of application. According to the appendix of the Technical Building Code (CTE), it is compulsory that the basic project contains an “approximate valuation of the material execution of the work, projected by chapters”, that is, that the basic project must contain at least an “approximate estimate” by chapter, trade or technology. This approximate estimate in the Basic Project is to be performed through the cost‐scaling technique, given that structural calculations, reconditioning plans and definitive contruction details of the envelope are still not available at this stage of the architectural project, insofar as specifications pertaining to the later project have not yet been developed. This approximate estimate of the cost of the works is easy to calculate through the implementation of the given model, both for students and professionals of the building sector. As explained and justified in this work, the implementation of the model for cost‐scaling during the preliminary stage is fast and accurate, as well as easy to apply both in single‐family houses (detached and semi‐detached) and collective housing (blocks). The model can also be applied in the field of the real‐estate valuation, official appraisal, analysis of the economic viability of real estate developments, estimate of the cost of finished projects and, generally, when an implementation project is not available and it is necessary to calculate the building costs of the projected works. The model can also be applied to check estimates calculated by the traditional analytical method (state of measurements broken down into price per unit cost details), both in private works and those promoted by Public Authorities. Finally, as potential lines for future research, the “five levels of calculation cost‐scaling model”, could be adapted and applied to purposes and typologies other than the residential one, such as service buildings and public facilities, valuation of historical buildings, interior and exterior development works, park and garden planning, etc… These lines of investigation are parallel to this one and, by way of a preview, can be found in the dissertations given in the International Congresses Scieconf/June 2013, Rics‐Cobra/September 2013 and in the IV Congress on building pathology ‐Ucam/April 2014.

Analysis of the Optimal Sharing of Construction Risk in Public Procurement Contracts

This paper discusses a model based on the agency theory to analyze the optimal transfer of construction risk in public works contracts. The base assumption is that of a contract between a principal (public authority) and an agent (firm), where the payment mechanism is linear and contains an incentive mechanism to enhance the effort of the agent to reduce construction costs. A theoretical model is proposed starting from a cost function with a random component and assuming that both the public authority and the firm are risk averse. The main outcome of the paper is that the optimal transfer of construction risk will be lower when the variance of errors in cost forecast, the risk aversion of the firm and the marginal cost of public funds are larger, while the optimal transfer of construction risk will grow when the variance of errors in cost monitoring and the risk aversion of the public authority are larger

New Constructive Solutions to Improve Energy Efficiency in Existing Buildings and their Economic Viability

The improvement of energy efficiency in existing buildings is always a challenge due to their particular, and sometimes protected, constructive solutions. New constructive regulations in Spain leave a big undefined gap when a restoration is considered because they were developed for new buildings. However, rehabilitation is considered as an opportunity for many properties because it allows owners to obtain benefits from the use of the buildings. The current financial and housing crisis has turned society point of view to existing buildings and making them more efficient is one of the Spanish government’s aims. The economic viability of a rehabilitation action should take all factors into account: both construction costs and the future operative costs of the building must be considered. Nevertheless, the application of these regulations in Spain is left to the designer’s opinion and always under a subjective point of view. With the research work described in this paper and with the help of some case-studies, the cost of adapting an existing building to the new constructive regulations will be studied and Energetic Efficiency will be evaluated depending on how the investment is recovered. The interest of the research is based on showing how new constructive solutions can achieve higher levels of efficiency in terms of energy, construction and economy and it will demonstrate that Life Cycle Costing analysis can be a mechanism to find the advantages and disadvantages of using these new constructive solutions. Therefore, this paper has the following objectives: analysing constructive solutions in existing buildings - to establish a process for assessing total life cycle costs (LCC) during the planning stages with consideration of future operating costs - to select the most advantageous operating system – To determine the return on investment in terms of construction costs based on new techniques, the achieved energy savings and investment payback periods.

Static Pressure Impact on Aerodynamics of High Speed Railway Tunnels

A pressure wave is generated when a high speed train enters a tunnel. This wave travels along the tunnel back and forth, and is reflected at the irregularities of the tunnel duct (section changes, chimneys and tunnel ends). The pressure changes are associated to these waves can have an effect on passengers if the trains are not suitably sealed or pressurized. The intensity of the waves depends mainly on the train speed, and on the blockage ratio (train-section-to- tunnel-section area ratio). As the intensity of the waves is limited by regulations, and also by the effects on passengers and infrastructures, the sizing of the tunnel section area is largely influenced by the maximum train speed allowed in the tunnel. The aim of this study is to analyse the increase in cost in a tunnel due to the existence of this difference in ground level, and evaluate the increase of construction costs that this elevation might involve.

Application of a building cost estimation model to the appraisal of the churches damaged by earthquakes in Lorca (Spain)

The objective of this paper is the development of a building cost estimation model whose purpose is to quickly and precisely evaluate rebuilding costs for historic heritage buildings affected by catastrophic events. Specifically, this study will be applied to the monumental buildings owned by the Catholic Church that were affected by two earthquakes on May 11, 2011 in the town of Lorca. To estimate the initial total replacement cost new, calculation model will be applied which, on the one hand, will use two-dimensional metric exterior parameters and, on the other, three-dimensional interior cubic parameters. Based on the total of the analyzed buildings, and considering damage caused by the seismic event, the final reconstruction cost for the building units ruined by the earthquakes can be estimated. The proposed calculation model can also be applied to other emergency scenarios and situations for the quick estimation of construction costs necessary for rebuilding historic heritage buildings which have been affected by catastrophic events that deteriorate or ruin their structural or constructive configuration.

Greenfield shopping center development. The integration between environmental features, building design and investment analysis at the decision making stage

The Shopping centre is a long term investment in which Greenfield development decisions are often taken based on risks analysis regarding construction costs, location, competition, market and an expected DCF. Furthermore, integration between the building design, project planning, operational costs and investment analysis is not entirely considered by the investor at the decision making stage. The absence of such information tends to produce certain negative impacts on the future running costs and annual maintenance of the building, especially on energy demand and other occupancy expenses paid by the tenants to the landlord. From the investor´s point of view, this blind spot in strategy development will possibly decrease their profit margin as changes in the occupancy expenses[ ] have a direct outcome on the profit margin. In order to try to reduce some higher operating cost components such as energy use and other utility savings as well as their CO2 emissions, quite a few income properties worldwide have some type of environmental label such as BREEAM and LEED. The drawback identified in this labelling is that usually the investments required to get an ecolabel are high and the investor finds no direct evidence that it increases market value. However there is research on certified commercial properties (especially offices) that shows better performance in terms of occupancy rate and rental cost (Warren-Myers, 2012). Additionally, Sayce (2013) says that the certification only provides a quick reference point i.e. the lack of a certificate does not indicate that a building is not sustainable or efficient. Based on the issues described above, this research compares important components of the development stages such as investments costs, concept/ strategy development as well as the current investor income and property value. The subjects for this analysis are a shopping centre designed with passive cooling/bioclimatic strategies evaluated at the decision making stage, a certified regional shopping centre and a non-certified standard regional shopping centre. Moreover, the proposal intends to provide decision makers with some tools for linking green design features to the investment analysis in order to optimize the decision making process when looking into cost savings and design quality.

Parametric analysis on bridge reinforced concrete elevated pile-cap foundations

Current design practices recommend to comply with the capacity protection principle, which pays special attention to ensuring an elastic response of the foundations under ground motion events. However, in cases such as elevated reinforced concrete (RC) pile-cap foundation typologies, this design criterion may lead to conservative designs, with excessively high construction costs. Reinforced concrete elevated pile-cap foundations is a system formed by a group of partially embedded piles connected through an aboveground stayed cap and embedded in soil. In the cases when they are subjected to ground motions, the piles suffer large bending moments that make it difficult to maintain their behavior within the elastic range of deformations. Aiming to make an in-depth analysis of the nonlinear behavior of elevated pile-cap foundations, a cyclic loading test was performed on a concrete 2x3 pile configuration specimen of elevated pile-cap foundation. Two results of this test, the failure mechanism and the ductile behavior, were used for the calibration of a numerical model built in OpenSees framework, by using a pushover analysis. The calibration of the numerical model enabled an in-depth study of the seismic nonlinear response of this kind of foundations. A parametric analysis was carried for this purpose, aiming to study how sensitive RC elevated pile-cap foundations are, when subjected to variations in the diameter of piles, reinforcement ratios, external loads, soil density or multilayer configurations. This analysis provided a set of ductility factors that can be used as a reference for design practices and which correspond to each of the cases analyzed.

The Economic Value of Residential Land in Historical Areas: An Application of the Residual Method to the Secondary Market

Land value bears significant weight in house prices in historical town centers. An essential aim for regulating the mortgage market, particularly in the financial and property crisis that countries such as Spain are undergoing, is to have at hand objective procedures for its valuation, whatever the conditions (location, construction, planning). Of all the factors contributing to house price make-up, the land is the only one whose value does not depend on acquisition cost, but rather on the location-time binomial. That is to say, the specific circumstances at that point and at the exact moment of valuation. For this reason, the most commonly applied procedure for land valuation in town centers is the use of the residual method: once the selling price of new housing in a district is known, the other necessary costs and expenses of development are deducted, including those of building and the developer’s profit. The value left is that of the land. To apply these procedures it is vital to have figures such as building costs, technical fees, tax costs, etc. But, above all, it is essential to obtain the selling price of the new housing. This is not always feasible, on account of the lack of newbuild development in this location. This shortage of information occurs in historical town cities, where urban renewal is slight due to the heritage-protection policies, and where, nevertheless there is substantial activity in the secondary market. In these circumstances, as an alternative for land valuation in consolidated urban areas, we have the adaptation of the residual method to the particular characteristics of the secondary market. To these ends, there is the proposal for the appreciation of the dwelling which follows, in a backwards direction, the application of traditional depreciation methods proposed by the various valuation manuals and guidelines. The reliability of the results obtained is analyzed by contrasting it with published figures for newly-built properties, according to different rules applied in administrative appraisals in Spain and the incidence of an eventual correction due to conservation state.

Environmental analysis of residential building facades through energy consumption, GHG emissions and costs

This paper provides some results on the potential to minimize environmental impacts in residential buildings life cycle, through façade design strategies, analyzing also their impact on costs from a lifecycle perspective. On one hand, it assesses the environmental damage produced by the materials of the building envelope, and on the other, the benefits they offer in terms of habitability and liveability in the use phase. The analysis includes several design parameters used both for rehabilitation of existing facades, as for new facades, trying to cover various determinants and proposing project alternatives. With this study we intended to contribute to address the energy challenges for the coming years, trying also to propose pathways for innovative solutions for the building envelope.

Facade typologies as a tool for selecting refurbishment measures for the Spanish residential building stock

Today, the building sector alone accounts for 40% of the total energy consumption in the European Union (EU). In most EU member states, about 70–90% of the buildings were constructed at least 20 years ago. Due to this, these buildings have a worse energy efficiency behavior than the new ones that comply with current regulations. As a consequence, acting on the existing building stock is needed, developing special methods on assessment and advice in order to reduce the total energy consumption. This article addresses a procedure allowing the classification and characterization of existing buildings facades. It can help researchers to achieve in-depth knowledge of the facades construction and therefore knowing their thermal behavior. Once knowing that, the most appropriate upgrading strategies can be established with the purpose of reducing the energy demand. Furthermore, the classified facade typologies have been verified, complying with current and future Spanish regulations and according to the results obtained, a series of upgrading strategies based on the opaque part and those in the translucent part, have been proposed. As a conclusion, this procedure helps us to select the most appropriate improvement measures for each type of facade in order to comply with current and future Spanish regulations. This proposed method has been tested in a specific neighborhood of Madrid, in a selected period of time, between 1950 and 1980, but it could be applicable to any other city.

Construction cost and energy consumption resulting from energy retrofitting in an apartment building in Madrid (Spain).

This theoretical study analyzes the relation between the measures necessesary for the energy retrofitting of a residential building constructed in Madrid, their cost and the improvement of the energy rating of the dwellings. The aim of this work is to establish an evaluation methodology that allows developers and architects to obtain conclusions and orientates therm in the decisioin-making process. It will allow finding the most suitable cost-effective solutions in each case. This paper describes the methodology and the findings obtained. Energy retrofitting and the improvement of the energy behaviour of the building depend on the selection of the retrofitting solutions and also on the investment. In this case study to achieve the best energy rates it is necessary to improve the thermal performance of the envelope as well as the energy systems. Energy retrofitting means an increase in property value but it can't only be considered in economic terms. It is necessary to take into account unquantifiable aspects as increased comfort, improved sound insulation, livability, health, or the elimination of energy poverty situations.

El análisis de la construcción sin pérdidas (Lean Construction) y su relación con el Project & Construction Management : propuesta de regulación en España y su inclusión en la ley de la ordenación de la edificación

El presente trabajo se basa en la filosofía de la Construcción sin Pérdidas (“Lean Construction”), analizando la situación de esta filosofía en el sector de la edificación en el contexto internacional y español, respondiendo las siguientes preguntas: 1. ¿Cómo surge el “Lean Construction”? 2. ¿Cuáles son sus actividades, funciones y cometidos? 3. ¿Existe regulación del ¨Lean Construction” en otros países? 4. ¿Existe demanda del ¨Lean Construction” en España? 5. ¿Existe regulación del ¨Lean Construction” en España? 6. ¿Cómo debería ser la regulación ¨Lean Construction” en España? 7. ¿Cuál es la relación del “Lean Construction” con el “Project & Construction Management”? 8. ¿Cómo debería ser la regulación de “Lean Construction” en España considerando su relación con el “Project & Construction Management”? Las preguntas indicadas las hemos respondido detalladamente en el presente trabajo, a continuación se resume las respuestas a dichas preguntas: 1. El “Lean Construction” surge en agosto de 1992, cuando el investigador finlandés Lauri Koskela publicó en la Universidad de Stanford el reporte TECHNICAL REPORT N° 72 titulado “Application of the New Production Philosophy to Construction”. Un año más tarde el Dr. Koskela invitó a un grupo de especialistas en construcción al primer workshop de esta materia en Finlandia, dando origen al International Group for Lean Construction (IGLC) lo que ha permitido extender la filosofía a EEUU, Europa, América, Asia, Oceanía y África. “Lean Construction” es un sistema basado en el enfoque “Lean Production” desarrollado en Japón por Toyota Motors a partir de los años cincuenta, sistema que permitió a sus fábricas producir unidades con mayor eficiencia que las industrias americanas, con menores recursos, en menor tiempo, y con un número menor de errores de fabricación. 2. El sistema “Lean Construction” busca maximizar el valor y disminuir las pérdidas de los proyectos generando una coordinación eficiente entre los involucrados, manejando un proyecto como un sistema de producción, estrechando la colaboración entre los participantes de los proyectos, capacitándoles y empoderándoles, fomentando una cultura de cambio. Su propósito es desarrollar un proceso de construcción en el que no hayan accidentes, ni daños a equipos, instalaciones, entorno y comunidad, que se realice en conformidad con los requerimientos contractuales, sin defectos, en el plazo requerido, respetando los costes presupuestados y con un claro enfoque en la eliminación o reducción de las pérdidas, es decir, las actividades que no generen beneficios. El “Last Planner System”, o “Sistema del Último Planificador”, es un sistema del “Lean Construction” que por su propia naturaleza protege a la planificación y, por ende, ayuda a maximizar el valor y minimizar las pérdidas, optimizando de manera sustancial los sistemas de seguridad y salud. El “Lean Construction” se inició como un concepto enfocado a la ejecución de las obras, posteriormente se aplicó la filosofía a todas las etapas del proyecto. Actualmente considera el desarrollo total de un proyecto, desde que nace la idea hasta la culminación de la obra y puesta en marcha, considerando el ciclo de vida completo del proyecto. Es una filosofía de gestión, metodologías de trabajo y una cultura empresarial orientada a la eficiencia de los procesos y flujos. La filosofía “Lean Construction” se está expandiendo en todo el mundo, además está creciendo en su alcance, influyendo en la gestión contractual de los proyectos. Su primera evolución consistió en la creación del sistema “Lean Project Delivery System”, que es el concepto global de desarrollo de proyectos. Posteriormente, se proponen el “Target Value Design”, que consiste en diseñar de forma colaborativa para alcanzar los costes y el valor requerido, y el “Integrated Project Delivery”, en relación con sistemas de contratos relacionales (colaborativos) integrados, distintos a los contratos convencionales. 3. Se verificó que no existe regulación específica del ¨Lean Construction” en otros países, en otras palabras, no existe el agente con el nombre específico de “Especialista en Lean Construction” o similar, en consecuencia, es un agente adicional en el proyecto de la edificación, cuyas funciones y cometidos se pueden solapar con los del “Project Manager”, “Construction Manager”, “Contract Manager”, “Safety Manager”, entre otros. Sin embargo, se comprobó la existencia de formatos privados de contratos colaborativos de Integrated Project Delivery, los cuales podrían ser tomados como unas primeras referencias para futuras regulaciones. 4. Se verificó que sí existe demanda del ¨Lean Construction” en el desarrollo del presente trabajo, aunque aún su uso es incipiente, cada día existe más interesados en el tema. 5. No existe regulación del ¨Lean Construction” en España. 6. Uno de los objetivos fundamentales de esta tesis es el de regular esta figura cuando actúe en un proyecto, definir y realizar una estructura de Agente de la Edificación, según la Ley de Ordenación de la Edificación (LOE), y de esta manera poder introducirla dentro de la Legislación Española, protegiéndola de eventuales responsabilidades civiles. En España existe jurisprudencia (sentencias de los tribunales de justicia españoles) con jurisdicción civil basada en la LOE para absolver o condenar a agentes de la edificación que son definidos en los tribunales como “gestores constructivos” o similares. Por este motivo, en un futuro los tribunales podrían dictaminar responsabilidades solidarias entre el especialista “Lean Construction” y otros agentes del proyecto, dependiendo de sus actuaciones, y según se implemente el “Lean Project Delivery System”, el “Target Value Design” y el “Integrated Project Delivery”. Por otro lado, es posible que el nivel de actuación del especialista “Lean Construcción” pueda abarcar la gestión del diseño, la gestión de la ejecución material (construcción), la gestión de contratos, o la gestión integral de todo el proyecto de edificación, esto último, en concordancia con la última Norma ISO 21500:2012 o UNE-ISO 21500:2013 Directrices para la dirección y gestión de proyectos. En consecuencia, se debería incorporar adecuadamente a uno o más agentes de la edificación en la LOE de acuerdo a sus funciones y responsabilidades según los niveles de actuación del “Especialista en Lean Construction”. Se propone la creación de los siguientes agentes: Gestor del Diseño, Gestor Constructivo y Gestor de Contratos, cuyas definiciones están desarrolladas en este trabajo. Estas figuras son definidas de manera general, puesto que cualquier “Project Manager” o “DIPE”, gestor BIM (Building Information Modeling), o similar, puede actuar como uno o varios de ellos. También se propone la creación del agente “Gestor de la Construcción sin Pérdidas”, como aquel agente que asume las actuaciones del “gestor de diseño”, “gestor constructivo” y “gestor de contratos” con un enfoque en los principios del Lean Production. 7. En la tesis se demuestra, por medio del uso de la ISO 21500, que ambos sistemas son complementarios, de manera que los proyectos pueden tener ambos enfoques y ser compatibilizados. Un proyecto que use el “Project & Construction Management” puede perfectamente apoyarse en las herramientas y técnicas del “Lean Construction” para asegurar la eliminación o reducción de las pérdidas, es decir, las actividades que no generen valor, diseñando el sistema de producción, el sistema de diseño o el sistema de contratos. 8. Se debería incorporar adecuadamente al agente de la edificación “Especialista en Lean Construction” o similar y al agente ¨Especialista en Project & Construction Management” o DIPE en la Ley de Ordenación de la Edificación (LOE) de acuerdo a sus funciones y responsabilidades, puesto que la jurisprudencia se ha basado para absolver o condenar en la referida Ley. Uno de los objetivos fundamentales de esta tesis es el de regular la figura del “Especialista en Lean Construction” cuando actúa simultáneamente con el DIPE, y realizar una estructura de Agente de la Edificación según la LOE, y de esta manera protegerlo de eventuales responsabilidades solidarias. Esta investigación comprueba que la propuesta de definición del agente de edificación DIPE, según la LOE, presentada en la tesis doctoral del Doctor Manuel Soler Severino es compatible con las nuevas definiciones propuestas. El agente DIPE puede asumir los roles de los diferentes gestores propuestos en esta tesis si es que se especializa en dichas materias, o, si lo estima pertinente, recomendar sus contrataciones. ABSTRACT This work is based on the Lean Construction philosophy; an analysis is made herein with regard to the situation of this philosophy in the building sector within the international and Spanish context, replying to the following questions: 1. How did the concept of Lean Construction emerge? 2. Which are the activities, functions and objectives of Lean Construction? 3. Are there regulations on Lean Construction in other countries? 4. Is there a demand for Lean Construction in Spain? 5. Are there regulations on Lean Construction in Spain? 6. How should regulations on Lean Construction be developed in Spain? 7. What is the relationship between Lean Construction and the Project & Construction Management? 8. How should regulations on Lean Construction be developed in Spain considering its relationship with the Project & Construction Management? We have answered these questions in detail here and the replies are summarized as follows: 1. The concept of Lean Construction emerged in august of 1992, when Finnish researcher Lauri Koskela published in Stanford University TECHNICAL REPORT N° 72 entitled “Application of the New Production Philosophy to Construction”. A year later, Professor Koskela invited a group of construction specialists to Finland to the first workshop conducted on this matter; thus, the International Group for Lean Construction (IGLC) was established, which has contributed to extending the philosophy to the United States, Europe, the Americas, Asia, Oceania, and Africa. Lean Construction is a system based on the Lean Production approach, which was developed in Japan by Toyota Motors in the 1950s. Thanks to this system, the Toyota plants were able to produce more units, with greater efficiency than the American industry, less resources, in less time, and with fewer manufacturing errors. 2. The Lean Construction system aims at maximizing the value of projects while reducing waste, producing an effective coordination among those involved; it manages projects as a production system, enhancing collaboration between the parties that participate in the projects while building their capacities, empowering them, and promoting a culture of change. Its purpose is to develop a construction process free of accidents, without damages to the equipment, facilities, environment and community, flawless, in accordance with contractual requirements, within the terms established, respecting budgeted costs, and with a clear approach to eliminating or reducing waste, that is, activities that do not generate benefits. The Last Planner System is a Lean Construction system, which by its own nature protects planning and, therefore, helps to maximize the value and minimize waste, optimizing substantially the safety and health systems. Lean Construction started as a concept focused on the execution of works, and subsequently the philosophy was applied to all the stages of the project. At present it considers the project’s total development, since the time ideas are born until the completion and start-up of the work, taking into account the entire life cycle of the project. It is a philosophy of management, work methodologies, and entrepreneurial culture aimed at the effectiveness of processes and flows. The Lean Construction philosophy is extending all over the world and its scope is becoming broader, having greater influence on the contractual management of projects. It evolved initially through the creation of the Lean Project Delivery System, a global project development concept. Later on, the Target Value Design was developed, based on collaborative design to achieve the costs and value required, as well as the Integrated Project Delivery, in connection with integrated relational (collaborative) contract systems, as opposed to conventional contracts. 3. It was verified that no specific regulations on Lean Construction exist in other countries, in other words, there are no agents with the specific name of “Lean Construction Specialist” or other similar names; therefore, it is an additional agent in building projects, which functions and objectives can overlap those of the Project Manager, Construction Manager, Contract Manager, or Safety Manager, among others. However, the existence of private collaborative contracts of Integrated Project Delivery was confirmed, which could be considered as first references for future regulations. 4. There is a demand for Lean Construction in the development of this work; even though it is still emerging, there is a growing interest in this topic. 5. There are no regulations on Lean Construction in Spain. 6. One of the main objectives of this thesis is to regulate this role when acting in a project, and to define and develop a Building Agent structure, according to the Building Standards Law (LOE by its acronym in Spanish), in order to be able to incorporate it into the Spanish law, protecting it from civil liabilities. In Spain there is jurisprudence in civil jurisdiction based on the LOE to acquit or convict building agents, which are defined in the courts as “construction managers” or similar. For this reason, courts could establish in the future joint and several liabilities between the Lean Construction Specialist and other agents of the project, depending on their actions and based on the implementation of the Lean Project Delivery System, the Target Value Design, and the Integrated Project Delivery. On the other hand, it is possible that the level of action of the Lean Construction Specialist may comprise design management, construction management and contract management, or the integral management of the entire building project in accordance with the last ISO 21500:2012 or UNE-ISO 21500:2013, guidelines for the management of projects. Accordingly, one or more building agents should be appropriately incorporated into the LOE according to their functions and responsibilities and based on the levels of action of the Lean Construction Specialist. The creation of the following agents is proposed: Design Manager, Construction Manager, and Contract Manager, which definitions are developed in this work. These agents are defined in general, since any Project Manager or DIPE, Building Information Modeling (BIM) Manager or similar, may act as one or as many of them. The creation of the Lean Construction Manager is also proposed, as the agent that takes on the role of the Design Manager, Construction Manager and Contract Manager with a focus on the Lean Production principles. 7. In the thesis it is demonstrated that through the implementation of the ISO 21500, both systems are supplementary, so projects may have both approaches and be compatible. A project that applies the Project & Construction Management may perfectly have the support of the tools, techniques and practices of Lean Construction to ensure the elimination or reduction of losses, that is, those activities that do not generate value, thus designing the production system, the design system, or the contract system. 8. The Lean Construction Specialist or similar and the Specialist in Project & Construction Management should be incorporated appropriately into the LOE according to their functions and responsibilities, since jurisprudence has been based on such Law to acquit or convict. One of the main objectives of this thesis is the regulate the role of the Lean Construction Specialist when acting simultaneously with the DIPE, and to develop a structure of the building agent, according to the LOE, and in this way protect such agent from joint and several liabilities. This research proves that the proposal to define the DIPE building agent, according to the LOE, and presented in the doctoral dissertation of Manuel Soler Severino, Ph.D. is compatible with the new definitions proposed. The DIPE agent may assume the roles of the different managers proposed in this thesis if he specializes in those topics or, if deemed pertinent, recommends that they be engaged.