Tasarım evresinde fonksiyonel elemanların miktarına dayalı maliyet kontrolüne ilişkin bir çalışma

Abstract

Bu tez çalışmasının amacı, bina liretim sürecinde gerekli olan maliyet tahmin modellerini ve maliyeti etkileyen faktörleri kısaca açıklayarak, tasarım evresinde fonksiyonel elemanların miktarlarına dayalı maliyet kontrolüne ilşkin bir çalışmaya girmek, elde edilen bulgular üzerinde tartışarak, bir sonuç geliştirmektir. Birinci bölümde, tezin kapsamı içinde geçen maliyetle ilgili kavramlar tanımlanmıştır. ikinci bölümde, proje düzeyinde maliyet tahmin mo delleri tanıtılmış, bina üretim sürecinin her evresinde maliyeti etkileyen faktörlerden bahsedilmiştir. üçüncü bölümde, tasarım evresinde fonksiyonel elemanların miktarlarına dayalı maliyet kontrolüne ilişkin bir çalışma dahilinde, konuyla ilgili daha önce yapılan bazı çalışmalar incelenmiş, çalışmanın amacı ve metodu anlatılmış, bulguları verilmiştir. Sonuç bölümünde, bir bilgi sistemi geliştirmek amacıyla yapılan bu çalışmanın sağladıkları ve bunlardan nasıl yararlanılabileceği tartışılmaktadır.

Since the very early years, cost is one of the most important criterias for construction process. With the help of Industrial Revolution, the improvement of industry has developed this conscious. The idea of profit making, the increase in the complication and gross of the projects, the movements in traditional economic and social situations, the necessity of housing which goes parallel with the increase of population have forced rational use of economic sources. In this case, decision making approach within the decided cost limits have developed. In our country, the demand for housing because of the increase in population causes problems such as houses to cover the population, land to cever the houses and finance to meet all in housing sector. Since the private sector is not capable of handling this situation, the solution is the mass housing projects which are being either done or supported by the state. Also in this case cost is very important as it is in each production field. The housing projects which we have included to our research have been chosen out of the projects which have been chosen out of the projects which have been chosen out of the project are big enough and the standards of the projects which have been met. The decisions which effect the cost of the buildings have been taken during the design process. During this time, the architects take an active role so with their decisions they directly effect the cost. As a designer, the goal of the architect should be to plan a building which provides the requirements of the user with a minimum of expenditure and maximum advantage. To do this, they have to know the factors into consideration. To effect the cost of the buildings depend on the evaluation scales that the architects are going to use. Related to this goal, during the project phase, various information systems have been formed by developing evaluation scales which are backed up by scientific bases. VI The aim of this study which has been done on building projects which are specific in quality and number, is to develop evaluation scales depending on functional building elements that are going to be identified in the next pages. When we go over the the sections; A. The Identification of the Concepts Related to the Cost In this section, concepts that are related to cost and building cost will be identified. * Cost is the total amount of production expenses. * Cost of building is the sum of expenses that start whit the definitionof a demand for a building and end when the building comes out of use. B. Cost Modelling at Project Level and the Factors That Effect the Cost During the Building Production Process B. a. fill estimating methods can be described as models, ft cost model's task may be to estimate the cost of a whole design or of an element of it or to calculate the cost effect of a design change. Models can be classified as follows: - in place quantities, - descriptive models, - realistic models. * In Place Quantities These methods have almost copleted their own development. Increasing the detail and complexity of quantity based aethods does not seem to produce greater overall accuracy and this is sign that the end of that development road has probably been reached. These methods can also classified as follows: - Single price estimating, Vll - Elemental estimating, - Estimating based on bill of quantities, - Resource based estimating. * Descriptive Models These models were characterised by intensive use of regression analysis. The relation ship between cost and factors which affect on it are formulated. The relationships represented are not necessarily causal. They are relatedto, but make no claim to cause variability in the dependent variable. In this respect, they are further from reality than methods based on quant it ies. The effect of a particular choice in a future of a design can obviously only be measuredby a regression model if the factor which describes the feature is presents. * Realistic Models These models appear to have begun in early 19S0' s. These have two central characteristics. Firstly, a willingness to admit to the existence of uncertainty and imprecision and a desire to the account of this by carrying out probabilistic estimates frequently based on Monte Carlo techniques. The second characteristic of the realistic models is also computer linked. The estimating accuracy of realistic models may initially be less but their potential for improvement is far greater. B. b. The Factors That Effect the Cost During the Building Production Process fit each phase during the production process, different people take different decisions towards their goals and these decisions effect the total cost of the buildings. The subject that we should go over- here is how these decisions effect the cost. vi 1 1 * The factors That Effect the Cost During the Predecision Phase: This phase is a phase which the necessities and limitations are discussed, which the resources are identified, which the study is done whether these necessities can be provided by divisional or resources and preparing a pre-necessit ies list. - The Function of the building, - The place of the building and land conditions, - Infrastructure of the building, - Vehicle cost, - Foundation cost, - The quality of the building, - Production scale - Technology - Finance source * The Factors That Effect the Cost During The Design Phases The cost which has been defined during the predecision phase changes with respect to the below meentioned factors during the design phase: - Plan shape, - Buiding size, - Settlement order, - Number of stories, - The height of story, - Circulation a.reB, - Story order, ix Conveyor system. * The Factors That Effect the Cost During the Realisation Phase: The cost which has been defined during the design phase change with respect to the below mentioned factor during the realization phase : - Changes done on the project, - Changes caused by the subjects that could not have been estimated precisely, - Changes caused by inflation estimates, - Changes caused by law, - Changes caused by the productivity of the employees and by the use of the resources, - Changes caused by working conditions and organization mistakes, - Changes caused by management mistakes. * The Factors That Effect the Cost During the Using Phase The cost caused by the use of the building and the land : - Maintenance of the infrastucture, - To make changeson the building during the usage period, - To change the function of the building. C. fi Study on Cost Controlling on the Basis of Functional Building Elements During Design Process The aim of this study is to develop a model which can control the cost during the design phase depending on the quantity of functional elements. The housing projects which we have included to our research have been chosen out of the mass housing projects which have been either constructed or supported by the state. The quantity of the functional elements were considered and by taking the arithmetical average, standard deviation, correlation and regression values of these quantities, it has been detected which functional element quantity changes to what extent depending on the room number and plan types. The findings were discussed in the results section.