External wall specifications and pollution relation in concrete based prefabricated elementary school buildings

Beton prefabrike ilköğretim binalarında dış duvar - çevre kirliliği ilişkisi

Abstract

The necessity quickly built educational buildings due to the changes in the education system and education periods punctuates the necessity of using prefabricated systems and development in these systems in many aspects. The low heat permeability resistance of concrete and the heat bridges occurring in the joints of the prefabricated systems cause great heating energy losses; and thus life cycle cost of the building increase. In case educational buildings are made via concrete based prefabricated systems, systems regarding production costs, speed and building eases should be evaluated along with the evaluation of heating energy efficiency of the external components of such systems, determination of problematic points and presentation of solution proposals. In case the outer coverings which are highly made of external walls, are made of concrete prefabricated systems, evaluation of problematic points of wall types of possible systems in view of heating energy efficiency and pollution emissions is the main subject of this study. Additionally, increase in carbon dioxide emissions due to high fuel consumption causes pollution. Atmosphere, defined as the gas layer surrounding the earth has been through many transformations for approximately two billion years. Consequently, concepts of “Atmospheric Pollution” and “Air Pollution” have emerged. The most general definition of Atmospheric Pollution can be made as “presence of foreign materials in the atmosphere in concentrations or periods that may be harmful for human health, other species, ecological balance and materials”. This study generally reveals the problem points in the classification of concrete based prefabricated external wall options and evaluation of energy efficiency. Primarily general classification of concrete based prefabricated external wall elements and external wall options to be used in the construction of educational structures have been determined. Thereafter, energy efficiency criteria for the options have been determined and problem points in inspection of heating energy efficiency of the external wall have been discussed. Building typologies and related external wall options have been listed. External wall options to be evaluated related to the building typology has been classified in general groups and sub groups under those general groups. The general group called structure bearing system setup has been divided into four subgroups namely; horizontal effect, vertical effect, horizontal-vertical effect and straight effect. Width based general group consists of three subgroups named, narrow, average and wide subgroups. General group related to bearing is divided into self bearing, borne and bearing subgroups. Regarding to the basic criteria the change energy efficiency in prefabricated external wall panels combinations depending on triple conditions consisting of one ideal and two problematic options in relation to every subgroup were constituted. The triple status in line with the subgroups can be summarized as ideal solution (without heat bridges), heat bridge in the pointing,, heat bridge in the panel body. Concrete is material that has high heat permeability value. Concrete based prefabricated external wall elements can be applied to the building so as to create heat bridges in the panel body in relation to the production technology or joint systems. When the spaces called pointing between the concrete based prefabricated external wall panels are not insulated, massive thermal losses occur. It is possible to find solutions to the above mentioned problem points or in other words; to establish correct application options. Therefore, it is assumed that transparent parts do not create a problem or there were no air leaks at the problem points, and it has been aimed to evaluate heating energy efficiency only in concrete based prefabricated external wall options and problem points of thereof. Also, heat current in the problem points of the option have been assumed to be vertical and in single direction and possible lateral heat currents have been ignored. Finally it is devoted to calculation and evaluation of atmospheric pollutant emissions of the options. In evaluation of the pollutant emissions of the options established according to the surface layout, panel width and bearing status, the surface panels in which seamless heat insulation is applied in “pre-positioned” pointings and panel bodies that completely cover the bearing system elements have the lowest heating energy consumption and therefore cause minimum level of pollutant emissions.

Özet

Değişen eğitim sistemine ve süresine bağlı olarak eğitim yapılarının hızla inşa edilmesi zorunluluğu, prefabrike sistemlerin kullanımını ve bu sistemlerin birçok açıdan geliştirilmesi gerekliliğini ortaya koymaktadır. Eğitim yapılarının beton esaslı prefabrike sistemlerle yapılması durumunda üretim maliyetinin, hızının ve yapım kolaylıklarına ilişkin sistemlerin değerlendirilmesi zorunluluğunun yanında, sistemlere ait kabuk bileşenlerinin de ısıtma enerjisi bakımından etkinliğinin değerlendirilmesi, problem noktalarının belirlenmesi ve çözüm önerilerinin sunulması gerekmektedir. Sekiz yıllık eğitim sistemimde yaklaşık 300.000 derslik kapasiteli eğitim yapılarının yapımı söz konusu olmakta ve ısıtma enerjisi tüketimini çok az düzeyde azaltacak bir çözümün geliştirilmesiyle bile yapı toplamında büyük oranda enerji tasarrufu sağlanmaktadır. Yapı kabuğunun büyük bir yüzdesini oluşturan dış duvarların betonarme prefabrike sistemlerle oluşturulması durumunda olası sistemlerin duvar tiplerinin problem noktalarının ısıtma enerjisi tüketim verilerine bağlı olarak kirletici emisyonlarının değerlendirilmesi bu çalışmanın ana konusunu oluşturmaktadır. Çünkü betonun ısı geçirgenlik direncinin düşük oluşu ve prefabrike sistemlerde birleşimlerde meydana gelen ısı köprüleri büyük miktarda enerji kayıplarına neden olmakta; bunun sonucunda da binanın yaşam dönemi maliyetleri artmaktadır. Bunlara ek olarak, yüksek yakıt tüketimi nedeniyle atık gaz emisyonlarının yükselmesi çevre kirliliğinin artmasına neden olmaktadır. Bu nedenle bina tasarımında ısıtma enerjisi kapsamında etkin sistemlerin araştırılması ve çözümlerin geliştirilmesi zorunluluğu ortaya çıkmıştır.