Bina Kabuğunun Dış Duvarları Ve Ara Kesitlerinde Isıl Ve Nemsel Performansın Kızılötesi Termografi İle Değerlendirilmesi Üzerine Bir Alan Çalışması

Abstract

Günümüzde enerji açısından verimli binalara olan talep yenilenemeyen kaynakların hızla tükenmesiyle birlikte önemli ölçüde artmıştır. Bu durum, iç mekan konfor şartlarının sağlanması için daha az enerji tüketilerek yenilenebilir kaynakların ve pasif iklimlendirme sistemlerinin kullanılmasını, yalıtım ve sızdırmazlık malzemeleri ile ısıtma - havalandırma sistemlerinin verimliliğine daha fazla önem verilmesini sağlamıştır. Bu bağlamda, gerek yeni, gerekse mecut yapı stoğunun kalitesini arttıracak, enerji korunumu ve optimum performans gösterecek bina kabuk çözümlerinin geliştirilmesine yönelik mimari çalışmalar da hız kazanmıştır. Tez çalışmasında enerji verimliliği ve çevresel sürdürülebilirlik konularına paralel olarak dış kabukta meydana gelen, ısı köprüleri, hava sızıntıları, nem ve yoğuşma sorunlarının yerinde belirlenmesiyle tasarım ve uygulama aşamasında alınabilecek önlemler ile kullanım aşamasında yapılabilecek iyileştirme çalışmalarına doğrudan katkı sağlanması hedeflenmiştir. Bina kabuğunda, özellikle dış duvarlar ve ara kesitlerinde ısıl ve nemsel performansın incelendiği bu çalışma literatür araştırması, alanda inceleme ve sonrasında değerlendirme için ön hazırlık kapsamında bir model oluşturulması ve alan çalışmaları olarak üç ana başlık altında işlenmiştir. Literatür araştırmasının ilk bölümünde bina dış kabuğunun en önemli alt bileşeni olan dış duvarlara ait yapı fiziğiyle ilgili temel konulara yer verilmiştir. Dış duvar sisteminin tanımı, sınıflandırılması, opak ve saydam alt bileşenleri ile bu bileşenlere ait yapısal özellikler ele alınmış; çevresel şartlar altında bina kabuğu bileşenleri ve birleşimlerinden beklenen ısıl ve nemsel performans gereksinmeleri irdelenmiştir. İkinci bölümünde ise, binaların dış kabuğunda ısıl ve nemsel performansın incelenmesinde ve yapı hasarlarının tespitinde kullanılan görüntüleme tekniği hakkında bilgi verilmiş; IR termografinin dayandığı fiziksel ilkelere genel olarak değinilmiş, IR kamerayla ölçüm ve değerlendirmeyi etkileyen faktörler özetlenmiştir. IR kamera kullanarak bina dış kabuğunu inceleyen araştırmacıların gerçekleştirdiği alan çalışmaları ve laboratuvar çalışmaları gözden geçirilmiştir. Böylece, tez kapsamında yapılan alanda cephe inceleme çalışmalarına bir alt yapı oluşturulmuştur. Ön hazırlık aşamasında, alan çalışmalarında binalarda sistematik bir inceleme yapabilmek amacıyla, bütüncül bir yaklaşımla ele alınan model üzerinden bir durum değerlendirme formu oluşturulmuştur. Dış duvar elemanının dış kabuktaki diğer bileşenlerle doğrudan ve dolaylı ilişkilerinin ve ortam şartlarının tam olarak ortaya konabilmesini sağlayan bu model, gerekli tüm bilgi ve verilerin düzenli olarak toplanması ve kaydedilmesine yardımcı olmuştur. Alan çalışmaları bölümü tezin amacına ve kapsamına bağlı olarak oluşturulan model çerçevesinde yürütülen inceleme çalışmalarından oluşmaktadır. Yapımı tamamlanmış ve kullanım aşamasındaki binaların dış kabuğunun çevresel etmenler karşısındaki durumu görsel analizler ve IR termografi tekniği ile belirlenerek, dış duvar bileşenleri ve birleşimleri incelenmiştir. İç ve dış ortamlardan termal kamera ile görüntülenen cephelerin oluşturulan model sistematiğine uygun olarak seçilen örnekler üzerinden ısıl ve nemsel performansının genel bir değerlendirmesi yapılmıştır.

The amount of energy consumption and its environmental effects throughout the life-cycle of buildings is gaining greater importance due to energy and environmental policies. Regarding heat losses and gains through buildings’ envelope, heating and cooling energy expenditure is required to be lower as a primary building performance today. According to the Construction Products Directive and the Standard Buildings Energy Performance regulations, buildings must be energy efficient and fullfill performance requirements over an economically reasonable working life. From an environmental sustainibility point of view, buildings’ energy efficiency is mainly associated with hygrothermal performance of their envelope by means of long-term performance, service life prediction and durability, in addition to user requirements such as thermal comfort and indoor air quality issues. Today, numerous investigations are carried out worldwide to determine the long-term thermal and moisture performance of newly designed building envelopes, as well as for the improving existing structures in use. As stated in the first chapter, this study focuses on thermal and moisture performance assessment of building envelope systems in general, and in-situ measurements of external walls visually and by a non-destructive method; infrared (IR) thermography. It consists of three main parts: i) literature review, ii) setting up a systematic model for field investigations and evaluation afterwards, iii) on-site inspections of external walls for thermal and moisture performance assessment. The main topics reviewed in the literature research, in chapter 2 and 3, can be counted briefly as: basic information on external wall system components, thermal and moisture performance requirements of external walls, technical specifications of IR camera, factors affecting data collection and interpretation by IR thermograpy, and scientific investigations based on condition monitoring of external wall systems by IR thermography method. When assesing the hygrothermal performance of building enclosure system, a series of inspections on different scales are conducted through building enclosure; from a smaller scale to larger, with a holistic approach. In this context, external wall system components divided into opaque (masonry unit, mortar, insulation, surface finishes, skeleton frame etc.) and transparent (frame casements, glazing, joint sealants etc.) sub-components. External wall elements which are directly or indirectly in contact with the other wall system elements are also analysed and considered in detail. The interrelations of adjacent external wall elements are classified as masonry wall, skeleton structural frame, wall opening, roof, ground and service system instalations. In-use thermal and moisture performance of examined case buildings are based on data obtained through in-situ IR camera records. Before receiving data in the field, a holistic approach is adopted to systematically organise data for collecting, documenting, and analysing the environmental conditions in local and micro levels. Thus, the general features of the building and the characteristics of its surrounding environment which may likely influence the external wall performance are taken into account together with the micro environmental conditions of the external envelope. In order to perform thermographic measurements easily, an inspection questionnaire, i.e. condition assessment protocol (CAP), in the form of a checklist is developed for a systematic visual examination, in-situ surface scanning, data recording, and further assessment. As explained in chapter 4, checklist consists of five main parts. In the first part, surrounding conditions of the inspected building, such as the location of the building and its amenities, orientation of facades according to surrounding buildings, and objects affecting the solar gain of facade etc. have been addressed. Information on general features of the examined building, in terms of settlement site/territory, building type, orientation of buildings, number of blocks, number of storeys in each block, independent flats/units on each floor, structural system, heating system, etc. are also covered in the first part. The main objective of the second part of the checklist is to inspect the external wall systems considering the interrelations between their components, to collect and document all obtained and measured data through facade scans (by means of IR thermography), pictures and schematic drawings in a systematic order. The framework of this survey model is based on the interrelations of elements, components and materials of external wall systems that are associated with the junction points mentioned above. The architectural characteristics of the studied external wall systems and the physical properties of wall components are analysed from existing drawings of detailed application projects and pictures taken during the construction phase. Some technical data regarding the detailed information is also required from the design offices, construction companies, or local government departments. Interior and exterior wall surface temperatures, indoor and outdoor ambient air temperatures, and relative humidity levels are recorded and data is arranged in a table format in the fourth part of the survey. Location and orientation of examined facades concerning temperature difference between indoor and outdoor environment, the prevailing wind direction and speed, emissivity values of surface finishing materials, intensity of precipitation, relative humidity in atmosphere, cloudiness/clearness of sky, extraneous heat sources, etc. may affect the IR results and distort the thermal images. Therefore, instant data related to the (indoor and outdoor) microenvironmental conditions at the time and date of field work is measured and documented. For each facade examined, the orientation of the studied wall, the approximate distance between the target surface and the IR camera perspective is plotted on a partial plan of the building floor in the last part of the checklist. In the 5th chapter, a series of external wall conditions from inspected cases are organized as seperate examples and the constructional deteriorations of the buildings exemplified for such as thermal bridges, water leakage, hidden condensation, potential moisture, air infiltration, mold formation, lack of insulation etc. The periodic measurements were taken from different types of buildings located in various districts of İstanbul and Bursa, during the winter period of 2009/2010 when the temperature difference between indoor and outdoor environment was the highest. IR images visualising thermal bridges and thermal patterns such as hot and cold spots on buildings’ envelope surfaces combined with digital image pairs captured at the same time, from nearly the same position along with the supporting measurements were all together assessed. All inspected buildings are particularly selected according to the opaque parts of their external walls which are built with a common masonry unit; pumice aggragated concrete block (PACB). The priority is given to the completed buildings, those the construction phases of which were observed and reported within a previous field work, and are already in use at the time of facade inspections. Before implementation, planning of time and date of inspections in advance according to the meteorological weather forecasts is important in order to capture the best thermal images. To avoid misinterpretation and complication in thermographic data, IR measurements are considered to be scheduled on the appropriate dates and times. Thermographic surveys are particularly conducted shortly after heavily overcast days. In addition, the temperature difference between indoor and outdoor environment is considered to be at least 5 ºC. Factors that complicate the collection and interpretation of thermographic data regarding the examined building element, environment and equipment are also considered during recording. Thermal and moisture performance of external wall is critical considering energy saver design approach. Thermal bridges inspected in some parts of the building envelope most likely originates from lack of thermal insulation or moisture ingress are determined to be the leading thermal issues in chapter 6. In this respect, prevention of thermal bridges, sufficient and proper insulation application, and improved enclosure protection are the subjects to be dealt with during design and construction stages of buildings. Both new and existing buildings need to be scanned to assess the actual themal and moisture performance of building envelope; since, the actual thermal performance of a building may have different hygrothermal characteristics than what the architect intended during the design stage. This may also have particularly changed during construction process or in the long-term use by the effects of environmental factors. In chapter 7, IR thermography imaging results of the case studies with the proposed systematic inspection model are summed up and presented by thermal atlases. The results were discussed through gathered information based on architectural features of the inspected buildings and specific conditions of their surrounding environment together with the technical data collected during the construction phase of the building.