Design principles for reducing thermal bridges at intersection details on building elements

Users need environments where their comfort conditions are covered to be able to carry out their actions effectively. The building envelope helps users to maintain comfort conditions when environmental factors are not ideal for users. It is important that the intersection details of the building envelope are designed to meet the required performances so that the buildings can adequately meet the user requirements. The problems that may arise and managing the design process in this context provide both economic and process advantages. The building elements that are not designed properly during the architectural design process can not meet the user requirements. Although these negative factors that reduce the performance of the structure are tried to be improved after the design process, it can not be efficient due to the difficulties in implementation. The performance of the building elements that make up the building envelope in terms of heat and humidity, affects the performance of the entire building. In particular, the details of different geometries and the combination of materials materials have a different thermal performance from the overall construction element. Due to the discontinuity of the material at the intersection details, the heat transfer is takes place more. In these regions, called heat bridges, undesired heat losses and gains are increased, especially with heat losses, the internal surface temperature is lower than regular part of the building element. In order to overcome this negative effect, thermal performance evaluations must also consider to reduce the effects of thermal bridges. There are various methods in the standards and regulations for calculating the thermal performances of the building elements. However, these methods are generally insufficient to calculate the thermal bridges because they generally address the homogeneous regions of the building elements. Most of the calculations of heat bridges are based on the specific details available. Since these details are specific to the structure and they are mostly restricted to the construction methods in the country where the work is done they only give an idea of similar details. For this reason, most of these studies are not enough to determine the general principles of thermal bridges. Measurement works on thermal bridges have difficulties both in terms of cost and process. Although simulation programs are the most effective method in terms of time and cost, it is difficult to make detailed analysis of the building elements and their combinations for each situation. Because the calculations for thermal bridges are less effective in the overall design process and the general design principles to prevent thermal birdges are not specified adequately, the design of the details without thermal bridges is difficult. The prevention of thermal bridges in detail design phase is also important in terms of user comfort, building health and overall cost. In this study, it is aimed to develop a model to abstract and evaluate the factors which effect on the thermal bridges and the details that would not create thermal bridges It is also aimed to determine general principles for detail design which does not create thermal bridge with developed model. Considering the cost, time, and efficiency for this study, it has been observed that computer simulation programs are cost effective, fast and efficient. For this reason, the use of simulation programs in the study was deemed appropriate. Existing physical examples have been tested in the simulation program depending on the abstracted material, size, geometry, surface properties and indoor and outdoor air temperatures. As simulation program, Heat3 and AnTherm programs which can calculate 3 dimensional heat transfer are used. An abstract two-dimensional intersection detail has been developed from the partially refined existing detail examples that forms thermal bridge. An abstract intersection detail of 3x3 9 equal square units is developed and it is aimed each unit to represent a part of intersection detail which is effective in forming the thermal bridge. The developed two-dimensional abstract intersection detail is modeled in the simulation program in the context of geometry, material and size and geometry, material, size and environmental factors were analyzed to determine the effectiveness of forming thermal bridge. As a result of the study, the effectiveness of both individual and combination of the variables such as geometry, material, size and environmental factors of the abstract intersection detail to form the thermal bridge were determined. As a result of the literature review and analyzes, it is shown that the effects of variables thermal bridges and proposed design principals for thermal bridge-free details that can be used in the detail design process