Soğutma Enerjisi Tasarrufu Açısından Yapı Kabuğu Dokusunun Pasif Sistem Ögesi Olarak Tasarlanmasında Kullanılabilecek Bir Yaklaşım

thumbnail.default.placeholder
Tarih
1996
Yazarlar
İspir, Pınar
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Institute of Science and Technology
Özet
Bu tez çalışmasının konusunu, ısıtmanın istenmediği dönemde soğutma enerjisi ekonomisi açısından tasarlanacak opak kabuk bileşen dokusunun pasif bir sistem öğesi olarak tasarlanmasında kullanılabilecek bir yöntem oluşturmaktadır. Bu çalışmanın amacı, aktif soğutmaya ihtiyaç duyulan dönemde binalarda kullanılacak yapma soğutma sistemlerinin enerji harcamalarım minimize edebilmek için opak yapı kabuğu dokusunun pasif bir sistem öğesi olarak opak kabuk bileşeninin optimal performansa sahip olacak şekilde tasarlanması için bir yaklaşım geliştirilmesidir. Çalışmada, ısıtmanın istenmediği dönemde, tasarlanan opak bileşen dokularının, direkt güneş ışınımını yönlere göre belirli alanlarda keserek opak bileşen yüzeyindeki sol-air sıcaklığı azaltıp, opak bileşende oluşan ısı akımı miktarını düşürmesi ve ısı kazancını minimize etmesi incelenmiştir. Bu inceleme beş ana bölümde yapılmıştır. Bölüm l'de, ısıtmanın istenmediği dönemde, iklimsel konfor koşullarının pasif soğutma sistemleri ile sağlanarak enerji korunumu yapılması ve bu enerji korunumunu zorunlu kılan faktörler kısaca anlatılmıştır. Bölüm 2'de, ısıtmaya ihtiyaç duyulmayan dönemde soğutma enerjisi korunumunda, yapma çevreye ait tasarım kiriterleri, opak kabuk bileşeninin optik ve termo.fiziksel özellikleri ve opak bileşen dokusunun etkileri tanıtlmıştır. Bölüm 3 'de, soğutma enerjisi korunumu için opak bileşen dokusunun opak bileşen yüzeyindeki güneş ışınımının direkt etkisini belirli alanlarda keserek pasif bir sistem öğesi olarak tasarlanmasında kullanılabilecek bir yöntem genel olarak anlatılmıştır. Bölüm 4'de, bir önceki bölümde anlatılan yöntemin, Antalya yöresi için enerji etkin bina kabuğu tasannu amacı ile uygulaması yapılmıştır. Bölüm 5'te, yapılan uygulamanın sonuçlan açıklanmış ve yöntemin pratikte kullanımı için öneriler sunulmuştur. Belirtilen bu yöntemin uygulaması sonucunda hazırlanan tablolar ve grafik sistemler yardımı ile yönlere göre uygun opak bileşen dokulan belirlenmiştir. Opak bileşen dokusu için sınırsız sayıda alternatif üretilebileceğinden dolayı uygulamada temel doku tipleri ele alınmıştır. Mimari uygulamalarda bu çalışmanın sonuçlarına göre uygun temel doku tipine karar verildikten sonra, doku, mimann cephede oluşturmak istediği etkiye bağlı olarak geliştirilip enerji korunumuna etkisi aynı yöntemle incelenebilir.
Building envelope texture was studied as a passive cooling system property in order to minimize cooling energy for buildings. In order to provide comfort conditions for users, it becomes necessary to use active systems in certain parts of overheated period but building envelope should be designed so that it works as a passive system element which reduces energy consumption as much as possible. This study is composed of five main chapters. In chapter 1, relationship between thermal comfort conditions and energy conservation through passive systems was briefly explained. In chapter 2 an explanation of design parameters affecting thermal comfort was given. Main design parameters which are effective on thermal comfort are ; * Orientation of building envelope, * Building envelope, * Building form, * Distance between buildings, * Solar control, Solar radiation intensity and wind pressure on the external surface of the building envelope, which are vary with orientation, affect thermal comfort. Building envelope is defined by its properties, which are effective in energy conservation like; * Optical properties like absorbtivity ( a ), transmissivity ( y ) and reflectivity ( r ) related with solar radiations. * Thermophysical properties like overall heat transfer coefficient ( U ), and transparency ratio ( x ) and, * Texture Optical properties are the ratios of absorbed, reflected, and transferred portion of the total solar radiation to the total solar radiation which reach to the external surface of the building envelope. Therefore their relations are as follows for opaque component; a +r = 1 o o for transparent component ; a +r +v = 1 g g 'g Overall heat coefficient ( U ) is defined as the total heat transfer from the unit component area in unit time when the difference between two air temperatures which are effective on both sides of the components is unit ( kcal/hm2°C, W/m2°C ). Transparency ratio ( x ) is the ratio of transparent component area to the facade area composed by transparent and opaque components. Texture of opaque building envelope effects the amount of direct solar radiation which hits the components. It is important to design texture of opaque components according to energy needs for an efficient energy conservation. Building form is effective on the changes of total heat loss and gain of the building, therefore it is a parameter which, determines active heating and cooling loads. Distance between buildings should be designed so that, according to regions and seasons optimum solar radiation and wind intensities should be provided. Solar control is performed by two different ways, first one is by taking measures on external surface of the building envelope such as texture, reflectivity, insulation, second one is by shading devices which are naturel shading devices such as plants, earth shape etc. and artificial interior and exterior shading devices. In chapter 3, a method which can be used for designing the texture of opaque building. components as a passive system property from the standpoint of cooling energy efficiency is introduced. In the design of building envelope, texture of the opaque component should be design in accordance with cooling energy efficiency because intensity of the solar radiation can be adjusted by texture of the opaque component. The method which is proposed to be used to design the building envelope texture as a property of passive cooling system composed of following stages; * Design of the alternatives of opaque building envelope components with different textures depending on optimal thermophysical properties, * Calculation of the heat gain, from unit area for different opaque components with various textures, * Comparison of heat gain, and selection of the appropriate texture. 1. Design of the alternatives of opaque building envelope component with different textures consist of three main steps, r Determination of the optimal values of thermophysical properties of building envelope composed of folowing sub-steps ; XI * Selection of design day, P$ In this study the design day which represents the period when the cooling is necessary. 21 st. of July is the respectively the design day of overheated periods. * Determination of outdoor design conditions. (^Regional, climatic values should be determined according to " real sky " conditions in the design day. * Determination of indoor design conditions. Inner surface temperature of a building envelope is effective on thermal comfort. In over overheated periods, permissible limit value of inner surface temperature of a building envelope as follows ; T. = T. + e SI 1 -where, Tgi : required value of the inner surface temperature of building envelope for the design day of overheated period, °C T. : comfort value of indoor air temperature, °C e : permissible limit value for difference between inner surface temperature and indoor air temperature, 3°C. * Selection of other design parameters which affect indoor thermal comfort and effective in building envelope design Other design parameters, such as orientation, thermophysical properties of the transparent components in reference to window type, color of the opaque component, transparency ratio of the building facade should be selected. - Design of building envelope texture alternatives which can be used in construction market. - Development of the opaque component alternatives with textured surfaces. In order to develop" these alternatives, permissible maximum overall heat transfer coefficient will be used for each opaque component with different textures is given below; Uo= U,*VU2xA2+ +UnxAn w +\ where U : Weighted average overall heat transfer coefficient of opaque component, (it should be equal to the permissible maximum overall xn heat transfer coefficient ) kcal/hm20C, W/m2°C Up U2..... Un : Overall heat transfer coefficient of each different section created by texture, kcal/hm2°C, W/m2°C Aj, Aj An : Heat transfer area parts of whole opaque component which have different sections caused by texture, m2, A}+ A^ An = Aj. and 1 Up u2 un= where 1/h. + l./k1+L/k_+....,...+ 1 /k +l/h 1112/ n n o Up U2 Un : Overall heat transfer coefficient of each different section created by texture, kcal/hm2°C, W/m2°C h., h : Surface heat transfer coefficient, kcal/hm2°C, W/m2°C r o. ' ' İp L 1 : Thickness of each layer, ( m. ) kp k,.:.. k : Thermal conductivity of each layer, kcal/hm2°C, W/m2°C 1,2,.n : Layer numbers. Because opaque component has different sections in partials areas by means of texture, overall heat transfer coefficients of these parts are different than each other. Overall heat transfer coefficient of the whole component (U )is the average of the overall heat transfer coefficients of these parts in accordance with their surface areas. The first formula written above provides to determine the average overall heat transfer coefficient of the whole opaque component and the second formula is used to calculate the overall heat transfer coefficient for each different section 2\ Heat gain, through the unit area of opaque component alternatives with different textures, depends on sol-air temperatures and the shaded areas caused by texture at each hour in the design day. - Calculation of shaded areas caused by texture at each hour in design day. In the calculation of shaded areas ; * Profile Angle ( Q) and * Wall-Solar Azimuth Angle ( 8 ) are used. Profile angle can be determined as the angle between the horizontal projection of earth-sun line onto a vertical plane which is normal to the wall and a normal line to the wall. Xlll Wall-solar azimuth angle can be defined as the angle between vertical projection of earth-sun line onto a horizontal plane and a normal line to the wall. In accordance with these angles the areas which do not have direct solar radiation because of texture can be determined, therefore total solar radiation can be calculated accordingly. - Calculation of total solar radiation intensities for shaded and sunny areas for each day hour in the design day. Total solar radiation intensities ( I{) are calculated by means of direct solar radiation intensity ( ID ), diffused solar radiation intensity ( Id ) and reflected solar radiation intensity ( I ). Because of the texture in some areas there is no direct solar radiation, in this type of cases total solar radiation is the sum of diffused and reflected solar radiation. IT = I. + I T d r - Calculation of sol-air temperature Sol-air temperature is a theoretical external temperature which determines a temperature equal to the combined effect of solar radiation and external air temperature on any building component so that it is higher than actual air temperature. In this study, because the effect of texture on opaque components are compared, only the hourly values of sol-air temperatures are calculated by means of following formula for opaque components ; T =T +Lxa /h eo o T o o where T eo T o IT Hourly values of sol-air temperature influencing the opaque component, °C External air temperature, °C Intensity of total solar radiation on the component surface, kcal/hm2°C, W/m2°C a : Absorbtivity of the surface o h : External surface heat transfer coefficient, kcal/hm2°C, W/m2°C o XIV - The performances of the differently textured opaque components can be determined by calculating hourly heat gain amount per unit area of each alternative for overheated period. Hourly heat gain amount of each opaque component alternative for overheated period is calculated under steady-state conditions, because the U- value of each different section created by texture of an opaque component is different, the average heat gain of the component can be calculated by means of the following formula; V U,(T -T.^A +U,(T.-T.)fA. + + U(T -T.)xA +Ux(T,-T.)xA, I eos i is 1 eosh ı ish n eos i ns n eosh ı nsh A + A, + + A + A, is isn ns nsh where, Qd : Hourly heat gain amount per unit area of opaque component, kcal/hm2°C U, +IL+... +TJ : Overall heat transfer coefficients of each different section,. which compose the whole opaque component, kcal/hm2°C T,T, : Sol-air temperatures of opaque components which have direct solar. radiation and does not have direct solar *> radiation,,. ' respectively, °C T. : Indoor air temperature, °C A, Aigh... A, A. : Sunny and shaded partial opaque component areas of each different section width each different U- value which composed the whole opaque component. In the study, unit areas are studied, \S + AM + K + ^sh +....+ Ans+ Ansh = l m* 3- Comparison of heat gain calculated and selection of the appropriate opaque component texture are done by means of graphics. Hourly heat gains of each opaque component with different texture alternatives according to orientations, are indicated in graphics and are compared accordingly. The alternative which causes the optimum energy conservation by providing the least heat transfer through the envelope in overheated periods on the design day is picked. In chapter 4, the method, explained in previous chapter is applied for Antalya region by using the data which were the results of TUBÎTAK, INT AG 201 research in order to determine the appropriate textures which can be applied to the building envelope component hot regions. XV In chapter 5, conclusions and suggestions for practical uses of the method were explained generally according to the results obtained in chapter 4. In this study a method is proposed to be used in hot regions where there is a great cooling energy consumption. There are unlimited texture options, because of this reason in this thesis only the basic texture types are used in order to achieve a general conclusion. By means of the graphics produced as a result of this study, basic texture type can be determined according to orientation and improved according to facade design by architect.
Açıklama
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1996
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 1996
Anahtar kelimeler
Enerji tasarrufu, Soğutma sistemleri, İklimsel konfor, Energy saving, Cooling systems, Climatic comfort
Alıntı