Enerji etkin konut ve yerleşme birimi dizaynında uygulanabilecek bir yaklaşım

Abstract

Bu çalışmada enerji etkin konut ve yerleşme birimi dizaynında uygulanabilecek ve bugüne kadar geliştirilmiş olan yöntemler tanıtıl maktadır. Yapılan çalışmada amaç, binalarda kullanılan yapma ısıtma ve iklimlendirme sistemlerinin beraberinde getirdiği enerji harcamaları nı minimuma indirebilmek için, binaların ve yerleşme birimlerinin müm kün olabildiğince pasif sistemler olarak çalışmalarının sağlanmasıdır. Ayrıca, enerji etkin konut ve yerleşme birimi dizaynında kullanılan yapma çevreye ilişkin dizayn değişkenlerinin bu amaç doğrultusunda in celenerek uygun "Değerler Kombinezonları" belirlenmektedir. Bu çalış ma, Gümüşhane yöresi için uygulamasını da içeren altı ana bölüm ile ekler bölümünden oluşmaktadır. Bölüm 1 'de, yapılan çalışmayla ilgili kısa bilgi verilerek, enerji etkin konut ve yerleşme birimi dizaynında etkili olan dizayn değişkenlerine ait ele alınan hedefler belirtilmektedir. Bölüm 2 'de, enerji kullanımını zorunlu kılan faktörlerden baş lı cası olan iklimsel konfor gereksinmesi incelenmektedir. Bölüm 3 'de, enerji korunumunu zorunlu kılan faktörler kısaca açıklanmaktadır. Bölüm 4 'de, enerji korunumu sürecinde etkili olan fiziksel çev resel etkenler ve yapma çevreye ilişkin dizayn değişkenleri yer almak tadır. Bölüm 5'de, yapma çevreye ilişkin dizayn değişkenlerine ait uy gun değerlerin belirlenmesinde kullanılabilecek olan ve bugüne kadar geliştirilmiş olan yöntemler açıklanmaktadır. Bu yöntemler;. Bina kabuğu termofiziksel özelliklerine ait uygun değerlerin belir lenmesinde kullanılabilecek yöntem,. Bina kabuğu termofiziksel özelliklerine bağlı olarak uygun yönlendi ril iş durumu ve bina formu kombinezonlarının belirlenmesinde kulla nılabilecek yöntem,. Uygun bina aralıklarının belirlenmesinde kullanılabilecek yöntem olarak sıralanmaktadır. Bölüm 6'da, yapma çevreye ilişkin dizayn değişkenlerinin belir lenebilmesi için 5. Bölümde açıklanan yöntemler, Gümüşhane yöresi için uygulanmaktadır. Bu çalışmada kullanılan yöntemler sonucunda hazırlanan grafik sistemler ve tablolar yardımıyla yapma çevreye ilişkin dizayn değiş kenlerine ait uygun değerlerin seçiminde büyük esneklik sağlanmaktadır.

In this study, an approach which can be used in energy effi cient building and settlement design is introduced. Buildings and settlement units should be designed as optimum passive systems which consume supplementary mechanical heating and cl imatisation energy at the minimum level during the occupancy period. This study comprises six main chapters. In chapter 1, a brief explanation of design parameters related to energy efficient building and settlement design is given. In chapter 2, the main factors which make energy utilization compulsary -climatic comfort requirements- are examined. In chapter 3, the factors, which make energy conservation com pulsary are shortly described. In chapter 4, climatic factors effective on the determination of optimal values of design parameters which are used in the defini tion of the built environment as passive heating system are classi fied. The main climatic factors are;. solar radiation,. external air temperature,. relative humidity and,. air velocity. A group of primary design parameters which are related to built environment and affective on energy conservation are as follows.. orientation of building,. building forms,. distance between buildings,. solar radiation and thermophysical properties of the building enve lope. Orientation of buildings is one of the most important factors effecting indoor climate, the solar radiation intensity on the exter nal surface of building elements varies with orientation. Solar radiation properties of the building envelope are;. absorbtivity, -- vi - . transmissivity,. reflectivity. For opaque components transmissivity is not valid. The main thermophysical properties of the building envelope are:. overall heat transfer coefficient,. transparency ratio. Total heat loss or heat gain change with building form. Building form can be defined basing on the shape factor of the building, building height, roof type and roof slope. Buildings work as wind and sun obstructions for each other. The optimum value of the distance between buildings, changes with slope angle of the site, slope orientation, orientation of buildings and building heights. In chapter 5, the previous methods which have been used for the determination of the optimal values of design parameters are introduced. 1- The method for the determination of the optimum values of the thermophysical properties consists of 3 main steps: o Determination of the optimum values of the overall heat transfer coefficient for the opaque component. o Development of the opaque component alternatives. o Evaluation of the opaque component alternatives from the standpoint of condensation risk. Determination of the optimum values of the overall heat trans fer coefficient for the opaque component comprises the following steps: - Gathering the Regional Climatic Data. - Selection of the Design Days. To minimize the supplementary mechanical energy demand, the optimum value of the overall heat transfer coefficient for opaque components should be determined according to the climatic conditions of the predominant period of the region. Instead of repeating the calculations for each day of the chosen predominant period it is convenient to choose a representative design day. - Determination of the Indoor Design Condition's. Indoor design conditions can be derived from the comfort condi tions. The indoor climatic elements are air temperature, relative humidity, air velocity and inner surface temperatures. The comfort values of air temperature can be estimated by using the relationship between required value of the inner surface temperature vn (t-jyo) and the comfort value of indoor air temperature (ti). The following formula represents the relationship between surface and air temperatures, since it is proper to set the relationship between ther mal comfort and building envelope. tiyo = ti ± e where. e : permissible limit value for the difference between inner surface temperature and the comfort value of indoor air temperature, °C - Selection of Variation Range and Intervals of the Design Parameters Affecting Indoor Climate. - Computation of the Sol -Air Temperatures for Opaque and Trans parent Components. Hourly values of sol-air temperatures influencing the variously orientated opaque components and windows (te0 and tec, respectively) should be calculated separetely. Daily average sol-air temperature for opaque components (te00) and windows (teC0) are the arithmetic mean of hourly values. - Calculating the Required Values of the Inner Surface Tempera ture of the Opaque Component. The weighted average inner surface temperature of the opaque and transparent components relevant to the transparency ratio, should be equal to (t-j-e) for the design days of underheated period. This can be expressed by the following formula: tiyo = t0-jo(l-x) + tc-}o,x where, t.,-y0: required value of the inner surface temperature of building envelope, °C. t0-j0: daily average inner surface temperature of the opaque component, °C. tc-j0» daily average inner surface temperature of the transparent com ponent, °C. x : transparency ratio. Hourly values of the inner surface temperature for the trans parent component can be calculated by means of the following formula: tci = t-j + [kc(tec-t.j) - (Fs.lD-TD+IyTy)] / ai where, tci- : hourly values of the inner surface temperature for the trans parent component, °C. kc : overall heat transfer coefficient of the transparent component, W/m2oc, Kcal/m2h°C. - vm tec : sol -air temperature for window, °C. iQ.Iy: direct and diffuse solar radiation intensities on the surface, respectively, W/m2, Kcal/m2h. tD,Ty: transmissivity of the glass for direct and diffuse solar radia tion, respectively. F$ : sunlit fraction of the transparent component surface. The daily average value (tcl-0) is the arithmetic mean of the hourly values. - Determination of the Optimum Values of the Overall Heat Transfer Coefficient for the Opaque Component. The optimum value of the overall heat transfer coefficient (k0) can be calculated by using the following equation; k = ai (tpjo-tj) (teoo-ti) k0 : overall heat transfer coefficient of the opaque component, W/m2°C, Kcal/m2h°C. a-j : inner surface heat transfer coefficient, W/m2oC, Kcal/m2h°C. te00: daily average sol -air temperature for the opaque components, °C. t-j : comfort value for indoor air temperature, °C. Evaluation of the various building envelope alternatives (com binations of k0 and transparency ratio) can be carried out by calcu lating the heat loss per unit area of each alternative and comparison of the heat loss amounts. Hourly heat loss per unit area of building envelope can be calculated in two different ways. a) Under the "real sky" conditions, the amounts of the hourly heat loss per unit area of building envelope can be calculated by basing on the sol -air temperatures. b) In the second way of heat loss calculations are based on the outdoor air temperatures enforced by the Chamber of Mechanical Engineers. After the comparison of the amounts of hourly heat losses, the combination of the values of thermophysical properties which provides the minimum heat loss is qualified as the most appropriate one. For all opaque component alternatives which are developed by basing on the chosen k0 and transparency ratio combinations, the con densation risk should be examined. As the result of these calculations and evaluations, combina tions of appropriate values related to the thermophysical properties of the building envelope that indicate optimum performance in respect to achieving climatic comfort, energy conservation and elimination of the condensation risk, can be determined. ix - 2- Determination of the appropriate building orientation and form combinations, the calculations of total heat loss through whole building envelope are executed; a) Basing on the sol -air temperatures affective on the vari ously oriented facade elements. b) Basing on outdoor air temperature values (-12°C for Gümüş hane region) enforced by the Chamber of Mechanical Engineers. By comparing the amounts of daily average hourly heat loss thru the whole building envelope for varies building alternatives, the alternative which ensure the minimum heat loss can be determined. This alternative defines the building which performs as a passive heating system at the optimal level. And the values of design para meters which define this alternative are also can be considered as the components of the optimal combinations. 3- In the determination of the appropriate distances between buildings, the aim is maximization of the solar radiation affects. Accordingly, the distances between buildings must be equal to the maximum depth of the shaded area casted the neighbouring buildings. In terms of the heating affect of solar radiation, the factors which are effective on the determination of the distances between buildings are;. Regional factors: The latitude and climatic conditions of the region under consideration.. Factors related to the buildings: The orientation and the height of the buildings.. Factors related to the site: The slope orientation and the slope angle.. Factors establishing the relationship between sun and building: Profile angle. The appropriate distances between buildings are determined ac cording to the depth of the shaded area on the ground. In cold and warm climatic regions, solar heat gain can be maximized by providing the direct solar radiation effects on building, during the day-time period. The longer the distance between buildings the higher the direct solar radiation gain. When higher land prices taken into considera tion for each orientation an appropriate distance between buildings should be determined for a more rational use of land by caring of human health and heating economy at the same time. In chapter 6, the methods, described in previous chapters are applied for Gümüşhane region, in order to determine the appropriate values for design parameters related to built environment. Finally, as the results of this thesis study some graphic sys tems and tables are proposed. These graphic systems and tables in clude the combinations of appropriate values for design parameters and provide architects great flexibility in the selection of appropriate values of design parameters related to the built environment.