Investigation of the Effects of Building Envelopes Received Solar Radiation on Residential Energy Consumption: A Case of SW and SE Orientation in Shiraz*

Energy has been considered as one of the most important factors for formation and development of industrialized countries. Furthermore، countries accessibility for different types of energy can be indicated as a sound development index، as well as political and economical power. Restrictions on resources of non-renewable energy، on one hand، and high cost of production and also low efficiency of distribution and transfer process، on the other hand، have encouraged the politicians and stakeholders of the field of energy to adopt optimal policies for optimal use of the produced energy because different types of energy production depends on high capital investment and is possible in long term. In this study، multiple-regression analysis with stepwise selection method was employed to investigate the effect of solar radiation (Er) on energy consumption (E Primary، E cooling، E heating) in residential sector in one of semi arid cities of Iran. In Shiraz city (with high capacity of solar energy utilization to provide some parts of the required energy and with different types of house)، residential buildings were divided based on orientation into two group (i. e. NW-SE، and NE-SW). The houses were selected randomly in different parts of city with different characteristics and type. The presence of autocorrelation in the residuals، checked by Durbin- Watson test، was rejected. To remove the influence of adverse factors (as step no.، window to wall ratio، length to width) from E Primary، AHP was used to define the adverse factors’ weights using software (i. e. EC 9. 5). The received solar radiation in samples has divided into three main parts; horizontal envelope (roof)، main vertical envelope (south elevation) and other envelopes. Each of mentioned envelopes has an effective role in annually and monthly energy consumption behavior. In investigation of each house about the effect of solar radiation of building envelope on E Cooling، E Heating، and E Primary، it was indicated that two types of house have closer correlations: the houses with low energy consumption and climatic Er، and those with high energy consumption and high non-climatic Er. According to the relation between average radiation on vertical envelope (Evr)، and E Cooling، E Heating، and E Primary in each group، the primitive hypothesis (climatic orientated houses can achieve lower E Cooling، E Heating، E Primary) was proved. The annually vertical surface radiation from whole radiation on buildings has 28. 89 % in group 1، and 15. 72 % in group 2. The results indicated houses with climatic orientation have low energy consumption. On the other hand، one of the results indicated that about 74. 99% of received radiation in houses is related to the horizontal envelope. The annually horizontal surface radiation from whole radiation on buildings is 68. 50 % in group 1 and 81. 48 % in group 2. Therefore، in both group the role of roof in absorbing radiation is more significant. Finally، some solutions for deploying the solar radiation in order to decrease the residential energy consumption in Shiraz city were proposed and suggestions for future researches were presented.