بهروز محمدکاری

Designing buildings with the lowest possible cost base is an essentiality in sustainable architecture. Previously, due to the computational complexity of building's energy consumption, the environmental impact on thermal and lighting energy consumptions haven't been considered simultaneously. As non-linear relationships are often disclosed, a comprehensive approach is necessary to reduce the total energy need of a building and optimize the façade configuration at the same time. Solar radiation affects thermal and lighting energy consumption which depends on building fabric’s characteristics. In this paper a parametric method to optimize the window size and sunshade dimensions of an educational building in mild climate of Iran is presented. Through integrating thermal and lighting energy consumption, 6750 window and sunshade configurations are studied and compared. First, climatic parameters and thermal analysis are validated by on-site measurements. Then, the characteristics of the simulated model and all thermal and lighting parameters have been defined. Finally, the best solution is optimized through genetic algorithm. The results show that, in the first phases of the design process building’s characteristics should comply with national code regulations and then components of the building will be optimized. Additionally the horizontal windows with higher sill levels are more energy-efficient in classrooms.

Considering the determinant role of energy efficiency opportunities in the building sector, proposing guidelines and technical solutions in order to improve the thermal performance of glazing systems is in priority in Iran and other countries. In glazing systems, a substantial amount of radiative heat transfer results from absorption and emission. Applying low-E (low emissivity) coatings on the glazing system is a solution for reducing the radiative heat transfer by radiation in glazing systems, without a noticeable decrease of visible light transmittance. By selecting the proper glazing type, in a hot climate, the amount of solar heat gain can be reduced significantly. Vice versa, in cold climate, the heat loss by long wave radiation of inner surfaces can be reduced. In this paper, first, the thermal and optical characteristics of local clear and Low-E glasses have been measured in BHRC (Road, Housing & Urban Development (National) Research Center) laboratory, by the spectrophotometer and then the thermal performance of single and double glazing units, with and without low-E coating, in different orientations (North, South, East and West) are computed, compared and analyzed for cold (Ardebil) and hot (Bandar-Abbas) climates in Iran. The selection of these two cities is based on maximum heating and cooling degree day values obtained respectively for Ardebil and Bandar-Abbas. The simulation results indicate that using double clear glazing unit with low-E coating reduces the energy consumption significantly in very hot climates, using mostly electrical energy for cooling. In cold climates like Ardebil, double glazing with low-E coating has a minor impact on annual heating load, because of the great amount of thermal radiation, even in the cold season, the high cost of low-e coating and the considerable payback time, compared to the building life cycle.