Mohammad Gholamzadeh devin - Faculty of engineering, Islamic Azad University, Mashhad Branch, Mashhad;

The rapidly growing of world energy use has already raised concerns over supply difficulties, exhaustion of energy resources and heavy environmental impacts(ozone layer depletion, global warming, climate change, etc.). Growth in population, increasing demand for building services and comfort levels, together with therise in time spent inside buildings, assure the upward trend in energy demand to continue in the future. Forthis reason, energy efficiency in buildings today is aprime objective for energy policy at regional, national and international levels. The principal concern of this paper is to use solarenergy for decreasing building energy consumption by CFD Modeling, 3D simulating. In this regard, by usingsolar absorption coefficient of different colors, the bestcolor for external walls of Mashhad’s buildings were chosen to reach the most optimal temperaturesimultaneously in cold and warm days. Solar load was calculated by solar calculator based on geographical information of Mashhad, CFD simulations of theturbulent flow field were carried out using the standard k–ɛ turbulence mode, finally internal temperature in the range of solar absorption coefficient (0.4 to 0.9) wasdetermined and we chose the color which decrease temperature 1.5 Celsius degree in warm days andincrease about 1 Celsius degree in cold days, this meansa significant reduction in building energy consumption. This paper shows us that we can estimate suitable colorfor each region in the world depends on its geographical information and share of solar energy.

solar absorption coefficient, solar energy,CFD modeling, 3D simulation, building energy consumption