Optimum envelope design toward zero energy buildings in Iran

Abstract

Buildings, commercial and residential combined, account for around 40% of total energy consumption in Iran. Energy consumption in buildings is predicted to increase in the the coming decades decades and immediate actions are required to meet the needs of future generations. Zero energy building (ZEB) is an important concept that can help nations to have a sustainable future. An important step for building a ZEB is to minimize the energy lost from the building, and the envelope of buildings plays a vital role in achieving minimal energy losses. In this paper, a life cycle cost (LCC) analysis is adopted to find the optimum insulation thickness for the common wall structure in Iran. Then, the Iranian standard (Chapter 19) for building envelopes have been reviewed and compared with the minimum requirements of the ASHRAE standard 90.2. The comparison shows that the Iranian standards for buildings envelopes are comparable with the ASHRAE standard 90.2 for the external wall, while ASHRAE requires higher minimum thermal resistance for ceiling compare to chapter 19. The optimization results suggest smaller minimum thermal resistance compare to chapter 19; this is mainly resulting from the characteristic of the Iranian economy (high inflation rate) and subsidized energy sector. Therefore, energy policy in the country needs to be reformed to promote energy conservation in buildings and hence zero energy buildings.