Achieving energy efficiency of building in north part of Kazakhstan is very critical due to the large temperature difference during long harsh and severe winter and short hot summer seasons. Energy efficient building shows significant savings to homeowners including costs reduction from energy, water, waste, and lower operations and maintenance costs. In terms of building materials, lightweight aggregate concrete (LWAC) due to its thermal properties is often used to maintain thermal comfort levels in buildings and to reduce building energy consumption. In this paper, the potential of LWAC to improve the energy performance of building was assessed for LWAC with three different mixture proportions and a normal weight concrete (NWC) for comparison purpose. The energy saving effect of LWAC was simulated using OpenStudio software tools with an EnergyPlus engine. Moreover, annual heat loss and amount of heat transfer of construction wall of building were calculated. Results showed that LWAC can improve the energy efficiency of building and thus the use of LWAC can be a good alternative to the traditional NWC.