Embodied energy and associated carbon emission of key building materials in Nepal

The number of concrete buildings in Nepal increased by 23.90 percent within the last decade. Life Cycle Assessment (LCA) of the buildings shows that Cement, Brick and Reinforcement steel are the three major building materials which account for about half of the total life cycle energy use and emission from the building materials. However, there is no national database for energy use and emissions from these building materials in Nepal. So, the study aims to evaluate energy use and its associated emissions in the production of these materials using the LCA framework and guidelines from ISO 14040: 2006 and ISO 14044: 2006. The data from embodied energy is based on the energy audits of 26 cement industries, 21 metal industries, and 27 brick industries sampled across the country. The study shows that the production of one tonne of cement accounts for 6051.07 MJ energy and is responsible for 739.49 kgCO2-eq.; the production of 1000 pieces of standard size burnt brick from fixed chimney bull trench kiln accounts for 4124.56 MJ energy and 502.89 kgCO2-eq. emission; and the production of one tonne of reinforcement steel accounts for 26,033.14 MJ energy and 2565.5 kgCO2-eq emission. The major source of energy and emission in building material production is coal. A shift in energy sources from coal to hydroelectricity would reduce the energy-related emissions from the materials production. Also replacing high emission construction materials with locally available natural materials like stone, wood and bamboo could minimize the emissions from the built environment.