Cost analysis comparison of reference and near-zero energy office building design in Indonesia: a life cycle approach and its sensitivity analysis

This study compares the life-cycle costs (LCC) of a conventional office building and a near-zero-energy building (NZEB) in Indonesia to assess the cost-effectiveness of NZEBs using a life-cycle approach. A hypothetical 10-storey office building model in Jakarta is used as a case study, with the reference case having an Energy Use Intensity (EUI) of 226.38 kWh/m2/year and the NZEB case incorporating passive design, active systems, and renewable energy technologies, resulting in an EUI of 120.18 kWh/m2/year. The LCC calculation considers the design and construction, operational, maintenance, and end-of-life costs over a 50-year lifetime. The results showed that the NZEB case had 11 % higher construction costs, 2.2 % higher maintenance costs, and 43 % higher end-of-life costs than the reference case. However, the NZEB case achieved a 47.6 % reduction in operational costs, leading to a 10.8 % lower LCC than the reference case. Sensitivity analysis revealed that lower inflation rates and longer building lifetimes are more beneficial for NZEBs and that variations in operation and maintenance costs have a more significant impact on the LCC than those in the construction or end-of-life phases. These findings highlight the economic advantages of NZEBs over conventional buildings in Indonesia, and emphasize the importance of considering the entire life cycle when evaluating the cost-effectiveness of sustainable construction practices.