Development of Work Breakdown Structure (WBS) in High-Rise Office Buildings using Green Retrofitting based on GBCI and Minister of PUPR Regulation No. 21 of 2021 to Improve the Quality of Resource Planning

Buildings built before the 2000s are still vulnerable to exposure to the importance of energy efficiency, so renovations are needed on this existing building through renovation (green retrofitting) for sustainability goals that reduce energy expenditure. Modification is an effort to adjust the performance of built buildings to obtain a certificate as a green building. Both government and non-government agencies certify customization with different benchmarks/ parameters. In Indonesia, there are two regulations and benchmarks in the assessment of BGH performance, namely the Green Building Council Indonesia (GBCI) and PUPR Regulation Number 21 of 2021. The portion of existing high-rise office buildings is 98% of the total number of office buildings, which is very significant in achieving the government's target. The obstacle to implementing Green Retrofitting in High-Rise Office Buildings is the high cost. To be able to make green retrofitting costs efficient, researchers conducted a statistical analysis using the Relative Important Index (RII). The results of this study showed that the most influential factors at the planning stage were the energy-saving SOP document with an index of 0,996, the construction stage was Document on the implementation of ideas and innovations in construction methods with an index of 0,992, and the post-construction stage was Certificate of Expert Building Management Manager with an index of 0,998. The implementation of customization can be through the development of a Work Breakdown Structure (WBS), to detail the resources needed in project planning, monitoring, and control. The results of the study are proof that the WBS structure of customization work based on GBCI and PUPR Regulation Number 21 of 2021 affects improving the quality of resource planning using survey methods and literature studies.