Retrofit Strategies for Nearly Zero Energy Building Concept in Educational Building

Abstract

Indonesia has set a roadmap to achieve energy-efficient buildings by 2050. This study explored potential energy demand reduction through building retrofit between 2024 and 2050, aligning with Indonesia's roadmap and Paris Agreement to promote Nearly-Zero Energy Buildings (NZEB) concept. This study examines the impact of combining insulation retrofitting and photovoltaic (PV) system integration on reducing energy demand in existing buildings in Indonesia, considering both the 2024 and 2050 climate conditions. Three insulating materials with a thickness of 50 mm were selected, based on their thermal properties and material cost. The selected materials were rockwool, polyisocyanurate (PIR), and aerogel board as an internal layer of the walls. In addition, an economic evaluation was conducted to compare the cost-effectiveness of the three insulation materials, assessing not only energy savings but also payback periods. The results were obtained through U-value calculation, energy simulation, Photovoltaic (PV) panels simulation and economic evaluation. From the three selected insulation materials, PIR showed the highest energy demand reduction with a reasonable payback period of 15 years. Based on the simulation, PIR potentially reduced Energy Use Intensity (EUI) by 22.5% and 29.9% in the 2024 and 2050 climate database, respectively. PV panels, particularly the 300 Wp system with a shorter payback, covered an average of 31.5% of the building's final energy demands after adding PIR as an insulation in the 2024 climate database. The combined retrofit strategy reduced the overall payback period to 8.3 years. These findings highlight the NZEB approach as a viable pathway to support Indonesia’s energy-efficient building and renewable energy targets.