The overlooked criteria in green building certification system: Embodied energy and thermal insulation on non-residential building with a case study in Malaysia

A green building certification system (GBCS) is essential for sustainable city development. However, the building's embodied energy (EE) and thermal insulation have often been overlooked in GBCSs. The correlation of thermal insulation envelopes to EE and operational energy (OE) has also yet to be extensively investigated. This study adopts life cycle energy assessment methodology to evaluate the EE and OE of non-green and green-rated non-residential buildings with hotspot analysis and analyse the trade-offs between EE production and OE saving for five types of insulation envelopes. Taking Malaysia as a reference, results show EE holds 16-19% of total energy in non-green and green-rated non-residential buildings; hence EE should not be neglected in GBCS. The material consumption phase incurs half a quarter of the total EE, indicating that major recycled and low -embodied building materials (e.g., recycled steel and green cement) should be rewarded with higher points in GBCS. Insulated building envelopes save 84-87% of cooling demand than non-insulated walls, with cellulose fibre insulators consuming the least EE. It is hoped that this study can provide evidence-based outcomes to policymakers when formulating the proportion of EE and OE, and integrating insulation envelopes in GBCS to enhance energy savings further.