An evaluation of the retrofit net zero building performances: life cycle energy, emissions and cost

ABSTRACT This study aims to assess the comprehensive energy, environmental and economic performance of a retrofit zero energy building (ZEB). Three life cycle assessments were conducted: life cycle energy (LCE), life cycle carbon emissions (LCCE) and life cycle cost (LCC). Actual building construction cost data and energy use data were used in the assessments. The analysis results indicated that during the whole building life span, the operational life stage (B6) was a major contributor to LCE (82%) and LCCE (77%), but not to LCC (18%). Within the life cycle embodied carbon (LCEC), A3 was the life stage with the highest contribution (56%), which is mainly related to the manufacturing of building assemblies. This case study provides new empirical evidence of ZEB performance in the United States. The findings suggest that to achieve the carbon neutrality goal, current ZEB certifications or designations are not adequate to measure actual building performance. A further reduction of operational energy, in addition to reducing the embodied carbon released during manufacturing, should be the focus.