Cost-effectiveness assessment of retrofitting construction equipment for reducing diesel emissions—A life cycle and public health effects perspective

Retrofitting construction equipment is widely recognized as an effective strategy to reduce diesel emissions. However, limited research exists on comprehensive models for assessing the cost-effectiveness of retrofitting—a critical metric in developing successful retrofitting programs. This study addresses this gap by developing a novel model that integrates life-cycle analysis and public health effects. The model consists of three key components: calculating the life-cycle average annualized cost (LCAAC) associated with employing retrofitting technologies, quantifying the corresponding reduction in public health effects emissions equivalent (PHEEE), and analyzing cost-effectiveness. The model's applicability is demonstrated through a case study on 6428 pieces of construction equipment in Hong Kong, grouped into 71 categories for analysis. The study finds that retrofitting achieves an average of 4873.34 kg PHEEE reduced per million HK$ spent. Among the categories, excavators with rated power between 300 and 600 hp. and compliant with US Tier 1 emission standards (labeled as E-HP7-T1) are identified as the most cost-effective to retrofit. Notably, the study highlights that fuel penalties associated with retrofitting—often overlooked in traditional assessment—constitute 53.86 % of total costs, significantly influencing cost-effectiveness outcomes. From a life-cycle and public health effects perspective, this model enables a more accurate cost-effectiveness assessment. It equips policymakers with tools to prioritize retrofitting investments that maximize emissions reductions and health benefits. Additionally, it offers valuable insights to construction fleet managers for improving retrofitting efficiency, particularly through strategies to mitigate fuel penalties.