LIFE-CYCLE COSTS AND LIFE-CYCLE CO₂ EMISSIONS OF A WATER DISTRIBUTION NETWORK —ANALYSIS BASED ON DIFFERING LIFE CYCLES FOR WATER PIPE AND PUMP—

Abstract

 This study analyses Life Cycle Costs (LCC) and Life Cycle CO₂ (LCCO₂) emissions in a virtual water distribution network, accounting for the effects of differing life cycles for water pipes and pumps and the depopulation Japan is now facing. First, this study compares basic properties of LCC and LCCO₂ based on a scenario of replacing both pipes and pumps every 20 years. For LCCO₂, this study finds a simple correlation that LCCO₂ decreases as pipe diameter increases. As for LCC, this study also finds a trade-off, not found for LCCO₂ that pump operation costs increase as pipe construction costs decrease due to smaller pipes. Thus, it is suggested that there is an optimum diameter which can minimize LCC. Second, this study examines nine life cycle combinations (pipe: 20/ 40/ 80 years, pump: 20/ 40/ 80 years) respectively through comparative analysis. The results demonstrates that long pipe replacement intervals and short pump replacement intervals are most advantageous in curbing both LCC and LCCO₂.