Estimating construction waste in New Zealand: a focus on urban areas, residential and non-residential building activities

This paper examines the significant increase in construction waste (CW) due to urbanisation and population growth in New Zealand and worldwide. The aim is to estimate CW using available data in New Zealand and identify relevant indicators to employ estimation methods. Various methods and models for estimating CW at the urban level and from building activities are reviewed. According to the best available data, the paper uses the per-capita multiplier and waste generation rate methods to estimate CW in New Zealand. New Zealand's per-capita multiplier for CW is 943.46 kg/per capita. The waste generation method using the floor area indicator is applied at residential and non-residential building levels. The estimated CW in 2021 was 531,109 tonnes for residential and non-residential buildings using the floor area indicator. The findings reveal a positive relationship between residential building activity and population growth, with Auckland generating the highest rate of CW. Because of the limitations of the available data and estimation methods, the paper highlights the need for standardised data collection systems and outreach programs to improve CW estimation practices. Further research is recommended to enhance waste reduction strategies and identify high-waste-generating materials and methods. It is vital to have accurate CW estimations to support project waste management plans and sustainable construction practices and to inform waste management policies and regulations at the regional or national level.