Post Date: 23 July 2024

Preferences for Decentralized Water Technologies to Improve Freshwater Conservation in New High-rise Residential Buildings: Choice Modelling and Incentive Design

Abstract:

Decentralized water systems (DWS) present a promising solution for addressing global water scarcity, yet their widespread adoption and implementation remain limited, especially in high-rise high-density Asian cities such as Hong Kong. This research aims to investigate the heterogeneous preferences for DWS in the residential sector of Hong Kong. Three types of DWS, namely rainwater harvesting (RWH), greywater recycling (GWR), and wastewater reuse (WWR) systems were examined. 

An online questionnaire survey incorporating discrete choice experiments was conducted in January 2024 in Hong Kong, and validated samples were collected from 1,010 respondents. A latent class choice model (LCCM) was employed to categorize respondents into distinct preference classes. These latent classes were identified as value maximizing, cost-conscious, neutral and nonchalant, practical budget-conscious, and those prioritizing water safety and long-term lifespan in DWS adopters. We then proposed computations for freshwater saving volumes and associated costs for high-rise residential buildings equipped with these DWS types. Leveraging the insights from the LCCM results and capital costs computed from the proposed formulas, we created several scenarios to explore the potential adoption of different DWS in the Northern Metropolis, a new town in Hong Kong in the future. Our findings revealed that GWR, supported by government subsidies, is the preferred system in residential buildings among both apartment buyers (who may be relocating or purchasing a new apartment) and apartment renters (who may be considering purchasing an apartment). It demonstrated a comparatively higher probability of adoption on average, followed by WWR and RWH. Interestingly, while apartment buyers tend to favor WWR, renters are more inclined to opt for GWR and RWH. Nonetheless, without government subsidies, both buyers and renters tend not to adopt DWS or opt for RWH instead. These results hold significant implications for residential building developers, water system professionals, and government bodies involved in crafting sustainable urban freshwater management strategies in Hong Kong and other cities with similar built environments.