A GHG metric methodology to assess onsite buildings non-potablewater system for outdoor landscape use

This paper documents a water:energy greenhouse gas (GHG) metric methodology for a decentralized non-potable water system that was developed as part of a Professional Doctorate in Engineering (DEng) research project by the first author. The project identified the need to investigate the challenges in changing the use of potable water to recycled water for landscape irrigation (LI) and for water features (WFs) at a medical facility case study (MFCS) in Abu Dhabi (AD) (the capital city of the United Arab Emirates (UAE). The drivers for the research project were based on the need for AD to decrease desalinated potable water as well as reduce the environmental impact and operational costs associated with the processing and use of desalinated water. Thus, the aim of the research discussed and presented in this paper was to measure the impact of using recycled and onsite non-potable water sources at the MFCS to alleviate the use of desalinated potable water and reduce associated energy consumption, operational costs, and GHG emissions (latterly in terms of carbon dioxide equivalent (CO_2e), for LI and WFs. The analysis of three case scenarios at the MFCS compared different approaches to alleviate energy use, costs, and GHG impacts for the use of recycled water in LI and WFs against a baseline. The findings led to a proposed sustainable water conservation and reuse (SWC) strategy, which helped save 50% desalinated potable water for LI use by soil improvement, building water system audits, and alternate non-potable water reuse. The recommendations for this paper are to develop a SWC strategy forming the basis for a water protocol by the competent authority for regional medical facilities including an assessment methodology for building decentralized non-potable water systems to measure their energy, GHG emissions and financial impact.