This study evaluates an existing non-potable water system serving outdoor services for a medical facility case study (MFCS) in Abu Dhabi (AD), United Arab Emirates, using mixed methods research to identify water demand and availability of non-potable water, and to optimize water reuse for reducing waste, energy consumption and greenhouse gas emissions (GHG). The MFCS footprint includes 50% landscaping. The water used for irrigation is from non-clinical/non-potable water, treated condensate water, a by-product of air conditioning. For 5 months per year, there is a predicted non-potable water deficit, so costly and non-sustainable desalinated potable water is required for irrigation. The findings include that there is a non-potable water deficit due to an excessive consumption for landscape irrigation (LI) and water features (WF), and that 177,288 m³ of condensate and desalinated water was wasted (equivalent to 71 Olympic swimming pools). The contribution of this research is to demonstrate that water wastage, a contributor to GHG emissions, is due to inadequate field testing and verification, water tank storage problems and a lack of LI and WF water demand management. Strategies to address these issues are suggested and will be useful to building owners, operations and maintenance teams and facility managers to substantially decrease water consumption in any type of buildings with a non-potable water system, as well as helping AD to achieve its target of a 22% reduction in GHG emissions by 2030 (Environment Agency- Abu Dhabi (EAD 2017)).

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.

This paper discusses recycled non-potable water (NPW) quality test results from an existing, decentralized, treated air handling unit (AHU) air conditioning (A/C) condensate water (CW) system in a medical facility case study (MFCS) in Abu Dhabi (AD), the capital city of the United Arab Emirates (UAE). The MFCS, a 364-bed hospital that opened in 2015 with 50% landscaping, is targeting 100% non-clinical/non-potable water use for landscape irrigation (LI) from 179,700 m³/year treated CW, which is a by-product of AHU A/C. For seven months per year, however, a deficit of 14,340 m³ AHU A/C CW occurs, so costly and non-sustainable, desalinated potable water is required. The proposed change project, using a mixed methodology, develops a sustainable NPW strategy, including a protocol to extract water from recycled, onsite, organic food waste, fire sprinkler pump test water (FSPTW), and reverse osmosis reject water (RORW) to meet the AHU A/C CW shortfall by adapting, enhancing, and monitoring the medical facility’s NPW treatment system. The hospital’s sustainability strategy implemented by the author could be legislated and mandated by the relevant authority for regional medical facilities, taking the form of a water conservation protocol including the classification and characterization of different types of NPW to understand their impact on LI, human health, and building water systems. The outcome is a novel change in practice to reuse 25,141 m³/year RORW and 1136 m³/year FSPTW as makeup water for the A/C CW shortfall in winter. The results identify key considerations to be addressed by the target audience (building owners, landscape contractors, and facility managers) when reusing NPW to protect the environment against soil degradation—a major aspect of decarbonization.