Cost-Benefit Analysis and Life Cycle-Assessment of Rainwater Harvesting in a Commercial Building

This study presents a life cycle assessment (LCA) of a rainwater harvesting (RWH) system and an air-conditioning condensate harvesting (ACH) system for non-potable water reuse. U.S. commercial buildings were reviewed to design rooftop RWH and ACH systems for one- to multi-story buildings’ non-potable water demand. A life cycle inventory was compiled from the U.S. EPA’s database. Nine scenarios were analyzed, including baseline RWH system, ACH system, and combinations of the two systems adapted to 4-story and 19-story commercial buildings in San Francisco and a 4-story building in Washington, DC. Normalization of 11 life cycle impact assessment categories showed that RWH systems in 4-story buildings at both locations outperformed ACH systems (45–80% of ACH impacts) except equivalent in Evaporative Water Consumption. However, San Francisco’s ACH system in 19-story building outperformed the RWH system (51–83% of RWH impacts) due to the larger volume of ACH collection, except equivalent in Evaporative Water Consumption. For all three buildings, the combined system preformed equivalently to the better-performing option (≤4–8% impact difference compared to the maximum system). Sensitivity analysis of the volume of water supply and building occupancy showed impact-specific results. Local climatic conditions, rainfall, humidity, water collections and demands are important when designing building-scale RWH and ACH systems. LCA models are transferrable to other locations with variable climatic conditions for decision-making when developing and implementing on-site non-potable water systems.

The Food Waste Atlas: An important tool to track food loss and waste and support the creation of a sustainable global food system

Life-cycle assessment and life-cycle cost analysis of decentralised rainwater harvesting, greywater recycling and hybrid rainwater-greywater systems

Due to population growth, urban water demand is expected to increase significantly, as well as the environmental and economic costs required to supply it. Rainwater harvesting (RWH) systems can play a key role in helping cities meet part of their water demand as an alternative to conventional water abstraction and treatment. This paper presents an environmental and economic analysis of RWH systems providing households with water for laundry purposes in a life cycle thinking perspective. Eight urban RWH system scenarios are defined with varying population density and storage tank layout for existing buildings. Storage tank volume required is calculated using Plugrisost software, based on Barcelona rainfall and catchment area, as well as water demand for laundry, since laundry is a fairly constant demand of non-potable water. Life cycle assessment (LCA) and life cycle costing (LCC) methodologies are applied for this study. Environmental impacts are determined using the ReCiPe 2008 (hierarchical, midpoint) and the cumulative energy demand methods. Net present value (NPV), internal rate of return (IRR), and payback (PB) time were used in LCC. Savings from laundry additives due to the difference in water hardness was, for the first time, included in a RWH study. LCA results indicate that the best scenario consists of a 24-household building, with the tank spread on the roof providing up to 96% lower impacts than the rest of scenarios considered. These results are mainly due to the absence of pumping energy consumption and greater rainwater collection per cubic meter of built tank capacity. Furthermore, avoided environmental impacts from the reduction in detergent use are more than 20 times greater than the impacts generated by the RWH system. LCC indicates that RWH system in clusters of buildings or home apartments offer up to 16 times higher profits (higher NPV, higher IRR, and lower PB periods) than individual installations. LCA and LCC present better results for high-density scenarios. Overall, avoided environmental and economic impacts from detergent reduction clearly surpass environmental impacts (in all categories except terrestrial acidification) and economic cost of the RWH system in most cases (except two scenarios). Another important finding is that 80% of the savings are achieved by minimizing detergent and fabric softener by using soft rainwater; and the remaining 20% comes from replacing the use of tap water.

To minimize the environmental impacts of construction and simultaneously move closer to sustainable development in the society, the life cycle assessment of buildings is essential. This article provides an environmental life cycle assessment (LCA) of a typical commercial office building in Thailand. Almost all commercial office buildings in Thailand follow a similar structural, envelope pattern as well as usage patterns. Likewise, almost every office building in Thailand operates on electricity, which is obtained from the national grid which limits variability. Therefore, the results of the single case study building are representative of commercial office buildings in Thailand. Target audiences are architects, building construction managers and environmental policy makers who are interested in the environmental impact of buildings. In this work, a combination of input–output and process analysis was used in assessing the potential environmental impact associated with the system under study according to the ISO14040 methodology. The study covered the whole life cycle including material production, construction, occupation, maintenance, demolition, and disposal. The inventory data was simulated in an LCA model and the environmental impacts for each stage computed. Three environmental impact categories considered relevant to the Thailand context were evaluated, namely, global warming potential, acidification potential, and photo-oxidant formation potential. A 50-year service time was assumed for the building. The results obtained showed that steel and concrete are the most significant materials both in terms of quantities used, and also for their associated environmental impacts at the manufacturing stage. They accounted for 24% and 47% of the global warming potential, respectively. In addition, of the total photo-oxidant formation potential, they accounted for approximately 41% and 30%; and, of the total acidification potential, 37% and 42%, respectively. Analysis also revealed that the life cycle environmental impacts of commercial buildings are dominated by the operation stage, which accounted for approximately 52% of the total global warming potential, about 66% of the total acidification potential, and about 71% of the total photo-oxidant formation potential, respectively. The results indicate that the principal contributor to the impact categories during the operation phase were emissions related to fossil fuel combustion, particularly for electricity production. The life cycle environmental impacts of commercial buildings are dominated by the operation stage, especially electricity consumption. Significant reductions in the environmental impacts of buildings at this stage can be achieved through reducing their operating energy. The results obtained show that increasing the indoor set-point temperature of the building by 2°C, as well as the practice of load shedding, reduces the environmental burdens of buildings at the operation stage. On a national scale, the implementation of these simple no-cost energy conservation measures have the potential to achieve estimated reductions of 10.2% global warming potential, 5.3% acidification potential, and 0.21% photo-oxidant formation potential per year, respectively, in emissions from the power generation sector. Overall, the measures could reduce approximately 4% per year from the projected global warming potential of 211.51 Tg for the economy of Thailand. Operation phase has the highest energy and environmental impacts, followed by the manufacturing phase. At the operation phase, significant reductions in the energy consumption and environmental impacts can be achieved through the implementation of simple no-cost energy conservation as well as energy efficiency strategies. No-cost energy conservation policies, which minimize energy consumption in commercial buildings, should be encouraged in combination with already existing energy efficiency measures of the government. In the long run, the environmental impacts of buildings will need to be addressed. Incorporation of environmental life cycle assessment into the current building code is proposed. It is difficult to conduct a full and rigorous life cycle assessment of an office building. A building consists of many materials and components. This study made an effort to access reliable data on all the life cycle stages considered. Nevertheless, there were a number of assumptions made in the study due to the unavailability of adequate data. In order for life cycle modeling to fulfill its potential, there is a need for detailed data on specific building systems and components in Thailand. This will enable designers to construct and customize LCAs during the design phase to enable the evaluation of performance and material tradeoffs across life cycles without the excessive burden of compiling an inventory. Further studies with more detailed, reliable, and Thailand-specific inventories for building materials are recommended.

Seeking urbanization security and sustainability: Multi-objective optimization of rainwater harvesting systems in China

Rainwater harvesting (RWH) system is a technology that focuses on sustainability and supports the sustainable environment development. The implementation of RWH systems provides many environment and financial benefits. Some of the environment benefits of RWH system are as follows: reduce the surface runoff, reduce the burden of soil aquifer, and provide the availability of clean water. This study analyzed the RWH system implementation benefits in both environment and financial sides. The financial benefits of RWH system implementation are calculated based on rainwater that can be used to replace the need for clean water. The environment benefits are defined by the reduction in main water tap use and the reduction in generated roof runoff volume. This study used a simple RWH system that uses the roof as a catchment area, the pipeline as a distribution system, and the tank as a storage system. The water use is for domestic potable and nonpotable for a household with up to four occupants in Bandung. The catchment area is taken up to 70 m2. A water balance model for various scenarios was developed to calculate the algorithm of the system. The costs taken in RWH system include the construction, installation, maintenance, and operational costs. The analysis shows that the implementation of RWH systems provides advantages over the use of conventional systems. It can save clean water usage up to 54.92% and provides runoff reduction up to 71.53%. RWH system requires additional costs approximately 0.66% from the value of the house. It was found that it is possible to achieve payback in RWH system implementation under several scenarios.

Multi-objective optimization integrated with life cycle assessment for rainwater harvesting systems

Coastal areas in Bangladesh are finding it harder to get safe, cheap drinking water because saline water is getting in, rainfall is unpredictable, and other water sources are pricey. This study looks at whether it is worthwhile for families to set up Rainwater Harvesting (RWH) systems in Mongla, a salinity area in Bagerhat. This study used a Cost-Benefit Analysis (CBA) to figure out if it pays off. This study looked at things like Net Present Value (NPV) of 293938.6 BDT, Benefit-Cost Ratio (BCR) of 20.9, Internal Rate of Return (IRR) of 236.09%, Health Cost and how long it takes to get money back. The study got info from surveys of 100 people who use RWH and 100 who don’t, including costs for setting up, maintenance, health, and time spent. RWH systems really cut down on the time and money people spend getting water and going to the doctor because of unpurified water. Even if initial costs go up or benefits go down, the system still works well. RWH looks like a cheap and easy way to deal with the drinking water problem in coastal Bangladesh. The study says RWH should be included in the country’s water plans, give poor families money to set up these systems, and train people to keep them running.

Feasibility analysis of a small-scale rainwater harvesting system for drinking water production at Werrington, New South Wales, Australia

With more than 60% of the inventory being over thirty years old, commercial office buildings represent a substantial global energy consumer. The Australian government has attempted to lower greenhouse gas emissions through legislation, but the implementation of these efforts has only resulted in annual reductions of 1-3%. It is essential to focus energy-efficient interventions on the stock of current commercial buildings if we are to achieve net zero emissions by 2050. Energy performance, efficiency, and greenhouse gas emissions can all be improved in commercial buildings by reducing energy consumption. According to Climate Works Australia and the IPCC, there is a 30% chance of avoiding current energy use while still reaping net economic benefits. To lessen global warming, the IPCC has also recommended that developed nations, like Australia, reduce emissions by 45% by 2030. Buildings with passive technologies can have better energy efficiency without sacrificing comfort. One of the main tactics for lowering energy consumption and carbon emissions in already-existing commercial buildings is energy retrofitting. "Providing a machine with a part, or a place with equipment which was not originally present when it was built" is what the Cambridge Dictionary defines as "retrofitting." However, in this context, it refers to any intervention activity that involves modernizing or repurposing the current structure to satisfy an appropriate requirement. Both cases deal with increasing a building's level of sustainability and energy efficiency through renovations. Multiple combinations of applicable energy consumption-reducing measures that can be applied to retrofit a building present a major challenge to decision-makers in energy retrofit. The evaluation of life cycle cost (LCC) and life cycle analysis (LCA) during retrofits present additional difficulties. LCC and LCA are not used in tandem; additionally, selecting the most appropriate retrofitting strategy or set of measures can occasionally be challenging due to the inclusion of unqualified sustainable technology in listings and selections. The current study intends to address the problems by creating a strong decision support system (RDSS) that integrates sustainable criteria, or triple bottom line TBLs (environmental, social, and economic benefits), in the energy retrofit decision-making process. This will lessen the difficulties encountered in making decisions that will lead to successful building appraisals. The predetermined objectives are meant to lead to the goal. Because of various technological alternatives, it may be vital to have a comparison to simplify sustainable technologies (STs) tools using SWOT/multiple criteria in TBL aspects. Providing an assessment method to merge LCA & LCC to balance environmental and economic performances and determine the impact of the building life cycle on the energy retrofit decision process. Address the challenges decision-makers encounter in dealing with changes due to building markets and regulations since legislation and public expectation drive sustainable buildings. To develop and validate a holistic optimum strategic decision model to select the best retrofit alternatives for a particular building which maximizes the sustainability ranking of the building. Initial research focuses on conducting a life-cycle cost analysis of a commercial office car park building in Sydney, New South Wales. The evaluation includes assessing energy performance through retrofit measures to determine long-term benefits. By using life-cycle cost analysis, the study aims to enhance decision-making in energy assessment. To examine energy consumption intensity, lifecycle costing, CO2 emissions, and cost efficiency, data will be collected from non-green buildings and one building's envelope will be simulated using the Energy Plus tool. Experimental measurements will be compared to validate simulated models. The study includes a case study on a 12,000 square meter commercial office building used as a commercial parking facility. Retrofitting activities were initiated on three office rooms, focusing on HVAC, lighting, and equipment improvements, resulting in a 1.9-year payback period, 15% emissions reduction, 25% energy savings, and 23% cost savings. The subsequent phase involves utilizing various methods such as concept mapping, focus groups, interviews, Questionnaire surveys, and statistical analysis (SPSS) to develop a robust decision support system (RDSS) for sustainable energy retrofits. The overall goal is to establish a systematic decision support system to aid decision-makers and policymakers in improving energy efficiency in commercial office buildings by implementing passive technologies. The system will also recommend strategies to enhance financial outcomes through smart building operations and management implementations.

Spatially optimized distribution of household rainwater harvesting and greywater recycling systems

Copyright © 2014 Journal of Southeast University

Reliability and financial feasibility assessment of a community rainwater harvesting system considering precipitation variability due to climate change

The rapid urbanization and the constant expansion of urban areas during the last decades have locally led to increasing water shortage. Rainwater harvesting (RWH) systems have the potential to be an important contributor to urban water self-sufficiency. The goal of this study was to select an environmentally optimal RWH strategy in newly constructed residential buildings linked to rainwater demand for laundry under Mediterranean climatic conditions, without accounting for water from the mains. Different strategies were environmentally assessed for the design and use of RWH infrastructures in residential apartment blocks in Mediterranean climates. The harvested rainwater was used for laundry in all strategies. These strategies accounted for (i) tank location (i.e., tank distributed over the roof and underground tank), (ii) building height considering the number of stories (i.e., 6, 9, 12, and 15), and (iii) distribution strategy (i.e., shared laundry, supply to the nearest apartments, and distribution throughout the building). The RWH systems consisted of the catchment, storage, and distribution stages, and the structural and hydraulic calculations were based on Mediterranean conditions. The quantification of the environmental performance of each strategy (e.g., CO2eq. emissions) was performed in accordance with the life cycle assessment methodology. According to the environmental assessment, the tank location and distribution strategy chosen were the most important variables in the optimization of RWH systems. Roof tank strategies present fewer impacts than their underground tank equivalents because they enhance energy and material savings, and their reinforcement requirements can be accounted for within the safety factors of the building structure without the tank. Among roof tanks and depending on the height, a distribution strategy that concentrates demand in a laundry room was the preferable option, resulting in reductions from 25 to 54 % in most of the selected impact categories compared to distribution throughout the building. These results may set new urban planning standards for the design and construction of buildings from the perspective of sustainable water management. In this sense, a behavioral change regarding demand should be promoted in compact, dense urban settlements.