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An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building Sim, Douglas; Sato, Erika; Lei, Kevin; Wu, Tim 2010-11

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UBC Social Ecological Economic Development Studies (SEEDS) Student Report             An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building Douglas Sim, Erika Sato, Kevin Lei & Tim Wu University of British Columbia APSC261 November 30, 2010         Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report”.              An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building                     Course: Applied Science 261 Tutorial Instructor: Craig Hennessey Authors: Douglas Sim, Erika Sato, Kevin Lei & Tim Wu Date Submitted: November 30th, 2010 An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page ii        Abstract To achieve net zero water consumption for our new SUB, the report first identifies the methods for capturing clean water such as rainwater harvesting and dew water collection. These two methods can greatly reduce the portable water usage. Suggestions for reducing water consumption such as different fixtures and reusing grey water are investigated. According to literature review, grey water reuse can save significant clean water usage; thus, making net zero consumption feasible. In order to utilize rainwater and greywater, both water types need to go through different water treatments such as an in-Line Filtering, Activated Carbon Filtering and chemical treatments such as coagulation, ultra membrane filtration (UF) system, and ozonation. This report also covers a triple bottom line assessment involving water collection and filtration. From the economic aspect, a large initial cost must be invested. From the environmental aspect, reducing potable water consumption and capturing clean water locally implies less power consumption. From the social aspect, the idea of reusing grey water may cause some concerns but can also promote sustainability and raise awareness within a community. An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page iii      Table of Contents  Abstract ........................................................................................................................................... ii  List of Figures ................................................................................................................................. v  List of Tables ................................................................................................................................. vi  Glossary ........................................................................................................................................ vii  List of Abbreviations ................................................................................................................... viii  1.0 Introduction ............................................................................................................................... 1  2.0 Dew Collection ......................................................................................................................... 2  2.1 Dew collection System and Concepts ................................................................................... 2  2.2 Calculating Dew Yields ........................................................................................................ 3  3.0 Rainwater Harvesting ................................................................................................................ 6  3.1 Rainwater Harvesting System and Concepts ........................................................................ 6  3.2 Calculating Rain Yields ........................................................................................................ 8  4.0 Water Management ................................................................................................................. 10  4.1 Fixtures ............................................................................................................................... 11  4.2 Urinals ................................................................................................................................. 11  4.3 Faucets ................................................................................................................................ 11  4.4 Sewage pipes ....................................................................................................................... 12  4.5 Grey water ........................................................................................................................... 14  5.0 Rainwater Treatment ............................................................................................................... 17  5.1 Pre-Storage Treatment - In-Line Filter ............................................................................... 17  5.2 Post Treatment Filters: Activated Carbon Filter ................................................................. 19  5.3 Post Treatment Disinfection: Ozonation ............................................................................. 21  5.4 Post Treatment Disinfection: UV Light .............................................................................. 21  An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page iv       6.0 Grey Water Treatment ............................................................................................................ 23  7.0 Total Yield .............................................................................................................................. 28  8.0 Triple Bottom .......................................................................................................................... 30  8.1 Social Aspects ..................................................................................................................... 30  8.2 Economic Aspects ............................................................................................................... 30  8.3 Environmental Aspects ....................................................................................................... 31  9.0 Conclusion .............................................................................................................................. 33  References ..................................................................................................................................... 34  Appendix ....................................................................................................................................... 37  Appendix A: Advantages and Disadvantages of Dew collection ............................................. 38  Appendix B: Factors Affecting the Condensation and Yield of Dew ...................................... 39  Appendix C: Estimated Water Demand VS Months for the New SUB ................................... 41  Appendix D: Advantages and Disadvantages of Suggested Water Storage Techniques .......... 42  Appendix E: Approximate Price of Possible Building Materials ............................................. 43  Appendix F: Summary of domestic fresh water use in an experiment ..................................... 44  Appendix G: Estimated Rainwater Treatment Efficiency ........................................................ 45  Appendix H: Estimated Price of Water Treatment Equipment ................................................ 46    An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page v       List of Figures Figure 1: Simple dew collection system ......................................................................................... 2  Figure 2:Real life implementation of a dew collection system ....................................................... 3  Figure 3: Dew condenser system used in Croatia ........................................................................... 4  Figure 4: Simple Roof Catchment Design ...................................................................................... 6  Figure 5: Simple Ground Catchment Design .................................................................................. 7  Figure 6: Yearly Precipitation for Vancouver UBC ....................................................................... 8  Figure 7: Water consumption in public and residential buildings ................................................ 10  Figure 8: Cross section of Eco Trap system ................................................................................. 11  Figure 9: Water saving rate of different kitchen faucets ............................................................... 12  Figure 10: Sewage system of KSI ................................................................................................. 13  Figure 11: Sewage header of KSI ................................................................................................. 14  Figure 12: Conventional and alternative schemes for urban water use and treatment ................. 15  Figure 13: Rainwater Treatment System ...................................................................................... 17  Figure 14: In-line Filter ................................................................................................................. 18  Figure 15: In-line Filter Connection ............................................................................................. 19  Figure 16: Post Treatment Filters: Activated Carbon Filter ......................................................... 19  Figure 17: Filter Connected to a Control System ......................................................................... 20  Figure 18: How Activated Carbon Works .................................................................................... 21  Figure 19: Ultraviolet Water Disinfection System ....................................................................... 22  Figure 20: Flow Diagram of Grey Water Treatment .................................................................... 25  Figure 21: Protruding Roof ........................................................................................................... 29   An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page vi       List of Tables Table 1: Summary of dew collection results from Croatia ............................................................. 5  Table 2:Estimated Rainwater Yeild using 100% of the roof space ................................................ 9  Table 3: Distribution of applications for grey water reuse in review systems .............................. 16  Table 4: Quality of grey water different categories ...................................................................... 23  Table 5: Reclaimed manicipalwastewater guidelines ................................................................... 24  Table 6: Total Yield's Losses and Efficiency ............................................................................... 28  Table 7: Net Yeild and roof space correlation .............................................................................. 28  Table 8: Yearly water demand and average operation level correleation ..................................... 29     An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  vii        Glossary Glossary Definition  Biochemical Oxygen Demand (BOD)  “is the amount of oxygen required by microbes, mainly bacteria, in the stabilization of organic materials under aerobic conditions” (Reynolds p.106). Catchment Area  Surface area dedicated to dew and rainwater harvesting Chemical Oxygen Demand (COD) is a measure of the organic materials in a wastewater in terms of the oxygen required to oxidize the organic materials chemically. It is measured by boiling and refluxing the sample with a strong oxidizing agent and determining the amount of oxidizing agent used” (Reynolds p.104) Coliforms  “Species that exist in large numbers in the intestines of humans and other warm- blooded animals, so they are present in large numbers in municipal wastewaters” (Reynolds p. 30). Distillation The volatilization or evaporation and subsequent condensation of a liquid, as when water is boiled in a retort and the steam is condensed in a cool receiver Halogen Any of the electronegative elements, fluorine, chlorine, iodine, bromine, and astatine, that form binary salts by direct union with metals Halophenols Halogen elements (group 7 elements) that are a derivative of a phenol compound (contains at one hydroxyl group –OH and is attached to a benzene ring). Oxidize To convert (an element) into an oxide; combine with oxygen PH Degree of how acidic or basic a solution is Radative Cooling Rate The process in which heat is loss by radiatation Rainwater Harvesting  (RWH) Method of collecting rainwater Reverse Osmosis Water pressure is used to force water molecules through a membrane that has extremely tiny pores, leaving the larger contaminants behind. Purified water is collected from the "clean" side of the membrane, and water containing the concentrated contaminants is flushed down the drain from the "contaminated" side. Scraping  The act of “wiping” a surface Total Organic Carbon (TOC)  “A measure of the organic materials in a wastewater in terms of the amount of carbon in the organic materials. It is measured by removing the carbon dioxide present, combusting the sample, and measuring the amount of carbon in the carbon dioxide evolved” (Reynolds p.104). TP Total phosphorus content. Total Suspended Solids (TSS) Solids that are “separated by filtering a sample and drying and weighing the residue” (Reynolds p. 103). Turbidity  “Is mainly due to suspended organic solids, which range in size from colloidal to coarse suspensions. Municipal wastewater is about 99.95% water, but the organic solids present have a pronounced effect in that they exert a biochemical oxygen demand” (Reynolds p. 102) UV Radiation lying within the Ultraviolet Spectrum World Health Organization  (WHO)  An agency of the UN that specializes in coordinating and monitoring standards of international public health.  An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  viii        List of Abbreviations Abbreviations Expansions BOD Biochemical Oxygen Demand COD Chemical Oxygen Demand GAC Granular Activated Carbon HDPE Pipe High-Density Polyethylene Pipe KSI System Kodan Skelton Infill System RWH RainWater Harvesting SBAC Solid Block Activated Carbon TN Total nitrogen content. TOC Total Organic Content TP Total phosphorus content. TSS Total Suspended Solids UV Ultra Violet WHO World Health Organization   An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page 1       1.0 Introduction In this investigation, a water management plan is proposed for the new SUB with the ultimate goal of promoting sustainability and therefore earning credit towards a LEED Platinum status. The water management strategy proposed is outlined from the collection to the treatment procedure and finally the distribution of the treated water. The objective is to nullify the new SUB’s water consumption by managing the availability of fresh water and proposing a storage strategy and treatment techniques. More specifically, rainwater will be collected and treated. The treatment goes as follows: pre-storage treatment or in-line filter, post-treatment filters with activated carbon and finally through a disinfection step with ozonation. This rainwater will be used in all sectors’ taps. The treated rainwater after usage will become grey water, going through a sequence of physical and chemical treatments. The proposed sequence goes as follows, screening pretreatment step, a dual-media filter, coagulation, flocculation, ultra membrane filtration (UF) and optional disinfection treatment, photocatalysis. This treated grey water can then be potentially used in toilet flushing, laundry, air conditioning landscape irrigation, fire protection and street washing. An evaluation of the proposed management strategies is made via a triple-bottom line assessment and finally a conclusion is made of whether net-zero water is achieved.  An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page 2       2.0 Dew Collection Our atmosphere contains an abundant reservoir of water. Dew collection is one method that provides a viable solution for tapping into this free, clean and ‘unlimited’ source of water. Water sources based around dew collection has proven to be relatively clean and sometimes even satisfies the average requirements set by the W.H.O [1]. However, the quality of dew water is very dependent on the surrounding air quality and the location where the dew is collected. 2.1 Dew collection System and Concepts This method of collecting moisture trapped in our atmosphere occurs naturally and does not need any external energy input making the process 100% environmentally friendly. The water quality obtained is relatively clean and very low in metal and mineral content. A detailed list of advantages for dew collection can be found in Appendix A. The concept of dew collection is very simple and figure 1 outlines the basic idea and concept of the system. A real-life implementation of this system can also be seen in figure 2  Figure 1: Simple dew collection system Source: http://www.appropedia.org/Dew_collection_roof_retrofit   An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page 3        Figure 2: Real life implementation of a dew collection system Source: http://www.appropedia.org/Dew_collection_roof_retrofit To implement a dew collection system, the system itself would have to take advantage and optimize the factors which influence dew collection. The main physical and environmental factors contributing to dew collection can be seen in appendix B and the dew collection system should be built and modeled based on these factors [2]. 2.2 Calculating Dew Yields The climate in Vancouver falls under the Oceanic climate category. This zone usually exhibits relatively warm winters and cool summer and is comparable to the Mediterranean climate category. Instead of taking into consideration each individual atmospheric factor, the similarities in climate conditions allow us to use dew collection results performed from experiments conducted in the Dalmatian Coast, Croatia to predict our theoretical dew yields for Vancouver. The dew experiment was carried out in two different sites Zadar and Komia, with Zadar having favorable climate conditions and Komia having unfavorable climate conditions for dew collection [2]. Both locations used identical dew condenser systems, see Figure 3 [2]. From these results, we can use the data collected from Zadar as our maximum expected yield and data from An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page 4       Komia as our minimum expected yield to predict collection values for the new SUB. A summary of results obtained in Komia and Zadar can be seen in table 1. From these results we can calculate the mean expected maximum and minimum yield.  Figure 3: Dew condenser system used in Croatia Source: M. Muselli, D. Beysens, M. Mileta & I. Milimouk, 2009     An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page 5       Dew collection results Year Zadar Komia Yield (mm) Before scraping After Scraping Before Scraping After Scraping 2004 8.622 19.029 8.144 10.366 2005 10.672 20.688 5.452 8.302 Mean 9.647 19.859 6.798 9.334 Table 1: Summary of dew collection results from Croatia Source: M. Muselli, D. Beysens, M. Mileta & I. Milimouk, 2009 Assuming we are including scraping in our dew collection system, the yield from our dew collection system in the new SUB can be found by the follow formula: ܦ݁ݓ ܿ݋݈݈݁ܿݐ݁݀ ሺ݈ሻ  ൌ ܧݔ݌݁ܿݐ݁݀ ݕ݈݁݅݀ ሺ݉݉ሻ ൈ ܥ݋݊݀݁݊ݏܽݐ݅݋݊ ܣݎ݁ܽሺ݉ଶሻ If we assume that the entire roof of the new SUB (251,000 ft2 ≈ 23318.663 m2) is used for dew collection, the maximum expected value would be 463,085 liters/year, the minimum expected value to be 217,656 liters/year and the average to be 340,371 liters/year [3]. These expected values are only for a single sheet of foil spread over an area of 251,000 ft2. We could further improve the system by having multiple layers of foil evenly spaced from one another. Moreover, considering that we are implementing this system in an oceanic climate condition, our yields for summer would be higher than that of the expected values due it is cooler on average.  An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page 6        3.0 Rainwater Harvesting Rainwater provides a free and clean source of water and the implementation of rainwater harvesting (RHW) systems integrates well into the dew collection system mentioned in the previous section. The collection and storage of rainwater is encouraged due to the new SUB having a roof space of about 251,000 ft2 which can be utilized towards RWH [3]. Moreover, Vancouver’s weather makes this collection method viable as we experience a high level of annual rainfall. 3.1 Rainwater Harvesting System and Concepts Due to the uncertainty in the viability of utilizing ground water around the new SUB, the proposed RWH system focuses on the “roof catchment” method (see Figure 4). Since the RWH system will use the same catchment area as the dew collection system, the system for both processes is essentially the same [4].   Figure 4: Simple Roof Catchment Design Source: M. Sturm, M. Zimmermann, K. Schütz, W. Urban, H. Hartung, 2009 An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page 7        Figure 5: Simple Ground Catchment Design Source: M. Sturm, M. Zimmermann, K. Schütz, W. Urban, H. Hartung, 2009  An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page 8       3.2 Calculating Rain Yields Statistical figures of UBC’s annual precipitation levels will be used when calculating the expected yield for rainfall collection.  Figure 6: Yearly Precipitation for Vancouver UBC Source: http://www.climate.weatheroffice.gc.ca/Welcome_e.html Using the entire roof, (251,000 ft2 ≈ 23,318.663 m2) and the numerical figures from figure 6, the total amount of rain collected per unit area can be calculated by the following equation:  The table below shows the amount of rainwater collected if the entire roof space of the new SUB were to be used. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Snowfall (cm) 16.1 12.3 3.1 0.6 0 0 0 0 0 0.3 2.8 15.6 Rainfall (mm) 146.5 125.2 118.7 89 68.3 55.5 39.3 48.1 58.6 113.3 196.1 167.9 Total Precipitation (mm) 162.7 137.5 121.9 89.6 68.3 55.5 39.3 48.1 58.6 113.6 198.9 183.5 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Precipitation Month Yearly Precipitation for Vancouver UBC An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page 9        Collection Period Months Total Precipitation (mm) Total Collected amount (x106 l) Fall  Jan – Apr 511.7 11.93 Summer  May – Aug 211.2 4.92 Winter  Sept – Dec 554.6 12.93 Total Yearly 722.9 16.86  Table 2:Estimated Rainwater Yeild using 100% of the roof space An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  10        4.0 Water Management There are two main water cycles in our water system: clean water cycle and grey water cycle. The first cycle deals with clean water usage such as drinking and shower. This will be maximized by utilizing rainwater and dew water to reduce potable water usage and therefore achieve net zero water. The second water cycle involves the use of grey water. There are two ways to reducing water consumption: implementing fixtures and systems which consume less water and recycling grey water, lessening the overall building’s water consumption. This is especially important for the new SUB since the amount of water used in a restaurant is greater compared to other buildings (See Figure 7).  Figure 7: Water consumption in public and residential buildings Source: Library for Sustainable Urban Regeneration, 2008   An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  11        4.1 Fixtures Kitchens and washrooms will have the largest water usage in the new SUB. Therefore, reducing the water usage of fixtures from these two places will have a significant impact on the water consumption. 4.2 Urinals By carefully designing the shape of the bowl and flushing, Falcon Waterfree Technology has developed waterless urinals [5]. The major issue with waterless urinals is the smell of urine. To seal the smell of urine, waterless urinals use an Eco-trap system (See Figure 8). Urine passes though the drain where it flows through a floating layer of Blue Seal [5]. Blue Seal is a liquid that is less dense than urine forming a barrier that prevents the smell of urine from coming out of the pipes. However, this technology requires replacement of cartridges three to four times a year [5].  Figure 8: Cross section of Eco Trap system Source: An Investigation into Net Zero Water Usage and Water Reduction for the Proposed Student Union Building, 2010 4.3 Faucets In the washroom, the traditional taps tend to waste a significant amount of water. The most common situation is that people are careless when it comes to turning off the taps, leading to An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  12        water losses. To prevent unnecessary flowing, automatic faucet using sensors is strongly recommended. In the kitchen, there are two options: automatic faucet and the foot-touch faucet. Washing dishes uses the most water in the kitchen. Besides automatic faucet, foot-touch faucet is also an ideal choice. It is very convenient to stop water by your foot while both of your hands are occupied [6]. Figure 9 shows the saving rate of the traditional taps, automatic faucet and the foot-touch faucet. The foot-touch faucets can save water by approximately 10% [6].  Figure 9: Water saving rate of different kitchen faucets Source: Library for Sustainable Urban Regeneration, 2008 4.4 Sewage pipes A sustainable building often is made so that it can last more than 100 years. As a result, pipes must be replaced several times in a building’s total lifespan even with the most durable piping. In many buildings, pipes are rarely replaceable, especially sewage pipes, since they are installed in the central part of the buildings [6]. To make replacement easier, Kodan Skelton Infill system An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  13        (KSI) can be implemented in the new SUB. In KSI systems, vertical pipes are located outside. Sewage piping is designed using a header and replaceable horizontal pipes to assure the sewage system last longer [6]. Figure 10 and 11 show a sample of KSI system. Regarding to the water efficiency, high-density polyethylene (HDPE) pipe is a good option comparing to other materials for several reasons. HDPE pipes have very smooth interior surface, providing exceptional hydraulic characteristics [7]. It prevents the biological or chemical constituent being carried from adhering to the pipe surface. Their inner surfaces do not deteriorate like other types of materials; therefore, their flow capacity will remain the same throughout their life cycle. Furthermore, HDPE pipes have virtually no water leaks due to their fused joints. Other types of materials typically have 10 to 20% water leakage rates [7].  Figure 10: Sewage system of KSI Source: Library for Sustainable Urban Regeneration, 2008  An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  14          Figure 11: Sewage header of KSI Source: Library for Sustainable Urban Regeneration, 2008 4.5 Grey water In a drinking water stream, majority of water that has been used in bathtubs, showers, hand- washing basins, laundry machines, and kitchen sinks forms grey water. The remaining water is used to flush toilets, which creates black water. Grey water and black water are different in their composition. Black water is highly contaminated and can hardly be reused. On the other hand, grey water can be reused with proper treatment depending on the application [8]. Generally, 50 to 80% of wastewater in a household is grey water [9]. In order to reuse grey water, we have to separate grey water and black water. This requires a dual plumbing system for separate collection (See Figure 12) [8].  An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  15         Figure 12: Conventional and alternative schemes for urban water use and treatment Source: Desalination, 2004 There are several reuse options including toilet flushing, irrigation, fire suppression and cooling. Among them, toilet flushing and irrigation are the two main focuses for grey water distribution due to their water consumption. It is been reported that reusing grey water alone in toilet flushing can save potable water resources up to 60-70%. Also, using grey water for irrigation can result in savings of 12-65% of fresh water usage [9]. Table 3 shows a sample of the distribution of application for grey water reuse. An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  16         Table 3: Distribution of applications for grey water reuse in review systems Source: https://dspace.lib.cranfield.ac.uk/.../Greywater_recycling- A_review_of_treatment_options-2007.pdf   An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  17        5.0 Rainwater Treatment The main objective for the treatment method of cycle one of our water usage management is to treat rainwater. Our goal is to provide potable water for usage in washrooms, sinks and kitchens. Another goal is to be able to treat the collected rainwater quickly and efficiently. There are three main types of contaminants that can be found in water: biological, organic, and inorganic [10]. Figure 13 is a diagram of the complete treatment system aimed to treat these contaminants. Rainwater from the rooftop passes through a screen which then enters the storage tank. After that, water is pumped into the ozone system and filtered. Lastly, the filtered water is treated with UV light. Below is a more detailed explanation of the technologies and why these were chosen.  Figure 13: Rainwater Treatment System Source: http://www.spartanwatertreatment.com/rainwater-harvesting-water- treatment.html 5.1 Pre-Storage Treatment - In-Line Filter The process of pre-storage treatment of water is very important. The main goal for pre-treatment is to prevent the larger contaminants from entering the storage tank. The in-line filter is a device specifically designed for RWH. This powered independent filter effectively prevents larger contaminants such as dust, leaves, twigs, and rocks from entering the storage system [11]. Figure An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  18        14 and 15 shows an in-line filter system (for a 32000 cubic ft roof) which filters out particles larger than 380 micron and needs to be replaced twice a year. It can handle a load up to 60 tons and operate at 90% efficiency [11]. Figure 16 shows how the inline filter can be connected to smaller rainwater collection pipes coming from different parts of a roof.  Figure 14: In-line Filter Source: http://www.jrsmith.com/green_building/select_rainwater_filter.htm An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  19         Figure 15: In-line Filter Connection Source: http://www.jrsmith.com/green_building/select_rainwater_filter.htm  Figure 16: Post Treatment Filters: Activated Carbon Filter Source: http://www.jrsmith.com/green_building/select_rainwater_filter.htm 5.2 Post Treatment Filters: Activated Carbon Filter The main advantage of the activated carbon filter (AC) is its ability to absorb organic compounds. This means it is very effective in removing bacteria and also improves the taste and odour of the water [12]. Figure 18 shows how an activated carbon works. Depending on the type of activated carbon, it can be very effective in eliminating organic contaminants of 0.1 micron to 30 micron [12]. The filters need replacements every several months [12]. The two main An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  20        technologies of carbon filters are: granular activated carbon (GAC) and solid block activated (SBAC) [12]. Even though SBAC is better at contaminant reduction and has a higher water output efficiency rate [13], GAC is recommended. GAC’s main disadvantage compared to SBAC is its ability to filter out the smaller contaminants. GAC will filter out contaminants larger than 30 microns compared to SBAC’s 1 micron [12]. Ozonation will destroy the contaminants GAC missed. The main reason we recommend GAC is because of its ability to output filtered water at a higher rate than SBAC. This factor is a crucial component in the proposed strategy due to the SUB’s high demand for water. Figure 17 shows a GAC system hooked up to a control system.  Figure 17: Filter Connected to a Control System Source: http://www.aquamasterwater.co.uk/commercial%20reverse%20osmosis%20systems.html  An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  21         Figure 18: How Activated Carbon Works Source: http://www.cyber-nook.com/water/Solutions.html 5.3 Post Treatment Disinfection: Ozonation Ozone is an unstable gas composed of three oxygen atoms (O3). Due to its reactive nature, the extra oxygen atom will oxidize with other unwanted contaminants such as mold, yeast spores, organic material, and viruses [14]. The advantage of using ozone is that the treatment process does not need to introduce chemicals into the water to eliminate a wide variety of inorganic, organic, and microbiological compounds. Also, ozonation is more effective than chlorination at eliminating doors [14]. Since water demands are high and rainwater is not plentiful, a slow and wasteful water treatment processes such as distillation and osmosis will not keep up with the demand of water for the SUB. Though it provides a much faster treatment method, ozonation is an expensive technology to maintain [15]. Cheaper technologies such as UV light can be used to replace ozonation with the sacrifice of some treatment effectiveness against certain contaminants. 5.4 Post Treatment Disinfection: UV Light Ultraviolet light is another water treatment method used to destroy bacteria and viruses. Water is pumped through a clear chamber where it is exposed to UV light. The UV rays efficiently remove various organic contaminants, such as humid acid (HA), herbicides, pesticides and An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  22        halophenols [16]. The more energy dosage given to the UV light, the more effective it will be at removing contaminants. UV treatment require only seconds of contact time with water therefore becoming a good final treatment method before usage [17]. Figure 19 shows the components of a UV system.  Figure 19: Ultraviolet Water Disinfection System Source: http://www.rahawater.com/uv.htm  An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  23        6.0 Grey Water Treatment Grey water has been receiving more and more attention with the demand in water. Reuse and recycle of grey water has been seen as an attractive alternative for reaching sustainability standards as it constitutes 50 to 80% of the total household wastewater [18]. Also, the typical volume of grey water varies from 90 to 120 L/day. This is an average amount as this value depends on factors such as living standards, customs and habits, water installations and the abundance of water [18]. “Grey water is defined as the urban wastewater that includes water from baths, showers, hand basins, washing machines, dishwashers and kitchen sinks, but excludes streams from toilets [18].  Moreover, grey water is known to consist of low levels of contaminating pathogens and nitrogen.  Table 4 below demonstrates the quality of grey water; however, as mentioned earlier, it is important to note that there are many variables in such characterization.  Table 4: Quality of grey water different categories Source: Fangyue Li, Knut Wichmann and Ralf Otterpohl, 2009 Another consideration that has to be accounted for the treatment for grey water is the standards for such water source recycling. Although there are not such specific guidelines to be found, the reclaimed municipal wastewater guidelines will be used (Table 5) as a basis for the proposed scheme.   An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  24         Unrestricted reuses Restricted reuses Treatments Goals BOD5: ≤10 mg/l Turbidity: ≤2 NTU pH: 6–9 Faecal coliform: ≤10 / ml Total coliforms ≤100/ ml Residual chlorine: ≤1 mg/l BOD5: ≤30 mg/l TSS: ≤30 mg/l pH: 6–9 Faecal coliforms ≤10/ml Total coliforms ≤100/ml Residual chlorine: ≤1 mg/l Applications Toilet flushing; laundry; air conditioning, process water; landscape irrigation; fire protection; construction; surface irrigation of food crops and vegetables (consumed uncooked) and street washing Landscape irrigation, where public access is infrequent and controlled; subsurface irrigation of non-food crops and food crops and vegetables (consumed after processing) Table 5: Reclaimed municipal wastewater guidelines Source: Fangyue Li, Knut Wichmann and Ralf Otterpohl, 2009 The table above divides the non-potable reuses of grey water into restricted and unrestricted reuses. Obviously, the water quality for the unrestricted non-potable is of better quality than the restricted one.         An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  25        The flow diagram below outlines the steps in treating grey water.  Figure 20: Flow Diagram of Grey Water Treatment Firstly, the grey water should undergo a pretreatment such as a septic tank, filter bags or screen, removing larger particles, oil and grease which can damage other finer physical treatments. The treatment begins with a dual-media filter. As the name denotes, the solid-liquid separation occurs with the liquid, in this case, grey water, passing through a porous material, crushed anthracite and sand, to remove fine suspended solids. A dual-media is chosen over a single-media since the available pore volume will be greater. In other words, it has a greater gradient in pore volume (the top layer having a pore volume greater than the bottom with a gradual decrease in between). Also, dual-media filter has a higher filtration rate than just a sand media filter. The commonly GREY WATER Storage and pre‐treatment (sedimentation /screening) Chemical Treatment (coagulation ion exchange etc ) Membrane  Sand  Restricted  non potable Disinfection RECLAIMED grey water for  unrestricted non potable urban     An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  26        used dual-media filter comprises of 457 to 610mm layer of crushed anthracite and 152 to 305mm layer of sand [19]. Secondly, the proposed treatment involves the soil-filtered grey water to undergo a chemical treatment: coagulation. The chemistry behind this process is very complex. In simple terms, coagulation is the “addition and rapid mixing of a coagulant, the resulting destabilization of the colloidal and fine suspended solids, and the initial aggregation of the destabilized particles” [19]. In other words, a coagulant, or iron salt, is added to the wastewater, destabilizing the colloids and forming flocs of coagulants. In the water, the coagulant salt dissociates, the metallic ion hydrolyzes, yielding positively charged hydroxo-metallic ions. As these possess high positive charges, they have the tendency of adsorbing to the surface of the colloid, which are negatively charged. There is an interparticle attraction between the destabilized particles and the hydroxo- metallic complexes due to Van der Waals forces. The constant agitation of the system aids in the aggregation of the destabilized particles. The flocs are then left to settle, facilitating their removal. It is important to note that the variables here are: settling velocity of the flocs, the type of coagulant used, and type of mechanical agitator [19]. The next step would be to have the water undergo an ultra membrane filtration (UF) system. This consists of a series of tubes with fine pores on their walls. The water is left to pass through the clustered tubes, specifically through the pores. Membrane filtration is seen as an attractive technique due to its quick and selective removal of suspended solids as well as pathogenic agents.  Li et al. (2008), has conducted a study in which TOC from the influent dropped from 161mg/L to 28.6/L, that is an 83.4% elimination rate. Also, the total nitrogen and total phosphorus has decreased to 16.7mg/L and 6.7mg/L, respectively [18]. In addition, the permeate was low in turbidity and free of suspended solids and E.coli, not to mention the physical appearance. To guarantee that the grey water can be reclaimed and reused for unrestricted uses, a process of disinfection should be incorporated. Photocatalysis is seen as a promising method. It uses a semiconductor photocatalyst and UV radiation for the degradation of organic pollutants. It has An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  27        been reported that various organic contaminants, such as humic acid (HA), herbicides, pesticides and halophenols can be efficiently removed using this technique [20]. An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  28        7.0 Total Yield The process of collection, filtering and treatment is not 100% efficient. The total net water yield from dew, rain and grey water reuse can be calculated based on the efficiency table below [5]. Losses and Efficiency (%) Process Rain Dew Grey Water Average Collection 100.00 80.00 65.00 Loss from evaporation 20.00 Evaporation are accounted for in collection Treatment Process 25.00 25.00 48.75 Prelimary Filtration 10.00 10.00 43.875 Efficiency 54.00 67.50 43.875 Table 6: Total Yield's Losses and Efficiency Source: CIRS team, 2008 As 50-80% (average of 65%) of waste water in a building falls under the category of grey water, the total amount of grey water collected can be calculated base on our initial water yield from rain and dew collection [9, 18]. Table 7 shows the calculation based on the efficiency levels of table 6 and our results from section 2 and 3.  Roof Area used (%) Yield after filtration and treatment process (106 L) Dew Rain Grey Total 100 0.230 9.104 4.095 13.430 75 0.172 6.828 3.072 10.072 50 0.115 4.552 2.048 6.715 30 0.069 2.731 1.229 4.029 25 0.057 2.276 1.024 3.357 20 0.046 1.821 0.819 2.686 10 0.023 0.910 0.410 1.343 5 0.011 0.455 0.205 0.671 Table 7: Net Yield and roof space correlation Comparing the calculated net yield to the new SUB’s yearly water demand, net-zero water consumption has successfully been achieved, but the calculation assumes that the entire 251,000 ft2 of roof space is used for water collection [3]. However in reality, only a portion of roof space will be dedicated to water collection which will linearly decreases our calculated yearly yield. On the other hand, it is highly unlikely that the SUB will constantly operate at full capacity as An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  29        shown in appendix C and the average expected operation level of the SUB is approximately 25% to 37.5% (500 – 750 occupants out of a maximum of 2000 occupants) and table 8 shows a change in yearly water demand based on the average operation level of the SUB [3]. Average Operation Level (%) Yearly Water Demand (x106 l) 100.00 9.60 75.00 7.20 50.00 4.80 37.50 3.60 31.25 3.00 25.00 2.40 10.00 0.96 5.00 0.48 Table 8: Yearly water demand and average operation level correlation Comparing tables 7 and 8, if we were to assume that the SUB would be operating at an average rate of 31.25%, to achieve net-zero water  the minimum roof size needed as a dew and rainwater collection system would be approximately 25%. However, 25% of the roof space dedicated to rainwater and dew collection may still be a lot in the real scenario. One solution to maintain the required yield while limiting the collection area is to build protruding/external roofs. This will not only provide shelter for students but also increase out catchment/condensation area. Figure 21 shows an example of this solution.  Figure 21: Protruding Roof Source: http://www.builderbill-diy-help.com/butterfly-roof.html An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  30        8.0 Triple Bottom 8.1 Social Aspects Since the new SUB aims to achieve net-zero water its water consumption will impose responsibilities not only on the students, but also kitchen staff, cleaners and other workers. This requires education for workers and staff members and the need for awareness to be created among students Among the fixtures suggested, the one with greatest concern is water-free urinals and its odors. Although the technology can stop the smell of urine from coming out of the pipes, there will still be the some coming from the surface of the urinals. To solve this, windows should be kept open in the washroom to keep the air flow. Furthermore, the surface of the urinals needs to be cleaned regularly to eliminate the smell. The implementation of this water management strategy can be seen negatively from the new SUB users’ perspective. The water collection and treatment systems will have to either sacrifice the roof space or underground/basement space of the new SUB, which could potentially be used for other purposes. Sacrificing such spaces could also impact the building’s design and infrastructure, which can also be aesthetically not appealing for the users (student body). Regarding the usage of rainwater and grey water, there is another social concern: the skepticism of such practice. In other words, awareness would have to be raised within the community about the different treatment methods, showing their reliability in meeting acceptable quality standards. Using grey water for irrigation and garden watering for instance can be seen as unreliable. Some are afraid that the contaminants will accumulate in the plants. This requires the new SUB to have strict standard of its water treatment and to present the results to the public. 8.2 Economic Aspects The main economical factor of dew and rainwater harvesting system mainly composes of the implementation of the storage tank(s) and catchment area. Appendix D gives two suggested water storage techniques as well as their advantages and disadvantages. Maintenance cost would include annual cleaning of the tank, replacement of the condensation sheets and regular An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  31        inspections of the catchment area, gutters and pipes. An estimate maintenance price cannot be calculated due the price being heavily dependent on the size of the system and the type of materials used to construct the system. For example, the condensation surface material can vary from glass to corrugated steel which will only need to be cleaned and not replaced, to plain aluminum and specialized OPUR foil which needs to be replaced once a year. Appendix E gives the prices of some possible building/maintenance material. To obtain a net zero building, we need to have a huge initial cost to implement more expensive equipment in order to do so. However, most of the equipment can last longer than the one being replaced and can save significant water usage and power consumption in the long term. The equipment proposed also reduces the amount of money needed for maintenance. The cost of rainwater treatment varies with the types of technology used. The table in appendix H shows the cost for a specific technology. Although ozone is shown to be very expensive, it is a very effective treatment method. Ozone is an attractive option for larger systems such as the SUB. Ozonation can be replaced by a SBAC filter instead of a GAC filter or by an increase of water contact time with UV radiation. This method will reduce the overall cost, but will slow the treatment process. As water in BC is not charged based on consumption rates, water collection methods and treatment would increase the cost of water usage in operating the technologies being proposed as well as the maintenance required by such technologies. In other words, it is all dependent on the consumption rate of water in the new SUB. 8.3 Environmental Aspects Using fixtures with new technologies and reusing grey water aid in reducing the usage of potable water and contamination in effluents. Reducing potable water usage also implies reduction in power consumption. Even though implementation will cost more, being environmentally friendly promotes sustainable practices for others to follow. The rainwater treatment system has barely any negative environmental impact. The in-line filter does not require power to operate. There are no chemicals introduced to the water in the An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  32        treatment cycle. The ozone system does require a significant amount of electricity to operate, but it not comparable to the energy the SUB uses overall. The proposed treatment method for grey water is environmentally sound as it does not use any hazardous chemicals which could pose any health risk to the community or its effluents. The management strategy proposed focuses on minimizing the water requirement from the utility provider. By making use of the water that would be discarded, grey water will substitute in some sectors of the SUB the use of clean municipal water that could be used for drinking water. In other words, conserving natural resources in the long run will benefit the environment and compensate for the disturbance caused by the construction of the new SUB. An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010     Page  33        9.0 Conclusion In conclusion, net zero water can be achieved by using at least 30% of the total roof area (≈7000 m2) and assuming the SUB will operate on average around 30% of maximum its capacity. The two rainwater collection methods are dew collection and roof catchment. In order to maximize the rainwater usage, the water will be used for two cycles. The first usage cycle involves using the treated rainwater for cleaner purposes such as sinks and the second usage cycle will reuse the drainage water from the sinks (greywater) for toilets. Our treatment method for rainwater involves using an in-line filter, ozonation, carbon filtration, and UV disinfection. Our treatment method for grey water involves a septic tank, dual-media filter, coagulation, ultra-membrane filtration, and UV disinfection. The rainwater treatment system is a major investment. Because water is free in British Columbia, it does not make sense in an economic point of view to build such a system. However, because the main goal of the new SUB is to achieve LEED Platinum, a net zero water system will help achieve this goal. Also, the net-zero system will help in a social standpoint in that it will promote for a greener planet. Furthermore, the rainwater system has very little negative environmental impact. Based on the SUB’s goals for LEED Platinum, positive social effect, and small environmental impact it is recommended to implement the net-zero rainwater system. An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010            References  [1] P. Gandhidasan & H.I. Abualhamayel, Modeling and testing of a dew collection system,Saudi Arabia: Desalination, 22 November 2004. [2] M. Muselli, D. Beysens, M. Mileta & I. Milimouk, Dew and rain water collection in the Dalmatian Coast, Croatia, Croatia, Europe: Atmospheric Research 92, 14 January 2009. [3] Andreanne, Doyon (2010, November), New SUB Project Coordinator e-mail conversations [4] M. Sturm, M. Zimmermann, K. Schütz, W. Urban, H. Hartung, " Rainwater harvesting as an alternative water resource in rural sites in central northern Namibia," Physics and Chemistry of the Earth, vol. 34, pp. 776–785, 2009. [5] Arthur Leung, Jian Liew, Brendan Tonner, and James Wan, “An Investigation into NetZero Water Usage and Water Reduction for the Proposed Student Union Building,” 2010  [6] M. Kamata and M. Mae. “Water Management in Sustainable Buildings,” in Library for Sustainable Urban Regeneration, vol. 1, Part I, 3-28. [7] GreenBuildingSolutions.org, “Piping & Water-Management Solutions,” [Online document], 2010, [cited 2010 Oct 20], Available HTTP: http://www.americanchemistry.com/s_greenbuilding/sec_subject.asp?CID=2172&DID=9 048 [8] J.G. March, M. Gual, and F. Orozco, “Experiences on greywater re-use for toilet flushing in a hotel,” in Desalination, vol. 164 iss: 3 pp. 241 -247 [9] A, Jamrah, A. Al-Futaisi, S. Prathapar and A. Al Harrasi, “Evaluating greywater reuse potential for sustainable water resources management in Oman,” in Environmental monitoring and assessment, vol. 137 iss:1 pp. 315 -327  An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010            [10] Darryl W. Hawker et al., “A screening level fate model of organic contaminants from advanced water treatment in a potable water supply reservoir”, Nathan: QLD 4111, 2010. [11] B. Kus, J. Kandasamy, S. Vigneswaran, and H.K Shon, “Cost effective in-line filtration system to improve water quality in rainwater tanks”, Sydney: UTS, 2007. [12] W.A.M. Hijnen et al., “GAC adsorption filters as barriers for viruses, bacteria and protozoan (oo) cysts in water treatment”, Rotterdam: KWR Watercycle Research Institute, 2010. [13] J. Cromphout, E. Walraevens, R. Vanhoucke, “Improvement of water quality in the drinking water plant of Kluizen by the use of ozone in combination with GAC”, Tribune de L’Eau 58 (1) (2005) 15–18. [14] S.A. Parsons, “Advanced Oxidation Process for Water and Wastewater Treatment”, London: IWA Publishing, 2005. [15] Von Gunten, U., “Ozonation of drinking water: Part I. Oxidation kinetics and product formation”, Water Resources, 37, 1443–1467, 2003. [16] D. Avisar, Y. Lester, and H. Mamane, “pH induced polychromatic UV treatment for the removal of a mixture of SMX, OTC and CIP from water”, Israel: Geography and the Environment, 2009. [17] Frank McDonald. (2007, June 15) Water and Wastewater Plant UV [online]. Available: http://www.waterandwastewater.com/plant_directory/Detailed/328.html [18] Fangyue Li, Knut Wichmann and Ralf Otterpohl, “Review of the technologicalapproaches for grey water treatment and reuses," Science of the Total Environment, no. 407, pp. 3439-3449, 2009. An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010            [19] T. D. Reynolds and P. A. Richards, Unit Operations and Processes in Environmental Engineering, Second ed., Stamford: Cengage Learning, 1996. [20] Ning Ma et al., “Performing a microfiltration integrated with photocatalysis using an Ag- TiO2/HAP/Al2O3 composite membrane for water treatment: Evaluating effectiveness for humic acid removal and anti-fouling properties,” Water Research, pp. I-II, 2010. [21] CIRS team. (2008, June). CIRS. Retrieved March 2010, from Design Charettes: http://www.cirs.ubc.ca/building/design/charettes/Water%20Supply,%20Treatment%20an d%20Reuse%20Charette%20(2nd%20Gen).pdf An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010                      Appendix An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010            Appendix A: Advantages and Disadvantages of Dew collection  Advantages Disadvantages Formation of dew occurs naturally and does not need any external energy inputs N/A The process of dew formation is environmentally friend N/A Water quality obtained from dew is usually expected to contain low amount metal and mineral content The water quality of dew has a strong relation to the air quality. The dew composition is determined the by the dissolution of surrounding gas and particles which settle on top of the condensing surface. As a result, dew collection in urbanized or heavily industrialized location will lead to a poor water quality. In extreme cases dew water itself can be corrosive. Dew formation is dependent on multiple atmospheric conditions. This makes its availability higher and more dependent (e.g. compared to rain)  Although dew collection will still occur, the amount of dew collected will deteriorate in unfavorable climate conditions The location of dew collection is flexible and can occur in a variety of locations N/A The cost of setting up a simple dew collection system is relatively cheap Materials used as a condensation surface may not be environmentally friendly (e.g. plastic) Collection systems can easily be integrated into pre-existing houses or buildings Used up roof space Low maintenance cost May require yearly maintenance check for larger and more efficient dew collection systems.  An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010            Appendix B: Factors Affecting the Condensation and Yield of Dew  System factors Dependency Maximization Suggestions Radative Cooling Rate The radiative cooling rate is the rate at which heat is dissipated from the surface. When the surface drops below the dew point of water, moisture in the air will start to condensate onto the surface To maximize the condensation rate of dew, materials with high radian cooling properties will be used as the surface for dew collection  Suggested materials are materials that are smooth and impervious. For example, tiles, a sheet of corrugated steel, Cement, plastic and glass. The material used at Dalmatian Coast experiment was a condensing foil made up of TiO2 and BaSO4 microspheres embedded in low-density polyethylene. Humidity Humidity plays an important role in dew collection. Relative humidity represents the amount of moisture in the surrounding air. The higher the relative humidity, the higher the rate of dew formation. The dew system will have to be set up in a way to keep humidity levels around the collection surface as high as possible As UBC is located on the coast of Vancouver, the most common and strongest winds are expected to come from the direction of the sea (blowing from west to east). The dew systems collection surface should be slanted facing the east to avoid as much direct wind contact. This setup will allow high dew yields with incoming winds from that direction.    An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010            System factors Dependency Maximization Suggestions Scraping Scraping with the respect to dew collection is a process of removing water droplets from the surface (much like the windscreen wiper of a car).  For the automatic collection of dew to occur, the water droplets formed on an angled surface will have to be big enough so that the gravitational pull on the droplet can overcome the cohesion forces between the water and the condensation surface. Scraping allows smaller water droplets to be harvested from the condensation surface before the droplets evaporate. Scraping also re-exposes the condensation surface to the atmosphere which allows quicker dew formation. Experimental data has shown that scraping increases the amount of dew yield by about 25-50%. Scraping should be incorporated into the dew collection system. The evaporation rate of water increases with atmospheric temperature (e.g. when the sun rises). In order to maximize the dew yield, an automated scraping system could be set to scrape the condensation surface in the early hours of the morning (much like the windscreen wiper on a car). If scraping occurs too frequently, the movement of scraping disturbs humidity levels between the condensation surface and the atmosphere resulting in the opposite effect, a decrease in dew condensation rate. Condensation Surface Area Heat dissipation and condensation are both related to the surface area. The larger the surface area, the more heat can be dissipated. The surface area of the cooled material also provides a larger condensation site for dew. To maximize the dew yield, we will have to maximize the surface area of the dew collection system. Ideally the dew collection system would span across the whole roof of the new SUB. However, the drawback is that the roof would be unusable for anything else. Another suggestion is to have multiple thin layers of collection foil equally spaced from one another. This would allow dew condensation to occur on each sheet. Surrounding temperature For condensation to occur, the temperature of the surface will have to be below the dew point of water. The condensation surface will have to be thermally insulated from any heat sources present in its surrounds. However, the surface area has to still have the ability to dissipate heat into its surroundings As the dew collection system will be taking place on the roof of the new SUB, the major heat source would be the SUB itself. The foil of the condenser will have to be thermally insulated from the SUB. One way to do this is to place insulation layer between the foil and the frame of the condenser.   An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010            Appendix C: Estimated Water Demand VS Months for the New SUB Graph showing the water demand rate of the new SUB operating at 100% and the estimated available precipitation given a 5,200m2 catchment area on the roof. An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010            Appendix D: Advantages and Disadvantages of Suggested Water Storage Techniques  Water Storage Underground Tank Above Ground Tank Advantages Disadvantages Advantages Disadvantages Saves physical space Hard to clean and Maintain as they tank is located underground. Drainage of the water for cleaning will also be a hassle Easier to maintain and clean Takes up Physical Space Keeps water cool and at a relative constant temperature Requires a pump to distribute stored water Easy to detect cracks and leaks Subjected to weather conditions Keeps algal and other organisms from growing due to there being no light Risk of contamination from groundwater Possibility of using gravity to help the distribution of water Requires strong Anchoring to support the Tank Possibility of the collection collection process uses gravity to direct water to the tank Significantly more costly than a tank located above ground Cost of implementing is significantly less than that of a tank underground Tank is protected from Weather conditions Risk of taking damage from growing tree roots Can be easily integrated with the ground catchment technique for rainwater collection     An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010            Appendix E: Approximate Price of Possible Building Materials  Parts Specifications Price (CAD) Use Gutters Approx 3.25"x2.5"x120'' - 9.6"x9.6''x120.4'' (Material Plastic, Aluminum, Vinyl) 11.00 -15.00 Water Management Leaf Guards Approx 5.25''x72''x0.5'' (Material Vinyl/ Aluminum 8.00 – 10.00 Filtration Pipes/Spouts Approx 34.75''x3''x3'' to 120''x3.25''x3.25'' (Material Vinyl, Aluminum, Plastic) 11.00 – 14.00 Water Management Glass Sheet Approx 3''x6'' to 4''x4'' 1.00 – 3.00 Collection Area High Performance Aluminum Foil Approx 47.25''x2165.36'' 550.00 – 650.00 Collection Area OPUR Condensation Foil Specialized condensing foil made up of TiO2 and BaSO4 microspheres embedded in low-density polyethylene. Unknown Price Collection Area   An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010             Appendix F: Summary of domestic fresh water use in an experiment An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010            Appendix G: Estimated Rainwater Treatment Efficiency  Rainwater Treatment Output Efficiency Treatment Technology Percentage In-Line Filter 90% Ozone System 95% Activated Carbon Filter (GAC) 90% UV 100% Total Output Water for Usage 76.95%   An Investigation into Developing a Net-Zero Water Management Strategy for the New Student Union Building November 30, 2010            Appendix H: Estimated Price of Water Treatment Equipment   Initial Cost ($) Details Maintenance Cost ($) Annual In-line Filter -$1.57 per m2 of roof space -Assuming using whole roof space 23000m2 , it cost approximately $36000 -$200-$400 per replacement filter -Assume filter needs to be replaced 3 times a year: $600- $1200 Ozone -$20000-$80000 -more expensive require less maintenance and more efficient -Assuming electricity rates at $0.06/KWh we get $8 per day plus $3 for plumbing and plus $20 for capital we get $31 for O&M cost per day -it comes to $11315 per year GAC Filter -$3000-$6000 per unit -depends on the quality and size of filter -$0.50 to $3.00 per 1,000 gallons (3785 L) depending on the quality filter -Assume in one year SUB collect 17 million liters of water per year, so the cost can range from $2200-$13474 per year UV  -$700-$1500 per unit -depends on quality of unit such as: -flow restrictors-(capacity of unit is not exceeded -solenoid-shut of the water if power is down -intensity meter-close down system if bulb is not strong anymore -treatment speed from 4L per minute to 150L per minute -$100-$200 bulb replacement per unit -Assume bulb needs to be replaced twice every year which comes to $200-$400 

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