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Water Conservation |
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Water is one of our most precious natural resources. Potable water is an increasingly valuable global commodity, and the U.S. is one of the highest per capita water users in the world. Although the United States has abundant overall supply of water, it is not evenly distributed, leaving many parts of the country undersupplied. Water efficiency programs can be part of any energy management program, be a way to even out the imbalance of water supply, and save money.
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Contents
1. Definition
2. Use/Application
a. Established Techniques
b. Emerging Trends
3. Use an Integrated Approach
4. Resources
5. Associated Strategies
6. Case Studies |
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Definition
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Water is one of our most precious natural resources. Potable water is an increasingly valuable global commodity, and the U.S. is one of the highest per capita water users in the world. Although the United States has abundant overall supply of water, it is not evenly distributed, leaving many parts of the country undersupplied. Water efficiency programs can be part of any energy management program, be a way to even out the imbalance of water supply, and save money.
The introduction of water conservation measures (WCMs) is one of the most immediately and technologically available and cost-effective actions we can take. WCMs can:
- Save energy input for supply treatment, water transport and pumping, and disposal treatment.
- Save expenditure of energy and money on expanded treatment plant and infrastructure by reducing water volumes, particularly important in localities with combined storm and sanitary systems (conveys both sanitary sewage and storm water in one piping system)
- Save resources including water, energy and labor.
- Protect the environment by reducing storm water runoff, untreated sewage, and use of chemical treatment.
- Easily reduce water usage in commercial buildings by 30%.
Based on 650 occupants using 20 gallons per day (gpd), a typical 100,000 square-foot office building can realize a reduction of one million gallons of water per year using low-flow fixtures combined with sensors and automatic controls. Non-potable water can be used for building systems, toilet and urinal flushing, and landscape irrigation.
The Energy Policy Act of 2005 mandated use of water saving standards for water closets, urinals, shower heads, and faucets, saving an estimated 6.5 billion gpd. Toilet flushes account for 4.8 billion gpd, the greatest single water use in residential and commercial buildings. Older water closets used 4.0 to 8.0 gallons per flush, while plumbing codes now require fixtures with 1.6 gallons per flush. Water closets are now available that achieve 1.0 to 1.3 gallons per flush.
Commercial and industrial facilities use large amount of process water that can be run using gray water sources resulting in substantial cost saving and reduction in water supply demand. Businesses such car washes, industrial cleaning operations, and industrial operations that require equipment cooling require great volumes of water that can be made up with recycled gray water. Gray water sources may involve wastewater from lavatories, showers, washing machines, and other building activities that do not involve food processing and human waste. This makes sense from both the standpoints of energy reduction, environmental good practice, and bottom line economics.
Consumption of lower volumes of potable water on the supply side, and less need for water treatment, will result in energy savings and carbon reduction. A large quantity of energy must be spent to collect, treat and distribute potable supply water, and in collection and treatment of wastewater for environmentally save disposal back into our waterways. If the volume of water used can be reduced, the plant, equipment, and electric power needed to produce the water be reduced, thereby reducing carbon emissions involved to produce that power.
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Use / Application |
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Reduce indoor potable water consumption by using fixtures that exceed the performance requirements set by the Energy Policy Act of 2005. Highly efficient fixtures are also available at a cost premium.
- Residential Buildings: Employ strategies that use 30% less water(combined)
- Commercial Buildings: Employ strategies that use 20% less water (combined)
Plumbing Fixture selection:
- Install low-flow showerheads (1.75 gallons per minute or less) in all showers.
- Install low-flow sink aerators in all bathrooms (1.0 gallons per minute or less) and kitchens (2.0 gallons per minute).
- Install low-flow toilets (1.3 gallons per flush or less) OR dual flush toilets (these typically have 0.8 and 1.6 gallons per flush modes).
- Install low-flow (1/8 gallon per flush) or waterless urinals in commercial/public restrooms.
- Install automatic-sensing infrared fixtures on all commercial/public restroom lavatories.
- Reduce indoor water consumption by using water efficient appliances and equipment.
- Specify and install residential and commercial front-loading Energy Star® clothes washers with a Water Factor less than or equal to 5.5.
- Install only ENERGY STAR® dishwashers, which save water as well as energy (and generally run quieter because of better insulation).
- Install a domestic hot water recirculation loop system.
- Consider tankless hot water heaters.
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 Rainwater catchment system with cisterns at
Philip Merrill Environmental Center, Annapolis,
Maryland
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Site use of water:
- Reduce potable water used for irrigation.
- Use water-efficient irrigation systems with low-flow sprinkler heads and water-efficient scheduling practices.
- Specify xeriscaping - native and drought tolerant plant species to minimize need for watering.
- Consider capturing rainwater to reduce water consumption used for irrigation and building and sidewalk maintenance activities.
- Maximize on-site absorption and filtration of stormwater through the use of non-structural storm water management measures.
Building Design:
- Utilize vegetated, "green" roofs and/or roof gardens to:
- reduce impervious areas
- reduce peak time discharge
- reduce heat island effect
Reduce negative impacts of construction process:
- Develop and implement an Erosion and Sedimentation Control plan (ESC) as dictated by State and/or local requirements.
- Install erosion control measures to prevent any soil or sediment from leaving the site.
- Stockpile and stabilize topsoil, surrounding with silt fence or similar to prevent topsoil from mixing with other soils onsite
Potable Water Recycling:
- Consider capturing graywater from lavatories, showers, sinks, laundry, and dishwashing facilities for treatment and reuse by individual residents for flushing toilets and by the building staff for cooling tower makeup (if applicable), maintenance needs, and irrigation. Review code requirements to ensure that all codes are met.
Mechanical Systems:
- Consider conserving water in HVAC systems and cooling towers.
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Established Techniques |
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- Optimize water systems with efficient water systems design, leak detection, and repair.
- Use water conservation measures.
- Utilize water reuse and recycling systems.
- Educate water consumers and maintenance personnel in appropriate water conservation techniques
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Emerging Trends |
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- More highly regulated water conservation environment due to increased development pressure on limited water supplies:
- Limited availability of fresh water supply in many parts of the country. Vast new building development in California and the Sunbelt states has taxed already highly burdened water supplies. Recent droughts, forest fires, and temperature warming have exacerbated that debate.
- Aquifers near shorelines are becoming unable to meet increased demand because of salt water intrusion.
- Development pressure threatening previously pristine watershed areas.
- A relatively new technology emerging on the scene is the Living Machine, which takes blackwater (also known as sewage) and returns it to its natural whitewater state (unpolluted by human waste). Microorganisms are the basis for the process:
§ anaerobic septic tank,
§ anoxic reactor,
§ closed aerobic tank (with plants to filter gases),
§ open aerobic tank(s) (with snails, shrimp and fish),
§ sludge is redirected back to the septic tank (or composted), while water goes to a wetland (usually indoor);
§ further treated (without chemicals) studies show that the water could even be consumed more safely than when first polluted.
- Constructed wetland systems (CWS) pretreat wastewater by filtration, settling, and bacterial decomposition in a natural-looking lined marsh. Constructed wetland systems have been used nationally and internationally with good results, but performance levels decrease in cold climates during winter.
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Use an Integrated Approach |
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A new way of thinking must be adopted in order to meet the goal of reducing carbon emissions associated with buildings. Your solutions can begin by integrating four possible methods. None works alone, and they are not all relevant in considering every strategy. However, considering the following tactics is necessary:
- Reduce the overall energy use in your building
- Water usage for site and building systems can be reduced in volume to make way for further energy saving in water treatment, plant and infrastructure.
- Specify energy efficient equipment and technologies
- Specify water-efficient plumbing fixtures to reduce energy use.
- Specify use of non-potable water sources for building systems, irrigation, and toilet and urinal flushing to preserve potable water supply.
- Use renewable strategies and purchase green power
- Recycle gray water for non-potable water uses to reduce energy need to produce and treat fresh water.
- Educate building owners, operators, and occupants
- On cost and energy savings advantages of water conservation measures
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Last modified at 2/26/2009 11:11 PM by jamie nace
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