1. Questions How do resource use (energy+ water) and CO2 emissions compare in 9 cities across the U.S for 1 average swimming pool? Evaluation of potential.

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Life Cycle Environmental Implications of Residential Swimming Pools

Nigel Forrest and Eric Williams

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QuestionsHow do resource use (energy+ water) and

CO2 emissions compare in 9 cities across the U.S for 1 average swimming pool?

Evaluation of potential energy and water savings from simple measures in Phoenix

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Importance of the ResearchConnection to our in-class reading “When the rivers run

dry”First research of its kind that focuses on environmental

implications of a residential pool.Water issue 1)Water scarcity 2)Arid climate in Arizona and reliance on distant and

nonrenewable resources.Chemical issue (chlorine and acids)1)Manufacture of chlorine mercury emissions2)Chlorine effluents-water toxicity3)Atmospheric emissions from swimming pools4)Ozone layer formation

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Energy Use IssuePool pumps are second after space heating in terms

of energy use in an average household.

Goals: Water depletion, energy consumption, global warming potential.

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MethodsHybrid Life Cycle AssesmentEnergy =process + EIO-LCA (economic input-output)Process – material input (can be estimated)Such as electricity use. Direct energy input.

EIO-LCA – economic data of production impact.(can not be estimated such as energy cost).Secondary consumption of energy (how is water delivered,

pipe systems)They use literature, regional water and electricity data to

calculate it.3. Regional energy consumption, state electric consumption,

generation and emissions data (CO2)

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Life CycleConsider:1) Input, Output and Impact of 1 swimming

pool in 1 year.2) Operation and Maintenance

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Purpose of LCAInform decision makers of environmental

impacts of products (chemicals) and processes.

Make reasonable and appropriate choices

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The pool system showing inputs, outputs, and processes

Published in: Nigel Forrest; Eric Williams; Environ. Sci. Technol.  2010, 44, 5601-5607.DOI: 10.1021/es100422sCopyright © 2010 American Chemical Society

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ResultsModel results for a standard pool system in 9 different U.S cities.

a) Annual water use (gallons) by process.

b) Annual energy use (killowatt-hours) by source.

c) Annual carbon emissions (kg of CO2)

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ImportanceSending “message to the public” about the

potential impact and measures of consumptions and emissions

Measures

- Pool covers - Efficient pumps- Reduction of pumping schedule

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Phoenix area energy and water savings from pool impact mitigation measures

Action Water (gallons) Energy (kW per hour)

Reduced pump schedule(3-5 h summer, 2-3 h winter)

1720

Warm climate winterization(cover pool and extend winter by 1 month)

5870 1330

Efficient central air conditioning

1420

Low flow shower heads 2650

Efficient clothes washer 4630

Efficient lightning (switch all bulbs to fluorescent bulbs)

1270

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Relevance to Sustainability“Hope” for environmental improvementWater and energy savings from measures are

significant and easy to achieve

Covering the pool

Reducing pumping schedule

Savings

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Relevance to Sustainability Savings of water and energy use are especially important in

such areas as Phoenix1) A more vulnerable area to negative effects of swimming

pools2)Hot, arid climate 3)Reliance on distant (upstream of Colorado river) and non-

renewable resources (ground water) for water supply4) Every 4th household has a swimming pool

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Something Interesting

Phoenix metro area.

Portland metro area. Beaverton suburbs

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Ways of ImprovementA couple terms..Backwash- process of cleaning the pool

filter after it becomes insufficientMitigation measures- minimization of the

potential impact of a threat or warningMore detailed explanation of the relationship

between energy consumption and water consumption.

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Future ExperimentsCompare different citiesFocus on one aspect of swimming pools

specifically, such as:-Ozone layer formation as consequence of

atmospheric emissions of chlorineOR-Alteration of regional hydrology by chemical

inputs (acids, chlorine etc)

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References Niegel Forrest and Eric Williams. (2010) Life Cycle Environmental Implications of

Residential Swimming Pools. Environmental Science and Technology. 44, 5601-5607 What is Backwashing. Liner World. May 8, 2011. Retrieved from

http://www.linerworld.com/pool_info/articles/103/1/What-Is-Backwashing-And-What-Is-Its-Purpose/Page1.html

Wentz; Gober. Determinants of small-area water consumption for the City of Phoenix, Arizona. Water Resour. Manage. 2007, 21 (11), 1849-63

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Questions