Life Cycle Environmental Implications of Residential Swimming Pools Nigel Forrest and Eric Williams 1
Dec 24, 2015
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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