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Ms.Sc. María Violeta Vargas Parra PhD Student at the Institute of Environmental Science and Technology of the Autonomous University of Barcelona
Junior Researcher Sostenipra; www.sostenipra.cat
Dr. María Rosa Rovira Val, Dr. Xavier Gabarrell Durany, Dr. Gara Villalba Méndez
Life cycle cost implications of urban rainwater harvesting in hot-arid areas.
07/10/2015
1. Introduction
2. Methodology
3. Case study
4. Results
5. Final remarks
INDEX
Introduction
Mexico Sonora Hermosillo
Population 784,342
Population density
49.89/km2
Annual mean
precipitation 250 mm
Hot desert climate
(BWh)
Introduction
1994
150, 000, 000 m3
2010
0
2015
3, 000, 000 m3
Independencia aqueduct (2013)
Longitud: 135 km
Cost: 216.74 million EUR; 153.21 million GBP
Supply: 75 million m3/year = 35% Hermosillo’s
demand
Methodology
Software:
Plugrisost®(1) simulation model.
References
(1) Nederlands Normalisatie-Institut, ISO 15686-5:2008 - Buildings and Constructed Assets -- Service-Life Planning -- Part 5: Life-Cycle Costing, 2008. (2) Gabarrell X, Morales-Pinzón T, Rieradevall J, Rovira MR, Villalba G, Josa A, et al. Plugrisost: a model for design, economic cost and environmental analysis of rainwater
harvesting in urban systems. Water Pract Technol 2014;9:13. doi:10.2166/wpt.2014.028.
http://sostenipra.ecotech.cat/downloads/plugrisost.php user manual available in English
Databases: Experts in the field and supply stores
Financial tools:
Net Present Value (NPV)
Internal Rate of Return (IRR)
Payback Time (PB)
The lifespan of the systems was considered as 50 years
LCC methodology was applied following the ISO 15686-5:2008(1).
Methodology
Costs
Dismantling
50 10 5 1 0
Replacement of pumps
(every 15 years)
Maintenance and replacement of
filters (every 5 years)
Electricity for pumping (every 1 year)
Construction (Initial
investment)
years
Tap water savings
(every 1 year)
Savings
System boundaries
Use Construction End-of-life
Case study
LIFE STAGE INPUT LIFETIME (years)
Construction
HDPE Tank 50
Emplacement materials 50
Pipes 50
Pump 15
Filter 5
Construction services 50
Transport of materials to site 50
Use
Electricity 1
Pump 15
Filter 5
Maintenance services 5
End-of-life
Transport of deconstructed materials
0
Deconstruction services 0
Case study
House size: 78 m2, 130 m2 and 210 m2
Tank location:
Ground level Underground
• Only one floor
• Potable water tank
• Backyard
Other factors
Case study
Characteristics Collecting area (Roof)
78 m2 130 m2 210 m2
Total demand (year) Laundry
Car-washing
17.7 m3 14.4 m3 3.3 m3
21 m3 14.4m3 6.6m3
21 m3 14.4m3 6.6m3
Tank size 1.10 m3
Rainwater supply (year) 17.3 m3 19.2 m3 19.2 m3
NOTE: Tank sizing was calculated using Plugrisost software and then adapted to available market solutions, in consequence, supply was reduced in some cases.
-20
10
40
70
100
0 5 10 15 20 25 30 35 40 45 50
Tho
usa
nd
MX
N
Years
CUMULATIVE CASH FLOWS
78 GROUND LEVEL 78 UNDERGROUND
130 GROUND LEVEL 130 UNDERGROUND
210 GROUND LEVEL 210 UNDERGROUND
Results
TANK LAYOUT HOUSE SIZE INITIAL INV. NPV IRR PB
GROUND LEVEL
78 $ -11,196.76 $21,231.12 9% 14.92
130 $ -11,196.76 $30,455.98 11% 13.36
210 $ -11,196.76 $30,455.98 11% 13.36
UNDERGROUND
78 $ -16,049.50 $12,703.51 6% 18.84
130 $ -16,049.50 $21,928.38 8% 17.00
210 $ -16,049.50 $21,928.38 8% 17.00
Results
Final remarks
• For more or less the same price of a washing machine
• It helps to relieve water supply problems
30% installation cost
30%- 40% better financial performance
Ground level
RWH
Tank
House size
better financial performance Collection surface
Dr. María Rosa Rovira Val, Dr. Xavier Gabarrell Durany, Dr. Gara Villalba Méndez
Ms.Sc. María Violeta Vargas Parra PhD Student at the Institute of Environmental Science and Technology of the Autonomous University of Barcelona
Junior Researcher Sostenipra; www.sostenipra.cat
Life cycle cost implications of urban rainwater harvesting in hot-arid areas.
07/10/2015 Thank you! Comments and Questions
Acknowledgements The authors would like to thank the project “Análisis ambiental del aprovechamiento de aguas pluviales” (Spanish Ministry for Science and Innovation, ref. CTM 2010-17365) for financing this
study and express appreciation for the grant awarded to M. Violeta Vargas-Parra by Conacyt (National Council of Science and Technology, decentralized public agency of Mexico’s federal
government).
