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WATER-ENERGY NEXUS

HOLISTIC SOLUTIONS FORCLIMATE CHANGE ANDRESILIENCY

PG&E Energy Center04/24/2019

Lyle Keck, PE, LEED AP BD+CBuilding Performance Consultant

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Agenda• Drivers for Rapid Water and Sewer Cost Increase• Understanding the Energy:Water Nexus

• Wholistic Accounting of Energy and Water• Water Modeling - Challenges & Opportunities

PERKINS+WILL

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Drivers for RapidWater & SewerCost Increase

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Rising Cost of Water & Sewer

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Drivers for Rapid Cost Increase

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Local Understanding: Results May Vary

AFFILIATED ENGINEERS, INC

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Local Understanding: Results May Vary

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Energy:WaterNexus

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WATER for ENERGY

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WATER for ENERGY

1 Macknick et al. 20112 UNESCO-IHE 2011

44 gal/kWh135 gal/kWh1

65 gal/kWh2

HydroelectricCoal

Natural Gas Nuclear

36 gal/kWh1

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ENERGY for WATER

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Wholistic AccountingEnergy + Water

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Wholistic Accounting - Site vs. Source• Water-cooled chiller VS. evaporative cooling• Consider both site and source consumption

indirect/direct evaporative cooling water-cooled chiller

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Wholistic Accounting - Site vs. Source

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Wholistic Accounting - Site vs. SourceIndirect/direct evaporative cooling saves 38,500 kWh/year

SITE SOURCE

178,500 gallons Source Water Reduction (-)

218,000 gal Site Water Increase (evap.)

88,500 gallons Total Site Water Increase (+)

- 129,500 gal Site Water Decrease (cooling tower)

• Net electricity savings of 38,500 kWh/year (site)• Net water savings of 90,000 gallons/year (site + source)

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Water Modeling

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Whole Building Water Modeling• Benchmark and goal set

• Preliminary water budget, early water balance

• Refine calculations as information and models become available

• Work design alternatives into BOD and design documentation

• Final models and calculations to support compliance

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Whole Building Water ModelingBenchmark and goal set

USEPA

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Whole Building Water ModelingBenchmark and goal set (challenges)

USEPA

USEPA

Data Source Metric End-Uses Included

USEPA (14 building types)

Per sfPer customerPer bedPer employee

Varied by program

CBECS(large hospitals)

Per sfPer bed

Building, landscape, central plant

AWWA(11 building types)

Per person/customer

Building, landscape

Pacific Institute(numerous building types)

Per person/employeePer sf

Building, landscape

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Whole Building Water ModelingPreliminary water budget, early water balance

• Establish WUI baseline

• Identify water end-uses and develop preliminary water balance

• Consider water use by month, quality requirements, water reuse potential

• Demonstrate savings potential and identify strategies with high impact

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

1,800,000

2,000,000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

[Gal

lons

]

Water Consumption by End-Use: Alternate Scenario

Medical Equipment:

Laundry:

Kitchen/Dishwashing:

Landscaping:

Cooling and Heating:

Domestic/Restroom:

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

1,800,000

2,000,000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

[Gal

lons

]

Potential Potable vs. Non-Potable Consumption: Alternate Scenario

Non-Potable End-Uses

Potable End-Uses

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Whole Building Water ModelingRefine calculations as information and models become available

• Energy Modeling + Water Modeling (detailed hourly modeling)

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Whole Building Water ModelingRefine calculations as information and models become available

• Energy Modeling + Water Modeling (detailed hourly modeling)

• Hourly diversity schedules (challenge)

Ref: Madison, WI Water Utility screen shot

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Whole Building Water ModelingRefine calculations as information and models become available

• Energy Modeling + Water Modeling (detailed hourly modeling)

• Hourly diversity schedules (challenge)

• Precipitation data (challenge)

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Whole Building Water ModelingFinal models and calculations to support compliance

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QUESTIONS?Lyle Keck, PE, LEED AP BD+CLkeck@aeieng.com

aeieng.com

AEI/Affiliated Engineers, Inc.@AEITweets