LEED AP® BD+C Exam Preparation Guide, LEED® v4 Edition by American Technical Publishers

LEED AP BD+C ®

EXAM PREPARATION GUIDE BUILDING DESIGN

AND

CONSTRUCTION

AMERICAN TECHNICAL PUBLISHERS Orland Park, Illinois

Fulya Kocak Gin, LEED® Fellow™

LEED AP® BD+C Exam Preparation Guide contains procedures commonly practiced in industry and the trade. Specific procedures vary with each task and must be performed by a qualified person. For maximum safety, always refer to specific manufacturer recommendations, insurance regulations, specific job site and plant procedures, applicable federal, state, and local regulations, and any authority having jurisdiction. The material contained herein is intended to be an educational resource for the user. American Technical Publishers, Inc. assumes no responsibility or liability in connection with this material or its use by any individual or organization.

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Advanced Buildings is a trademark of the New Buildings Institute. Chemical Abstract Service Registry Number and CAS RN are registered trademarks of the American Chemical Society. Health Product Declaration and HPD are registered trademarks of Health Product Declaration Collaborative, Inc. Greenbuild, Green Building Rating Systems, Leadership in Energy and Environmental Design, LEED, LEED AP, LEED Certified, LEED Green Associate, LEED Green Associate Exam, LEED Platinum, LEED Gold, LEED Silver, and USGBC are trademarks or registered trademarks of the U.S. Green Building Council. Sustainable Sites Initiative and SITES are registered trademarks of The Board of Regents of The University of Texas System. Quick Quiz, Quick Quizzes, and Master Math are trademarks or registered trademarks of American Technical Publishers, Inc.

About the Author Fulya Kocak Gin, LEED® Fellow™ LEED AP BD+C, LEED AP ID+C, USGBC Faculty Director of Sustainability Clark Construction Group, LLC Since 1999, Fulya Kocak Gin has followed her personal mission—and professional passion—to become a leader and innovator in sustainable design and construction. Fulya has played a significant role in more than 90 public- and private-sector projects nationwide, educating the development community about the importance of sustainability and guiding project teams toward LEED certification. Fulya started her career in field operations as a construction project manager. While managing commercial projects, Fulya, on her own initiative, started a sustainability committee within her company and created LEED certification tools, including best practices. Fulya then created a green building education curriculum. In 2010, Fulya was promoted to a full-time sustainability leadership position. In her current role as Director of Sustainability at Clark Construction Group, Fulya continues to advise project teams across the U.S. on how to best meet and exceed their sustainable goals. Fulya also leads environmental responsibility efforts across all departments at Clark, mentors and educates young and veteran employees, develops continuing education curricula, and assists clients in designing and developing sustainable projects. Fulya shares her extensive green building and corporate sustainability experience by regularly speaking at events and conferences, teaching LEED credentialing courses, and organizing green building workshops. In 2014, Fulya was named a LEED® Fellow™ by the U.S. Green Building Council (USGBC). Fulya is the recipient of the 2014 Mayor’s Sustainability Award for the District of Columbia (DC) and served as the Chair of the Board of Directors for the USGBC National Capital Region Chapter. As a voting member of the DCRA Green Technical Advisory Group, Fulya has been influential in the development of the first green building codes for Washington, DC. Fulya is also a member of the USGBC Materials & Resources Technical Advisory Group and on the committee for ANSI/ASHRAE/USGBC/IES Standard 189.1, Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential. Fulya has a bachelor’s degree in architecture from Middle East Technical University and has earned both a master’s degree in architecture and a master’s degree in architectural engineering from Penn State University.

Acknowledgments The author and publisher are grateful for the technical information and assistance provided by the following technical reviewers, companies, and organizations: Technical Reviewers Scott Adams LEED AP BD+C, ID+C Principal Sustainable Integration LLC

Anne Hicks Harney AIA, LEED AP BD+C Sustainability Director Ayers Saint Gross

Kelly Kelechi Adighije CEng IMechE, LEED AP BD+C, GGP Senior Mechanical Engineer Baumann Consulting

Dave Intner AIA, LEED AP BD+C, CEM Architect Southern California Edison

Bahar Armaghani LEED Fellow Faculty University of Florida

Molly A. Jones AIA, LEED AP BD+C, O+M, GGP, GPCP President Jones Design Studio, PLLC

Vickie S. Breemes CSI CCS, LEED AP BD+C, WELL AP (provisional) Director of Advanced Building Technologies Little Diversified Architectural Consulting, Inc.

Christina Macken LEED Green Associate Managing Principal blueprintgreen

Stephen K. Cook ASLA, LEED AP O+M Senior Landscape Architect VIKA Maryland, LLC

Neil Rosen AIA, LEED AP BD+C, CEM Director of Sustainability North Shore-LIJ Health System

Amy A. Costello PE, LEED O+M Sustainability Manager Armstrong World Industries

Natasha Samson PEng, LEED AP BD+C Director of Energy Services Recollective Consulting

Michael D. DeVuono PE, CPESC, LEED AP BD+C Senior Staff Engineer T&M Associates

Mike Schofield LEED AP Homes, LEED Homes Faculty Senior Project Manager CLEAResult

Diane Kaufman Fredette AIA, LEED AP BD+C Partner Fredette Architects, PLLC

Erica Weeks AIA, NCARB, EDAC, LEED AP BD+C, ID+C, Homes, ND Architect greenSTUDIO | Hastings Architecture Associates, LLC

Charalampos Giannikopoulos LEED AP BD+C, O+M, ID+C Founder DCarbon

Companies and Organizations Aldo Leopold Foundation Armstrong Autodesk, Inc. Ballogg Photography Bently Holdings Clark Construction Group, LLC Contech Engineered Solutions LLC Covanta Extech Instruments Fluke Corporation Frank Domin/Mogavero Notestine Associates Hoachlander Davis Photography Honeywell Chemicals Kohler Co.

KT Innovations Linden Group Architects Milwaukee Tool Corporation NREL Ozinga Bros., Inc. Retrotec Inc. Schott Solar USDA NRCS USGBC Viega Weathermatic W. W. Grainger, Inc. ZipWall

Introduction LEED AP® BD+C Exam Preparation Guide, LEED® v4 Edition, is a comprehensive study reference used to prepare for the LEED AP® BD+C specialty exam. Written by an accomplished LEED® Fellow™, this exam preparation guide provides a detailed and efficient approach to studying through the use of concise text and detailed, full-color illustrations and photos. This exam preparation guide is designed to complement the LEED v4 Reference Guide for Building Design and Construction. LEED AP® BD+C Exam Preparation Guide emphasizes the mastery of the key topics of the LEED v4 BD+C prerequisites and credits and aids in exam success through the following: • an overview of the LEED AP BD+C credential and its benefi ts • the process of registering for, studying for, and taking the LEED AP BD+C specialty exam • the core concepts, themes, and structure of the LEED v4 BD+C rating system • an overview of the knowledge and task domains of the LEED AP BD+C specialty exam • comprehensive reviews that focus on the key topics of each LEED v4 BD+C credit category and its respective prerequisites and credits • 172 Checkpoint Questions located throughout the guide that provide continual assessment • Knowledge Retention Exercises and Calculation Exercises • a 100-question practice exam • an Appendix that contains a sample LEED v4 BD+C checklist and a list of standards and references To aid in the successful passing of the LEED AP BD+C specialty exam, each feature in the exam preparation guide and the digital learner resources is designed to promote quick comprehension. These features include objectives, key terms lists, factoids, checkpoint questions, key term definitions, knowledge retention exercises, and calculation exercises. Factoids supply information related to chapter topics.

Checkpoint Questions provide a sample of questions that review the information in each prerequisite or credit.

Objectives address the main concepts, task domains, and knowledge domains within each chapter.

Knowledge Retention Exercises provide questions that extensively review the information in a chapter.

Key Terms and Deﬁnitions provide detailed explanations for the key terms listed at the beginning of each chapter.

Key Terms provide a list of terms to understand for taking the LEED AP BD+C specialty exam. Calculation Exercises provide questions that review the use of equations in LEED v4 credit categories.

Contents Chapter 1

Becoming a LEED AP® 1 USGBC and LEED • LEED Professional Credentials • LEED AP BD+C Credential • Credential Maintenance • Education @USGBC • Green Business Certification Inc. (GBCI)

Chapter 2

The LEED AP Exam Process

LEED AP BD+C Specialty Exam • Exam Registration • Exam Content • Study Tips • Exam Day Tips

Chapter 3

LEED Certification Process

Overview of the LEED Rating Systems • LEED BD+C Rating System • Credit Categories • LEED Rating System Selection—40/60 Rule • LEED Impact Categories • Minimum Program Requirements (MPRs) • LEED Certification Process • LEED Work Plan • Certification Programs • LEED Checklist • Project Team Roles and Responsibilities • Other Personnel • LEED Online • Credit Interpretation Rulings (CIRs) • LEED Interpretations • Addenda • Alternative Compliance Paths (ACPs) • LEED Pilot Credits • Certification Application Consistency • Special Project Situations • Renovations and Additions • Tenant Sales and Lease Agreements • Credit Core Concepts • Triple Bottom Line • Benefits of Green Building • Cost of Green Building • Building Codes Knowledge Retention Exercises____________________34

Chapter 4

Integrative Process

The Integrative Process • Phases of the Integrative Process • The Iterative Process • Integrative Process (IP) Category • IP Prerequisite—Integrative Project Planning and Design (Healthcare Only) • IP Credit— Integrative Process Knowledge Retention Exercises____________________48

Chapter 5

Location and Transportation

Location and Transportation • Location and Transportation Terms and Concepts • LT Credit—LEED For Neighborhood Development Location • LT Credit—Sensitive Land Protection • LT Credit—High-Priority Site • LT Credit—Surrounding Density and Diverse Uses • LT Credit—Access to Quality Transit • LT Credit—Bicycle Facilities • LT Credit—Reduced Parking Footprint • LT Credit—Green Vehicles Knowledge Retention Exercises____________________89 Calculation Exercises____________________________91

Chapter 6

Sustainable Sites

Sustainable Sites • SS Prerequisite—Construction Activity Pollution Prevention • SS Prerequisite—Environmental Site Assessment (Schools and Healthcare Only) • SS Credit—Site Assessment • SS Credit—Site Development – Protect or Restore Habitat • SS Credit—Open Space • SS Credit—Rainwater Management • SS Credit—Heat Island Reduction • SS Credit—Light Pollution Reduction • SS Credit—Site Master Plan (Schools Only) • SS Credit—Joint Use of Facilities (Schools Only) • SS Credit—Tenant Design and Construction Guidelines (Core and Shell Only) • SS Credit—Places of Respite (Healthcare Only) • SS Credit—Direct Exterior Access (Healthcare Only) Knowledge Retention Exercises___________________128 Calculation Exercises___________________________131

Chapter 7

Water Efficiency

133

Water Efficiency • WE Prerequisite—Outdoor Water Use Reduction • WE Credit—Outdoor Water Use Reduction • WE Prerequisite—Indoor Water Use Reduction • WE Credit—Indoor Water Use Reduction • WE Prerequisite— Building-Level Water Metering • WE Credit—Water Metering • WE Credit—Cooling Tower Water Use Knowledge Retention Exercises___________________161 Calculation Exercises___________________________163

Chapter 8

Energy and Atmosphere

165

Energy and Atmosphere • EA Prerequisite—Fundamental Commissioning and Verification • EA Credit—Enhanced Commissioning • EA Prerequisite—Minimum Energy Performance • EA Credit—Optimize Energy Performance • EA Prerequisite—Building-Level Energy Metering • EA Credit—Advanced Energy Metering • EA Prerequisite—Fundamental Refrigerant Management • EA Credit—Enhanced Refrigerant Management • EA Credit—Demand Response • EA Credit—Renewable Energy Production • EA Credit—Green Power and Carbon Offsets Knowledge Retention Exercises___________________211 Calculation Exercises___________________________215

Chapter 9

Materials and Resources

217

Materials and Resources • Life-Cycle Assessments (LCAs) • Permanently Installed Building Products • Product Costs • Qualifying Products and Exclusions • Components of an Assembly • Location Valuation Factor • MR Prerequisite—Storage and Collection of Recyclables • MR Prerequisite—Construction and Demolition Waste Management Planning • MR Credit—Construction and Demolition Waste Management • MR Prerequisite—PBT Source Reduction – Mercury (Healthcare Only) • MR Credit—PBT Source Reduction – Mercury (Healthcare Only) • MR Credit—PBT Source Reduction–Lead, Cadmium, and Copper (Healthcare Only) • MR Credit—Building Life-Cycle Impact Reduction • MR Credit—Building Product Disclosure and Optimization – Environmental Product Declarations • MR Credit—Building Product Disclosure and Optimization – Sourcing of Raw Materials • MR Credit—Building Product Disclosure and Optimization – Material Ingredients • MR Credit—Furniture and Medical Furnishings (Healthcare Only) • MR Credit—Design for Flexibility (Healthcare Only) Knowledge Retention Exercises___________________272 Calculation Exercises___________________________277

Contents Chapter 10

Indoor Environmental Quality

279

Indoor Environmental Quality • Ventilation System Types • Space Types Based on Occupancy • EQ Prerequisite— Minimum Indoor Air Quality Performance • EQ Prerequisite—Environmental Tobacco Smoke Control • EQ Prerequisite—Minimum Acoustic Performance (Schools Only) • EQ Credit—Acoustic Performance • Enhanced Indoor Air Quality Strategies • EQ Credit—Low-Emitting Materials • EQ Credit—Construction Indoor Air Quality Management Plan • EQ Credit—Indoor Air Quality Assessment • EQ Credit—Thermal Comfort • EQ Credit— Interior Lighting • EQ Credit—Daylight • EQ Credit—Quality Views Knowledge Retention Exercises___________________343 Calculation Exercises___________________________349

Chapter 11

Innovation and Regional Priority

351

Innovation • Pilot Credit Library • Exemplary Performance • IN Credit—Innovation • IN Credit—LEED Accredited Professional • Regional Priority • RP Credit—Regional Priority Knowledge Retention Exercises___________________362

Chapter 12

Synergies and Trade-Offs

363

Synergy • Synergistic Strategies • Trade-Offs • Common Green Building Trade-Offs

Chapter 13

Practice Exam

373

Answer Key

389

Appendix

411

Book References__________________________________________________________________411 LEED Certification Standards________________________________________________________412 LEED v4 for Building Design and Construction Checklist___________________________________422

Glossary

423

Index

437

How to Use the LEED AP® BD+C Exam Preparation Guide LEED AP® BD+C Exam Preparation Guide provides a comprehensive review of the concepts of the design and construction of sustainable, green buildings. By using and studying this exam preparation guide in conjunction with the primary references and exam specifications, an exam candidate can achieve exam day success. This guide is divided into the following chapters and sections: • Chapter 1 introduces the LEED AP credential and explains why the BD+C specialty is beneficial and important to professionals in fields related to the design, construction, and operation of buildings. • Chapter 2 explains the process of registering for, studying for, and taking the LEED AP exam. • Chapter 3 provides an overview of the LEED certification process and other core concepts, addressing the LEED v4 impact categories and how to select the appropriate rating system adaptation for a project. • Chapters 4 through 11 provide a comprehensive review of the LEED v4 BD+C credit categories. • Chapter 12 explains the concepts of synergies and trade-offs. • Chapter 13 is a 100-question practice exam. • The Checkpoint Questions and Knowledge Retention and Calculation Exercises in the chapters of this exam preparation guide, along with the 100-question practice exam, allow an exam candidate to practice acquired knowledge and determine areas where further study is needed. The Answer Key provides a comprehensive list of answers to all the questions in this guide. • The Appendix provides other helpful reference materials. Credit Category Chapters The credit category chapters, Chapters 4 through 11 in the LEED AP® BD+C Exam Preparation Guide, provide a comprehensive review of every prerequisite and credit in the LEED v4 BD+C rating system. Each prerequisite and credit is discussed in the context of the information an exam candidate must understand to successfully pass the LEED AP BD+C specialty exam. Prerequisites and credits presented in this exam preparation guide include the following sections: Intent and Requirements. Prerequisites and credits begin with a statement of intent that provides a general outline of the goals of the requirements. Next, the requirements are explained, and the details of the different options or pathways to achievement are listed. Concepts key to understanding the prerequisite or credit are also introduced. Any project type or rating system adaptation variation is also explained. Exemplary Performance. The requirements for achieving exemplary performance and earning extra points are explained in this section, if applicable. Implementation. Implementation charts are provided for each prerequisite and credit. Each chart is a step-by-step guide showing all options and pathways for achieving the prerequisite or credit. Documentation. The items and calculations that project teams must submit for the certification review are explained in the documentation paragraphs. Calculations. The calculations that project teams must perform while attempting to achieve credits are explained in this section. Calculations Example. This section provides example scenarios that demonstrate how project teams use credit calculations to earn points, if applicable. Good to Know. The Good to Know section provides a precise synopsis of the key points that an exam candidate should remember for each prerequisite and credit.

UNDERSTANDING THE TASK AND KNOWLEDGE DOMAINS The LEED AP BD+C specialty exam contains 100 multiple-choice questions that reflect task and knowledge domains. For the benefit of the exam candidate and to enhance the educational aspects of this exam preparation guide, these domains and where they are addressed in this guide are detailed below. Task Domains The task domains for the LEED AP BD+C specialty exam reflect the tasks that LEED professionals must know in order to perform LEED safely and effectively. Exam candidates should consult the LEED v4 AP BD+C Candidate Handbook for the complete list of task domains and their associated skills. The USGBC strongly recommends that exam candidates have prior LEED project experience before taking any LEED AP with specialty exam, though this is not mandatory. Exam candidates previously involved with LEED projects have practical, real-world experience in the task domains and are better prepared for exam day success. The task domains and the percentage of exam questions each domain represents include the following: • • • •

LEED Project and Team Coordination (22%) LEED Certification Process (32%) Analysis Required for LEED Credits (32%) Advocacy and Education for Adoption for LEED Rating System (14%)

Knowledge Domains The knowledge domains for the LEED AP BD+C specialty exam reflect the LEED v4 rating system credit categories, specifically those in the BD+C rating system adaptations, and what an exam candidate must know. Exam candidates should consult the LEED v4 AP BD+C Candidate Handbook for the complete list of knowledge domains and the details of their components. This exam preparation guide addresses the concepts covered by the knowledge domains, including the LEED process, integrative strategies, the LEED credit categories, and project surroundings and public outreach. The knowledge domains, the number of exam questions each domain represents, and the components of each domain include the following: • LEED Process (9 questions) Covered in Chapter 3 and Chapter 12 - Different avenues to achieve LEED goals - LEED system synergies - Project boundary; LEED boundary; property boundary - Prerequisites and/or minimum program requirements (MPRs) for LEED certification - Knowing the evolutionary characteristics of LEED • Integrative Strategies (9 questions) Covered in Chapter 4 - Integrative process - Integrative project team - Value of collaboration • Location and Transportation (9 questions) Covered in Chapter 5 - Site selection (development constraints and opportunities; community connectivity terms/definitions) - Access to quality transit—knowledge of access and quality concepts/calculations - Alternative transportation: infrastructure and design - Green vehicles - Sources

• Sustainable Sites (9 questions) Covered in Chapter 6 - Site assessment - Site assessment; site as a resource - Construction activity pollution prevention - Site design and development (habitat conservation and restoration; exterior open space; exterior lighting; rainwater management; heat island reduction; joint use) • Water Efficiency (9 questions) Covered in Chapter 7 - Outdoor water use reduction: irrigation demand - Indoor water use reduction: fixtures and fittings; appliance and process water - Water performance management: water use measurement; types and quality of water • Energy and Atmosphere (14 questions) Covered in Chapter 8 - Building loads (design; space usage; opportunities for passive design) - Energy efficiency (assemblies/components; operational energy efficiency; commissioning) - Demand response - Alternative and renewable energy - Energy performance management (advanced energy metering; operations and management; benchmarking) - Environmental concerns: resource and ozone depletion - Energy model as a tool - Process loads - Iterative optimization • Materials and Resources (12 questions) Covered in Chapter 9 - Reuse (building reuse; material reuse; transit-oriented development) - Life-cycle impacts (life-cycle assessment; material attributes; human and ecological health impacts) - Waste (construction and demolition waste management; operations and ongoing) - Environmental concerns of materials • Indoor Environmental Quality (11 questions) Covered in Chapter 10 - Indoor environmental quality (ventilation levels; tobacco smoke control; management of and improvements to indoor air quality; low-emitting materials) - Lighting: electric lighting quality - Daylight - Acoustic performance - Occupant comfort, health, and satisfaction: controllability of systems - Thermal comfort design - Quality of views • Project Surrounding and Public Outreach (4 questions) Covered in Chapter 11 - Regional design - Cultural awareness, impacts and challenges, historic or heritage awareness - Educational outreach, public relations for the building

RELATED PRODUCTS The LEED AP exam is available as a standalone exam or as a two-part exam that consists of the LEED Green Associate exam and the LEED AP with specialty exam. The knowledge and study tools in this exam preparation guide focus on the standalone exam for the LEED AP BD+C credential. To study for the LEED Green Associate exam, it is highly recommended that exam candidates familiarize themselves with the contents and knowledge contained in LEED Green Associate™ Exam Preparation Guide, LEED® v4 Edition. LEED AP® BD+C Study Cards are a useful tool for learning the concepts presented in this guide. The study cards contain 400 questions and answers that cover LEED concepts, the LEED v4 BD+C rating system credit categories, plus basic prerequisite and credit calculations. Both of these products are available at atplearning.com.

LEED AP® BD+C Study Cards

LEED Green Associate™ Exam Preparation Guide LEED® v4 Edition

Learner Resources LEED AP® BD+C Exam Preparation Guide includes digital learner resources that enhance chapter concepts and promote learning. These digital learner resources can be accessed by either of the following methods: • keying ATPeResources.com/QuickLinks into a web browser and entering the QuickLink™ code: • using a QR code reader app to scan the QR code with a mobile device

Learner Resources included with this guide: • Quick Quizzes® that provide interactive questions for each chapter, with embedded links to content within the guide and to the Illustrated Glossary • An Illustrated Glossary that provides a helpful reference to commonly used terms, with selected terms linked to illustrations from the guide • Flash Cards that provide an interactive self-study/review tool for exam preparation • A Media Library that consists of videos and animations that reinforce and expand on content found in the guide • ATPeResources.com, which links to online reference materials that support continued learning

CHAPTER 7 Water Efficiency Water is a natural resource that is necessary for human survival. Every day, clean water is required for drinking, food production, and energy generation. According to the U.S. Geological Survey (USGS), 355 billion gallons of freshwater was withdrawn each day in the United States in 2010 for various uses, including power generation, agriculture, and public use. The Water Efficiency (WE) category focuses on the conservation of potable water for indoor and outdoor use as well as the uses of nonpotable and alternative water sources, in context of water conservation and creative reuse for LEED projects.

OBJECTIVES • Identify the prerequisites and credits associated with the Water Efficiency (WE) category, as well as their intents, requirements, and required documentation. • Explain how the Water Efficiency (WE) prerequisites and credits are used to reduce and monitor the amount of indoor and outdoor potable water use. • Describe the methods to reduce the amount of potable water used for irrigation. • Identify the different types and qualities of alternative water sources. • Describe the methods used to reduce the amount of potable water used by indoor fixtures, fittings, appliances, and process water-using equipment. • Identify the advantages of measuring water use. • Perform the calculations required by Water Efficiency (WE) prerequisites and credits.

KEY TERMS • adapted plant • alternative water source • baseline water consumption • blowdown • closed-loop cooling • combination oven discharge • conductivity • conventional irrigation • cooling tower blowdown • drift • evapotranspiration • external meter

• • • • • • • • • • • •

foundation drain graywater hardscape hydrozone industrial process water landscape water budget landscape water requirement (LWR) makeup water metering control native vegetation nonpotable water peak watering month

133

• • • • • • • • • • •

potable water private meter process water public water supply (PWS) rainwater harvesting reclaimed water reference evapotranspiration rate softscapes WaterSense wet meter xeriscaping

134 LEED AP® BD+C Exam Preparation Guide

WATER EFFICIENCY The U.S. Environmental Protection Agency (EPA) describes water efficiency as the smart use of water resources through water-saving technologies and simple steps. Even though about 70% of the Earth’s surface is covered by water, less than 1% is readily available for human consumption. Per the EPA’s estimates, buildings account for 13.6% of potable water use in the U.S., which is the third-largest category, behind thermoelectric power generation and irrigation. Per the 2009 Green Building Market Impact Report, total water savings from LEED projects through 2009 is estimated at 15 billion gal. (56.7 billion L). It is evident from this research that designers and builders can significantly reduce potable water consumption by incorporating adapted and native plants that eliminate the need for irrigation, installing water-efficient fixtures, and utilizing alternative nonpotable water resources, such as harvested rainwater, for various water needs. Water that meets the EPA’s drinking water standards as fit for human consumption is considered potable. Public water supplies, on-site wells, and on-site potable water treatment systems are all counted as potable water

resources. The Water Efficiency (WE) category focuses on reducing potable water usage since significant energy resources are used to extract, convey, treat, and deliver potable water as well as to collect, treat, and dispose of wastewater. In 2010, the U.S. water system consumed over 600 billion kWh, or approximately 12.6% of the nation’s energy, according to a study by researchers at the University of Texas–Austin. The study also found that water systems use about 25% more energy than what is used for residential or commercial lighting in the U.S. The WE category addresses indoor water (used by fixtures, appliances, and processes, such as cooling), outdoor water (irrigation water), and water metering. The WE category has three prerequisites and four credits. See Figure 7-1. In an “efficiency first” approach to water conservation, the prerequisites require water efficiency and reductions in potable water use. The credits for indoor and outdoor water use reduction encourage the use of nonpotable water resources. The credits also encourage the use of alternative water resources, such as rainwater runoff from roofs and property grounds, graywater from faucets and showers, and condensate from air-conditioning equipment, cooling towers, steam systems, and ice machines.

WATER EFFICIENCY PREREQUISITES AND CREDITS Available Points

Prerequisite or Credit

Prerequisite/ Credit Name

Applicable Adaptations

New Construction

Core and Shell

Schools

Retail

Warehouses and Distribution Centers

Data Centers

Hospitality

Healthcare

Outdoor Water Use Reduction

ALL

N/A

Indoor Water Use Reduction

ALL

N/A

Building-Level Water Metering

ALL

N/A

Outdoor Water Use Reduction

ALL

N/A

1–2

Indoor Water Use Reduction

ALL

YES

1–6

1–7

1–6

1–7

Cooling Tower Water Use

ALL

N/A

1–2

Water Metering

ALL

N/A

Exemplary Performance

Figure 7-1. The Water Efficiency (WE) category contains three prerequisites and four credits that address indoor and outdoor water use and metering.

Chapter 7 — Water Efficiency 135

WE Prerequisite Outdoor Water Use Reduction The intent of WE Prerequisite—Outdoor Water Use Reduction is to reduce water consumption for irrigation purposes. Outdoor water use can account for between 5% and 30% of the total water used by a commercial or institutional building. See Figure 7-2. Significant water savings can be achieved through improved landscape design and more efficient irrigation equipment. There are many strategies to reduce irrigation water usage that are based on plant types (such as native and adapted selections), plant density, and irrigation system selection. To meet this prerequisite, project teams must meet one of the following two options: Option 1. No Irrigation Required To meet Option 1, a project team must design and implement a landscape design with no permanent irrigation system beyond a maximum two-year establishment period. Option 2. Reduced Irrigation To meet Option 2, a project team must reduce, through plant species selection and irrigation system efficiency, the project’s landscape water requirement by at least 30%, as measured from the calculated baseline for the site’s peak watering month. Reductions should be

calculated using the EPA’s WaterSense Water Budget Tool online application for U.S. projects or the downloadable spreadsheet for international projects. The WaterSense Water Budget Tool calculates a baseline water requirement for a typical landscape. See Figure 7-3. Different plant species and their arrangement in the landscape are entered into the tool, which then estimates the effect of these design variables on the landscape water requirement (LWR). The LWR is the amount of water that the site landscape area(s) requires for the site’s peak watering month. The factors used to calculate LWR are plant type, plant density, and irrigation system components. The WaterSense Water Budget Tool serves as a landscape design tool that is based on a regionally appropriate amount of water. This site-specific tool calculates an allowable amount of water used by the landscape. The tool takes into account plant type, plant water needs, irrigation design, and the water that the landscape receives by irrigation or precipitation.

WATER USE BY COMMERCIAL AND INSTITUTIONAL BUILDINGS 100%

MEDICAL EQUIPMENT

80%

POOLS OTHER

60%

LAUNDRY KITCHEN/DISHWASHING

40%

COOLING AND HEATING DOMESTIC/RESTROOM 20%

LANDSCAPING

0% HOSPITALS

OFFICE BUILDINGS

SCHOOLS

RESTAURANTS

HOTELS

Figure 7-2. Water for outdoor irrigation accounts for 5% to 30% of all the water used in a commercial and institutional buildings.

136 LEED AP® BD+C Exam Preparation Guide

WE Prerequisite Outdoor Water Use Reduction (continued)

WATERSENSE WATER BUDGET TOOL

Figure 7-3. The WaterSense Water Budget Tool is used to calculate the baseline landscape water requirement for a project.

Ozinga Bros., Inc.

Hardscapes, such as a paved pedestrian path, should be excluded from WaterSense Water Budget Tool calculations.

Exam candidates should know what is included and excluded in the WaterSense Water Budget Tool calculations, as well as which areas are at the team’s discretion. The tool should be used for vegetated areas only. Hardscapes (whether pervious or impervious) or unvegetated softscapes, such as mulched paths and playgrounds, should be excluded. Athletic fields and playgrounds (if vegetated) and food gardens may be included or excluded at the project team’s discretion. Additional savings gained by using alternative water sources and smart sensor technologies are addressed in WE Credit—Outdoor Water Use Reduction. Calculations for this prerequisite do not take those strategies into account.

Chapter 7 — Water Efficiency 137

WE Prerequisite Outdoor Water Use Reduction (continued) Implementation Outdoor Water Use Reduction (Prerequisite) STEP 1

Projects Outside U.S. Only—Obtain precipitation and evapotranspiration data to determine irrigation requirements.

STEP 2

Determine vegetated areas.

STEP 3

Select plant types and coverage.

STEP 4

Select one option.

Option 2. Reduced Irrigation

Option 1. No Irrigation Required

STEP 1

Develop the plant species and water requirement narrative.

Documentation Required documentation for Option 1 of WE Prerequisite—Outdoor Water Use Reduction includes a site plan showing vegetated areas and a narrative for plant species and water requirements. Required documentation for Option 2 of WE Prerequisite—Outdoor Water Use Reduction includes a site plan showing the location and size of landscape zones and the report from the WaterSense Water Budget Tool or downloadable calculator.

STEP 1

Reduce irrigation needs by altering design.

STEP 2

Calculate landscape water budget.

• Using turf for groundcover will make it very difficult to meet the threshold of WE Prerequisite—Outdoor Water Use Reduction. • Once established, native and drought-tolerant plants generally require little to no irrigation.

Good to Know • Projects with no vegetative areas, such as those in urban areas with zero-lot-lines, are exempt from WE Prerequisite—Outdoor Water Use Reduction. • The EPA WaterSense Water Budget Data Finder is used for U.S. projects to estimate the evapotranspiration rate (ETo) in inches per month for the critical month of the year, based on a project’s zip code. ETo varies based on a location’s climate. See Figure 7-4. This information is needed when using the WaterSense Water Budget Tool spreadsheet. • LWR is the amount of water that the site landscape area(s) requires for the site’s peak watering month. • Project teams outside the U.S. may use the WaterSense Water Budget Tool with local data. For U.S. projects, the WaterSense Water Budget Tool online application automatically derives rainfall and evapotranspiration from the project’s zip code.

NREL

Xeriscaping can be used to reduce the amount of irrigation required for a project.

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WE Prerequisite Outdoor Water Use Reduction (continued)

WATERSENSE WATER BUDGET DATA FINDER

Figure 7-4. For projects in the U.S., the project’s zip code can be used to determine the peak watering month, the evapotranspiration rate, and the average amount of rainfall. Projects outside the U.S. should use other sources, such as the Food and Agricultural Organization of the United Nations.

Chapter 7 — Water Efficiency 139

Checkpoint Questions 1. A landscape architect is creating the landscape water budget to confirm compliance with WE Prerequisite— Outdoor Water Use Reduction. Which of the following must be excluded? (select 2) A. Mulched paths B. Pervious pavement C. Existing trees that will be kept D. Turf grass E. Food garden 2. A project team is pursuing Option 1. No Irrigation Required to comply with WE Prerequisite—Outdoor Water Use Reduction. Which of the following must be submitted for documentation? (select 2) A. Calculations made using the WaterSense Water Budget Tool B. A site plan showing vegetated areas C. List of nonpotable water resources used for irrigation D. A narrative for plant species and water requirements

WE Credit Outdoor Water Use Reduction WE Credit—Outdoor Water Use Reduction rewards projects that do not require permanent irrigation or that reduce outdoor water use more than the requirements for WE Prerequisite—Outdoor Water Use Reduction. One significant difference between the prerequisite and the credit is that nonpotable water resources are included only in the calculations for the credit. The prerequisite only concerns efficiency, whereas the credit requirements encourage the use of nonpotable water resources after efficiency measures are put in place.

Some project types, such as residential and Hospitality projects, may desire colorful annual plants for aesthetic reasons. Annuals perform their entire life cycle in one growing season. Landscape architects and design teams should clearly understand project owners’ expectations before specifying plants, so as to balance outdoor water use reduction goals with those expectations.

Strategies to achieve the highest number of points under this credit include xeriscaping, choosing native and/or adapted plants, implementing drip and bubbler irrigation systems and weather-based controllers, and using suitable alternative nonpotable water resources for irrigation when needed. To achieve the requirements of WE Credit—Outdoor Water Use Reduction, water use for irrigation should be reduced through one of the following options:

Option 1. No Irrigation Required (2 points; Healthcare 1 point) No permanent irrigation is designed and installed beyond a maximum two-year establishment period. Option 2. Reduced Irrigation (2 points; Healthcare 1 point) The project must reduce its landscape water requirement (LWR) by at least 50% from the calculated baseline for the site’s peak watering month. See Figure 7-5. A minimum reduction of 30% must first be achieved through plant species selection and irrigation system efficiency, as calculated in the WaterSense Water Budget Tool. Once a minimum reduction of 30% in irrigation water use is achieved, additional reductions may be achieved using any combination of efficiency, alternative water sources, and smart scheduling technologies.

POINTS FOR REDUCING IRRIGATION WATER Points (Healthcare)

Percentage Reduction from Baseline

Points (Except Healthcare)

50%

100%

—

Figure 7-5. Additional reductions in water use beyond what is required in WE Prerequisite—Outdoor Water Use Reduction can yield one to two additional points in WE Credit—Outdoor Water Use Reduction.

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WE Credit Outdoor Water Use Reduction (continued) Implementation Outdoor Water Use Reduction (Credit) STEP 1

Follow methodology in WE Prerequisite— Outdoor Water Use Reduction.

STEP 2

Select one option.

Option 2. Reduced Irrigation

Option 1. No Irrigation Required

Documentation For Option 1, project teams should review the required documentation for WE Prerequisite—Outdoor Water Use Reduction. Required documentation for Option 2 of WE Credit—Outdoor Water Use Reduction, in addition to prerequisite documentation, includes alternative water source and smart irrigation controls calculations. Calculations If alternative water sources are used to reduce the use of potable water for irrigation for Option 2, the monthly supply of alternative water sources must be calculated.

STEP 1

Reduce irrigation needs by altering design.

STEP 2

Consider alternative water sources.

STEP 3

Consider alternative irrigation controls.

STEP 4

Calculate landscape water budget.

STEP 5

Calculate adjusted landscape water requirement.

STEP 6

Calculate additional reduction from baseline for smart irrigation controls.

the soil if the nonpotable water resource is not analyzed and treated. The availability of water for irrigation should also be enough to last during the peak watering periods. If a project team has multiple possibilities for alternative water use, the source that requires the least treatment is preferred.

SMART IRRIGATION CONTROLLERS

Good to Know • WE Prerequisite—Outdoor Water Use Reduction should be reviewed to understand WE Credit— Outdoor Water Use Reduction. • By using smart controllers, such as a weatherbased irrigation controller system, a project earns a 15% reduction to use toward WE Credit—Outdoor Water Use Reduction. See Figure 7-6. • If a project team is considering alternative water sources for irrigation, they should also address salinity, storage, and availability. Salinity could harm

Weathermatic

Figure 7-6. Smart irrigation controllers allow for the precise control of irrigation by combining irrigation system information with current weather conditions.

Chapter 7 — Water Efficiency 141

Checkpoint Questions 3. For a Hospitality project, the owner requests perennial plants and turf grass that will be irrigated by overhead sprinklers. The project team addresses this by designing a rainwater-harvesting cistern that supplies 75% of the irrigation demand. Without the cistern, the project achieves outdoor water use reduction at 10% from the baseline. Which one of the following statements is correct? A. WE Prerequisite—Outdoor Water Use Reduction is not met. B. The project would earn one point for WE Credit—Outdoor Water Use Reduction. C. The project would earn two points for WE Credit—Outdoor Water Use Reduction. D. The project would earn an exemplary performance point for WE Credit—Outdoor Water Use Reduction. 4. When a landscape water requirement (LWR) is estimated for a project that is pursuing Option 2 of WE Credit— Outdoor Water Use Reduction, which items are included in the calculations from the landscape professional? (select 3) A. Irrigation system components B. Plant types C. Plant density D. Gross area of vegetated areas E. Rainwater harvesting from roof 5. A project team in an arid climate is considering using alternative sources of water for irrigation, such as rainwater and water from cooling tower blowdown. Which of the following should be addressed? (select 3) A. Plant types B. The salinity of the water C. The timing and reliability of the alternative water supply D. Storage E. The use of no turf 6. A project site has two landscaped areas and one area of hardscape. Out of the two landscaped areas, one requires irrigation and the other does not. How should the project team calculate the landscape water budget if they are pursuing Option 2 of WE Credit—Outdoor Water Use Reduction? A. By only including the irrigated area B. By including the hardscape area and both landscaped areas in the WaterSense Water Budget Tool C. By creating a customized tool instead of using the WaterSense Water Budget Tool and providing a narrative explaining the approach D. By not including the hardscape area and making two separate calculations for each landscaped area 7. For a Schools project, the school board decided to replace a portion of the paved areas with a turf grass athletic field after the calculations for WE Credit—Outdoor Water Use Reduction were already completed. Which one of the following is correct based on this change? A. The project team must revise the calculations to include the athletic field. B. The athletic field can be included or excluded in the calculations for WE Credit—Outdoor Water Use Reduction at the project team’s discretion. C. The project is not eligible for LEED certification. D. The turf grass must be irrigated by an alternative nonpotable water source.

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WE Prerequisite Indoor Water Use Reduction The intent of WE Prerequisite—Indoor Water Use Reduction is to reduce indoor water consumption. Indoor water use is separated into two categories: 1) building water use and 2) appliance and process water use. Building water use addresses the typical plumbing fixtures found in almost every building, such as toilets, urinals, and faucets. Appliance and process water use addresses appliances and equipment that are found only in some buildings, such as clothes washers, dishwashers, ice machines, and cooling towers. This prerequisite addresses only the efficiency of fixtures, fittings, appliances, and equipment. Alternative or nonpotable water sources that offset potable water demand are addressed in WE Credit—Indoor Water Use Reduction. Building Water Use WE Prerequisite—Indoor Water Use Reduction lists six common fixtures and fittings for building water use. As applicable to the project scope, these fixtures and fittings must reduce water consumption by 20% from the baseline volume and flow rates. See Figure 7-7. Exam candidates should know these baseline rates. All newly installed toilets, urinals, private lavatory faucets, and showerheads that are eligible for labeling must be WaterSense labeled (or a local equivalent for projects outside the U.S.). The EPA’s WaterSense labeling program is a voluntary partnership that was launched in 2006. Products with WaterSense labels use 20% less water and perform as well as (or better than) conventional models. For every product that can earn the WaterSense label, the EPA has developed rigorous water efficiency, performance, and testing requirements.

Appliance and Process Water Use Appliances, equipment, and processes within the project scope that may use potable water must meet the standards for appliances and processes listed in WE Prerequisite—Indoor Water Use Reduction. See Figure 7-8. Healthcare, Retail, Schools, and Hospitality Only In certain buildings, such as hospitals, schools, and retail establishments such as restaurants, appliance and process water use may exceed the water used by fixtures and landscape irrigation. Water-consuming appliances, equipment, and processes used in Healthcare, Retail, Schools, or Hospitality projects must meet specific standards listed in WE Prerequisite—Indoor Water Use Reduction. See Figure 7-9. Core and Shell Projects Only plumbing fixtures, appliances, and process water installed as part of a Core and Shell project’s scope of work should be included in the calculations. If plumbing fixtures are installed by the developer in otherwiseincomplete tenant spaces, those plumbing fixtures should also be included in the calculations. The ease of achieving high indoor water use reduction percentages typically depends on a building’s function. For example, very-low-flow fixtures in an office building may be feasible since significant water use is only due to flushing and handwashing. However, reducing significant water consumption through very-low-flow showerheads in residential or Hospitality projects may be challenging for project teams due to the possibility of occupant dissatisfaction.

BASELINE WATER CONSUMPTION OF FIXTURES AND FITTINGS Fixture or Fitting Toilet (water closet)* Urinal*

Baseline (IP Units)

Baseline (SI Units)

1.6 gpf

6 lpf

1.0 gpf

3.8 lpf

0.5 gpm at 60 psi all others except private applications

1.9 lpm at 415 kPa, all others except private applications

Private lavatory faucets*

2.2 gpm at 60 psi

8.3 lpm at 415 kPa

Kitchen faucet (excluding faucets used exclusively for filling operations)

2.2 gpm at 60 psi

8.3 lpm at 415 kPa

2.5 gpm at 80 psi per shower stall

9.5 lpm at 550 kPa per shower stall

Public lavatory (restroom) faucet

Showerhead* * WaterSense

label available for this product type

Figure 7-7. In order to meet WE Prerequisite—Indoor Water Use Reduction, the amount of indoor water used must be reduced by 20% of the baseline volume and flow rates.

Chapter 7 — Water Efficiency 143

WE Prerequisite Indoor Water Use Reduction (continued)

STANDARDS FOR APPLIANCES Appliance

Requirement

Residential clothes washers

ENERGY STAR or performance equivalent

Commercial clothes washers

CEE Tier 3A

Residential dishwashers (standard and compact)

ENERGY STAR or performance equivalent

Prerinse spray valves

≤ 1.3 gpm (4.9 lpm)

Ice machines

ENERGY STAR or performance equivalent and use either air-cooled or closed-loop cooling, such as chilled or condenser water system

STANDARDS FOR PROCESS Process

Requirement

Heat rejection and cooling

No once-through cooling with potable water for any equipment or appliances that reject heat

Cooling towers and evaporative condensers

Equip with • Makeup water meters • Conductivity controllers and overflow alarms • Efficient drift eliminators that reduce drift to maximum of 0.002% of recirculated water volume for counterflow towers and 0.005% of recirculated water flow for cross-flow towers

Figure 7-8. Appliances, equipment, and processes within the project scope that may use potable water must meet the standards for appliances and processes listed in WE Prerequisite—Indoor Water Use Reduction.

Compliance Paths WE Prerequisite—Indoor Water Use Reduction has two compliance paths: prescriptive achievement and usage-based calculation. • Compliance Path 1. Prescriptive achievement The prescriptive achievement path is applicable when all installed fixtures are at or below WaterSense maximum levels. While teams using the prescriptive achievement path do not need to perform any calculations, they must provide product cutsheets and fixture schedules. The prescriptive achievement path is available only for WE Prerequisite—Indoor Water Use Reduction. • Compliance Path 2. Usage-based calculation The usage-based calculation compliance path is for projects that cannot demonstrate the required 20% reduction for every fixture based on manufacturer documentation. Instead, the project team must show that the fixtures collectively comply with the 20% reduction requirement by using the USGBC Indoor Water Use Calculator available

on the USGBC website. In addition, projects pursuing points under WE Credit—Indoor Water Use Reduction must use this compliance path.

To earn a WaterSense label, a high-efficiency urinal flush valve must not exceed 0.5 gpf (1.9 lpf).

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WE Prerequisite Indoor Water Use Reduction (continued)

STANDARDS FOR APPLIANCES Kitchen Equipment Dishwasher

Food Steamer Combination Oven

Requirement (IP Units)

Requirement (SI Units)

Undercounter

≤ 1.6 gal./rack

≤ 6.0 liters/rack

Stationary, single tank, door

≤ 1.4 gal./rack

≤ 5.3 liters/rack

Single tank, conveyer

≤ 1.0 gal./rack

≤ 3.8 liters/rack

Multiple tank, conveyer

≤ 0.9 gal./rack

≤ 3.4 liters/rack

Flight machine

≤ 180 gal./hour

≤ 680 liters/hour

Batch

≤ 6 gal./hour/pan

≤ 23 liters/hour/pan

Cook-to-order

≤ 10 gal./hour/pan

≤ 38 liters/hour/pan

Countertop or stand

≤ 3.5 gal./hour/pan

≤ 13 liters/hour/pan

Roll-in

≤ 3.5 gal./hour/pan

≤ 13 liters/hour/pan

PROCESS REQUIREMENTS Process

Requirement

Discharge water temperature tempering

When local requirements limit discharge temperature of fluids into drainage system, use tempering device that runs water only when equipment discharges hot water OR Provide thermal recovery heat exchanger that cools drained discharge water below code-required maximum discharge temperature while simultaneously preheating inlet makeup water OR If fluid is steam condensate, return it to boiler

Venturi-type flow-through vacuum generators or aspirators

Do not use device that generates vacuum by means of water flow through device into drain

Figure 7-9. Healthcare, Retail, Schools, and Hospitality projects have specific requirements for water-consuming appliances, equipment, and processes.

Implementation Indoor Water Use Reduction (Prerequisite) Compliance Path 1. Prescriptive Achievement

STEP 1

Select compliance path.

STEP 2

Select WaterSense-labeled products.

STEP 1

Confirm prescriptive compliance.

STEP 3

Select high-efficiency fixtures.

STEP 2

Collect manufacturers’ information.

STEP 4

Select high-efficiency appliances.

STEP 5

Design process water systems.

STEP 6

Develop cooling tower narrative, if applicable.

Compliance Path 2. Usage-Based Calculation

STEP 1

Compile cutsheets or prepare plumbing fixture schedule.

STEP 2

Gather information for calculator.

STEP 3

Complete calculations.

Chapter 7 — Water Efficiency 145

WE Prerequisite Indoor Water Use Reduction (continued) Documentation Projects pursuing the prescriptive achievement compliance path should provide product cutsheets and manufacturers’ information, as well as fixture schedules. Calculations are not needed. Projects that cannot demonstrate the 20% reduction requirement for each fixture must select the usagebased calculation compliance path. This also applies to projects pursuing WE Credit—Indoor Water Use Reduction. Under this compliance path, the fixtures for the project, in aggregate rather than individually, should meet the requirements. Product cutsheets and manufacturers’ information should be provided along with calculations for all applicable fixtures, fittings, appliances, and process water.

Kohler Co.

Plumbing cutsheets contain information on water use and are available from the plumbing fixture manufacturer.

Calculations Calculations are required when using the usage-based calculation compliance path. An exam candidate should know that the USGBC Indoor Water Use Calculator requires the following information: • project occupancy (number of FTEs, visitors, etc.) • gender ratio • days of operation • project fixture types Equation 1. Basic indoor water use reduction calculation Daily water use = Flush or flow rate × Duration × Users × Uses per day The duration of use, number of users, and uses per person per day must be the same in both the baseline and the design cases. Dual-flush toilet flush rates must be calculated as the average using a 1:2 (high flush to low flush) ratio. Equation 2. Faucet flow rate conversion Metering faucets measured in gallons (liters) per cycle (gpc, lpc) and cycle duration in manufacturer documentation must be converted to a flow rate in gallons (liters) per minute (gpm, lpm). Equation 2 is used to perform this conversion. Flow rate (gpm) =

Gallons per cycle (gpc) × 60 sec Cycle duration (seconds)

Equation 3. Indoor water use reduction Once the performance volume has been calculated, the baseline and performance volumes are input into Equation 3 to determine the percentage of improvement from the baseline volume. % improvement from baseline =

Baseline volume – Performance volume Baseline volume

× 100

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WE Prerequisite Indoor Water Use Reduction (continued) Calculations Example The project team is calculating the daily baseline indoor water use for an office building. There will be six FTEs in the office. What is the daily baseline water usage based on the default flow rates, duration, and number of uses? To determine the daily baseline water usage, the number of users is multiplied by the uses per person per day by the flush or flow rate and the duration of use. The defaults needed for this calculation can be found in Table 1 (page 267) and Table 8 (page 277) in the LEED Reference Guide for Building Design and Construction. This calculation needs to be performed for each type of applicable fixture. Then, the daily water uses for all fixtures are added together to find the total daily water use for the office building. • Urinals and Water Closets Note: The default gender ratio for FTE occupants is 50:50. Water Closets Women (3 FTE) Daily water use = Flush or flow rate × Duration × Users × Uses per day Daily water use = 1.6 gal. × 1 flush × 3 FTE users × 3 uses per day Daily water use = 1.6 × 1 × 3 × 3 Daily water use = 14.4 gal./day Men (3 FTE) Daily water use = Flush or flow rate × Duration × Users × Uses per day Daily water use = 1.6 gal. × 1 flush × 3 FTE users × 1 uses per day Daily water use = 1.6 × 1 × 3 × 1 Daily water use = 4.8 gal./day Urinals Men (3 FTE) Daily water use = Flush or flow rate × Duration × Users × Uses per day Daily water use = 1 gal. × 2 flush × 3 FTE users × 2 uses per day Daily water use = 1 × 2 × 3 × 2 Daily water use = 12 gal./day • Sink Faucets Woman and Men (6 FTE) Daily water use = Flush or flow rate × Duration × Users × Uses per day Daily water use = 0.5 gpm × 30 sec (0.5 min) × 6 FTE users × 3 uses per day Daily water use = 0.5 × 0.5 × 6 × 3 Daily water use = 4.5 gal./day • Total Daily Water Use Total daily water use = Total daily water use of fixtures Total daily water use = 14.4 + 4.8 + 12.0 + 4.5 Total daily water use = 35.7 gal./day Good to Know • Reductions for both WE Prerequisite—Indoor Water Use Reduction and WE Credit—Indoor Water Use Reduction are from baseline flow rates as specified in the Energy Policy Act (EPAct) of 1992, as amended in 2005. • WaterSense labels can be found for fixtures in the following product categories: tank-type toilets (water

closets), water-using urinals, private lavatory faucets, and showerheads. • The following fixtures are not eligible for WaterSense labels: tankless toilets, composting toilets, waterless toilets, waterless urinals, and public lavatory faucets. • Non-U.S. projects are allowed to use an acceptable WaterSense substitute. However, all project fixtures

Chapter 7 — Water Efficiency 147

WE Prerequisite Indoor Water Use Reduction (continued)

•

must comply with the 20% reduction from baseline requirement regardless of availability of WaterSense-labeled fixtures. For indoor water use consumption calculations, lavatory faucets must be classified as public or private. Fixtures used by residential and residential-type occupants who use the building for sleeping accommodations are considered private use. Fixtures in dormitory bathrooms, patient bathrooms in hospitals and nursing homes, and prisoner bathrooms are also considered private use. The distinctions between public and private determine which thresholds each fixture and fitting must meet. If it is unclear whether the classification should be public or private, project teams should default to public use flow rates for the calculations. Exam candidates should know typical private and public faucet applications. The Indoor Water Use Calculator requires total occupant counts by type in the following categories: - Employees and staff, expressed as full-timeequivalent (FTE) employees - Residents, including residential occupants in dormitories, hospital inpatients, prisoners, hotel guests, and any other people who use the building for sleeping accommodations - K–12 students for Schools projects - Retail customers - Visitors, excluding retail customers (Report visitors as a daily average total.) The default gender ratio for full-time-equivalent (FTE) occupants is 50:50. This value can be altered if the project is specifically designed for an alternative gender ratio, such as a single-gender dormitory, or if there is documented justification for a differing gender ratio. Using aerators is an acceptable water-savings strategy, but all newly installed aerators or flow restrictors added to private lavatories or showers must have a WaterSense label. For private lavatories, a maximum flow rate of 1.5 gpm at 60 psi (5.7 lpm at 415 kPa) and a minimum flow rate of 0.8 gpm at 20 psi (3 lpm at 138 kPa) is required for a WaterSense label. Commercial projects with noncommercial, standardsized dishwashers must comply with the residential dishwasher requirements. Residential criteria include all noncommercial-grade clothes washers in buildings such as office spaces and daycare centers. Exam candidates should know the fixtures and appliances that may be excluded from calculations.

•

See Figure 7-10. The fixtures and appliances that may be excluded are as follows: - equipment that uses water on materials intended for human consumption (such as coffee machines) - fixtures whose flow rates are regulated by health codes - process-water sinks, such as janitorial sinks and laboratory sinks - commercial kitchen (foodservice) sinks and prep sinks - surgical scrub sinks, exam or procedure room sinks for clinical use, and medication room sinks - clean or soiled utility room hand-washing sinks If a mixed-use project uses the same fixture types throughout the building, one calculation for the whole-building water use is sufficient. If the fixture types and patterns of occupancy vary significantly, then the Indoor Water Use Calculator should be completed separately for each space type. For additions, all fixtures within the project boundary must be included in the prerequisite calculations. If the project boundary includes only the addition, the fixtures or fittings outside the addition do not need to be included in the calculations for prerequisite compliance, even if used by project occupants. In high-rises and in different areas where water pressure can vary, it is important for the mechanical, electrical, and plumbing (MEP) engineer to address the delivery pressure of the water. During the discovery phase of the integrative process, the MEP engineer and the architect can work to set specifications so no water pressure issues occur. For K–12 schools that close for weekends, holidays, and eight weeks of school vacation, it is assumed that they have 195 days of operation. The requirements for cooling towers and evaporative condensers in WE Prerequisite—Indoor Water Use Reduction are different than WE Credit—Cooling Tower Water Use. The prerequisite requires that the equipment has makeup water meters, conductivity controllers and overflow alarms, and efficient drift eliminators.

Water reduction technologies progress significantly every year. Specifiers should stay up to date with the latest technology to be able to maximize water savings and performance.

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WE Prerequisite Indoor Water Use Reduction (continued)

INDOOR WATER USE REDUCTION EXCLUSIONS

Figure 7-10. Water-using equipment related to human consumption such as soda machines, coffee-making machines, misters for producing bread, and commercial kitchen sinks can be excluded from the prerequisite and credit requirements for indoor water use.

Checkpoint Questions 8. Which of the following would be classified as a private lavatory faucet? (select 2) A. A bathroom faucet in a hotel room B. A locker room faucet in a private spa C. A sink faucet in a retail facility D. A sink faucet in a correctional facility cell 9. What is the allowed maximum flow rate for aerators without a WaterSense label in private lavatories to meet the WE Prerequisite—Indoor Water Use Reduction? A. 0.40 gpm at 60 psi (1.5 lpm at 415 kPa) B. 1.5 gpm at 60 psi (5.7 lpm at 415 kPa) C. 1.75 gpm at 60 psi (6.7 lpm at 415 kPa) D. 2.0 gpm at 60 psi (7.6 lpm at 415 kPa) 10. A design team is identifying strategies to meet WE Prerequisite—Indoor Water Use Reduction for a project with cooling towers using 100% potable water for cooling. Which of the following strategies should be implemented? (select 2) A. Add conductivity controllers to the cooling towers. B. Submeter cooling tower water use. C. Hire a water treatment professional to conduct a water analysis. D. Add a meter for makeup water.

Chapter 7 — Water Efficiency 149

WE Credit Indoor Water Use Reduction Implementation

The most significant difference between WE Prerequisite—Indoor Water Use Reduction and WE Credit—Indoor Water Use Reduction is that the credit allows consideration of alternatives to potable water sources. Alternatives to potable water include municipally supplied reclaimed water (“purple pipe” water), graywater, rainwater, stormwater, treated seawater condensate, foundation dewatering water, used process water, and reverse-osmosis reject water. To meet the requirements of WE Credit—Indoor Water Use Reduction, project teams should further reduce fixture and fitting water use from the calculated baseline in WE Prerequisite—Indoor Water Use Reduction. Alternative water sources can be utilized for additional potable water savings beyond the prerequisite requirements. Project teams should include fixtures and fittings necessary to meet the needs of the occupants, including those outside the project boundary. Points are awarded according to the percentage of reduction achieved. See Figure 7-11.

Indoor Water Use Reduction (Credit) STEP 1

Complete calculations in prerequisite.

STEP 2

Consider alternative water sources.

STEP 3

Calculate additional savings from using nonpotable water.

STEP 4

Select high-efficiency specialized appliance and process water systems, where applicable.

Documentation Cutsheets and manufacturers’ information should be submitted for all applicable fixtures and fittings, appliances, and process water based on the requirements. Calculations from the USGBC Indoor Water Use Calculator should also be submitted. Project teams need to enter the following information into the calculator: • type of fixture • flush or flow rate • manufacturer and model • percentage of occupants using the fixture If alternative water sources are utilized, alternative water source calculations, plumbing system design drawings, and an alternative water narrative should also be submitted for documentation.

Healthcare, Retail, Schools, and Hospitality Only Retail, Healthcare, and Schools projects may earn one to two points, and Hospitality projects one point, by meeting the requirements of one or two (one for Hospitality) of the appliance and process water tables in the credit requirements. In all cases, appliance and process water-using equipment installed in the project must meet the requirements of WE Prerequisite—Indoor Water Use Reduction. Exemplary Performance Projects achieving 55% savings are eligible to receive an exemplary performance point.

POINTS FOR REDUCING WATER USE Percentage Reduction

Points (BD+C)

Points (Schools, Retail, Hospitality, Healthcare)

25%

30%

35%

40%

45%

50%

—

Figure 7-11. The additional reduction of water use beyond the requirements for WE Prerequisite—Indoor Water Use Reduction can earn between one and six points, depending on the percentage of reduction and the project type, for WE Credit—Indoor Water Use Reduction.

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WE Credit Indoor Water Use Reduction (continued) Calculations Projects that are using alternative, nonpotable water sources must calculate the total annual projected water savings using the following equation. Equation 1. Indoor water use reduction with nonpotable supply Annual baseline – water consumption

Annual Annual design case water – nonpotable water supply consumption × 100

Total water savings = Annual baseline water consumption

Good to Know • WE Prerequisite—Indoor Water Use Reduction should be reviewed to understand WE Credit— Indoor Water Use Reduction. • Untreated water sources that are ineligible as alternative, nonpotable water sources for WE Credit— Indoor Water Use Reduction include raw water from naturally occurring surface bodies of water, streams, rivers, groundwater, well water, and water discharged from an open-loop geothermal system. • When choosing alternative sources of water, project teams should target the uses that require the least treatment first. In most cases, water can be reused outside the building (for irrigation) or inside (for toilet flushing) with minimal treatment, but other uses will require more energy-intensive and costly treatment. • The amount of alternative nonpotable water meant for indoor and outdoor uses cannot exceed the total annual alternative nonpotable water supply. • For Core and Shell projects, project teams may earn credit for the efficiency of not-yet-installed future

plumbing fixtures by submitting a signed, legally binding tenant sales or lease agreement. The agreement must state the performance requirements for the future fixtures, including the maximum water flush or flow rates and presence of the WaterSense label (or a local equivalent for projects outside the U.S.) for all newly installed fixtures eligible for labeling. The tenant sales or lease agreement must be fully executed for the project to earn credit this way. • The USGBC Indoor Water Use Calculator accounts for reduced usage of certain fixtures by visitors in its assumption of lower daily usage rates for items such as kitchen faucets, which are unlikely to be used by visitors.

Storage tanks for alternate water systems must be properly sized in order to meet the water needs of a building. Storage tanks are often made out of steel, polypropylene, fiberglass, polyethylene, or concrete.

Checkpoint Questions 11. Which of the following can use harvested rainwater to earn points? A. WE Credit—Indoor Water Use Reduction and WE Credit—Outdoor Water Use Reduction B. WE Prerequisite—Indoor Water Use Reduction and WE Credit—Indoor Water Use Reduction C. WE Prerequisite—Outdoor Water Use Reduction and WE Credit—Cooling Tower Water Use D. WE Prerequisite—Outdoor Water Use Reduction and WE Credit—Outdoor Water Use Reduction

Chapter 7 — Water Efficiency 151

Checkpoint Questions (continued) 12. A LEED AP is reviewing alternative sources of water to achieve WE Credit—Indoor Water Use Reduction. Which of the following are acceptable? (select 3) A. Used process water B. Foundation dewatering water C. Seawater D. Raw water from a stream on the property E. Reverse-osmosis reject water 3. A hotel building project will not pursue WE Credit—Indoor Water Use Reduction. What information should be 1 documented for the prescriptive path of WE Prerequisite—Indoor Water Use Reduction? A. Product cutsheets and fixture schedules B. Aggregate fixture calculations C. Occupancy usage-based calculations D. WaterSense water budget tool calculations 1 4. A project team is pursuing WE Credit—Indoor Water Use Reduction. Which one of the following should be confirmed? A. 20% of the fixtures are WaterSense labeled (or equivalent). B. 100% of the fixtures are at least 20% efficient compared to credit baseline. C. 100% of the fixtures are WaterSense labeled (or equivalent). D. The project fixtures, in aggregate, meet the requirements.

WE Prerequisite Building-Level Water Metering The intent of WE Prerequisite—Building-Level Water Metering is to support water management and identify opportunities for additional water savings by tracking water consumption at the building level. See Figure 7-12. To meet this prerequisite, permanent building-level metering should be provided for the potable water use of the building and associated grounds. Examples of potable water sources that must be metered include public water supply, on-site wells, and on-site potable water treatment systems. Meter data must be compiled into monthly and annual summaries. Meter readings can be manual or automated. In addition, this prerequisite requires the project owner to commit to sharing water-use data with the USGBC for five years, beginning on the date the project accepts LEED certification or typical occupancy, whichever comes first. This commitment must carry forward for five years or until the building changes ownership or lessee.

Implementation Building-Level Water Metering STEP 1

Identify all potable water end uses.

STEP 2

Determine scope of public water supply metering, if applicable.

STEP 3

Determine number, location, and type of all meters.

STEP 4

Track water consumption.

STEP 5

Share water consumption data with USGBC.

The first step in improving water efficiency is to install a water meter to track water consumption of both the project building and any associated grounds.

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WE Prerequisite Building-Level Water Metering (continued)

BUILDING-LEVEL WATER METERING

Figure 7-12. By requiring building-level metering of potable water use, the USGBC aims to collect and analyze performance data to help future project teams find the most effective solutions. Documentation To document WE Prerequisite—Building-Level Water Metering, project teams should submit a meter declaration and proof of shared commitment via a USGBC-approved data template or a third-party data source. Good to Know • If the project is not served by a public water supply, or if the project uses multiple sources of potable water, two or more meters may be required. A single meter installed downstream of multiple potable water supply systems may be used if it is upstream of all project water uses.

• There are no requirements for the type of meters except that they must be permanent. • Meter location, its accessibility for reading, and its method of reporting metered data should be verified. • The project teams can track water usage through monthly billing statements if the meter is inaccessible. Although most projects include building-level meters for utilities, campus projects, such as a university campus, may have a single meter for the whole campus. These projects must invest in building-level meters despite the campus paying a single bill for all buildings.

Checkpoint Questions 15. A project’s building-level meter is provided by a water utility organization. However, the meter is inaccessible for reading. Which one of the following should the team do to achieve WE Prerequisite—Building-Level Water Metering? A. No action is necessary, as the prerequisite is met. B. The project team can track water usage through monthly billing statements. C. Install a temporary water meter downstream of the public water supply meter. D. Use the design case calculations for the indoor and outdoor water use prerequisites.

Chapter 7 — Water Efficiency 153

Checkpoint Questions (continued) 16. A project team is identifying required meters to meet WE Prerequisite—Building-Level Water Metering. Which of the following must be metered? (select 2) A. Water from an on-site well B. Cooling tower condensate to be used for flushing toilets C. Harvested rainwater to be used for irrigation D. The municipal water supply

WE Credit Water Metering The intent of WE Credit—Water Metering is to support water management and identify opportunities for additional water savings by tracking water consumption for various end uses. The submetering of a building’s water and energy use can dramatically improve building performance and lead to reduced resource consumption. As a rule of thumb: what can be measured, can be managed. Early incorporation of a metering strategy in the building design helps successful implementation. Late decisions may be costly and make it challenging to locate the meters and tie them into the relevant building systems. When deciding which water subsystems to meter, project teams may consider choosing the subsystems that are the most expensive to operate, the highest consumers of water, and most closely aligned with the goals of building management for maximized benefits. To meet the requirements of this credit, project teams should install permanent water meters for two or more of the following water subsystems, as applicable to the project: • Irrigation water systems serving at least 80% of the irrigated landscaped area should be metered. Landscape areas fully covered with xeriscaping or native vegetation that requires no routine irrigation may be excluded from the calculation. • Water systems serving at least 80% of the indoor fixtures and fittings described in WE Prerequisite— Indoor Water Use Reduction should be metered either directly or by deducting all other measured water use from the measured total water consumption of the building and grounds. • Water use of at least 80% of the installed domestic hot water heating capacity (including both tanks and on-demand heaters) should be metered. • Boilers with aggregate projected annual water use of 100,000 gallons (378,500 liters) or more, or boilers of more than 500,000 Btuh (150 kW), should be

metered. A single makeup meter may record flows for multiple boilers. • Reclaimed water should be metered, regardless of rate. A reclaimed water system with a makeup water connection must also be metered so that the true reclaimed water component can be determined. • At least 80% of expected daily water consumption for process end uses, such as humidification systems, dishwashers, clothes washers, pools, and other subsystems using process water, should be metered. • In addition to the requirements above, Healthcare projects must install water meters in any five of the following: - purified water systems (reverse-osmosis, de-ionized) - filter backwash water - water use in dietary department - water use in laundry - water use in laboratory - water use in central sterile and processing department - water use in physiotherapy and hydrotherapy and treatment areas - water use in surgical suite - closed-looped hydronic system makeup water - cold-water makeup for domestic hot water systems

Meters and submeters can deteriorate with age and should be inspected, tested for accuracy, and calibrated on a regular basis. The frequency of inspection varies depending on the size and application of the meter.

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WE Credit Water Metering (continued) Implementation Water Metering STEP 1

Identify candidate systems for submetering.

STEP 2

Determine scope of submetering.

STEP 3

Select metering equipment.

Documentation Project teams should provide a water-metering strategy narrative for documentation.

For a Healthcare project, a reverse-osmosis water-purifying system is one of the systems that can be metered to meet the requirements of WE Credit—Water Metering.

Calculations If a project team is claiming WE Credit—Water Metering for metering irrigation, indoor plumbing fixtures, domestic hot water, or other process water, at least 80% of water distribution for these end uses must be submetered. If 100% of the water used by a subsystem is metered, no calculation is necessary. The following equations are used to determine how much of the total water system will be submetered. Equation 1. Landscape area Metered irrigated landscape area ≥ 0.8 Total irrigated landscape area

Unirrigated landscape areas should not be included in either the numerator or denominator of Equation 1. Equation 2. Fixtures Number of metered indoor fixtures and fittings ≥ 0.8 Total number of indoor fixtures

Equation 3. Domestic hot water Heating capacity of metered domestic water heating units ≥ 0.8 Total heating capacity of all domestic water heating units

Equation 4. Other process water Daily metered gallons (or liters) for process-type end uses ≥ 0.8 Total expected daily gallons (or liters) for process-type end uses

Good to Know • Although cooling tower submeters are not included in WE Credit—Water Metering, they are addressed under WE Prerequisite— Indoor Water Use Reduction.

• For multifamily projects, water use in common areas can be submetered to earn WE Credit—Water Metering. While metering in residential units may be included or excluded, it should be done uniformly.

Chapter 7 — Water Efficiency 155

WE Credit Water Metering (continued) Multifamily projects still need to meter full subsystems (for common areas or the whole building) to earn WE Credit—Water Metering. • For additions to existing buildings, the submetered systems may either follow the project boundary or include both the addition and the original building. If the original building is included within the project boundary, then

all submeters must account for old and new building water use. If the project boundary includes only the addition, the project team may choose to submeter the water use of only the addition. If the fixtures used by the addition are all within the original building, the project boundary must include the original building for the team to earn credit for the fixture submetering.

Checkpoint Questions 17. Which one of the following systems is not included in WE Credit—Water Metering? A. Indoor plumbing fixtures and fittings B. Domestic hot water C. Cooling towers D. Irrigation water 18. Which water subsystems need to have 100% of the source submetered for WE Credit—Water Metering? (select 2) A. Domestic hot water B. Irrigation C. Boiler water D. Reclaimed water

WE Credit Cooling Tower Water Use The intent of WE Credit—Cooling Tower Water Use is to conserve potable water used for cooling tower makeup without negatively impacting the condenser water system. A cooling tower circulates water to cool building interiors by dissipating heat to the atmosphere through the evaporative process. See Figure 7-13. When a portion of the recirculated water evaporates, dissolved solids become concentrated in the remaining water and deposit scale on cooling tower or evaporative condenser elements, causing deficiencies. To prevent deposit buildup, the concentration of minerals is diluted by removing some water (blowdown) and replacing it with fresh makeup water, by chemically treating the water, or by doing both. WE Credit—Cooling Tower Water Use refers to the term “cycles of concentration.” Cycles of concentration are the number of times that a volume of water can circulate through a cooling tower system before dissolved minerals become concentrated. This excess of dissolved minerals can cause deposits or scaling that may lead to the reduced efficiency of the cooling system. A higher number of cycles means better water efficiency

because maximizing cycles of concentration minimizes blowdown water quantity and reduces makeup water demand. However, dissolved solids increase as cycles of concentration increase, which can cause scale and corrosion problems unless carefully controlled. In addition to maximized cycles, using alternate sources of makeup water is also a strategy to reduce cooling tower water use. For this use, it is ideal to give preference to alternative water sources that require the least treatment. Water from other equipment within a facility, such as air handler condensate, can be recycled and reused for cooling tower makeup with little or no pretreatment. Runoff from the ground may require treatment because of the pollutants, such as fertilizers and oil, picked up from the ground. Graywater may also have dissolved solids and require treatment. A qualified cooling tower water treatment specialist should conduct necessary testing, analysis, and recommendations. Failure to do so may be costly and result in elevated dissolved minerals, scaling, and corrosion that damage expensive equipment and disrupt building operations.

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WE Credit Cooling Tower Water Use (continued)

COOLING TOWERS

Figure 7-13. A cooling tower circulates water to cool building interiors by dissipating heat to the atmosphere through the evaporative process.

The first step of meeting the requirements for WE Credit—Cooling Tower Water Use is to optimize cooling tower cycles by conducting a one-time potable water analysis for cooling towers and evaporative condensers. At least five control parameters, as listed in this credit, should be measured in the analysis. See Figure 7-14. Once the analysis is complete, the project team should calculate the number of cooling tower cycles by dividing the maximum allowed concentration level of each parameter by the actual concentration level of each parameter found in the potable makeup water. Cooling tower cycles should be limited to avoid exceeding maximum values for any of these parameters. See Figure 7-15.

MAXIMUM CONCENTRATIONS FOR PARAMETERS IN CONDENSER WATER Parameter

Maximum Level

Ca (as CaCO3)

1000 ppm

Total alkalinity

1000 ppm

SiO2

100 ppm

Chloride (Cl –)

250 ppm

Conductivity

2000 µS/cm

Figure 7-14. A one-time potable water analysis must be performed to test for the levels of the five parameters required by WE Credit—Cooling Tower Water Use.

Chapter 7 — Water Efficiency 157

WE Credit Cooling Tower Water Use (continued) Implementation

POINTS FOR COOLING TOWER CYCLES

Cooling Tower Water Use

Cooling Tower Cycles

STEP 1

Obtain water analysis.

STEP 2

Calculate cycles of concentration.

STEP 3

Identify limiting factor.

STEP 4

Set cooling tower or evaporative condenser cycles.

STEP 5

Increase system performance.

Documentation To document WE Credit—Cooling Tower Water Use, the project team should provide potable water analysis results and a narrative, as well as calculations for the cycles of concentration. If the project team is pursuing the second point for utilizing nonpotable water sources, they must provide nonpotable water calculations, water treatment calculations, and the nonpotable water analysis (if using 100% nonpotable water).

Points

Maximum number of cycles achieved without exceeding any filtration levels or affecting operation of condenser water system (up to maximum of 10 cycles)

Achieve a minimum 10 cycles by increasing the level of treatment in condenser or makeup water OR Meet the minimum number of cycles to earn 1 point and use a minimum 20% recycled nonpotable water

Figure 7-15. Points in this credit can be achieved by maximizing the number of cooling tower cycles and using nonpotable water as an alternate source of makeup water.

Building facilities staff should be included in decision making for cooling tower water use strategies.

Calculations Cycles of concentration should be calculated for each one of the following five parameters: calcium (CaCO3), alkalinity, SiO2, chloride, and conductivity. Equation 1. Cycles of concentration Cycles of concentration =

Acceptable maximum concentrations in condenser water Parameter concentrations in makeup water

The next step is identifying the “limiting factor” that determines the maximum number of cycles for the cooling tower or evaporative condenser. Limiting factor is the number of the fewest calculated cycles for the five parameters before it exceeds the maximum concentration. Calculations Example The maximum cycles of concentration for water used for a cooling tower must be determined. A project team hires a water treatment professional to analyze the makeup water for a cooling tower and receives the following test results for the makeup water concentration in the table below.

Parameter

Maximum Allowable Concentrations

Makeup Water Concentrations

Calcium (CaCO3)

1000 ppm

100 ppm

Alkalinity

1000 ppm

100 ppm

SiO2

100 ppm

20 ppm

Chloride

300 ppm

50 ppm

Conductivity

2000 micro µS/cm

400 micro µS/cm

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WE Credit Cooling Tower Water Use (continued) The first step is to calculate the cycles of concentration for each parameter by dividing the maximum allowable concentrations by the makeup water concentrations (Equation 1). Cycles of concentration =

•

Calcium (CaCO3):

•

Alkalinity:

•

SiO2:

•

Chloride:

•

Conductivity:

Acceptable maximum concentrations in condenser water Parameter concentrations in makeup water

1000 = 10 cycles 100

100 20

= 5 cycles 300 50

= 6 cycles

2000 = 5 cycles 400

The next step is to identify the limiting factor, which is the lowest number per the calculations above. Both SiO2 and conductivity have five cycles as the limiting factor. Therefore, makeup water can cycle the water five times before concentrations exceed maximum allowable limits for SiO2 and conductivity. Once the maximum number of cycles is known, the cooling tower or evaporative condenser settings can be adjusted to achieve that number without exceeding concentration levels or affecting operation. Good to Know • The first step to achieve WE Credit—Cooling Tower Water Use is engaging a qualified water treatment professional to perform a potable water analysis. If the analysis has already been completed, it must be no more than five years old. • The blending of potable and nonpotable water resources is an acceptable strategy for WE Credit— Cooling Tower Water Use. However, project teams should identify the types of dissolved solids that may

exist in each alternative water source by first having the waters tested. Potable water with high phosphates and a reclaimed water supply with high calcium may form calcium phosphate, which will lead to scaling in the condenser. • Suitable alternative nonpotable water sources should have relatively low levels of dissolved solids. Suitable nonpotable water sources include air conditioner condensate, rainwater, steam system condensate, food steamer discharge water, fire pump test water, and ice machine condensate.

Checkpoint Questions 19. Which of the following should be done for a project utilizing 100% potable water for its cooling towers to achieve WE Credit—Cooling Tower Water Use? A. Add submeters for cooling tower water use. B. Engage a water treatment professional to perform a potable water analysis. C. Use nonpotable water for at least 50% of makeup water use. D. Decrease the number of cycles of concentration. 20. A project team needs to achieve 2 points for WE Credit—Cooling Tower Water Use. Which one of the following actions should the project team proceed with? A. Increase the number of cycles of concentration and use 20% alternative water sources. B. Decrease the number of cycles of concentration and use 20% alternative water sources. C. Increase the number of cycles of concentration and use 100% potable water. D. Hire a water treatment professional and increase the number of cycles of concentration.

Chapter 7 — Water Efficiency 159

Checkpoint Questions (continued) 21. Which one of the following alternative nonpotable water sources is the most suitable to offset cooling tower makeup water? A. Graywater and ice machine condensate B. Stormwater runoff from the property grounds and food steamer discharge water C. Ice machine condensate and rainwater from roofs D. Rainwater from roofs and stormwater runoff from the property grounds

Key Terms and Definitions adapted plant: Vegetation that is not native to a particular region but that has characteristics that allow it to live in the area. Adapted plants do not pose the same problems as invasive species. alternative water source: Nonpotable water from other than public utilities, on-site surface sources, and subsurface natural freshwater sources. Examples include graywater, on-site reclaimed water, collected rainwater, captured condensate, and rejected water from reverse-osmosis systems. baseline water consumption: A calculated projection of building water use, assuming code-compliant fixtures and fittings with no additional savings compared with the design case or actual water meter data. blowdown: The removal of makeup water from a cooling tower or evaporative condenser recirculation system to reduce concentrations of dissolved solids. closed-loop cooling: A system that acts as a heat sink for heat-rejecting building and medical equipment by recirculating water. Because the water is sealed within the system, some closed-loop cooling systems use nonpotable water (such as recycled process water harvested from an air handler’s cooling coil condensate). combination oven discharge: Water released from an oven that includes a steam cycle or option. conductivity: The measurement of the level of dissolved solids in water, using the ability of an electric current to pass through water. Because it is affected by temperature, conductivity is measured at 25°C for standardization. conventional irrigation: A region’s most common system for providing water to plants by nonnatural means. A conventional irrigation system commonly uses pressure to deliver water and distributes it through sprinkler heads above the ground. cooling tower blowdown: The water discharged from a cooling tower typically because increased salinity or alkalinity has caused scaling. Cooling tower blowdown may be too saline for use in landscape irrigation. drift: Water droplets carried from a cooling tower or evaporative condenser by a stream of air passing through the system. Drift eliminators capture these droplets and return them to the reservoir at the bottom of the cooling tower or evaporative condenser for recirculation. evapotranspiration: The combination of evaporation and plant transpiration into the atmosphere. Evaporation occurs when liquid water from soil, plant surfaces, or water bodies becomes vapor. Transpiration is the movement of water through a plant and the subsequent loss of water vapor. external meter: A device installed on the outside of a water pipe to record the volume of water passing through it. Also known as a clamp-on meter. foundation drain: The water discharged from a subsurface drainage system. If a building foundation is below the water table, a sump pump may be required. Discharge from the sump may be stored and used for irrigation. graywater: Untreated household wastewater which has not come into contact with toilet waste. Some states and local authorities allow kitchen sink wastewater to be included in graywater. Other differences can likely be found in state and local codes. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area. hardscape: The inanimate elements of the building landscaping, including pavement, roadways, stone walls, wood and synthetic decking, concrete paths and sidewalks, and concrete, brick, and tile patios. hydrozone: A group of plantings with similar water needs.

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Key Terms and Definitions (continued) industrial process water: Any water discharged from a factory setting. Before this water can be used for irrigation, its quality needs to be checked. Saline or corrosive water should not be used for irrigation. landscape water budget: A method used to calculate the amount of water a landscape needs, taking into account the inputs and outputs of water to and from the root zone. Many factors are taken into consideration when calculating a water budget, such as plant type and irrigation system efficiencies. landscape water requirement (LWR): The amount of water that the site landscape area(s) requires for the site’s peak watering month. makeup water: Water that is fed into a cooling tower system or evaporative condenser to replace water lost through evaporation, drift, bleed-off, or other causes. metering control: A regulator that limits the flow time of water, generally a manual-on and automatic-off device, most commonly installed on lavatory faucets and showers native vegetation: A species that originates in, and is characteristic of, a particular region and ecosystem without direct or indirect human actions. Native species have evolved together with other species within the geography, hydrology, and climate of that region. nonpotable water: Water that does not meet drinking water standards. peak watering month: The month with the greatest deficit between evapotranspiration and rainfall. This is the month, typically a mid-summer month, when the plants in the site’s region potentially require the most supplemental water. potable water: Water that meets or exceeds U.S. EPA drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. private meter: A device that measures water flow and is installed downstream from the public water supply meter or as part of an on-site water system maintained by the building management team. process water: Water that is used for industrial processes and building systems, such as cooling towers, boilers, and chillers. It can also refer to water used in operational processes, such as dish washing, clothes washing, and ice making. public water supply (PWS): A system for the provision to the public of water for human consumption through pipes or other constructed conveyances. To be considered public, such system must have at least 15 service connections or regularly serve at least 25 individuals. rainwater harvesting: The capture, diversion, and storage of rain for future beneficial use. Typically, a rain barrel or cistern stores the water; other components include the catchment surface and conveyance system. The harvested rainwater can be used for irrigation. reclaimed water: Wastewater that has been treated and purified for reuse. reference evapotranspiration rate: The amount of water lost from a specific vegetated surface with no moisture limitation. Turf grass with height of 120 mm is the reference vegetation. softscapes: Elements of a landscape that consist of live, horticultural elements. WaterSense: A voluntary partnership and labeling program launched by the EPA in 2006 as a simple way for consumers to identify products that use 20% less water and perform well. wet meter: A device installed inside a water pipe to record the volume of passing water. xeriscaping: Landscaping that does not require routine irrigation.

Chapter 7 — Water Efficiency 161

Knowledge Retention Exercises 1. The following fixtures and appliances may be excluded from calculations for WE Prerequisite—Indoor Water Use Reduction:

_________________________________________

____________________________________________

_________________________________________

____________________________________________

_________________________________________

____________________________________________

2. Landscape water requirement (LWR) is defined as:

_________________________________________________________________________________________

3. What are the baseline flush or flow rates and the maximum installed flow rates to meet Compliance Path 1 of WE Prerequisite—Indoor Water Use Reduction?

Fixture or Fitting

Baseline Flow/Flush Rate

Maximum Installed Flow/Flush Rate

Toilet (water closet)

___ gpf

Urinal

___ gpf

Public lavatory (restroom) faucet

___ gpm

Private lavatory faucet

___ gpm

Kitchen faucets

___ gpm

Showerhead

___ gpm

4. WaterSense labels can be found for fixtures in the following product categories:

_________________________________________

____________________________________________

_________________________________________

____________________________________________

5. The following fixtures are not eligible for the WaterSense label:

_________________________________________

____________________________________________

_________________________________________

____________________________________________

_________________________________________

6. To meet WE Prerequisite—Indoor Water Use Reduction, cooling towers and evaporative condensers are required to be equipped with the following:

_________________________________________

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Knowledge Retention Exercises (continued) 7. To meet Option 2 of WE Prerequisite—Outdoor Water Use Reduction, a project team must reduce the project’s LWR through plant species selection and irrigation system efficiency by at least ___%, as measured from the calculated baseline for the site’s peak watering month. 8. To meet Option 2 of WE Credit—Outdoor Water Use Reduction, the project’s LWR must be reduced by at least ___% from the calculated baseline for the site’s peak watering month. A minimum reduction of ___% must first be achieved through plant species selection and irrigation system efficiency. 9. The USGBC Indoor Water Use Calculator requires the following information:

_________________________________________

____________________________________________

_________________________________________

____________________________________________

10. The basic indoor water use reduction calculation is the following: Daily water use for each fixture type = _________ × _________ × _________ × _________ 11. Private lavatory faucets are described in the prerequisite and credit for indoor water use reduction as the following:

_________________________________________________________________________________________

12. To meet Option 1 of WE Prerequisite—Outdoor Water Use Reduction, the project team must show that the landscaping does not require a permanent irrigation system beyond a maximum ___-year establishment period. 13. WE Credit—Outdoor Water Use Reduction has the following options: Option 1. ______________________________________ for ___ point(s); Healthcare ___ point(s) Option 2. ______________________________________ for ___ point(s); Healthcare ___ point(s) 14. The five control parameters that must be analyzed in condenser water for WE Credit—Cooling Tower Water Use include the following:

_________________________________________

____________________________________________

_________________________________________

____________________________________________

_________________________________________

15. To achieve WE Credit—Water Metering, permanent water meters must be installed on two or more of the following water subsystems, as applicable to the project:

_________________________________________

____________________________________________

_________________________________________

____________________________________________

_________________________________________

____________________________________________

16. To achieve exemplary performance for WE Credit—Indoor Water Use Reduction, a reduction of ___% from the calculated baseline must be achieved.

Chapter 7 — Water Efficiency 163

Calculation Exercises 1. A project team is calculating the daily baseline indoor water use for an office building for WE Prerequisite—Indoor Water Use Reduction. The design team estimates 300 FTEs. What is the daily baseline water usage in this office? To calculate the daily baseline water usage, the default duration and uses for each fixture type and baseline flow rates are needed. Use Table 1 (page 267) and Table 8 (page 277) of WE Prerequisite—Indoor Water Use Reduction located in the LEED Reference Guide for Building Design and Construction. The default gender ratio is 50:50. Urinals and Water Closets

Water Closets Women (___ FTE)

Men (___ FTE)

Urinals Men (___FTE)

Sink Faucets

Woman and Men (___ FTE)

Total Daily Water Use

Total daily water use = _____ gal./day

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Calculation Exercises (continued) 2. A project team pursuing WE Credit—Cooling Tower Water Use hires a water treatment professional to analyze the makeup water for a cooling tower. Determine the maximum cycles of concentration for makeup water using the following table of results.

Parameter

Maximum Allowable Concentrations

Makeup Water Concentrations

Calcium (CaCO3)

1000 ppm

100 ppm

Alkalinity

1000 ppm

100 ppm

SiO2

100 ppm

25 ppm

Chloride

300 ppm

50 ppm

2000 micro µS/cm

400 micro µS/cm

Conductivity

The first step is calculating the cycles of concentration for each parameter by dividing the maximum allowable concentrations by the makeup water concentrations. Calcium (CaCO3): Alkalinity: SiO2:

1000

100

Chloride:

1000

= ____ cycles

= ____ cycles 300

Conductivity:

= ____ cycles

2000

= ____ cycles

The next step is identifying the limiting factor, which is the lowest number per the calculations above. Makeup water can cycle the water _____ time(s) before concentrations exceed maximum allowable limits for _____.

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