The LEED program will change how plumbing professionals think about building design in terms of plumbing.

Issue: 9/02

The term "energy efficient" has never truly been applied to plumbing systems. In fact, terms such as "green," "sustainability" or "environmental" have sprung up around other utilities (gas, electric) to further complicate the issue as it relates to plumbing systems.

The new Leadership in Energy & Environmental Design (LEED) Program will change all that by solidifying definitions and actions for all utilities, including water. LEED defines a threshold for green buildings and introduces a tool to promote and guide comprehensive and integrated building design. LEED is performance-based where possible, compatible with standard design processes, self-evaluating, self-documenting, but not self-certifying. Certification is solely done by the U.S. Green Building Council (USGBC). The program will change how plumbing professionals think about building design in terms of plumbing. This article will explain LEED and discuss the implications from a plumbing point of view.

Born Within the U.S. Green Building Council

The USGBC is the nation's foremost coalition of leaders from across the building industry (architecture firms, engineering firms, builders, manufacturers, service contractors, government entities, real estate developers and owners) working to promote buildings that are environmentally responsible, profitable and healthy places to live and work ( The USGBC, formed in 1993, seeks to integrate non-residential building industry sectors, take the lead in market transformation and to educate owners and practitioners about the impact of "green" on buildings and our environment.

Why LEED Was Created

LEED was created by the USGBC to define "green" by providing a standard for measurement; prevent "greenwashing" (false or exaggerated claims); and promote whole-building, integrated design processes. It seeks to facilitate positive results for the environment, occupant health and financial return. As a comprehensive program, LEED seeks to establish design guidelines and recognize leaders who follow these guidelines, stimulating a kind of "green competition" among individuals. Ultimately, the program seeks to raise consumer awareness and transform the marketplace with an established, recognizable national "brand" of green.

For example, there are multiple economic benefits of a green design as far as plumbing is concerned. Green building projects that are well integrated and comprehensive in scope can result in lower or neutral project development costs. Rehabilitating an existing building can lower infrastructure and materials costs. Integrated design that has been "greened" can use the payback from some strategies to pay for others. Energy-efficient building envelopes can reduce equipment needs--downsizing some equipment, such as chillers, or eliminating equipment, such as perimeter heating. Using pervious paving and other runoff prevention strategies can reduce the size and cost of stormwater management structures.

In addition to lower project costs, operating costs will be reduced. Energy- and water-efficient buildings have been able to reduce their operating costs significantly. Use can be cut to less than half that of a traditional building by employing aggressive and well-integrated green design concepts. For example, a 1.0 gpf/4.0 Lpf flushing system for water closets and 0.5 gpf/1.8 Lpf urinal flush valve can make an enormous difference in water consumption for a building. Manufacturers have been working aggressively to refine and push the performance levels of tank-type toilets through the use of pressure-assist technology. Also, on-demand sensor faucets instead of slow-closing faucets cut usage in public restrooms by significant amounts. All add up to big savings.

The LEED Rating System

The development of LEED was initiated by the USGBC membership, representing all segments of the building industry, and was developed using a transparent process open to the public. Other international rating systems (European and Canadian) existed at that time and were reviewed before work on LEED began. The LEED standard was developed by USGBC members through volunteer committees, including work by the U.S. Department of Energy. LEED Version 2.0 is based on accepted energy/environmental principles and strikes a balance between known effective practices and emerging concepts. The rating system provides a framework to help move the U.S. building industry to more sustainable practices. It responds to the U.S. marketplace and to budgets of U.S. design practices.

Buildings seeking certification must be submitted by someone who is "LEED Certified" to qualify to a minimum standard in six main areas of building design. These areas are: 1) Sustainable Sites, 2) Water Efficiency, 3) Energy & Atmosphere, 4) Materials & Resources, 5) Indoor Environmental Quality, and 6) Innovation & Design Process.

In addition, prerequisites must be met in each of these six areas in order to qualify for any certification level. For example, the prerequisite for water in LEED is meeting the Federal Energy Act of 1992. To earn points toward certification levels, further reductions beyond the prerequisite have to be achieved.

The four levels of certification for buildings in the LEED program are:

    LEED Certified 26 - 32 points

    Silver Level 33 - 38 points

    Gold Level 39 - 51 points

    Platinum Level 52 + points (69 possible)

The total points achieved under LEED in these six areas determine the level of certification (minimum 26 points, maximum 69).

Water Efficiency Credits 3.1-3.2: Water Use Reduction

Credit 3 of the LEED Program, "Water Use Reduction," has maximizing water efficiency within buildings to reduce the burden on municipal water supply and wastewater systems as an objective. There are two possible credits. In Credit 3.1, building owners employ strategies that in aggregate use 20% less water than the water-use baseline calculated for the building (not including irrigation) after meeting Energy Policy Act of 1992 fixture performance requirements. To meet Credit 3.2, building owners reduce potable water by an additional 10% (30% total efficiency increase).

The 1.0 gpf/4.0 Lpf flushing system, which has recently been introduced into the United States, offers a significant way to meet this requirement. Traditional 1.6 gpf/6 Lpf flushing systems have been created to meet the Energy Policy Act of 1992 (minimum requirement for LEED). The new flushing system (at this writing, a pressure-assist unit) brings a 33% reduction in each flush, helping reach the reduction of potable water goals in LEED. In addition, a 0.5 gpf urinal flush valve can serve as a significant water conservation strategy. Also, on-demand sensor faucets serve as part of water conservation strategies. These faucets can save a high percentage of water while maximizing hygiene. In one application, for example, where year-old metering faucets were running water continuously, a changeout to sensor faucets produced an estimated 10 to 15% savings in water consumption.

Water Conservation Beyond LEED

In addition to LEED, engineers should reflect on water as a resource. The United States as a nation possesses abundant water resources, and has developed and used these resources extensively (the withdrawal of fresh and saline water in the United States during 1995 is estimated to have been 402,000 million gallons per day for all offstream uses--2% less than the 1990 estimate). The future health and economic welfare of our nation's population, however, are dependent upon a continuing supply of fresh uncontaminated water. Many existing sources of water are being stressed by withdrawals to meet offstream needs, along with increasing instream-flow requirements to meet human and environmental needs. Recent drought in some areas has accentuated the need to balance water demand with available supply. Approximately 339,000 million gallons per day of freshwater (about one quarter of the national renewable supply) were withdrawn during 1990 for use by the nation's homes, farms and industries, and about 220 billion gallons per day were returned to streams after use (U.S. Geological Survey (USGS)).

The following reasons are sound strategies for engineers to promote LEED objectives in the Water Use Reduction part of the program:

  • One half of the world's population lives and works in urban areas--a geographical concentration further intensified because demands are typically met through central water supply systems that bring water to only a few locations for treatment.

  • In many of these areas, urban demands cannot be met with local supplies, and additional water has to be imported from distant sources, implying that as urban populations increase, the economic costs of water supply will also increase.

  • The environmental impacts of urban water supply will intensify, as the "ecological footprint" of urban areas extends a long distance upstream and also some distance downstream when the partially treated or untreated sewage is discharged to watercourses or the sea.

  • A total of 32 states reported drought conditions in March 2002!

Commercial water use, which LEED strives to control, includes water used by commercial facilities such as hotels, motels, restaurants, office buildings, government and military facilities, hospitals, educational institutions and retail sales stores. Commercial water use in office buildings primarily is used for sanitation, maintenance and aesthetic appeal. Specific uses of water include toilet flushing, air-conditioning, washing floors and other surfaces, fountains and lawn watering.

The Use of Graywater Systems

The next wave of water conservation strategy is a logical progression to LEED and will include uses of graywater. Graywater is of a lesser quality than potable water but of higher quality than blackwater. While graywater is most suitably used for subsurface irrigation of non-edible landscape plants, its applications are expanding. In a commercial application, for example, chiller water can be directed to the plumbing system through filter techniques. While somewhat cost-prohibitive today, techniques to accomplish this are continually being refined and made more cost-effective.

Graywater offers potential financial advantages to regional sewage treatment facilities, since its use diminishes sewer flows and lessens the need to expand such facilities. For example, the state of California now allows graywater systems, and various municipalities and utility districts have passed specific graywater ordinances. The installation of graywater systems requires modifications to existing plumbing systems and the addition of certain components.


People are going to be asked to change their habits in many areas as LEED takes hold. Energy efficiency has always meant a change of life habits to a population. Cars using less fuel meant people had to get used to lower performance. The rolling blackouts in California used to conserve energy meant people had to adjust their lives accordingly. The more a product can maintain the habits of a population and conserve energy, the more acceptance that product will have. In other words, products that do not sacrifice performance, yet do conserve energy, will have a higher acceptance than those that give up performance in favor of energy efficiency.

In terms of water, for example, all "energy-efficient" products will be examined according to this point of view. The flushless fixtures promise maximum water conservation--but at a price of increased daily maintenance and increased hygiene risks. Four-Liter toilets reduce water consumption, but without requiring a habit change on the part of users. In both cases, plumbing engineers have to evaluate the contribution to a LEED certification goal while keeping in mind the habits of the people who will utilize these devices.

Buildings in the future are going to be increasingly designed with the LEED point of view in mind, and all types of products will be examined very carefully. It is to the plumbing engineer's benefit not only to learn about the program, but also to begin incorporating its strategies into the day-to-day routines of designing plumbing systems for buildings.

SIDEBAR: Getting Started With LEED

Since the release of LEED 2.0 in March 2000, project teams from more than 275 projects have registered their buildings, expressing their intent to apply for official LEED Certification by the USGBC. Increasingly, companies are turning to LEED as the blueprint by which a true "green building" can be designed.

LEED is a registered trademark of USGBC. Only buildings certified by USGBC under the LEED Green Building Rating System may refer to themselves as LEED buildings. The certification process involves the following:

    1. Register the project to initiate a relationship with USGBC and receive orientation materials. Registration during pre-design phase is highly recommended.

    2. Technical support comes in the form of the Reference Guide and Credit Rulings. In some cases, the design team may encounter questions about the application of a LEED prerequisite or credit to the specifics of their project. The project contact should first thoroughly consult the Reference Guide. If questions remain, the contact should use the following credit interpretation procedure:

  • The project contact reviews the intent of the credit or prerequisite in question to self-evaluate whether their project meets this intent.

  • The project contact reviews the LEED Credit Rulings Page for a previously logged Credit Interpretation Request (CIR) that may assist in answering their particular question. All LEED project contacts have access to this page.

  • If no similar or relevant credit interpretation has been logged, then the project contact may submit an online CIR to the USGBC.

  • Within two to five weeks, the USGBC Credit Ruling Committee posts its decision on the Credit Rulings Page.

    3. Apply for certification. Application review can take anywhere from six weeks to several months. There are several opportunities for response and appeal throughout the review stages (administrative, preliminary technical and final technical reviews).

    Also, consider the following:

  • The LEED Rating System is available for free download from the USGBC Web site (, along with the LEED checklist and summaries of the documentation requirements and the referenced standards.

  • The LEED Reference Package, available for purchase on contains an essential set of tools for green building and LEED certification. It includes the 270-page Reference Guide, the Welcome Packet, LEED Calculator spreadsheets, Application Template, Introductory Slideshow, the Rating System and the Accreditation Exam Study Guide. The Reference Guide is a design assistance manual and LEED user's manual. For each credit, it discusses green building concerns, a summary of any standards that are part of the credit or prerequisite, strategies and resources for achieving it, potential synergies and trade-offs with other credits and strategies, calculations and documentation requirements. Where possible, cost estimates and case studies are provided.

  • The Registered Project Welcome Packet provides instruction for LEED documentation and various tools, such as samples, calculation spreadsheets and a template to facilitate project management and the certification process.