Green building in general has become more mainstream and standard practice with the emergence and acceptance of design tools such as LEED by the U.S. Green Building Council.

Since the LEED v1 pilot program launched in 1998, the latest version – LEED v4 – has continued to transform the marketplace and looks to push the building industry forward along the path of environmental responsibility.

How can engineers excel as a LEED v4 participant? There is a wealth of new opportunities if engineers take a proactive approach. Although the foundation for LEED certification is laid during the design process, the intent must be implemented through the construction process. Often, creative design input is needed from all design entities, including the engineer.

Specifically, the engineer needs to be aware of LEED requirements because they can impact material and equipment procurement as well as construction requirements and costs. In addition, understanding LEED requirements will allow the engineering firm to effectively analyze and value-engineer the project for the owner within the LEED requirements.

Although the changes to LEED v4 affect all categories — with them come new rules and new challenges — a plumbing and mechanical engineer’s main focus is on the Water Efficiency section. As an integral part of green building operations, this section has been expanded to include all types of water use, not simply the water associated with fixtures and fittings, but also addressing process, appliances, cooling towers, outdoor water, as well as fundamental building metering requirements.

There is a new prescriptive compliance path for meeting selected flush or flow rates. Appliance and process water use is now addressed with special requirements for the education, retail, hospitality and health-care market sectors.

As such, the LEED v4 scope encompasses water-related initiatives in green building. The focus here is on the significant modifications in the water-efficiency category pertaining to indoor water use. Concentrating on the indoor water-related criteria, two of the prerequisites and the corresponding credits — building-level water metering and indoor water use reduction — will help projects reduce water consumption and realize water savings during the entire life of the project.

The prerequisite threshold for indoor water use reduction is 20%. This prerequisite was first established in LEED 2009; earlier versions of LEED actually awarded a point for a 20% reduction below 1992 EPAct levels. By eliminating the point and making the 20% reduction the prerequisite, the document reflects the growing understanding of just how important water savings is.

For example, there are currently 18 bills with the term “water savings” going through either at the federal level or state level. Another nine have the term “water conservation.” There is no crossover in these bills. In other words, they are different bills trying to accomplish the same goal. Current legislation at the federal, state and local levels includes more than 100 bills that address water conservation, water efficiency and/or LEED requirements.


Prerequisite Two: Indoor water use reduction baseline

The differentiating factor from previous versions of LEED is the requirement to use products certified under the EPA’s WaterSense program. This requirement applies to the prerequisite and carries over the indoor water reduction credit criteria.

This means all urinals and tank toilets plus some faucet applications need to be WaterSense-certified as well as reduce water usage compared to the allowable baseline. Flushometer water closets do not currently have a WaterSense specification, but they would also be required to reduce water consumption compared to the allowable baseline. Projects can earn additional points for reducing indoor water usage by 25 to 50% for new construction and 10 to 30% for existing buildings.

Another significant update to this credit category is water metering. Metering data must be shared with the USGBC for five years. Projects can earn an additional point for installing water meters on at least two types of subsystems such as irrigation, indoor plumbing and reclaimed water. Existing buildings have an opportunity to earn an additional point for submetering four or more subsystems.


High-efficiency solutions

In any building, restrooms are a cost center. Water, electricity, paper, maintenance and waste removal expenses add up quickly thus impacting the bottom line. Restrooms with high-efficiency products conserve water, reduce electrical consumption and eliminate waste. The reduction of water also means reduced drainage, which translates to less energy for treatment and discharge.

If an engineer is going to focus on such solutions, the plan should be on ultra-low-flow or waterless fixtures, as well as overall conservation with strategies such as rainwater capture and graywater reuse (these tactics are documented as an alternative compliance path in LEED online). Careful attention to fixture selection and building flow requirements are key factors in achieving water-efficiency goals.

By using a 1.28-gpf HET, a building can save thousands of gallons a year over the standard 1.6-gpf toilet. However, if an owner is seeking LEED Water Efficiency points using 1.28 gpf, it only helps to achieve the prerequisite. Further water reduction would be needed to achieve LEED point criteria.

Other considerations for tactics to employ include manual dual-flush toilets, which offer the option of a 1.6-gpf for solid waste or 30% less (1.1 gpf) for liquid waste. Electronic dual-flush toilets, either battery-powered or hardwired, carry the advantage of hands-free operation which, because it reduces contact in the restroom, promotes hygiene. For example, Portland (Ore.) International Airport, installed 330 manual and electronic dual-flush flushometers for a savings of more than 30,000 gal. of water a day.

Another option new to the market is 1.1-gpf toilet systems, which combine a vitreous china toilet fixture with either a manual or sensor-operated low-flush 1.1-gpf flushometer, providing consistent and reliable performance for new construction projects, thus helping lower water usage while maintaining performance expectations.

Regardless of which HET is chosen, the best-case scenario is achieved when the flushometer and fixture are optimized to work together in order to guarantee the flush volume of the flushometer is reached.

The Water Efficiency credit category in LEED v4 is critical because it addresses not only the initial design and construction of the building, but also provides a foundation for the building’s future water use.


This article was originally titled “Gaining perspective” in the July 2015 print edition of PME.

Author bio: Mike Gipson is in his third year as the product line manager — flushometers for Sloan Valve Co. He has more than 30 years of product management and marketing experience. Gipson graduated from Augustana College and earned his MBA from the University of Illinois. He can be reached at