By Laurie Gilmer, P.E., CFM, LEED AP and Gregory Hughel, Staff Engineer
Water is one of our most precious natural resources. We are accustomed to having clean, reliable drinking water provided by our municipalities to our buildings and our homes. We depend on it. For many regions across the United States, water is in short supply. According to the Environmental Protection Agency (EPA), a recent government survey showed at least 36 states are anticipating local, regional, or statewide water shortages by 2013. These statistics underscore our need to manage our resources better at every level.
So what can a facility manager do? According to the U.S. Department of Energy, commercial buildings consume 88% of the potable water in the United States. Facility managers have a unique opportunity to make a huge impact in our overall water consumption. In this article, we will discuss how you can benchmark your facility’s water use, and measures you can implement to improve overall efficiency.
Water Use in Buildings
Water use in commercial buildings varies with plumbing fixture type, equipment installed, and building function. For example, buildings that have commercial kitchens and cafeterias will have a higher process water consumption rate than those that do not. Similarly, buildings operating hydronic cooling systems will also have higher process water consumption rates.
While these systems may consume their share of water, they are not the majority users. Instead, that honor belongs to restroom plumbing fixtures: lavatories, water closets, urinals, and showers. The U.S. Department of Energy estimates restroom plumbing fixtures account for approximately 60% of the total water use in office and administrative buildings; the remaining 40% is estimated to be used by heating and cooling systems. According to a study performed by the Massachusetts Water Resources Authority, plumbing fixtures account for approximately 47% of commercial building water use with cooling systems and kitchens trailing at 34% and 14%, respectively.
With restroom fixtures accounting for the majority of commercial building water consumption, the best opportunities for increasing efficiency are found there. The good news is that higher efficiency plumbing fixtures are becoming more widely available.
Before 1992, plumbing fixtures consumed at least three times that of current fixtures (see Table 1). After the passing of the Energy Policy Act of 1992 that promoted the conservation and efficient use of energy and water, strict requirements for water fixture performance were put in place. In recent years, further strides have been made to increase water efficiency through codes and to increase awareness of the need to utilize our natural resources efficiently. The current International Plumbing Code and Uniform Plumbing Code are both more rigorous than the Energy Policy Act of 1992; however, it doesn’t stop there. Local communities, utility companies, and groups such as the U.S. Green Building Council (USGBC) are pushing the envelope to encourage increases in water efficiency. To meet these demands, several manufacturers have introduced innovative technologies to further reduce fixture water use well below code requirements.
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Common Plumbing Fixtures
- Water Closets — In commercial buildings, most water closets have valves which utilize water line pressure to meter out a set volume of water. Current valves provide flush volumes of 1.6 gallons per flush (gpf) while their older counterparts provide more than double that flow.
- Urinals — Similar to water closets, urinals in commercial buildings typically utilize water-line pressure valves. Current valves provide flush volumes of one gallon per flush (gpf) while their older counterparts may provide more than twice that amount.
- Sinks & Lavatories — Sinks, such as those in break rooms, often do not have flow restricting aerators installed. At a minimum, aerators restricting flow to 2.5 gpm should be installed. Lavatories, especially older installations, often have flow restrictors installed that are rated well above the current 0.5 gpm maximum requirement.
- Shower Heads — Current shower heads are now restricted to 2.5 gpm. For older, compliant shower head models, the flow stream was not always very effective. More current models provide a steady stream that has a much better delivery.
Calculating Your Baseline
When evaluating your building’s water use efficiency, USGBC offers a helpful method that allows you to benchmark annual water use and compare that use to current standards. First, water use is established based on past-annual-use records or by estimates of building occupancy. Then, a theoretical water use baseline is estimated based on the types of fixtures in the building and number of building occupants. For LEED© projects, USGBC standards require a reduction in the fixtures and fittings potable water usage to a level equal to or below the LEED for Existing Buildings: O&M baseline water usage. The baseline is calculated assuming 100% of the building’s indoor plumbing fixtures comply with the requirement of the Uniform Plumbing Codes (UPC) 2006 or the International Plumbing Codes (IPC) 2006 fixture and fitting performance requirements.
For buildings with plumbing systems installed after 1994, the baseline is calculated as 120% of the water usage that would result if all fixtures and fittings complied with the 2006 plumbing codes. For buildings with plumbing systems installed prior to 1994, the baseline is calculated as 160% of the water usage that would result from 2006 code-compliant fixtures and fittings. Once the baseline has been established for the building, the actual use can be compared and measures can be implemented to reduce water use and increase overall water efficiency. This baseline methodology is specific to LEED, however it can be used in buildings that are not seeking LEED certification.
Tracking Water Use
In order for a facility to become more water efficient, it is important to understand how water is being used. First, identify the key use types: restrooms, cafeteria, cooling tower make-up, or other processes. Installing sub-meters and monitoring these areas will allow the facility manager a better understanding of water usage. This will also help building engineers to more easily identify trouble areas and problems within the building’s systems. By evaluating and determining how the various systems use water, projects can be implemented to effectively reduce water use.
Increasing Water Efficiency
There are many ways to increase water efficiency in buildings, primarily through plumbing fixture replacement and implementing new technologies:
- Replace older high-flow water closets and flush valves with models that meet current UPC and IPC requirements. While current codes require the lower flow rate for new fixtures, existing buildings often have older high-flow flush valves. Despite the tremendous water savings available by updating the fixtures, facility managers often avoid the upgrade due to concerns about clogging. When the Energy Policy Act of 1992 was first enacted, many experienced problems with the new low-flow fixtures clogging due to fixture design issues. Those problems have long since been addressed and no longer present a problem.
- Utilize dual flush valves on water closets – Dual flush valves provide a full 1.6 gpf flush as well as an optional 0.8 gpf half flush.
- Consider replacing existing plumbing fixtures with high-efficiency fixtures that exceed UPC and IPC requirements.
- High efficiency water closets — New high-efficiency water closets use 1.3 gpf or less. When replacing older high-flow plumbing fixtures. In most cases, both fixtures and valves will need to be replaced to ensure proper operation of the fixture and reduce the chance of clogging.
- High efficiency urinals – New high-efficiency urinals use as little as 1 pint of water per flush, or less than 10% of current low-flow models. Before installing these fixtures, it is recommended that the drainage piping be cleaned to ensure proper drainage flow.
- Waterless urinals — These fixtures do not use water, but instead use a specially formulated liquid to maintain the trap seal. Careful consideration should be given to style and placement before installation. In addition, since these fixtures do not use water, maintenance staff must be specifically trained in the proper cleaning procedures.
- Ultra low-flow shower heads – typically use 1.5 gpm of water or less. While ultra low-flow shower heads allow for significant water savings when compared to code-compliant models, they do not always receive high marks from users.
- Install or replace existing lavatory and sink aerators with more restrictive aerators — Significant savings can be achieved by replacing 2.2 gpm aerators with 0.5 gpm aerators.
- Use alternative water sources — Some jurisdictions have or are planning to install grey water distribution systems. The water is considered non-potable, but is suitable for use in water closets and urinals. Use of grey water can considerably reduce consumption of domestic water.
The Federal Energy Management Program offers useful tools for estimating and improving water efficiency. Their on-line calculator, available at http://www1.eere.energy.gov/femp/procurement/eep_toilets_urinals_calc.html#output, estimates the 10-year life cycle cost of water closets and urinals in comparison to current code-compliant models. The life cycle cost can then be compared with the cost of replacement to determine the benefit of replacing fixtures.
Conclusion
Facility managers have a unique opportunity to dramatically impact water use in existing buildings. By measuring and monitoring water use, evaluating plumbing fixture types, and implementing simple water saving measures, you can easily improve your overall efficiency.
Laurie Gilmer is a mechanical engineer with Facility Engineering Associates (FEA). Gregory Hughel is a Staff Engineer with FEA. FEA is a national consulting firm focusing on extending the life of and making improvements to existing facilities. For more information about the company, please visit www.feapc.com.