Agencies are required to develop metering plans to inform how they will deploy meters through their building stock. Guidance on water metering is provided by the Federal Energy Management Program (FEMP) in the Federal Building Metering Guidance, which helps agencies prioritize the application of water meters to their building inventories. Meters cost money to purchase and install, and agencies and installations with multiple buildings distributed over a region or campus usually balance water metering needs with available funds in the current year and anticipated out-year funding. To do this, agencies and sites evaluate their building inventories to:
- Prioritize the order in which buildings should be metered for water
- Develop an implementation schedule that maximizes the potential benefits.
This section offers technical information to assist agencies in how to develop a prioritization for water metering of buildings. This recommended approach does not consider agency or site-specific needs and issues included in an individual prioritization effort.
Building Water Meter Prioritization Process
The Federal Building Metering Guidance requires metering for all federal buildings that are not specifically excluded per specific criteria outlined in the guidance. Additionally the guidance requires metering for irrigated landscapes greater than 25,000 square feet.
Developing a prioritization for building-level water metering requires investigation of specific water uses. Prioritizing water meter implementation should recognize unique uses among the buildings, as well as any special requirements that might apply to any of the buildings. The prioritization process should also assess the schedule of installation because water meters will likely be phased over several years due to resource constraints. An oversimplified approach that only takes into consideration building square footage, for example, will likely overlook water-intensive buildings.
Follow the steps below to prioritize buildings for water meters using a more comprehensive water use approach. These steps are focused on a single campus, but could also be utilized at the agency level. (Note that irrigation metering is handled separately from building water meters and should be prioritized by the size of the irrigated area.)
- Step 1: Develop a list of buildings with building type and square footage from the campus real property database
- Step 2: Identify the number of occupants per building from associated building data or human resources records
- Step 3: Determine the buildings' water consuming equipment such as plumbing, chiller plants, cooling towers, steam systems, commercial kitchens, vehicle wash, laundry facility, and lab equipment, which can be provided through equipment inventory databases or facility manger interviews. See FEMP's Best Management Practices for Water Efficiency for an extensive list of water consuming equipment.
- Step 4: Estimate the daily water use for each building based on the type of water using equipment identified.
- Step 5: Sort the building list by daily water use to determine the priority for which buildings should be metered for water.
Example Building Water Meter Prioritization
This table shows how the application of water meters is prioritized at a hypothetical federal campus using two different methods. In some cases, the buildings are excluded from meter application based on the appropriateness criteria, in which case these buildings receive a priority of "NA" for not applicable.
|Example Building Water Metering Prioritization|
|Building||Square footage||Occupancy||Water-using processes||Estimated daily water use (gal/day)||Priority based on square footage||Priority based on daily water use|
|Office 1||22,000||150||Plumbing and Cooling Tower||4,052||4||1|
|Dormitory||35,000||100||Plumbing and Kitchen||1,550||1||2|
|Laboratory||12,000||3||Plumbing and Lab Equipment||1,536||7||3|
|Central Steam Plant||5,000||4||Plumbing and Steam Generation||1,348||10||4|
|Maintenance Facility||5,000||2||Vehicle Wash||1,224||9||5|
|Office 2||13,000||50||Plumbing and Kitchen||775||6||NA. Does not meet daily use thresholds|
|Office 4||15,000||25||Plumbing||300||5||NA. Does not meet daily use thresholds|
|Training Center||8,000||50||Plumbing||600||8||NA. Does not meet daily use thresholds|
|Warehouse||35,000||2||Plumbing||24||2||NA. Does not meet daily use thresholds|
|Guard House Security Main||1,500||4||Plumbing||48||NA. Does not meet size threshold||NA. Does not meet daily use thresholds|
|Guard House Secondary||120||1||Plumbing||12||NA. Does not meet size threshold||NA. Does not meet daily use thresholds|
Prioritizing on building square footage (column F): Sorting the building list by square footage (column B) is the easiest method and requires the least amount of data and analysis. However, this approach does not take into account water intensive uses or processes.
Prioritizing based on daily water use (column G): Sorting the building list by daily water use is a more time intensive method, but this approach allows agencies to more accurately determine the largest water consuming buildings. Building occupancy (Column C) and water using processes (Column D) are used to estimate the daily water use for each individual building (column E).
When comparing the outcomes for both approaches (columns F and G) there are some distinct differences:
- Sorting by building size may over-prioritize buildings that do not need to be metered. For example, the warehouse building received the second highest priority for metering based on square footage. However, with only two occupants and no water-intensive processes, this building does not meet the minimum threshold of 1,000 gallons per day.
- Sorting by building size may miss buildings with water-intensive equipment. For example, the central steam plant and maintenance facility received a low priority when sorting by size, but it has large water-intensive equipment, which drives up the priority when sorting by water use.
- Sorting by daily water use can help trim the number of required meters. In the example list, half of the buildings are determined not to meet the minimum threshold water use of 1,000 gallons per day. Sorting by building square footage, only two buildings are under the size threshold of 5,000 square feet.
- Which approach should you use? The estimated water use method provides facility and water managers a better approach to prioritize for meters based on their potential impact. This is especially true for large and/or diverse building portfolios.
Potential Data Sources
The following data sources may include the information necessary to build the prioritization as described in the table above.
- Real property data inventories track a wide range of information that usually includes a list of buildings being managed and information on those buildings including location, size, age, ownership, facility status, and use.
- Equipment inventory lists or databases include inventories of installed equipment in federal buildings. This information may be particularly useful when prioritizing buildings that are distributed across a region.
- Water utility invoices (such as water bills) identify water consumption at distributed facilities as well as the rate structures. This information will be more useful when prioritizing buildings across a region that has different water utility providers.
- Facilities management and maintenance staff are often knowledgeable about building systems and operations. Poll these individuals for information about water use observations, occupancy patterns, and other potentially relevant information.
Data can also be collected from:
- Human Resources offices, which can collect occupancy data by building to estimate plumbing and kitchen water use
- Building walk-downs, which provide firsthand information about the building, its use, and its water-using systems.
For more information, see:
- Best Management Practices for Water Efficiency, which provide an extensive list of water consuming equipment and systems
- Estimating Methods for Determining End-Use Water Consumption, which provides techniques for calculating daily water use of specific water end-uses for plumbing fixtures, batch processes, cooling towers, steam systems, and vehicle wash.