Pranav Phatak
December 9, 2022
WaterSense Technical Evaluation – Behind the Scenes
Overview
In February 2021, the U.S. EPA recognized Home Innovation Research Labs as a Home Certifying Organization (HCO) for the WaterSense Labeled Homes Program.
In this role, Home Innovation will administer verification and certification for the WaterSense program. Homes earning the WaterSense label must meet the water efficiency requirements using Home Innovation’s WaterSense Approved Certification Method (WACM), which is based on selected practices of the 2020 NGBS. Any home or building that has earned the WaterSense label is constructed at least 30% more efficient than standard construction.
Let’s go over these compliance pathways and the steps taken by Home Innovation team to evaluate the 30% water savings.
Building Eligibility
Home Innovation offers two options or pathways to demonstrate compliance with WaterSense efficiency requirement:
- Prescriptive path (New construction, Renovation)
- Performance path (New construction, Certified Path)
Home Innovation does not anticipate offering the WaterSense label prescriptive path independently. All homes must be seeking the WaterSense label via the prescriptive path concurrently with NGBS Green Certification under the 2020 NGBS version. Homes/buildings must be WRI certified to achieve the WaterSense label via performance path. Although, this could be done independently or under the 2020 NGBS version.
Prescriptive Path
The WaterSense Performance Path option is available for projects seeking NGBS Green certification for New Constructions or Renovation. The Prescriptive Path requires all the included practices to be met and verified, including the Mandatory Checklist for WaterSense labeled homes, which outlines leak detection and installation of WaterSense products.
When developing this pathway, the Home Innovation team calculated the water use associated with the eight reference homes (four single-family and four multifamily) to establish a water usage baseline. This analysis was split into two parts: indoor water use and outdoor water use. Calculations were based on EPA WaterSense Technical Evaluation Protocol. (https://www.epa.gov/sites/production/files/2019-04/documents/ws-homes-draft-technical-evaluation-v1.pdf)
For Indoor water use, reference homes with the varying designs and characteristics (like lot sizes, number of bedrooms, number of bathrooms, minimum features installed, etc.) for both single and multifamily, were selected. Indoor water use is heavily influenced by occupancy in addition to the efficiencies of the devices and appliances installed. The Home Innovation team started assessment by establishing indoor baseline for each reference home based on occupancy and appliance efficiencies. The objective was to meet the EPA’s water efficiency criteria of 30% total water savings across all reference home scenarios.
Outdoor water use is influenced by climate, irrigated area, irrigation method (type of technology and irrigation schedule/maintenance), and landscape features (plant type). The procedure was similar to indoor water use assessment; however, outdoor water use was calculated for the following locations:
- Green Bay, Wisconsin
- Raleigh, North Carolina,
- Doral, Florida
- Albuquerque, New Mexico
This was done to assess the impact of local climate conditions on outdoor water use. Various turf and irrigation efficiency options were applied to these reference homes to assess the impact of those selections.
Finally, the total water use was calculated by directly summing up the indoor and outdoor water use.
The next step was to assess the water use associated with reference homes that reflect the characteristics of Prescriptive Path criteria using the Efficient Home calculations described in the Technical Evaluation.
The results were as below.
- Indoor Water Use:
Single-family homes savings over baseline indoor water use ≈ 24%
Multifamily homes savings over baseline indoor water use ≈ 37 to 39%
- Outdoor Water Use:
Single-family homes savings over baseline outdoor water use ≈ 42 to 92%
Multifamily homes savings over baseline outdoor water use ≈ 41 to 57%
- Total Water Use:
Single-family homes savings over baseline total water use ≈ 37 to 86%; with an avg. saving of 59%
Multifamily homes savings over baseline total water use ≈ 37 to 73%; with an avg. saving of 49%
Performance Path
The WaterSense Performance Path option is available for projects seeking NGBS Green certification under the New Construction and Single-Family Certified compliance paths. The Performance Path requires achievement of a certified Water Rating Index (WRI) score, along with the Mandatory Checklist for WaterSense labeled homes.
The process began with a two-party analysis to identify the range of WRI scores that equate with at least 30% water savings.
- Generating WRI values for multiple efficient home designs
- Calculating savings over baseline water use using the efficient home calculations
The resulting WRI values and water savings were then plotted together to identify the minimum WRI value needed to achieve the required 30% savings.
Home Innovation performed this analysis on 144 efficient home design models that reflected geographic diversity and a range of indoor and outdoor water efficiency. Three pairs of cities with contrasting rainfall data were selected to assess the impact of local climate conditions on outdoor water use.
- Doral, FL / Albuquerque, NM
- Portland, OR / Scottsdale, AZ
- Memphis, TN / Denver, CO
For each home configuration, three versions were modeled representing high-, medium-, and low-water efficiency. Across all efficient home designs, WRI values below 64 resulted in savings above 30%.
What does this mean?
By seeking the WaterSense label, builders can draw attention to their homes’ water efficiency features by levering one of the most recognizable consumers labels for water efficiency. With EPA’s WaterSense labeled homes program, home buyers gain confidence that their homes will be at least 30% more efficient than typical construction.
To learn more, visit https://www.homeinnovation.com/watersensecertification
Back to Top