Showers are also included in the hotel template calculations. These were based on an average of sampled flow rates for showers in hotels throughout the U.S. and usage was calculated using a conservative shower duration length of 8 minutes per shower.

The post-program annual gallons saved = the difference between the two.

ASHRAE 189.1 was used as the basis for efficient plumbing fixture selection and use.


Water use for landscape irrigation in high performance landscapes is based on proper selection of plant material, proper soil preparation, and watering based on the actual needs of the plant material in the landscape. The basic principles of good landscape water practices include:

  1. Design Landscape to keep water (rainwater, storm water, and irrigation water) where it falls.
  2. Prepare soil shape and content to capture and hold water
  3. Design landscape to minimize the need for irrigation water (eliminate irrigation systems where possible)
  4. Minimize turf areas and choose adapted and drought tolerant plant materials
  5. Meter or sub-meter installed irrigation systems
  6. Capture and use on-site sources of water and/or reclaimed water
  7. Design efficient irrigation system using US EPA WaterSense principles
  8. Practice proper maintenance.

Water use is based on evapotranspiration of the plant material actually used. The equation is:

Water Demand = [Area of landscape × (ETo × Kc) - Effective rainfall)] × [FF] × 0.623 DU

  • ETo—Reference evapotranspiration
  • Kc—Crop Coefficient
  • Effective rainfall—assume 25% (WaterSense)
  • DU—Distribution Uniformity
  • FF—Freeze factor when system off in Winter
  • 0.623—Gallons per inch on one square foot of area

Monthly evapotranspiration for each site was taken into consideration along with plant material and practices common to those areas. Savings were based on the difference between the amounts of water given in the data templates and the water use based on good practice for all of the eight principles outlined above. These principles are reflected in ASHRAE 189.1

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