Green Building Water Efficiency Strategies: An Analysis of LEED NC2.2 Project Data

This study analyzes project compliance paths used by a sample of projects that earned water efficiency (WE) credits under LEED for New Construction v2.2. The sample of 448 projects that earned at least one of WE credits 1, 2, and 3 indicate that credit 3 (Water Use Reduction – 90%) and credit 1 (Water Efficient landscaping – 96%) were earned much more often than credit 2 (Innovative Wastewater Technologies – 13%).

The most commonly selected option to achieve credit 1 was to have no permanent irrigation rather than reducing water consumption for irrigation by 50%. For projects that did achieve the credit by reducing potable water used for irrigation, the most common sources of reduction used were from rainwater recovery (58%) and using public non-potable sources (49%).

Rather than implementing on-site wastewater treatment (21%), most projects obtaining credit 2 did so through the water savings calculation option (79%). High efficiency toilets and urinals were the most common sources of water savings used for wastewater reduction.

Credit 3 under LEED v2.2 was earned by reducing water consumption through efficient aerators and flush fixtures to reduce water use in the building by 20% for one credit or 30% for 2 credits. Dual flush (48%) and high efficiency (37%) were the most common water closets used. High efficiency urinals (49%) were used much more frequently than waterless urinals (20%). The most common tap fittings types were:

  • Showerhead:  1.5 gpm (43%)
  • Sink – Lavatory:  0.5 gpm (78%)
  • Sink – Kitchen:  2.2 gpm (32%)