LEED Water Efficiency Concepts 3 — Questions and Answers
Question 1: Which alternative water source is most commonly permitted under LEED for toilet and urinal flushing?
- Rainwater harvested and stored on-site (Correct answer)
- Municipal reclaimed water only
- Desalinated seawater
- HVAC condensate only
Correct answer: Rainwater harvested and stored on-site
Harvested rainwater is a widely accepted non-potable alternative water source for toilet and urinal flushing in LEED.
Question 2: What is the primary goal of the LEED prerequisite 'Indoor Water Use Reduction'?
- Reduce potable water consumption by at least 20% compared to a baseline (Correct answer)
- Eliminate all single-pass cooling systems in the building
- Require WaterSense labeling on all fixtures without exception
- Install sub-meters on every plumbing fixture
Correct answer: Reduce potable water consumption by at least 20% compared to a baseline
The prerequisite mandates a minimum 20% reduction in indoor potable water use compared to the EPAct 1992 baseline.
Question 3: Which of the following landscape design strategies earns the most LEED points for outdoor water reduction?
- Eliminating all irrigation for the entire landscape (Correct answer)
- Using drip irrigation for 50% of planted areas
- Specifying native plants with conventional sprinkler irrigation
- Installing a weather-based irrigation controller only
Correct answer: Eliminating all irrigation for the entire landscape
Eliminating all irrigation achieves the maximum outdoor water use reduction, earning the highest available points.
Question 4: In LEED, what occupancy type is used to calculate the number of full-time equivalent (FTE) occupants for water use baseline?
- 8-hour occupancy per person per day for FTEs, with transient occupants at fractional hours (Correct answer)
- All occupants counted as 8-hour FTEs regardless of actual hours
- Only permanent staff, excluding visitors and customers
- Occupant counts from the local building code occupant load table
Correct answer: 8-hour occupancy per person per day for FTEs, with transient occupants at fractional hours
LEED uses 8 hours per FTE and assigns fractional hours to transient occupants based on their typical daily duration.
Question 5: A project replaces a cooling tower with an air-cooled chiller. What is the primary Water Efficiency benefit?
- Eliminates cooling tower makeup water, reducing process water consumption (Correct answer)
- Reduces chilled water loop pressure and pipe leakage
- Lowers condenser water temperature, improving WaterSense scores
- Qualifies the building for the Water Metering prerequisite automatically
Correct answer: Eliminates cooling tower makeup water, reducing process water consumption
Air-cooled chillers eliminate the need for cooling tower makeup water, which can represent a significant portion of a building's total water use.
Question 6: What does 'cycles of concentration' measure in a cooling tower context within LEED?
- The ratio of dissolved solids in recirculating water versus makeup water, indicating water use efficiency (Correct answer)
- The number of times chilled water is recirculated per hour
- The percentage of condenser water that evaporates per cooling cycle
- The frequency of water testing required by LEED standards
Correct answer: The ratio of dissolved solids in recirculating water versus makeup water, indicating water use efficiency
Higher cycles of concentration mean less blowdown is required, reducing cooling tower water consumption.
Question 7: Which LEED certification system is most applicable to a large commercial office building pursuing water efficiency credits?
- LEED BD+C: New Construction (Correct answer)
- LEED O+M: Existing Buildings
- LEED ND: Neighborhood Development
- LEED for Homes
Correct answer: LEED BD+C: New Construction
LEED BD+C: New Construction is the rating system designed for new large commercial buildings including office projects.
LEED Water Efficiency Concepts 3
Which alternative water source is most commonly permitted under LEED for toilet and urinal flushing?