LEED Water Efficiency Concepts 4 — Questions and Answers
Question 1: Under LEED, which factor determines whether a building must comply with the outdoor water use reduction prerequisite?
- Whether the project has a vegetated landscape area that requires irrigation (Correct answer)
- Whether the building is located in a water-stressed region
- Whether the project has more than 10,000 square feet of roof area
- Whether the owner requests the prerequisite be applied
Correct answer: Whether the project has a vegetated landscape area that requires irrigation
The outdoor water use prerequisite applies when a project has a vegetated landscape that could be irrigated with potable water.
Question 2: What is the minimum flow rate reduction required for lavatory faucets to meet the LEED Indoor Water Use Reduction prerequisite?
- Fixtures must perform at or below 0.5 gpm at 60 psi (Correct answer)
- Fixtures must be at least 30% below the EPAct 1992 baseline of 2.2 gpm
- Fixtures must carry WaterSense certification regardless of flow rate
- Fixtures must achieve 1.0 gpm at any tested pressure
Correct answer: Fixtures must perform at or below 0.5 gpm at 60 psi
LEED requires lavatory faucets to perform at or below 0.5 gpm at 60 psi to meet the prerequisite.
Question 3: A LEED project team is analyzing their building's water budget. They identify that kitchen pre-rinse spray valves account for 15% of indoor water use. What rating do best-practice pre-rinse valves typically meet?
- WaterSense or EPA recommended performance at 1.3 gpm or less (Correct answer)
- NSF 61 certification for food-contact water safety
- ENERGY STAR certification for commercial appliances
- ASME A112.18 flow standards at 2.0 gpm
Correct answer: WaterSense or EPA recommended performance at 1.3 gpm or less
High-efficiency pre-rinse spray valves flow at 1.3 gpm or less, meeting EPA best-practice guidance and contributing to LEED water savings.
Question 4: In LEED, what is the difference between 'regulated' and 'non-regulated' water uses?
- Regulated uses are covered by plumbing codes (fixtures, fittings); non-regulated uses include process equipment like dishwashers and lab equipment (Correct answer)
- Regulated uses require permits; non-regulated uses do not
- Regulated uses apply to commercial buildings; non-regulated apply to residential
- Regulated uses are metered by the utility; non-regulated are privately managed
Correct answer: Regulated uses are covered by plumbing codes (fixtures, fittings); non-regulated uses include process equipment like dishwashers and lab equipment
Regulated water uses are those governed by plumbing codes, while non-regulated process water uses—like food service equipment—are addressed separately.
Question 5: Which strategy can help a LEED project earn additional points under 'Cooling Tower Water Use'?
- Using at least 20% non-potable water for cooling tower makeup and achieving 10+ cycles of concentration (Correct answer)
- Installing a VFD on the cooling tower fan motor
- Replacing the cooling tower with a ground-source heat pump system
- Selecting a cooling tower with MERV-8 filtration on the air intake
Correct answer: Using at least 20% non-potable water for cooling tower makeup and achieving 10+ cycles of concentration
Using non-potable makeup water and maximizing cycles of concentration are the primary strategies for the Cooling Tower Water Use credit.
Question 6: When performing a LEED water use calculation, how are part-time employees accounted for?
- Their hours are divided by 8 to calculate their FTE contribution to daily water use (Correct answer)
- They are excluded from the calculation as they are not full-time occupants
- They are each counted as one full FTE regardless of hours
- They are counted at double weight due to irregular usage patterns
Correct answer: Their hours are divided by 8 to calculate their FTE contribution to daily water use
Part-time employees are converted to FTE units by dividing their daily hours by 8, proportionally reducing their water use contribution.
Question 7: A project team is considering a greywater reuse system. Which source qualifies as greywater under most US plumbing codes referenced by LEED?
- Lavatory, shower, and bathtub drain water (excluding toilet and kitchen sink waste) (Correct answer)
- All wastewater from the building before treatment
- Roof-collected rainwater stored in cisterns
- HVAC condensate collected from air handling units
Correct answer: Lavatory, shower, and bathtub drain water (excluding toilet and kitchen sink waste)
Greywater typically refers to lightly contaminated drain water from lavatories, showers, and baths, excluding toilet waste (blackwater) and kitchen sink waste.
LEED Water Efficiency Concepts 4
Under LEED, which factor determines whether a building must comply with the outdoor water use reduction prerequisite?