Free LEED (Leadership in Energy and Environmental Design Certification) Water Efficiency Questions and Answers — Questions and Answers
Question 1: A project team is designing a new office building and must meet the WE Prerequisite: Indoor Water Use Reduction. According to LEED v4.1, what is the minimum aggregate water consumption reduction required for fixtures compared to the baseline, and what additional requirement applies to newly installed eligible fixtures?
- 10% reduction; no additional requirement.
- 20% reduction; they must be ENERGY STAR certified.
- 20% reduction; they must be WaterSense labeled. (Correct answer)
- 30% reduction; they must be sourced locally.
Correct answer: 20% reduction; they must be WaterSense labeled.
The LEED v4.1 WE Prerequisite for Indoor Water Use Reduction requires a minimum 20% aggregate reduction in water use from the calculated baseline. Additionally, all newly installed fixtures that are eligible for the WaterSense label (such as toilets, urinals, and faucets) must be WaterSense labeled.
Question 2: A project team is pursuing the WE Credit: Outdoor Water Use Reduction. Which of the following strategies would contribute to achieving this credit by reducing the landscape water requirement (LWR)?
- Installing a standard spray irrigation system with a timer.
- Using potable water from the municipal supply for all irrigation needs.
- Planting a turfgrass variety that requires frequent watering.
- Specifying native and adaptive plant species for landscaping. (Correct answer)
Correct answer: Specifying native and adaptive plant species for landscaping.
Using native and adaptive plant species is a primary strategy for reducing outdoor water demand because these plants are naturally suited to the local climate and soil conditions, thus requiring less supplemental irrigation. Standard irrigation is the baseline, potable water is what the credit aims to reduce, and high-water-demand plants increase the landscape water requirement.
Question 3: For the WE Credit: Cooling Tower Water Use, what is the primary metric used to measure the efficiency of water use in a cooling tower system?
- Gallons per minute (GPM) of makeup water.
- Cycles of concentration (COC). (Correct answer)
- Total dissolved solids (TDS) in the blowdown water.
- Evaporation rate in gallons per hour.
Correct answer: Cycles of concentration (COC).
Cycles of concentration (COC) is the fundamental measure of cooling tower water efficiency. It is the ratio of dissolved solids in the tower water to the dissolved solids in the makeup water. Maximizing the cycles of concentration means the same water is used more times before being discharged as blowdown, thereby conserving water.
Question 4: A project team wants to earn the WE Credit: Water Metering. To achieve the credit, they must install permanent water meters for at least two of the listed water subsystems. Which of the following is an eligible subsystem that can be metered for this credit?
- Fire suppression system.
- Coffee machines and soda fountains.
- Domestic hot water. (Correct answer)
- Unfiltered rainwater collection.
Correct answer: Domestic hot water.
The LEED v4.1 WE Credit for Water Metering lists several eligible subsystems, including irrigation, indoor plumbing fixtures, domestic hot water, boilers, reclaimed water, and other process water. Domestic hot water is explicitly listed as one of the key subsystems that can be metered to earn this credit.
Question 5: According to the Energy Policy Act (EPAct) of 1992, which serves as the baseline for LEED calculations, what is the maximum allowable flush rate for a standard commercial water closet (toilet)?
- 1.28 gallons per flush
- 2.2 gallons per flush
- 1.0 gallons per flush
- 1.6 gallons per flush (Correct answer)
Correct answer: 1.6 gallons per flush
The Energy Policy Act (EPAct) of 1992 established the baseline water conservation standards for plumbing fixtures in the U.S. For water closets (toilets), the maximum flush volume was set at 1.6 gallons per flush (gpf). This value is used as the baseline case in LEED calculations for the Indoor Water Use Reduction prerequisite and credit.
Question 6: A project in a large hospital is attempting to achieve the highest levels of indoor water use reduction. Beyond installing WaterSense labeled fixtures, which of the following represents a valid strategy for achieving additional points in the WE Credit: Indoor Water Use Reduction?
- Installing a second, separate potable water meter for the building.
- Using captured rainwater to meet the demand for kitchen dishwashers. (Correct answer)
- Documenting that all occupants have been trained on water conservation.
- Replacing all incandescent lighting with LEDs to reduce the cooling load.
Correct answer: Using captured rainwater to meet the demand for kitchen dishwashers.
The WE Credit for Indoor Water Use Reduction awards points for exceeding the 20% prerequisite savings. Additional potable water savings can be earned by using alternative water sources, such as captured rainwater, to meet the demand for appliances and process water, like commercial kitchen equipment. Metering is a separate credit, training is an operational strategy not credited here, and lighting affects energy, not process water use directly.
Free LEED (Leadership in Energy and Environmental Design Certification) Water Efficiency Questions and Answers
A project team is designing a new office building and must meet the WE Prerequisite: Indoor Water Use Reduction.
According to LEED v4.1, what is the minimum aggregate water consumption reduction required for fixtures compared to the baseline, and what additional requirement applies to newly installed eligible fixtures?