Adjusting irrigation schedules based on weather conditions is the best answer because LEED Water Efficiency encourages reducing outdoor potable water demand through efficient irrigation and climate-appropriate landscape strategies. Weather-based scheduling helps avoid overwatering by responding to rainfall, temperature, soil moisture, and evapotranspiration. This maintains plant health while reducing unnecessary water use. Manually operated valves are less reliable because they depend on human operation and may not respond to changing site conditions. High-emissivity plant materials is not a relevant LEED landscape-water strategy; emissivity relates to heat radiation from surfaces, not irrigation efficiency. Increasing potable water use contradicts LEED’s efficiency-first approach. Rainwater can further reduce potable water demand, but efficient scheduling is the action that directly improves irrigation efficiency.

Acomposting toileteliminates water use by not requiring any water for flushing, unlike traditional or low-flow fixtures:

“Composting toilets… operate without water use, thus eliminating indoor water demand for flushing.”

WaterSense toilets and low-flow lavatories reduce water use but do not eliminate it.

Pervious paving, also known as permeable paving, allows water to pass through it, facilitating the recharging of aquifers. This type of paving reduces runoff by allowing water to soak into the ground, which can help replenish groundwater supplies and reduce the impact on nearby water bodies. References: LEED Green Associate Candidate Handbook, U.S. Green Building Council resources

Methane is a potent greenhouse gas that contributes to global warming and climate change. It is produced when organic waste decomposes anaerobically (without oxygen) in landfills1. Construction and demolition waste, which accounts for about a third of all solid waste generated in the world2, often contains a large amount of organic materials, such as wood, paper, and food waste1. Therefore, disposal of solid waste from building construction and operations in landfills has a substantial effect on methane emissions13. Incineration of solid waste also produces greenhouse gases, such as carbon dioxide, carbon monoxide, and hydrochloric acid, but at lower levels than landfilling45. Volatile organic compounds (VOCs) are not greenhouse gases, but they can react with other pollutants to form ozone, which is a greenhouse gas and a health hazard4.

The Facility Manager is typically responsible for monitoring ongoing energy performance over the life of a building. They oversee the operation and maintenance of building systems, including HVAC, lighting, and other energy-using equipment, and can implement energy management strategies to optimize performance. References: LEED Green Associate Candidate Handbook, U.S. Green Building Council resources

One of the things that LEED promotes by encouraging compact development is walkability. Compact development is a form of urban planning that aims to reduce sprawland make more efficient use of land and resources by increasing density, diversity, and connectivity of land uses5. Compact development can enhance walkability by creating mixed-use neighborhoods that provide a variety of destinations within walking distance, such as shops, services, workplaces, schools, parks, and transit stops. Walkability can offer multiple benefits for the environment, health, economy, and social equity. For example, walkability can reduce greenhouse gas emissions and air pollution byreplacing car trips with walking or transit; improve physical and mental health by increasing physical activity and reducing stress; support local businesses and generate tax revenues by increasing foot traffic and property values; and foster social cohesion and civic engagement by creating vibrant public spaces and enhancing accessibility for all6. References: Compact urban development6; LEED v4 BD+C Reference Guide, Location and Transportation, page 15

Rainwater is considered an alternative water source because it is a sustainable source of water that is not supplied from fresh surface water or groundwater. Rainwater can be harvested from roofs or other surfaces and stored for later use. Rainwater can offset the demand for freshwater and reduce the pressure on water resources. Rainwater can be used for various purposes, such as irrigation, toilet flushing, cooling, and cleaning. LEED projects can earn credits for using alternative water sources under the Water Efficiency category. References: Best Management Practice #14: Alternative Water Sources1; LEED v4 BD+C Reference Guide, Water Efficiency, page 51

Rainwater is the type of water that would be most useful for landscape irrigation when considering water conservation and water efficient landscaping. Rainwater is water that falls from the sky as precipitation, and it can be collected and stored in tanks, barrels, cisterns, or ponds for later use1. Rainwater is a renewable and free source of water that does not require any treatment or pumping, unlike potable water, which is water that is safe for human consumption and often comes from municipal sources2. Potable water is a scarce and valuable resource that should be conserved for drinking,cooking, and hygiene purposes, rather than for irrigation2. Clean water is a vague term that can refer to any water that is free of contaminants, but it does not necessarily mean that it is potable or suitable for irrigation3. Blackwater is water that contains human or animal waste, such as sewage or toilet water, and it poses a health and environmental risk if used for irrigation without proper treatment4. Therefore, rainwater is the best option for landscape irrigation, as it reduces the demand for potable water, lowers the utility bills, and benefits the plants and soil1.

Rainwater Harvesting for Landscape Irrigation

Potable Water

Clean Water

Blackwater