How Does LEED Addresses Water Usage in Green Buildings?

Seventy percent of the earth’s surface is covered by water; however, fresh water only comprises 1% of the total volume and is the only percentage that is accessible for human use. According to the United Nations Environment Programme, if the current water consumption rates continue, two out of every three people will live in water-stressed conditions by the year 2025.

With the increase of residential, commercial, and industrial development, the use of potable water increases. From flushing toilets to industrial water uses, potable water is becoming wastewater, which overwhelms treatment facilities and results in heavy energy use during water treatment, as well as the creation of more greenhouse gases.

Green buildings need to address this issue by improving their water efficiency. “Efficiency” does not mean finding an alternative method; rather, it means doing the same thing by using less of the same resource. As a result, water will still be used, but it will be used in a smarter way.

The water balance approach, which aims to balance water supply with water consumption, is not achievable for every location. An example of the water balance approach would be to use only captured rainwater and/or underground water for the water needs of the building, so no water would be used from municipal lines. Nonetheless, getting as close as possible can still bring about a considerable change. LEED aims to reduce water usage by addressing projects’ both indoor and outdoor water consumption.

In some projects, potable water used for irrigation exceeds the total indoor water consumption of the building. Water reductions in irrigation can be established through water-wise landscaping designs, water-efficient irrigation technologies, nonpotable water use (such as using reclaimed water, graywater, or harvested rainwater), and installation of submeters to track and log irrigation trends.

Careful plant selection will make a great contribution to reducing outdoor water use. The use of native and adapted plants, or xeriscaping (a type of landscaping that does not need any irrigation), and clearing out any invasive plants can help considerably. Areas covered with turf or grass will need high amounts of irrigation water.

Using high-performance irrigation technologies such as drip irrigation systems, bubbler distribution systems, and channel water directly to root systems are other strategies to consider. The use of weather-based irrigation controllers, to respond to weather conditions, will avoid watering the vegetation while it is raining.

Now let’s take a look at how LEED aims to decrease indoor water usage. Use of water for urinals, toilets, showers, kitchen, and other applications all contribute to indoor water use. Indoor potable water consumption can be reduced by using water-efficient fixtures and fittings and/or using nonpotable water sources where appropriate.

The use of WaterSense-labeled products can be a good strategy that will contribute to reducing indoor water usage as well as satisfying LEED requirements. WaterSense is a program developed by the US Environmental Protection Agency to identify high-performance, water-efficient fixtures, and fittings. A fixture or a fitting that has a WaterSense label will guarantee high water efficiency.

In addition to high-efficiency fixtures, the use of harvested rainwater and/or greywater as the flush water of toilets can decrease potable water consumption and will also earn points for the LEED certification.

Graywater is the untreated household water that does not come into contact with toilet waste. Used water from bathtubs, showers, bathroom washbasins, and clothes washers and laundry tubs can be examples of greywater and may be used as flush water in toilets or urinals.

Installing submeters would be another plus for the projects to track and log water use trends and check fixture performance. Further, it would allow for the discovery of innovative ways to reduce potable water usage. Without any such data, it wouldn’t be possible to identify individual water use of the building systems and pinpoint the items that consume high amounts of potable water.

There are many strategies to go green and LEED can be a great reference to start your journey. LEED-certified buildings are proven to be environmentally friendly and to respect human health. However, there are other major benefits of a LEED certification that can be summarized as money savings over the lifetime of a project, increased project value, and increased building occupant satisfaction.

If you are in the design or construction industry, you can even think about earning a LEED credential to help other projects go green and enhance your career. All you need to do is a study for your LEED exam and become a LEED Green Associate or a LEED Accredited Professional.

Author: A. Togay Koralturk

Author of LEED Complete Study Guides

LEEDUCATE Inc. | LEED Exam Prep Provider

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