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Necessary Upgrades

Aug 1, 2008 12:00 PM, By John Watson

New and old schools alike can benefit by designing restrooms to be more water-efficient.

Because the focus is on fixture performance, the baseline is fairly flexible and is based on what's best for each facility, depending on its age. The baseline is established at 120 percent of the total water usage if all of the building's fixtures meet the Energy Policy Act of 1992 (EPAct) fixture performance requirements (see Table 1).

To better understand the LEED-EB: O&M calculation methodology, let's presume we have a university administrative building with two restrooms. The men's restroom has two urinals and two toilets. The women's restroom has four toilets. Each restroom has two sinks with a manual faucet. There are 50 men and 50 women who occupy the building during office hours.

Create a spreadsheet listing each water-using fixture and the frequency-of-use data. This should include the number of female and male daily uses, duration of use and water-volume use. There are no set criteria for determining daily use or duration of use, so these items can be estimated based on the project's program requirements. These values are used to calculate the total potable water used for each fixture type and gender. Use EPAct fixture flow rates for the baseline case. Then calculate 120 percent of that total (see Table 2).

Graywater or rainwater harvest volumes must not be included in baseline calculations. In our example, the EPAct 100 percent usage is calculated to 157,950 gallons of water used annually, and the building baseline is calculated at 189,540 gallons of water used annually. This baseline is referenced in further WE Credits 2.1, 2.2 and 2.3, where the thresholds are 10 percent for WE 2.1, 20 percent for WE 2.2, and 30 percent for WE 2.3.

In contrast, LEED for Schools guides the design and construction of new buildings and major renovations. Under LEED for Schools, WE Credits 3.1, 3.2 and 3.3 are achieved by employing strategies that in aggregate use 20 percent, 30 percent and 40 percent less water, respectively, than the water-use baseline calculated for the building, not including irrigation, after meeting the EPAct fixture performance requirements.

LEED for Schools also promotes water-efficient plumbing technologies that can be used to contribute to achieving WE 2.2, Innovative Wastewater Technology. This strives to reduce generation of wastewater and potable water demand, while increasing the local aquifer recharge. This often is the most challenging credit in the Water Efficiency section. To achieve this, one option is reducing potable water use by 50 percent through the use of water-efficient fixtures, such as toilets and urinals, or non-potable water, such as captured rainwater, recycled graywater, and on-site or municipally treated wastewater.

Calculations are based on estimated occupant usage and include only water closets, urinals, lavatory faucets, showers and kitchen sinks. Installing high-efficiency fixtures, such as low-flow faucets and waterfree urinals, and reusing stormwater and graywater for non-potable applications, such as toilet and urinal flushing and custodial uses, are among the ways to qualify for these credits.

Green construction can lead to a 32 percent reduction in water use, cutting costs for both the school and society in general through reduced infrastructure costs, according to “Greening America's Schools,” a report sponsored by the American Federation of Teachers, the American Institute of Architects, the American Lung Association, the Federation of American Scientists and the U.S. Green Building Council. By specifying plumbing systems that automatically save water, you're helping save water — even if restroom users are oblivious to the technology.

Watson is the director of technical services for Sloan Valve Company, Franklin Park, Ill., a manufacturer of water-efficient plumbing products and systems. He can be reached at john.watson@sloanvalve.com or (800)982-5839.

High on efficiency, low on water usage

Maximum Performance (MaP) testing results show that it is toilet design, not just water volume, that allows some toilets to operate better than others. In fact, toilets using less water than the standard 1.6 gallons of water per flush (gpf) can work as well, or better, than toilets that do. MaP tests, which are run by an independent research group, rank pressure-assist and tank-type toilets of various flush volumes according to how successfully they eliminate simulated waste.

High-Efficiency Urinals (HEU) and High-Efficiency Toilets (HET), which are fixtures that use less water than current federal maximum levels, are becoming increasingly popular as people recognize their value and hear about MaP testing and personal testimonies attesting to their effectiveness.

By definition, HEUs use no more than 0.5 gallons of water per flush, compared with the current maximum of 1.0 gpf for urinals, and they can flush very effectively with as little as 1 pint of water. Waterfree urinals are considered HEUs.

HETs lower water consumption by about 20 to 40 percent. Because toilets account for the highest amount of water used in the restroom, this adds up to big savings. HETs use 1.28 gpf or less and are required to meet the same flushing and drainline carry performance requirements as 1.6 gpf fixtures.

Dual-flush HETs provide a few basic advantages: They substantially reduce water usage and offer a good return on investment. Dual-flush flush valves can be activated manually or electronically. Manual dual-flush valves have been commercially available in the U.S. and Canada for a few years; electronic dual-flush valves are newer. Schools that already have installed dual-flush Flushometers are reporting water savings of as much as 50 percent.

Manual dual-flush systems give restroom users the option of a reduced or regular flush, depending on need. Push the handle one direction and get the full 1.6 gpf. Push the handle the other way for the reduced 1.1 gpf flush.

The new electronic dual-flush flush valves feature buttons for selecting a flush cycle. If a user walks away without pressing a button, the valve automatically initiates a full or reduced flush cycle based on how long the user stays in the sensor range. Consequently, this automatic operation immediately overcomes restroom visitors' learning curve because it doesn't rely on user selection or habit change.

Facilities can either add electronic or manual dual-flush functionality to installed Flushometers using a retrofit kit, or they can purchase a complete flush valve that includes dual-flush operation. When retrofitting a standard flush valve with a manual dual-flush kit, for example, you simply replace the standard Flushometer handle with a dual-flush handle. The dual-flush retrofit handle will work on most standard 1.6 gpf flush valves.

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