Environmental Design + Construction - March 2009 - (Page 34) STUDIO By Peter Jahrling How Low Can You Go? ANALYSIS OF LOW-CONSUMPTION OPTIONS IS ESSENTIAL WHEN RETROFITTING PLUMBING. As low-consumption plumbing technology has evolved to meet challenges within existing buildings, suitable retrofits are available the majority of the time to effectively meet the needs of specific applications. However, because so many options are available, thorough investigation is essential to make optimal choices. A retrofit for a building constructed around 1960, for example, requires careful scrutiny. Overall, such a building would not exactly be considered antique, but the waste plumbing may not be optimal for today’s high-efficiency fixtures. Depending on the restroom fixture layout, a 5.0 gallons per flush (20 liter) water-closet fixture may have had up to a 6-inch (15.2 cm) soil pipe installed during construction 50 years ago. This would depend on the number of fixtures and run of a waste pipe to the stack. Relationships exist between drain-line carry, quantity of water, diameter of soil pipe, pitch of soil pipe, and condition of the soil pipe’s inside diameter. Today’s high-efficiency fixtures flush with a fraction of the water described above and can approach 1.2 to 1.0 gallons per flush (gpf). With less water running through large-diameter 50-year-old pipes, fixtures using a minimum of 1.6 gpf (6.0 liters) might be best because of any combination of the previous relationships. If the facility is used irregularly or seasonally enduring periods of heavy use followed by vacant occupancy, the larger diameter drain pipe may experience lower water levels and dry out because of low or no flushing. Improperly sized drainpipes to the fixture volume can also result in less than optimal water depths each flushing cycle. Water efficiency can be improved in many older buildings by retrofitting fixtures with manual dual-flush handles or electronic dual-flush kits. Periodic reduced flushes of about 1.1 gpf (4.2 lpf ) can be more than compensated for by restroom visitors using the full 1.6 gallon (6.0 liter) flush. THE KEY FOR PROFESSIONALS IS TO UNDERGO PROPER COMMISSIONING PRIOR TO SPECIFICATION. with a lesser water volume than the 1.0 gpf federal standard; some that flush with as little as a pint of water are available and, indeed, function without sacrificing performance. Those who plan to retrofit existing plumbing fixtures for efficiency can choose kits that reduce water use or offer additional functions, such as those that enable sensor operation. HET and HEU fixture technology sometimes requires the installation of new fixtures because the volume of flush valve should match the fixture flush volume. Pressure-assist 1.0 gpf toilets require new fixtures, but overall water efficiency with the pressure-assist technology increases exponentially in a relatively short amount of time. As demand has grown, lowconsumption plumbing technology has become more refined and is available to fit nearly any existing structure application. The key for professionals is to undergo proper commissioning prior to specification. Through complete investigation of options in terms of project objectives, professionals can make educated, sustainable decisions regarding low-consumption plumbing. Highly Efficient Retrofits Retrofitting with high-efficiency fixtures should be initiated by consulting a plumbing engineer who can properly assess an older structure’s drain system. Structures built more recently generally would not have the same drain-line carry issues as older buildings because their soil-pipe diameter and pitch are compatible with contemporary low-consumption fixtures. Therefore, various high-efficiency toilets (HETs) and high-efficiency urinals (HEUs) can be ideal for many existing structures and new construction. These not only cut down on water consumption but they may also help achieve Leadership in Energy and Environmental Design (LEED) points. To receive the Environmental Protection Agency’s (EPA) WaterSense designation, HETs must flush at least 20 percent less than the current federal standard without sacrificing performance. This means toilets meeting the WaterSense requirements must feature a flush volume of 1.28 gpf or less. Both single- and dual-flush gravityfed toilets can be HETs as well as dual- and single-flush pressureassist toilets. HEUs must flush HIGH-EFFICIENCY URINALS AND HIGH-EFFICIENCY TOILETS CAN OFTEN BE IDEAL WHEN RETROFITTING AN EXISTING BUILDING. PHOTO COURTESY OF SLOAN VALVE COMPANY. PETER JAHRLING IS DIRECTOR OF DESIGN ENGINEERING FOR SLOAN VALVE COMPANY. HE CAN BE REACHED AT SLOANENGINEER@INTERLINEGROUP.COM. 34 ed+c M AR C H 09
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