With energy-consuming equipment, such as water heaters and refrigerators, we have good data on energy consumption and can set clear standards accordingly. In some product categories—clothes washers, for example—Energy Star standards were adopted because those standards provide a high enough threshold to represent just the very top segment of the product market (less than 10%). In other product categories—e.g., refrigerators and dishwashers—we set a higher threshold than ENERGY STAR: for example, exceeding those standards by 10% or 20%. With lighting and lighting control equipment, certain generic products qualify, such as compact fluorescent lamps and occupancy/daylighting controls, while in other categories only a subset of products qualify. In some cases, products that meet the energy efficiency requirements are excluded, because of evidence of poor performance or durability. Microturbines are included here because of the potential for cogeneration (combined heat and power) that they offer.
All toilets and most showerheads today meet the federal water-efficiency standards, but not all of these products perform satisfactorily. With toilets and showerheads, we include products that meet or exceed WaterSense standards, which includes performance requirements—although we go beyond WaterSense where there are issues not adequately addressed by the program. We also look for other products that conserve potable water, such as rainwater catchment and graywater recovery and reuse systems.
Alternative wastewater disposal systems reduce groundwater pollution by decomposing organic wastes or removing nutrients more effectively. Hand dryers reduce water and paper towel use, alternative treatments for cooling tower water reduce chemical use, and carpet tile allows modular replacement of worn areas. In screening products for this area, we focus on quantifiable environmental benefits and strong performance records.
Next Filtration offers next-ScaleStop, a scale-preventing water treatment that uses template-assisted crystallization (TAC) to effectively prevent scale without an electric draw or ion replacement. The next-ScaleStop process media, which should be replaced every three years, is calcium-coated beads of polystyrene pockmarked with small nucleation sites (the "template" in TAC). Calcium and bicarbonate ions will crystallize at the nucleation sites, forming "soft scale" which will drift through plumbing without accumulating or interfering with energy transfer. The next-ScaleStop is warranted for 10 years, and can handle water with a maximum hardness of 75 grains and temperatures ranging from 41°F–140°F. Single-unit systems can handle 1–75 gpm, while commercial systems can handle up to 900 gpm.
Water hardness refers to the concentration of calcium and magnesium cations. These positively charged ions dissolve in water as it percolates through alkaline soils or bedrock. Hardness is commonly measured either by the concentration of calcium and magnesium ions in the water or by the grains per gallon (gpg) of calcium carbonate dissolved in water. Hard water is closely linked with scale, in which calcium or magnesium carbonate crystallizes on the interior surface of pipes. Scale reduces the efficiency of heat-transfer equipment such as hot water heaters and is expensive and time-consuming to remove.
Water softeners typically work by replacing calcium and magnesium ions with sodium ions, which don’t form scale. Ion exchange water softeners operate with a slight, though continuous, electric draw, and require significant backwashing of sodium ions into the waste stream. Sodium backwashing is particularly problematic in landscape and agricultural settings.
An alternative to water softening is scale prevention without ion replacement. Template Assisted Crystallization (TAC), a relatively new technology, requires no power, and does not replace the positively charged ions with salt, as is common in other products.
TAC systems use tanks or cartridges filled with extremely small, negatively charged beads of polystyrene that are coated with calcium and pockmarked with small indentations, or nucleation sites (the “template” in TAC). When water passes over the beads, the calcium ions react with bicarbonate at the templates, forming calcium carbonate (scale) crystals. These scale crystals break off and float through plumbing colloidally suspended, meaning they wont attach to pipes and interfere with heat transfer.
Although the water treatment market is filled with unproven and questionable technologies, TAC systems have been shown to reduce scale buildup without environmental drawbacks such as electricity use or sodium backwashing. For this reason, GreenSpec lists TAC systems over water softening systems.
For more information, read Template-Assisted Crystallization: Scale Prevention Without Salt.
Ratings and Commentary