Water and wastewater costs have risen at a phenomenal rate over the last six years. According to a 2015 report by Circle of Blue, a group of scientists and journalists, rates nationally were up 41 percent since 2010. At the same time, the cost of electricity has stabilized, and in some areas actually decreased slightly. In the past, conventional chilled water/cooling tower air conditioning was the norm for large facilities. With all the new concern with Legionella, the concern over future water supplies in much of the nation, and the push for high-performance facilities, some are re-looking at water use for air conditioning cooling systems. In response, the industry is changing and evolving to become both more energy- and water-efficient. For facility managers, understanding these trends, as well as the energy/water nexus of large commercial air conditioning systems, is critical to saving money and truly moving toward high-performance and sustainability.
Twenty years ago, the choices that large facilities had for air conditioning were simply air-cooled or water-cooled systems. With facilities of 200,000 square feet or more, the clear choice was either a two- or four-pipe system with a cooling tower. The chiller/cooling tower/chilled water system was the workhorse. The energy efficiencies available with these systems versus direct expansion/air cooled systems made them the clear choice.
But these systems use significant volumes of water. Recent compilation of data from all across the nation shows that in a typical office building, the cooling towers can account for a third to over half of all the water use for that facility. While this type of system will continue to be a workhorse for the foreseeable future, the rapid rise in water and wastewater costs and water scarcity issues are causing many to look for new strategies.
There are three factors that will impact both design and systems choices in the future. These three trends are: the rising cost of water and wastewater, new technologies, and the need to be both energy and water efficient.
Delta Cooling Towers‘ Engineered HDPE plastic towers are becoming more popular in an effort to combat water waste. The plastic is specifically engineered so that the pH levels and chemicals in the water don’t affect the cooling tower itself. They last decades, rather than five to eight years. The evaporative processes that the water goes through in the tower mean that water loss is expected, and drift is also unavoidable. But these engineered plastic towers help to conserve some of the water that was being lost. Water loss is prevented with these towers, and water conservation efforts are focused on achieving zero blowdown status in order to reduce the water necessary to run.