Part 3: Cooling Towers Are Overlooked As Water Users
Cooling Towers Are Overlooked As Water Users
By H.W. (Bill) Hoffman December 2012 - Green
Cooling towers are often the forgotten part of water use. A hospital that may use only 15 percent of its water use for cooling tower makeup in the Northeast may use more than 40 percent of its water for that purpose across the South and Southwest. Cooling towers typically use between 2.0 and 2.5 gallons of water per ton-hour of air conditioning. Because most commercial properties contract out the chemical treatment of cooling towers, it is important that the contract contain specifications for water efficiency, usually in the form of a specified number of cycles of concentration or a specific conductivity setting for blowdown.
Conservation firms can assist facility managers to increase cycles of concentration, find alternate sources of water for use in cooling towers and provide innovative solutions to tower operation. As water and sewer rates continue to inflate at a much faster rate than electricity, the bottom-line savings by using cooling towers continues to shrink. Many are examining geothermal air conditioning systems, heat recovery systems to use compressor heat to heat water, hybrid cooling towers, side stream treatment of cooling tower water, variable refrigerant volume systems and other technologies to reduce water and wastewater costs.
No discussion of water conservation in commercial and institutional facilities would be complete without the mention of the significant changes that are occurring across the nation. Both major plumbing code bodies — the International Association of Plumbing and Mechanical Officials (IAPMO) and the International Code Council (ICC) — have, as of 2012, issued new green code supplements that will significantly affect the selection of water-using equipment from toilets to kitchen appliances. Several bodies such as ASHRAE are developing standards for water use similar to those developed for energy. Many states are promulgating legislation regarding water efficiency. Keeping up with the rapidly changing code and regulatory environment is a herculean task for facility managers. The past decades were about energy efficiency, but both energy and water will be on the radar screens of all who manage facilities wisely in the future.
Bill Hoffman, principal of H.W. (Bill) Hoffman and Associates, LLC, and senior technical advisor for Water Management, Inc., has more than 40 years of water conservation and water resource planning experience. He has been involved in the development of water conservation legislation and in the development of new rating tools for both the U.S. Green Building Council's LEED program and Green Globes.