One of the primary challenges that builders and facility managers face is ensuring that their buildings maintain optimal HVAC system performance. Over time, HVAC systems inevitably become less energy efficient as mold, biofilm, and other organic compounds accumulate on cooling coils restricting airflow and shortening equipment life. Evidence shows that up to a 25 percent drop in capacity can occur within five years or less of startup.
As coil performance degrades, the ability to maintain temperature set points can be compromised because of a decrease of heat transfer and restricted airflow brought about by increased coil pressure drop. In an attempt to clean coils, facility managers often resort to manual pressure washing or chemical treatments; these methods are costly, labor-intensive and, worst-of-all, temporary. The coils will foul again and require further attention.
A much more efficient and permanent solution to coil fouling and the inefficiencies it brings is Ultraviolet-C (UV-C) technology, which uses light in the UV-C spectrum to kill, or prevent the growth of, virtually all known microorganisms.
Installed downstream of the cooling coil in the direction of airflow, UV-C lamps can return HVAC systems to their original, design performance standards, or as-built conditions, in as little as 90 days. Improving heat transfer efficiency and reducing coil pressure drop slashes energy use by 10 to 25 percent on average.
Applied in new systems, UV-C lamps prevent the buildup of organic material, thus maintaining the original heat-transfer capacity, design pressure drop and the amount of energy needed to provide the necessary amount of cooling and ventilation.
Installing UV-C lamps in HVAC systems can, therefore, achieve the following benefits:
Level 1—HVAC system efficiency: Removing/preventing the buildup of organic material on the surfaces of cooling coils, drain pans, and interior duct surfaces to improve airflow, return and maintain the heat-transfer levels of cooling coils to “as-built” conditions and reduce maintenance.
Level 2—IAQ: UV-C improves airflow levels and eliminates organic material on surfaces, which helps improve indoor air quality (IAQ) by reducing airborne pathogens and odors. This improves occupant productivity, boosts comfort levels and reduces sick time.
Level 3—Economic Impact: The impact that UV-C has on mechanical systems and occupants translates into substantial economic benefits. These savings include reductions in energy consumption cost and related carbon emissions, reductions in hot/cold complaints and maintenance actions associated with occupant comfort, reductions in system downtime and staff time needed for chemical or mechanical cleaning, and increases in occupant satisfaction and productivity.
Costing as low as 8 cents per CFM, UV-C’s expense is more than compensated for by the improved energy efficiencies and reduced labor and maintenance it makes possible. For example, an installed price for adding UV-C technology to a 10,000 cfm system could be a low as $800. The systems are also simple to install and maintain. In fact, product designs are emerging that allow installation of UV-C in air-handling units in under an hour.
Overall, UV-C translates to greater HVAC energy efficiency, lower operating expenses, fewer occupant complaints and better IAQ. As facility managers and specifying engineers continue to recognize these benefits, the technology is fast becoming a must-have.