Copper HVAC Components May Help IAQ/Prevent Sick Building Syndrome
According to the EPA, the air within homes and office buildings can be more seriously polluted than outdoor air, even in the dirtiest cities.
As trends in energy efficiency lead to “tighter” building designs, indoor air quality (IAQ) issues are an increasingly common concern. Modern buildings are so well sealed that pollutants and disease-causing organisms are trapped inside. Microbial contamination has become an increasing source of what is often referred to as "sick building syndrome" (SBS).
Often, industrial HVAC systems present ideal conditions for the growth and distribution of harmful microorganisms — including bacteria, mold and viruses. Irritating, even deadly, contaminants can accumulate and breed on the damp, dark surfaces of heat exchange coils and fins, condensate drain pans, air filters and air ducts.
Now, studies show that surfaces made of copper alloys are effective antimicrobial agents. Copper’s antimicrobial properties have the potential to limit the spread of infectious diseases and allergens through HVAC systems.
In study after study, copper alloy surfaces have killed off pathogenic bacteria within 90 minutes at room temperature and within a few hours at chilled air (indoor air-conditioning) temperatures. The EPA now recognizes over 350 copper alloys as antimicrobial. Conversely, microorganisms can survive for up to a month, or more on stainless steel, or aluminum.
The fact that copper can kill microbes is not actually news. Always ahead of the curve, Ancient Egyptians, Greeks, Romans and Aztecs, used copper to treat illness and infection, as well as for day-to-day hygiene. And those other early adopters, the Phoenicians and Carthaginians, may have used copper sheathing on their ships to control biofouling.
The British navy figured it out a couple of hundred years ago. Some historians speculate that Admiral Nelson's Trafalgar victory in 1805 was partially due to his copper-clad ships – the copper reduced marine growth on the hull, making his ships faster. In any case, it was copper: 1, wood: 0.
Today, copper is already used extensively in the medical industry, in applications ranging from antiseptics and anti-fungal products, to medical devices and oral hygiene products.
Now, studies are showing that using copper and copper alloys in heat exchanger tubes, fins, filters and condensate drain pans, may control the growth of harmful fungi and bacteria that thrive in HVAC systems.
In the summer of 2010, researchers conducted a trial at the Fort Jackson U.S. Army base in Columbia, SC, to test the effectiveness of copper surfaces in HVAC on inhibiting the growth of microbes. A barracks HVAC system was retrofitted with copper components in places where contaminants tend to thrive – chilled water tubes, heat exchange fins and drip pans. A similar, nearby barracks acted as a control. The barracks with copper systems had significantly lower levels of microbes in the air.
Using copper in industrial HVAC systems could reduce the level of unwanted airborne biological pathogens and improve HVAC IAQ. An added bonus is that copper’s thermal conductivity can also boost energy efficiency. Besides that, copper is a beautiful material. Using it for exposed ductwork just adds to building aesthetics.
Copper industrial HVAC components show promise for helping alleviate SBS. We expect to see them become a popular option in critical environments, such as hospitals, nursing homes and military facilities.