What do you know about Ultra-violet light (UV)? Most think of tanning beds, sunlight and crime scene investigations when they think of UV. Did you know that using UV light in HVAC applications as a germicidal solution is another option? Probably not. In today’s post we are going to pose popular questions regarding UV and supply the answers…

What is Ultraviolet?

Ultraviolet (UV) light is one form of electromagnetic energy produced naturally by the sun. UV is a spectrum of light just below the visible light and it is split into four distinct spectral areas – Vacuum UV (100 to 200 nm), UVC (200 to 280 nm), UVB (280 to 315 nm) and UVA (315 to 400 nm).

What is Ultraviolet C?

The entire UV spectrum can kill or inactivate many microorganism species, preventing them from replicating. UVC energy at 253.7 nanometres provides the most germicidal effect. The application of UVC energy to inactivate microorganisms is also known as Germicidal Irradiation or UVGI.

UVC exposure inactivates microbial organisms such as bacteria and viruses by altering the structure and the molecular bonds of their DNA (Deoxyribonucleic acid). DNA is a “blue print” these organisms use to develop, function and reproduce. By destroying the organism’s ability to reproduce, it becomes harmless since it cannot colonize. After UVC exposure, the organism dies off leaving no offspring, and the population of the microorganism diminishes rapidly.

Ultraviolet germicidal lamps provide a much more powerful and concentrated effect of ultraviolet energy than can be found naturally. Germicidal UV provides a highly effective method of destroying microorganisms.

It’s not just dirt – it’s biological. What is HVAC biofilm?

Some people call it dirt. Some call it mud, slime or sludge. This gluey matrix growing on heating, ventilating and air conditioning (HVAC) evaporator coils, drain pans and ducts is, in fact, biofilm. Biofilm is an active, complex microbial matrix of mold and bacteria that adheres to the fins of the coil and protects the organisms from biocides.

The biofilms themselves give off prod­ucts of metabolism known as volatile organic compounds (VOCs) which may range in effects from watery eyes and head­aches, to more severe allergy and asthma responses.
Numerous studies have demonstrated that the HVAC system is a viable amplifier, reservoir and disseminator of pathogenic and opportunistic bacteria, viruses and mold. The list below identifies some of the many microorganisms that have been isolated from evaporator coils, drain pans, ducts, final filters and diffusers.No matter how good the coil cleaner, sprayer or pressure washer used, the effectiveness of these methods reaches about 1 inch into the coil and the organic and biologically active matter gets packed deeper into the coil fins.Installed on air effluent side of the condensate cooling coils and the drain pan, Solutions Inc UVC energy destroys surface biofilm and airborne microorganisms before they circulate throughout the HVAC system.

What are the most common biological contaminants found in air-handling systems?

Numerous studies have demonstrated that the HVAC system is a viable reservoir of pathogenic and opportunistic bacteria and mold. Below is a partial list of microorganisms that have been found on evaporator coils, drain pans and ducts:

Fungi cultured from HVAC Systems

How does HVAC biofilm impact indoor air quality?

The quality of indoor air, influenced by the levels of bioaerosols, contaminants and pollutants, can affect occupant health and development, resulting in reduced productivity and increased absenteeism. The biofilms themselves give off products of metabolism known as volatile organic compounds (VOCs) which can trigger occupant complaints of watery eyes and headaches and even severe allergy and asthma responses. The biological contaminants typically found on HVAC coils and drain pans have also been linked to Sick Building Syndrome (SBS) and hospital acquired infections.

Bacteria Cultured from HVAC Systems

How does HVAC biofilm impact HVAC energy use?

Biological fouling of evaporator fin and tube heat exchangers is a key contributor to decreased HVAC capacity. The biological fouling acts as an insulator, increasing air flow resistance and decreasing heat transfer. The fans run longer to maintain the building at the desired temperature, increasing kW draw with reduced cooling tonnage capacity. A mere 10% increase in fan motor run can significantly increase energy use. The chillers and pumps work harder to raise the leaving water temperature and achieve set temperature points. For each degree the water temperature is increased, a savings of 1-2% will be realized.
Solutions Inc high output UVC provides continuous cleaning of coils, eliminating the biofilm that causes reductions in operational efficiency. Studies have shown that removal of a .024” layer of biofilm can reduce HVAC energy usage by 21% by restoring heat transfer and system efficiency. Reduced cooling coil pressure drop helps save fan energy, while improved cooling coil heat transfer efficiency. Higher chilled water temperature setpoints allows the chiller plant to operate more efficiently.Read how Solutions Inc customers have improved system efficiency and achieved energy savings.

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How does UVC help conserve water?

A 10,000 square foot building can produce more than 15,000 gallons of condensate water per year. Typically, this condensate is wasted and diverted to sewer systems. In order to effectively repurpose HVAC condensate, it must be free of biological components. Using Solutions Inc’s patented installation methodology and high output UVC directed at the cooling coil and drain pan, the condensate is distilled and clean. The condensate can be effectively collected for use as cooling tower makeup water or for gray water uses.

How does UVC contribute to maintenance and operational savings?

Manual coil cleaning can be a major HVAC maintenance expense and may be very difficult to perform on small, tough-to-access packaged or unitary systems. Manually cleaning only temporarily removes the contaminants and in most cases, simply pushes the biological contaminants further back into the fins.

Solutions Inc UVC solves these problems by eliminating the need for chemical cleaning or pressure washing of any size coil. It also eliminates the associated downtime and inconvenience. Maintenance crews and building occupants are no longer exposed to harmful cleaning chemicals and disinfectants.
The surface cleaning effects of UVC helps restore older HVAC system to efficient operation and maintain new systems at factory design efficiency, while protecting system components against the acids that are emitted from the biofilm and the corrosive effects of chemical coil cleaning.

How does UVC for HVAC work?

The C wavelength of the UV spectrum targets the DNA of microorganisms, destroying their cells and making replication impossible. Directed at a cooling coil or drain pan, UVC energy destroys surface biofilm, a gluey matrix of microorganisms (bacteria, fungi, debris, et al.) that grows in the presence of moisture. Biofilm is prevalent in HVAC systems and leads to a host of indoor air quality (IAQ) and HVAC operational problems that are sometimes mistakenly attributed solely to mold. UVC also destroys airborne viruses and bacteria that circulate through an HVAC system.

By applying the power of UVC at the source of contamination – the HVAC evaporator coils and drain pan – Solutions Inc UVC destroys the reservoir of microorganisms. Without the ability to reproduce, microorganisms become inactive and harmless. The recirculating air in HVAC systems creates redundancy in exposing microorganisms to UVC, ensuring multiple passes so the light energy is effective against large quantities of airborne microorganisms. Solutions Inc UVC delivers the highest UVC output, driving HVAC system efficiency while improving indoor air quality.

Where should UVC fixtures be installed?

To keep coils clean and free of biofilm and other buildup, a high-output UVC-light source should be positioned perpendicular to the fins of the coil and 12 in. off the discharge coil face. When using high-output lamps to eliminate contamination from an existing system, a 24-in. centerline is recommended. With new systems, the centerline may extend to 30 in.

Is UVC lamp output important

Output is critical because it affects a UVC lamp’s performance. To effectively clean coils and eliminate biofilm, a UVC device should provide output measure at a minimum of 9 µW/cm2 per inch of glass from a distance of 1 meter, when tested in a 400 fpm airstream at 50 °F.

Solutions Inc has developed a UVC Application Standard that includes technical data and specifications, as well as installation, sizing, dosage and other guidelines to assist in the proper selection and application techniques of UVC lamp systems.

How do you know when to change the UVC Emitters?

For large or critical applications, change out should be performed when Emitter output decreases by 40% as measured by a radiometer, after about 9,000 hours or 12 months. For installations with no radiometer, change Emitters annually (after about 9,000 hours).

Does it produce ozone?

No, Solutions Inc devices do not produce ozone or other secondary contaminants. According to the U.S. EPA, “Recovery from the harmful effects can occur following short-term exposure to low levels of ozone, but health effects may become more damaging and recovery less certain at higher levels or from longer exposures (US EPA, 1996a, 1996b).”

How do you dispose of the used UVC Emitters?

Dispose of them as you would any fluorescent tubes, in compliance with your country, local or state codes.

Can UVC for HVAC contribute to LEED points?

The use of Solutions Inc UVC may contribute to LEED points across multiple project types in one or more of the following areas: Energy and Atmosphere, Water Efficiency, Indoor Environmental Quality, Innovation & Design Process and Regional Priorities.

Ultraviolet light is a misunderstood and under-utilized tool for improving indoor air quality. There are various reasons to take advantage of the possibilities that UV lighting provides. It is used in hospitals and research labs to sterilize equipment and rooms, and scientists have yet to find even a superbug that is resistant to UV-C rays.

History of UV Light Use for Disinfection

Ultraviolet light has been used to sterilize equipment in hospitals and research labs since the 1930s. In the 1990s there was a push to use UV-C to improve indoor air quality by reducing the microbial build-up within HVAC coils. In 2013, the Centers for Disease Control and Prevention (CDC) participated in a study on eliminating some “super bugs” common in hospital rooms using a disinfection system featuring germicidal UV-C light.

Studies have been done by Duke University Medical Center and the National Center for Biotechnology Information to determine whether UV light actually helps to remove fungal contamination and other harmful airborne particles from the air. The results were quite positive. In both studies, UV-C rays led to significant reductions in contamination.

Various Types of UV Rays

The types of ultraviolet light:

• UV-A light is the least harmful type and has the longest wavelength. It is commonly referred to as “black light.”
• UV-B light causes sunburns with extended exposure and increases the risk of skin cancer. Approximately 95% of this type of UV ray is absorbed by the ozone layer of the Earth’s atmosphere and never reaches Earth.
• UV-C has the shortest wavelength and is the most harmful type of UV ray. Almost all of it is absorbed by the Earth’s atmosphere. Because UV-C rays disintegrate the nucleic acids in the cells of microorganisms, they are used to sanitize food, air and water. UV-C light can be dangerous to humans if not used properly.

How UV-C Lamps Operate

UV-C light at appropriate dosages can eliminate many types of fungi, molds, bacteria, viruses as well as other microorganisms. With proper light placement, all pathogens can be eliminated from air passing through an HVAC/R unit.

How UV Light Improves Airflow and Heat-Transfer Efficiency

Over time, mold and fungi grow on HVAC/R coils and surrounding areas, reducing airflow and undermining unit efficiency. Installing UV lights in the duct system or within the coil system of an HVAC/R unit offers a highly effective layer of protection from many harmful airborne microorganisms. Placing UV lighting within the coil system has the added benefit of destroying the mold and fungi that grow on coils and restrict airflow, and this upgrade can restore coils to installation levels of efficiency and significantly increase airflow. An HVAC/R unit augmented with UV-C will last longer and require less maintenance, because it does not have to work as hard to move air through the coils.

UV-C Can Lower Costs Associated with HVAC/R Systems

Cost savings associated with the use of properly installed UV-C light result from increasing the operating efficiency of HVAC/R units, the reduction of lost work hours due to illness, in addition to the wider benefits that accrue from maintaining a healthier environment for the public. Bulbs are rated for approximately 9000 hours of use–or a little more than one year running 24 hours a day, 365 days per year. A regular replacement schedule must be adhered to ensure efficient operation of the HVAC/R system.

The Basic of UV lights

When your air conditioning is on it is constantly filtering your indoor air. During this process moisture can collect in your air conditioning system causing mold or mildew. These contaminants can lead to bacteria, viruses, and mold residing in your home.

Luckily, there is light at the end of the tunnel. UV lights and UV lamps installed into your heating and air system can combat these unwanted guests. When ultraviolet light is shined at the correct frequency it destroys viruses and bacteria, leaving your home safe and pure.

The process is actually quite scientific. UV light is able to destroy bacteria and viruses because of its wavelength. When the wavelength range is set between 200-280nm (that’s nanometers) the light becomes what is known as UVC (as opposed to UVA & UVB). When the wavelength is within the UVC light spectrum it has the ability to break down DNA. This destroys bacteria’s cellular process including its ability to reproduce.

The Reasons for Having UV Lights in Your HVAC

As previously stated UV lights are needed to destroy mold, mildew, and other undesirables from within your HVAC system. The power of ultraviolet light damages the organism and causes it to “forget” how to build proteins or reproduce itself. This is important because these types of organisms thrive in places that are damp and dark. Your air conditioner is the perfect hiding spot for them to grow unnoticed. UV lights make your air systems almost uninhabitable for these bad guys.

UV lights protect your home and your health. Studies have shown that ultraviolet light, when set to the correct wavelength, efficiently reduces the air germ contamination by over 93%. Ultimately reducing the chances of seasonal allergies and asthma. The system also transforms odor, smoke, and gases from cleaning products into harmless, odorless water vapor and carbon dioxide.

Top Things to Consider about UV Lights for HVAC

All UV lights are not made equal; they come in all sorts of shapes and sizes. Before purchasing your own be sure to call a professional from Solution Inc; we would be happy to perform an inspection and explain all the options you have for your home. In the meantime, consider the following factors when looking for UV lights:

UV-C Output Power

As expected, UV lights range in strength. Efficiency is important but strength should not be sacrificed haphazardly. Larger homes, larger ducts, or aggressive mold require a more powerful light. Remember that air and moisture travel from all areas of the home and can grow in any location within your air conditioning system. Your UV lights should be strong enough to wipe out every microbe regardless of how widespread it is. Self-inspections are doable but without the proper training you may be selling yourself short.

Power Consumption

We discussed how important strength is for a UV light because it is the foundation of destroying bacteria and viruses. Efficiency is an important balance to strength. No, you do not want a UV light that is weak and ineffective. However, a UV light that runs your electricity bill so high that you shut it off does not help you either; it gives the mold a chance to regroup.. Finding a balance is key. Be sure to pay attention to how the lights are designed. Some important parts to take note of are the wattage of the bulb and what kind of reflector technology is used. These are crucial indicators of how much energy you will be spending on the system. With this information you can find a system that fits your budget.

Light Bulb Replacement

With all the amazing features UV lights perform it can be easy to forget they are still simple light bulbs and therefore will eventually burn out. That is why it is important to consider their bulbs before purchase. You do not want to buy a build that is difficult to install or one that is difficult to find on the market.

What Type of UV Light Should You Choose?

UV lights for your HVAC system come in two main options:

Air Sterilization

This UV light sterilizes moving air. It is installed inside the return air duct and the cycle will go on at the same time as the air blower. This will only go for as long as you have the air conditioner turned on.

Coil Sterilization

This UV light is the more common type and it works non-stop. It is a “stick type” of light bulb that you install inside the return air duct. It is also the more reasonably priced option and may be your best bet if you are working with a tighter budget.

Benefits & Considerations of UV Lights

Benefits:

They help reduce illness

Plain and simple UV lights have the ability to exterminate bacteria and viruses from the air, improving overall air quality and reducing your risk of getting sick. Even if someone in your home is coughing or sneezing your UV light combined with your air conditioning will cycle the air through and destroy any of the bacteria. Less bacteria means there is a less of a chance you catch what your guest is spreading.

They help with allergy management

Cleaning the air with UV lights will remove irritating pathogens and help alleviate you from the allergens that may be floating around your home, thereby improving the overall, indoor air quality.

They eliminate odors

Ever smell something awful in your home but can’t figure out where it is coming from? Chances are it is coming from your HVAC system and the circulation is only making it worse. Microbes, pathogens, and all the other bacteria we have discussed so far leave unwanted odors in your ducts. By eliminating them with UV lights you are eliminating the associated smells. Don’t waste money masking the smell with plugins and perfumes. Destroy it at the source with UV lights.

They are low maintenance

Other than a bulb to change once in a while UV lights are a set and forget type of commodity. Not a bad price to pay for clean air.

Considerations

They may Age your AC system

Some materials found in ductwork or within your air conditioning unit may be sensitive to UV lights and will be damaged as time passes. Check your flex ducts and rain pans to see whether they are susceptible to being damaged. Any non-UV stabilized plastic items are at higher risk. Don’t know what any of this means? Don’t worry, your Solution Inc specialist will be happy to explain everything during your free estimate

They need to run 24/7

Depending on which model you went with your UV light bulb will be running constantly. For example, UV lights fitted in the air handler will be on all the time. In contrast, those placed inside the ductwork will only need to be on when the AC is running. The problem is that not too many of these models come with the option to be turned on and off.

FAQs

I have children and pets. Will a UV light pose any danger to them?

UV lights are only dangerous to pets and children if they come in direct contact with the bulb. Luckily, the lights go inside your air conditioning systems and won’t be accessible to your loved ones unless they are really looking for trouble. UV lights are more dangerous to the germs and bacteria located in your home and air ducts.

Can I purify the air even if the air conditioner is off?

Depending on which model you chose your UV lights will be either running constantly or in sync with your air conditioner. You may also purchase a model that is equipped with a switch.

How often do I have to replace the UV lights?

UV light bulbs typically last around one to two years. Consult with your Solution Inc HVAC professional for more information.

Your home is where you should feel safe and secure. Bacteria and viruses threaten that. Give yourself the best security against bacteria and viruses with its kryptonite: a UV light. Call or visit billhowe.com to find out more about our UV lights. Ask about our virtual estimates.

How do you keep your customers’ homes healthy? For starters, you can include wall caps and roof vents that protect a building’s rainscreen. But the building envelope isn’t the only source of contamination. Sometimes the HVAC equipment itself introduces unhealthy microbes into the air. One way to minimize this and ensure good indoor air quality (IAQ) is to install ultraviolet lights in the HVAC system.

How ultraviolet light works

Ultraviolet light (UV) is part of the electromagnetic (EM) spectrum, which is organized based on wavelength and frequencies. UV light, with wavelengths ranging from 180 nanometers (nm) to 400 nm, falls between visible light and X-rays on the EM spectrum. About 10% of the light from the sun is UV light. The UV spectrum is divided into three categories: UVA, UVB, and UVC. UVA has the longest wavelengths (315–400 nm) and UVC has the shortest (180–280 nm).

The lights used in HVAC work on the UVC spectrum. UVC radiation can break chemical bonds in a process called ionization in which electrons separate from atoms. This separation causes the atoms to break chemical bonds or form new ones. This process destroys bacteria and molds.

The germ-killing powers of ultraviolet light were discovered more than 100 years ago. In 1903, the Nobel Prize for Medicine was awarded to Niels Finson for his work using ultraviolet light to combat tuberculosis. Germicidal lamps have been used in hospitals, indoor garden operations, at food establishments, and for sterilizing water.

For HVAC application, UVC lights are typically installed inside the air handler where they remain turned on 24 hours a day. Any airborne or surface microbes (molds) within the light’s line of sight will be destroyed.

UVC in HVAC

Ultraviolet germicidal lamps destroy airborne and surface microbes. When installed with HVAC systems, they can:

•  Improve heat transfer performance
•  Reduce equipment maintenance costs
•  Improve IAQ

Microbial buildup, sometimes called biofilm, in coils, plenums, and other HVAC components is a common issue that can impact system performance and introduce contaminants into the air. Microbes can reduce system performance by as much as 25% within five years of installation if left unchecked. In some cases, this equipment is difficult to clean. UV lights minimize this buildup, allowing the equipment to run at its most efficient. The ongoing prevention of microbial buildup will also reduce maintenance costs.

Improved IAQ

According to the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE), HVAC systems can either accelerate or slow down the spread of infectious diseases such as influenza, the common cold, and even tuberculosis. With UV lights, building operators can minimize the microbes introduced into the air by destroying them.

In a 2012 study, researchers at Duke University Medical Center and the University of Carolina Hospital System used UVC to kill drug-resistant bacteria in patient rooms. In one example, 98.1% of colony-forming units of bacteria was reduced.

UV light deployment also means that the chemicals typically used to clean biofilm from HVAC equipment will not be introduced into the air, which avoids the introduction of potential respiratory irritants.

Other UV applications

UV technology can also be used in leak detection. The flex inject sealant tool features a UV dye that mixes with refrigerant sealant. The mixture is sent through the system as a mist, and the dye permeates hairline cracks and leaks, which can then be easily identified with a UV light.

By now you may be asking, if UVC is so great, why isn’t it a standard feature in HVAC equipment? One day it might be, but currently, the issue is cost. UVC lights are expensive. And not every household needs UVC lights in their HVAC system. But for individuals with allergies or buildings in humid environments, the additional expense is worth it.