Ventilation, Purification & Filtration, What’s the Difference?
Updated in 2025 / originally published August, 2020:
COVID-19 raised awareness of the importance of cleaning and decontaminating the air in our homes and workplaces. Recently, the media has been using the word “ventilation” a lot when talking about sending our kids back to school. However, ventilation alone will not provide the cleanest air possible. Ventilation isn’t synonymous with purification & filtration – it’s part of the clean air equation.
Ventilation, purification, & filtration each play an important role in achieving the best indoor air quality possible. When properly used together, the air in our homes & buildings can actually be cleaner than outdoor air.
While the media is only focusing on schools needing ventilation; we should really be considering decontaminating indoor air everywhere. Most importantly, in our homes where we spend the majority of our time. COVID-19 aside, there are many health benefits and even financial benefits (think lost time at work from sickness) to gain from improving indoor air quality.
I originally published this article in the summer of 2020 when, for obvious reasons, there was a spike in interest in indoor air quality. However, the desire to breathe clean air and make sure our children are breathing clean air is no less important now. The American Lung Association recommends many of the solutions we’re going to discuss in this article – and so do I.
I decided to update this article after seeing the following post in a Facebook group I’m a part of (a local neighborhood group):
Hi, friends! We’ve had our AC on the past few weeks, and my sinuses get so awful that I can’t sleep. I’ve been to several ENTs, so I’m beginning to think it’s my AC unit/vents. Could it be mold? Who do we call for this type of service? Thank you!!
I commented the following on that post and included a link to this article:
We publish a blog with dozens of articles that will help you understand what the best solution for YOU is. This one covers the basics and will give you a better understanding of where to start. From there, just use our search tool (magnifying glass icon) and you’ll definitely find the info that will help your particular issue!
What is Air Ventilation?
‘V’ is the Ventilation in HVAC (Heating, Ventilation, & Air Conditioning). It’s also the most overlooked, underutilized and often misunderstood part of my craft.
Defined, ventilation is the intentional addition of outside ‘fresh’ air and the removal of ‘stale’ indoor air. There are several ways to accomplish fresh air ventilation in a home or building. I’ll discuss some of these methods and/or provide links later on in this article.
It’s important to know that not all ventilation systems ‘clean’ the air they introduce into the building. However, according to the EPA (Environmental Protection Agency), outdoor air can be 10% cleaner than the air in our home. That said, if not filtered first, you’re still introducing contaminants, pollens, dust and other pollution into the building. For that reason, we recommend mechanical ventilation, I.E. bypass filtration or a recovery ventilator be used to clean the air first . These devices clean the fresh air through HEPA filters prior to blowing into the home.
What is Air Purification?
Air purification is the process of removing contaminants in the air by destroying or ‘killing’ them. Two of the most popular and effective air purification methods are UVC light (Ultraviolet) and Photocatalytic Ionization. Most commonly referred to as air scrubbers, photocatalytic ionizers combine UVC light with a catalyst to induce a chemical reaction. Basically, they kill contaminants and change their state to water or carbon dioxide. The first air scrubber to be used for this purpose was developed by NASA for the space shuttle program. NASA still uses this technology today.
What is Air Filtration?
Air filtration is the process of ‘trapping’ airborne contaminants such as dust, pollen, dust mites, and dander from recirculating. Filtration serves two important roles in the air quality equation. First, air filtration keeps dust from accumulating on your air conditioner coils. Even a slightly clogged air conditioner coil can significantly reduce an air conditioner’s efficiency and performance. Second, air filters trap dust and contaminants in a fibrous media to prevent us from inhaling them as we breathe.
Like any other consumer product, all air filters and filtration systems are not created equally. The most common type of air filter (1” disposable) like found in big box stores, are largely ineffective. Disposable filters are designed to offer some protection to the equipment coils, not to human lungs. Conversely, 4” MERV 16 pleated air filters are proven to be a very effective IAQ strategy and are endorsed by the American Lung Association.
Ventilation, Purification & Filtration Combined Equal the Cleanest Air Possible
I was originally prompted to write this article after receiving a question via Email from a Texas homeowner (outside of the Magic Touch Mechanical area). I thought the answer to her question would be helpful to many people, hence my response – this article.
Which Produces the Best Results Ventilation, Filtration or Purification?
Her contractor recommended installing a fresh air ventilation system instead of purification & filtration. Before I continue I should note that I’m actually familiar with her selected contractor, I’m very active in the national HVAC scene and have come across them before. They’re a very reputable HVAC Company and have seen her home’s application. In other words, although I recommend a three pronged clean air plan (ventilation, filtration, & purification), her home design may not make that feasible. Perhaps their recommendation is more feasible in this particular application.
This is a perfect example of why we (Magic Touch Mechanical) won’t give an exact quote on an installation without inspecting the home first. Everyone’s needs, budget, and application is different. We need to see the details personally to give the best advice for each application. Using her home as an example, site unseen, I do not know the location of her AC’s air handler, ducting, if there is attic space for equipment or not, etc.
Before asking her question, she explained what was most important to her and what she’d hoped to achieve. Her question was:
If money was the least important factor, should she purchase a ventilation system or a filtration/purification system?
I answer her question specifically at the end of this article. First thought I should elaborate on the equipment used to accomplish the three IAQ factors.
It’s Not Always Cut & Dry
Everyone’s health requirements are different and every application is a little different. Some people are battling allergies, others have lung diseases such as, COPD, lung cancer, or emphysema. Still others just want to make sure the air their family is breathing is as clean/healthy as possible – and whom amongst us doesn’t want to breathe clean air! Below are a few examples of what I mean.
Different Health Requirements
Allergy sufferers can be greatly impacted by pollens, dust, ragweed, dander, etc. For these folks, quickly removing these contaminants from the air they breathe is critical. In this case I’d recommend filtration and purification first, ventilation second (provided budget and space allows). This would also be my recommendation for anyone with asthma or chronic lung disorders such as COPD.
One product we highly recommend takes care of two of the three ingredients for air cleaning – the Lennox Pure Air. The Lennox Pure Air Purification System combines both UVC Light purification with MERV 16 air filtration in one device. The Pure Air is the only product on the market right now that both filters and purifies in one compact cabinet. It regularly tops Consumer Reports and Good Housekeeping lists for whole home air cleaners. I have access to many IAQ products and use the Lennox Pure Air in my own home.
Pro Tip: The Lennox Pure Air Purification System can be used with existing HVAC systems from most manufacturers. In other words, your existing system doesn’t have to be a Lennox in order to attach a Pure Air. Magic Touch installs a dozen different air conditioning brands and install the Lennox Pure Air with AC’s from other manufacturers almost daily.
Now would be a good time to mention that I am not being paid be Lennox for endorsing this product, nor do I own stock in the company. We sell plenty of Lennox products, but we also sell products from 11 of their competitors.
Different Applications & A Word of Caution
Some of today’s super ‘tight’ homes barely meet minimum ACH (Air Changes per Hour) code requirements. We highly recommend mechanical ventilation in these types of ‘tight’ homes. Stale, contaminated air is a health risk to us all but specifically to anyone with a breathing disorder.
The best way to accomplish mechanical ventilation in my opinion is an HRV (Heat Recovery Ventilator) or ERV (Energy Recovery Ventilator). Not only does this method pre-filter the air it brings into the home, it tempers the air for better energy efficiency.
Other methods, such as certain types of exhaust fans can create other issues, especially when designed or installed improperly. It’s best if the designer and installer understands building science, not just A/C when talking ventilation. These installations rely on natural infiltration of outside air to replace the volume of air removed by the fan. By natural infiltration, I’m referring to outside air being pulled in through cracks and crevices, around doors & windows and through attics and wall outlets. This method is not only bringing in unfiltered air, often its sucking in dusty, contaminated attic or wall-chase air. A poorly designed ventilation system can also wreak havoc on your A/C unit and utility bills by rapidly removing conditioned air. We see this most often when people install powered attic fans without properly sealing the home envelope first.
Pro Tip: Take the following statement as you’d like, just remember I’m providing information and not trying to sell you a product. I also hold multiple certifications in building performance, energy auditing, and indoor air quality.
99% of the time, I do not recommend installing attic fans. Many people do so thinking cooling their attic will keep their home cooler and reduce their power bill. I regularly see Phoenix air conditioning companies selling and installing them, often with the opposite results. You’re far better served with a good attic insulation plan, sealed and insulated ducts, and air sealing (if needed). This is also coming from a guy who could sell attic fan installations all day long and make good money doing so – but it’s not the right thing to do, so we don’t. There was a time when I did think attic fans were a good thing – now with better testing technology and better information I know they’re not.
Which is the Best Method for Decontaminating Indoor Air?
Again, in a perfect world, with no budgetary constraints or installation challenges, having good ventilation, filtration, and purification combined would be best. Assuming no special conditions or considerations for the occupants, and not being able to have them all for whatever reason – in order of importance: Filtration, Purification, then Ventilation.
The Answer
If money were no object and the application allowed for it (room for equipment, ducting, electrical, etc.), all three would be ideal. As ventilation, filtration and purification all produce a different result, all three combined deliver the best possible result – fresh, decontaminated air.
It is possible to install a product like the Lennox Healthy Climate HEPA Bypass Air Filtration system to run independently of your homes HVAC system. In other words, the home itself would have its own filtration separate from the air conditioners filtration system. If set up to run independently (not ducted through the cooling & heating ductwork), one could have both a bypass air filtration system and a product like the Lennox Pure Air. This would be the ultimate IAQ system in my opinion and provide ventilation, purification, & filtration to the entire home. Some might say such a setup is overkill but the question posed to me was, what would I recommend if budget was not a limitation.
Finally for my Texas friend: As we’ve exchanged Email before, you know I write these articles to help people better understand all things comfort, efficiency and clean air. That said, I can’t stress enough there are many variables from one homes application to the next. Since you happened to mention the company, and it just so happens I know who they are, I know you’re in good hands! I would pose this “ultimate option” to them and find out if it’s feasible, or even possible in your home. I would then go with their advice since they’ve seen the home’s design and application and I have not. Hope that helps!
