You’ve spent a pretty penny on an expensive air purifier. It filters particles, removes smells, even kills germs. It gently hums in the corner of the room as it does its work. As you contemplate your purchase, you wonder idly to yourself, ‘Can air purifiers cool a room?’
What Is An Air Purifier?
An air purifier is a device that removes particles from the air. These particles can be large, such as pollen, or beyond even microscopically small, such viruses, or even gasses. These particles are present to some extent in nearly all the air we breathe, however at high concentrations they can not only create an unpleasant environment but can pose serious risks to human health. An air purifier is used in such situations to create a safer, more pleasant living or working area.
Air purifiers use a variety of methods to cleanse the air. All commercial and home HVAC systems contain air purification apparatuses to remove dangerous particles and infectious agents from the air they blow. Most rely on filters to do so. A consumer-grade air conditioner filter is typically rated 1-4 on the MERV scale[1]. This will remove particles like pollen, dust mites, large aerosol particles, and carpet and textile fibers.
Commercial HVAC systems often use filters with higher MERV ratings, between 5 and 8. These filters remove most microbes, smaller aerosols, and most dust particles. In settings where even finer filtration is required, oftentimes in addition to a higher MERV rated filter, additional purification methods are often employed.
Can Air Purifiers Cool A Room?
Well, maybe. That depends entirely on what else your air purifier might do; purifying air, almost by definition, is not cooling air. However, your air purifier may actually function to cool off your room, at least a little bit. If it contains a strong enough fan, or a cooling element, it almost certainly will. However, it’s important to distinguish these features from air purification, as not all purifiers include them.
Other Ways To Purify Air
In addition to filters, many commercial HVAC systems include additional purification methods, to do things like containing and decontaminating even the smallest of pathogens, and to deodorize the air. One method seen in places like hospitals and research facilities is ultraviolet germicidal irradiation or UVGI. Ultraviolet radiation is the wavelength of light just above what is visible to humans. It’s the light that is emitted by a blacklight, as in a tanning booth, or a dental office.
UV radiation is just energetic enough to strip electrons off of DNA, causing the DNA to become ionized. This damages the DNA and is the mechanism by which UV light can cause both tanning and skin cancer. Sunblock works by absorbing this UV light with metallic oxides and preventing it from reaching the skin cells. Bacteria, viruses, and other pathogens have no such protection. The UV light shreds their DNA, rendering them nothing more than molecular junk. Air passed through a high-intensity UVGI apparatus is very sterile, and safe for humans to breathe.
Does My Air Purifier Just Clean Air, or Can It Cool Off The Room Too?
The answer to that question depends on two things: whether your purifier also contains an air conditioner, and how strong the fan in your air purifier is. Most air purifiers do not include an air conditioner, though all air conditioners function as air purifiers. While there are many options for a consumer to choose from when looking for a device that both cools and purifies the air, most of these devices are marketed and sold as air conditioners, not air purifiers.
Most devices marketed and sold as air purifiers do not contain a cooling apparatus. Barring the inclusion of such a component, air purifiers do not cool the air passing through them. That is not the question at hand, however; that is does an air purifier cool a room. Even without a dedicated cooling apparatus, your air purifier may still effectively be able to help cool your room. That depends on how powerful the fan in your air purifier is.
Fans As Cooling Devices
Fans act as cooling devices by moving air and thereby moving heat. An object loses heat to the air around it until the air reaches the same temperature as the object. Moving the air allows the hotter air to be constantly pulled off the object, with cooler air replacing it. That increases the rate of heat loss in the object, just as placing an object in a stream of cold water will cool it more quickly than placing it in a still body of cold water. A fan can then help to cool off an object by pulling the heat off it more quickly than it would lose it if the air were still.
The faster the air moves, and the more air moved, the faster the object cools. That is why the strength of a fan determines how effectively it can cool something. An air purifier with a powerful fan can cool a room or a person as effectively as a box fan might. An air purifier with a weaker fan may still move air, but it may not move enough air, or move it quickly enough, to effectively make any difference in the temperature of an object, a person, or a room. Placing the air purifier near an open window can increase its effectiveness if the air it draws in from outside is cooler than the air inside.
Should I Use My Air Purifier As a Cooling Device?
It’s probably not worth it. Everything an air purifier can do to cool a room, a fan can do better. And an air conditioner not only moves air around, it actively removes the heat from it. As well, anything your air purifier can do to clean the air, a good HVAC filter can do better. If you want both cool and clean air, the most effective solution is an air conditioning system with a high MERV rated air filter.
Glossary
[1] MERV Scale – Link
