Cleaning the Air: Part II

By Hannah McKenzie
Cleaning the Air: Part II

A high-efficiency pleated central air cleaner.

Q: I do not want a freestanding air cleaner sitting in my house. Is a whole house air cleaner a good alternative to improve the air in my home and my health?

A: A whole house air cleaner can be a simple air filter or an expensive cleaning device attached to your home’s HVAC system. An air cleaner cannot replace frequent house cleaning, use of exhaust fans or air filter replacement. Air cleaners can improve indoor air quality but have not been sufficiently researched for health benefits. Before proceeding with installation of an air cleaner, the ductwork should be properly sealed with bucket mastic.You should take three steps before considering an air cleaner.

Air filters

Most homes with forced air systems have a one-inch thick filter in the air return. This filter protects the guts of your HVAC system from getting coated and clogged with dust. If you want the air filter to also function as an air cleaner, trash the flat filter and use a pleated filter with a minimum efficiency reporting value (MERV) of 8 to 12. Pleated filters cost $5 to $15 and have a zigzag surface that creates more surface area to capture particles. Unfortunately, not all manufacturers label their filters with the MERV, so you might need to do a little homework to find the MERV to compare products.

Be diligent about changing dirty air filters because limited air flow can shorten the life of your HVAC system.

Another option is two-to-five-inch thick pleated filters that are installed by a mechanical contractor at the air return grill inside the house or at the air handler. These filters are often replaced annually, capture smaller particles and are more expensive than one-inch filters.  If the air handler is in the crawlspace or attic, be willing to crawl through cobwebs on a regular basis.

Whole house air cleaner

Spending upwards of $1,000 on a whole house air cleaner to improve your health or home is a gamble. 

In 2010, The Journal of Allergy and Clinical Immunology published an article that summarized the last 30 years of research on the health benefits of air cleaners. They concluded the health benefits are debatable because studies have not been long enough, not had enough participants, not included placebos, not gathered thorough data…and the list goes on. The authors say that air cleaners — portable, HVAC filters, or whole house units — are likely to keep allergies from getting worse but no one can be sure.

Aprilaire, Trane and Lennox are just a few of the many brand options. These systems attach to the HVAC system and clean the air with an air filter and/or electrostatic precipitator. Electrostatic precipitators capture particles similar to your hair sticking to a balloon, and generate low levels of ozone, a lung irritant. Air cleaners without electrostatic precipitators are preferable.

Do not bother with air cleaners featuring ultraviolet germicidal irradiation (UVGI) and photocatalytic oxidation (PCO) because they are marginally effective.  Find out the maintenance regime and filter replacement costs of whatever type of unit you are considering. Also, the unit’s location needs to be logical so you can easily maintain it.

Choosing an air cleaner is a judgment call based on your need for better indoor air quality and budget. Start with a better air filter. If you see improvement and would like more of an improvement, try a portable air cleaner or hire a contractor to install a four-inch air filter.

If you are gaga over the improvement and can afford it, perhaps you are ready to try a whole house air cleaner. Hopefully, in the coming years, research will reveal if these devices have the potential to improve our health

 

About the Author

Hannah McKenzie is a residential building science consultant at Advanced Energy in Raleigh who specializes in working with nonprofit developers like Habitat for Humanity to make new affordable housing energy efficient.

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