November 2025 EnergyWiseSM Tip: Clearing the Air
By: NPPD Energy Efficiency Program Manager Cory Fuehrer
In 2001, the Lawrence Berkeley National Laboratory published the results of the National
Human Activity Pattern Survey. It revealed that, on average, Americans spend 87% of their time
indoors and an additional 6% in enclosed vehicles. In 1800, 90% of Americans worked outside.
200 years later, less than 20% did. As more of our daily lives have been spent inside, the number
of people with respiratory diseases, heart disease, certain types of cancer and/or other health
problems has dramatically increased.
The U.S. Environmental Protection Agency (EPA) defines Indoor Air Quality (IAQ) as the air
quality within and around buildings and structures, especially as it relates to the health and
comfort of building occupants. Understanding and controlling common pollutants indoors can
help reduce the risk of indoor health concerns. While a great deal of energy can be used to purify
indoor air, the EPA suggests three basic strategies to mitigate the problems while minimizing the
impact on energy costs.
Source Control
Quite often, the most effective way to improve IAQ is to eliminate individual sources of
pollution or to reduce their emissions. Some sources, like those that contain asbestos, can be
sealed or enclosed. Others, like toxic and other byproducts from gas stoves or furnaces, can be
adjusted or replaced to decrease the amount of emissions. Many activities such as cooking,
painting, paint stripping, welding, soldering, or sanding can be taken outside or performed in a
mechanically ventilated area. Smoking should never be done inside. Pets can be bathed to reduce
their dander. Excess moisture in basements and other high humidity rooms can be managed with
a dehumidifier, if necessary, to lower relative humidity to 50% or lower. In many cases, source
control is also a more energy and cost-efficient approach to improving IAQ than increasing
ventilation.
Ventilation
As long as the outside air is fairly pollutant-free, bringing fresh air into the home is an effective
approach to lowering the concentrations of indoor air pollutants. However, ventilation often
requires filtering, heating, cooling, dehumidifying or humidifying. Some homes, especially much
older ones, are “leaky” and exchange plenty of indoor and outdoor air through gaps and cracks
around foundations, windows siding and attics. But others, especially newer ones, tend to be
sealed tightly and require additional ventilation. While opening a window and operating a
ventilation fan is a simple way to bring in outside air, considerable energy use is necessary to
make the air comfortable. For these homes, installing an energy recovery ventilator that replaces
indoor stale air with fresh outdoor air while transferring heat into or out of the incoming air
depending on the season is the most efficient and practical solution.
Air cleaning
Research shows that filtration can be an effective supplement to source control and ventilation. It
turns out that 67% of U.S. homes already have a central heating, ventilation and air-conditioning
(HVAC) system. If the system’s blower fan is powerful enough, a filter can be installed to create
a highly effective whole house air purifier. Filters are rated on a Minimum Efficiency Reporting
Value (MERV) scale that ranges from 1 to 20. The higher the number, the smaller the particles it
can effectively filter. A MERV rating of at least 13 is necessary to capture 95% of dust, pollen
and smoke particles, which can be as small as 0.3 microns in size. High-Efficiency Particulate
Air or HEPA filters have a MERV rating of at least 17. However, not all HVAC blowers are
powerful enough to overcome the increasing air resistance of the filter as the MERV rating
increases. Always check with a certified HVAC professional before installing a filter with a
higher MERV rating than your system currently uses.
Another way to filter air in a single room or area is to use portable air cleaners, also known as air
purifiers or air sanitizers. A standard room air cleaner, operating continuously, can use 250 to
500 kilowatt-hours a year in electricity. This is more than the energy used by some new
refrigerators! Note that the energy efficiency of an air purifier is determined by its Clean Air
Delivery Rate-to-Watt (CADR/Watt) ratio, where a higher number means more efficiency. Look
for a rating above 1.9 for smaller units and a rating above 2.9 for units designed to provide 150
cubic feet or more of filtered air per minute.
For more detailed and extensive information about IAQ, The EPA provides “The Inside Story: A
Guide to Indoor Air Quality.” In addition to expanding on the importance of IAQ in your home,
it offers additional ways to mitigate poor quality air and where to go for professional help.
In partnership with Nebraska Public Power District, your local public power provider is happy to
help you explore the most efficient way to keep the air in your home or business healthy and
clean. Contact them or visit www.energywisenebraska.com for more details.


