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.

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 for more details.