IAQ—Know the Basics, Implement Common Sense Strategies To Satisfy Heightened Awareness

COVID-19 has heightened awareness on the importance of adequate ventilation and indoor air quality (IAQ) for healthier homes, prompting more builders to incorporate some more of the recommendations from the long-established programs such EPA’s Indoor airPLUS initiative.

Every Indoor airPLUS home must first earn the ENERGY STAR Certified Home label, making them between 15% and 30% more energy efficient than code-built homes.  Additional home design and construction requirements include the careful selection and installation of moisture control systems, heating, ventilating and air-conditioning systems, combustion-venting systems, radon resistant construction and low-emitting building materials.  In order to put the Indoor airPLUS label on the finished product, builders must have their home’s energy performance and key indoor air quality features verified by an independent third-party inspector to ensure that they have met all of EPA’s rigorous guidelines for energy efficiency and indoor air quality.

EPA studies show that levels of many indoor air pollutants can be two to five times higher than outdoor levels. And since most people spend close to 90% of their time indoors, keeping indoor pollution levels as low as possible is the right thing to do.

Too often, modern construction practices tighten a home’s building envelope to the extent that it chokes off essential air that needs to be exchanged through the building shell, potentially contributing to the buildup of indoor air pollutants such as radon, dust mite feces, and volatile organic compounds (VOCs).

Experts claim that nearly 20 percent of the population have higher-than-average chemical or allergen sensitivities.

Measures that can be taken to improve indoor air quality (IAQ) and prevent indoor air pollution include:


Adding mold and moisture protection with water-managed roofs, walls, and foundations is an essential first step.  Care should be taken to create continuous drainage planes and ensure proper site grading, adequate flashing and air sealing, damp-proofing of foundation walls, sealing of capillary breaks and use of drain tile.  The Indoor airPlus program stipulates that basements and crawlspaces are required to be sealed and conditioned and are required to have a drain or sump pump, a layer of aggregate or sand with geotextile matting installed below slabs with radon control techniques applied in certain zones.  If the home has no gutters, it must demonstrate protection from water splash damage.  Supply piping in exterior walls is required to be insulated with pipe wrap and hard surface flooring is required in kitchens, bathrooms, entries, laundry rooms and utility rooms.


Combining physical barriers with proper pest management techniques may reduce pesticide use which is a major IAQ concern.  Fully sealing, caulking, or screening likely pest entry points to keep unwanted critters out reduces allergens in the home and protects against the serious damage the pests can do that can threaten the integrity of walls, woodwork and wiring. The Indoor AirPLUS program requires all openings in the building envelope that cannot be fully sealed to have corrosion-proof rodent/bird screens installed.


Employing best-practice design and installation of HVAC equipment and ducts to minimize condensation problems, whole-house and spot ventilation to help dilute and exhaust indoor pollutants, and air filtration to remove airborne particulates.  EPA requires all IAQ certified homes must be verified to be dry and clean with new filters installed at completion of the project. HVAC equipment must demonstrate the ability to keep relative humidity below 60% in “Warm-Humid” climates.  Duct systems must be protected from construction debris and no building cavities may be used as air supplies or returns.  No air-handling equipment or ductwork may be installed in garages.  Central forced-air HVAC systems must have minimum MERV 8 filters and temporary filters should be installed during construction to protect from dust.  Ozone generators are not allowed.  Clothes dryers must be vented to the outdoors or plumbed to a drain according to manaufacturer’s instructions.

Reducing potential exposure to combustion gases by installing direct- or power-vented gas- and oil-fired equipment, properly vented fireplaces, garages fully sealed from living spaces and equipped with an exhaust fan, and carbon monoxide alarms in each sleeping area. EPA requires that fuel-burning and space-heating appliances must meet emissions standards.  Carbon monoxide alarms are required in each sleeping zone and multi-family buildings are required to implement smoking restrictions and minimize environmental tobacco smoke transfer pathways.  Door closers are required to be installed on all connecting doors to attached garages.  In homes with attached garages with exhaust-only whole-house ventilation either a 70 cfm exhaust fan must be installed in the garage or a pressure test must be conducted to verify the effectiveness of the garage-to-house air barrier.

Reducing sources of pollutants by selecting materials that minimize risk of moisture damage and have reduced chemical content, and ventilate a home prior to occupancy. To attain the Indoor AirPLUS certification, all composite wood products, paints, finishes, carpet, carpet adhesives and carpet cushioning must be certified as low emission.

Meritage Homes is the first national production home builder to make the Indoor airPLUS 100% Commitment across all their divisions, meaning that  thousands of new Indoor airPLUS labeled homes will be added to the national housing stock this year.

Savvy builders achieve superior IAQ with a basic understanding of chemistry, a specific set of construction practices, and a whole house systems approach.

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