Reducing Indoor Air Pollution in Residential Construction and Home Contracting.

Indoor Air Quality should be a major goal for all residential construction companies

Asheville NC is well known in the residential construction industry for having many green home builders and custom construction companies proficient in building healthy, eco-friendly homes. While not everyone is willing to spend extra to lessen their custom home’s environmental impact, most people are interested in having a home with healthy Indoor Air Quality IAQ.

Diagram showing the many sources of indoor air pollution. Building a new custom home is an excellent opportunity to address these problems

Building a new custom home is a great opportunity to address Indoor Air Pollution.

Healthier Indoor Air Quality is one of the best reasons for building a new home. Much like improving an existing home’s building envelope or energy efficiency, its far easier to build IAQ into a new home as opposed to fixing existing construction.

Three main approaches for improved indoor air in residential construction:

1. Choose construction materials that limit harmful off-gassing.                                                  examples: Low VOC paint, Open web floor trusses instead of TJIs to                                                      reduce formaldehyde exposure.

2. Limit the “occupant behavior” factor. Reduce pollutants through behavior and         removal at the source.                                                                                                                    examples: No tobacco smoke or indoor insecticides. Bath fans for                                                         humidity control, Vent hoods for reducing NO2 and cooking                                                   particulates.

3. Provide Outdoor Air with mechanical ventilation.                                                                      example: Supply fresh air per ASHRAE 62.2 ventilation standards.

Many residential construction products emit harmful gasses like formaldehyde and Volatile Organic Compounds VOCs. There are many options and alternatives available that can reduce exposure. This approach helps but often healthier building products tend to be more expensive and sometimes less durable.

For the most part, its almost impossible to eliminate ALL of the offending construction materials. Then comes electronics, furnishings, appliances, CO2, humidity, etc.. and it becomes clear that solution #1 is not enough to provide sufficient IAQ.

Pie chart showing that building materials are only a small part of the IAQ pollution sources in new, residential construction

Construction companies, new homes and custom home builders should be focusing on outdoor air introduction with mechanical ventilation above all else. According to NIOSH, building materials account for only 4% of a typical home's Indoor Air problems.

Outdoor Air is MUCH more important than eco-friendly building materials.


Most experts agree that mechanical ventilation is the best way of providing better IAQ. A better term for mechanical ventilation may be fresh air introduction. Outdoor air is almost always cleaner than indoor air. No matter how much we reduce harmful materials inside the living space, its a best practice to supply outdoor air to a home in a controlled manner through mechanical ventilation.

Be a control freak

Controlling air is good. Having control over conditioned air and fresh air should be one of a builders and homeowners most important goals. This is why it is important to build air-tight. The more leaky and drafty a home, the less control over expensive conditioned air and delivery of fresh air. Building air-tight is another good reason for going with new construction and custom homes.

Be conservative and extremely careful with combustion appliances

The best way to eliminate risks from combustion appliances is to avoid them altogether. This is an increasing trend among high performance home builders. “All-electric” homes are safer from danger of fire and have healthier indoor air quality.

Picture from Energy Vangaurd blog showing atmoshpheric combustion water heater existing house construction

Energy Vangaurd's picture of an atmospheric combustion water heater in existing construction

Do not use atmospherically vented appliances and especially vent free fireplaces. Power vented and direct vented combustion appliances need to be meticulously installed and regularly inspected. Even a properly installed, power vented appliance can eventually be a source for indoor air pollution.


Induction Cooktop with cross section of pan and half melted chocolate bar.

Induction cooktops have the best indoor air quality.


Strongly consider an Induction cook top instead of gas. Due to their cool surfaces, they have better indoor air quality than conventional electric cook tops. Gas cook tops have the worst Indoor air quality. Vent hoods should always be vented outside. Down draft vent hoods require special care in layout and installation and rarely perform as well as overhead.

Avoid parking the car in your house

Garages are a major source of indoor air pollution and can introduce dangerous situations. Detached garages are the best. The more attached the garage, the greater the risk. There are strategies available for dealing with the dangers of attached garages but its always risky when a garage shares a wall with the home. There have been many cases of death from automobiles left running in a garage.

Diagram of a home construction showing sources of carbon monoxide

The Attached Garage is an often overlooked source of Indoor Air Pollution in residential construction.

Avoiding attached garages and combustion appliances in new construction is an easy way to eliminate indoor air pollution sources.

Air-tight Building Envelopes and mechanical ventilation gives us control over the where, when and how air moves in our houses and new construction.


Providing fresh air introduction is easier when we know exactly where it is going and coming from. A leaky basement or sub-floor can introduce radon, excess moisture and mold spores. A drafty attic can bring in hot temperatures and outdoor humidity. Humid air leaking through random cracks in the building envelope can cause mold growth inside walls and other hidden building cavities.


We can also control when the building breathes.  In extreme weather or times of high pollen, turning down the ventilation might be better. During times of kitchen use, cooking odors and smoke, dialing up the ventilation can help clear the air quicker.


How we provide the ventilation is where things get more interesting. ASHRAE 62.2 provides the minimum ventilation requirements that International Building Codes recognize. There are many strategies and variables to consider in a well designed ventilation system for new home construction. We will explore much more in our future posts. How exciting!

Providing fresh, outdoor air with mechanical ventilation is probably the best way to reduce indoor air pollution in residential construction and home contracting projects. Visit our understanding ASHRAE 62.2 for builders and new construction home buyers for more on this important topic.

Springtime Homes are custom green builders that specialize in Indoor Air Quality among North Carolina new home builders.


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