Healthy Homes

Home Builders’ Basics — Indoor Air Quality



indoor air qualityProfessional builders strive to build homes that meet the demands and needs of home buyers. As consumers begin to learn more about indoor air quality, they will start asking more of the home builder. Many consumers are already asking about radon, and as consumer awareness grows, they will be asking more about indoor air quality in general. The purpose of this brief guide is to give home builders, designers and developers, a general understanding of indoor environmental quality and ways to control it in new home construction so that they can respond to growing consumer concerns

Recent research indicates that pollutant levels in the air inside our homes and offices may be two to five times higher than the air outside. Since people spend 75 to 90 percent of their time indoors, the quality of the indoor air has become a major concern. Many of the adverse human health effects arising from indoor air pollution are still not well understood.

Known discomfort, symptoms and health effects of exposure to indoor air pollutants range from mild short-term acute effects, such as sneezing, itchy eyes, and general discomfort, to more serious long-term effects, such as respiratory disorders and perhaps lung cancer. Short-term high exposure to some pollutants, such as carbon monoxide, can cause death. People react differently to different types and levels of indoor pollutants. Some people are very tolerant and rarely experience discomfort or health problems; others are more sensitive to indoor air pollutants.

The National Institute of Allergy and Infectious Diseases has estimated that 11 percent of us, or 22 million Americans, suffer from allergies or asthma caused primarily by reactions to pollen and spores. Allergies can be aggravated by house dust and other pollutants. We are just beginning to recognize the importance of indoor air quality concerns and ways to address them. However, some steps have already been taken to improve the quality of the air in the indoor environment in new and existing residential and commercial buildings.

Examples of steps taken to improve Indoor Environmental Quality:

  •  Radon-resistant construction techniques are becoming standard practice among many builders.
  • Lower formaldehyde-emitting products are being used by many builders and in the manufacture of mobile homes.
  • Asbestos-containing products have been banned or are being phased out by rules issued by the EPA.
  • Lead in solder may not be used in public or private drinking water systems.
  • Builders are learning about mechanical ventilation as a way to control humidity and pollutants.
  •  Electronic air filters have become a popular feature of modern heating, ventilation, and air conditioning (HVAC) systems.
  •  Builders are using sealed combustion furnaces and water heaters or forced draft in an effort to improve energy efficiency and IAQ.

What Are Principal Indoor Air Quality Concerns?

common iaq pollutantsAir pollutants have always been present in the indoor environment. Serious short-term health effects have been alleged and headaches, dizziness and other symptoms have been attributed to higher concentrations of indoor air contaminants, while the consequences of long-term exposure to low levels of indoor pollutants is not known. The levels reached indoors are a function of the presence of pollutant sources, the strength of such sources, the volume and mixing rate of enclosed spaces, indoor moisture vapor and temperature, air exchange rates, pollutant interaction and reactivity rates, and outdoor air quality levels.

Air pollutants and their sources are numerous. Some common indoor air pollutants are carbon monoxide, nitrogen oxide, suspended particulates, formaldehyde and other organic compounds, allergens, smoke, and radon gas and its decay products or “progeny.” Sources of air pollutants are as varied and numerous as the pollutants themselves.

Pollutants are generated indoors from sources such as: fireplaces, woodstoves, smoking, solvents, cleaning products, pesticides, pet dander, micro-organisms, furnishings, certain building materials, water supplies, surrounding soil, fossil-fuel-fired appliances, leaking furnaces, chimneys, and outdoor air which may enter an enclosed space as airborne gases or particles, or carried inside as attached particles or dust.

Other factors which influence indoor air quality are sitting, weather, ventilation and infiltration, environmental control systems, the durability of materials, structure contents, furnishings, structure maintenance, deterioration of both structure and contents, design and human factors.

To address many of these indoor air quality concerns, codes and/or basic standard building practice assure the following conditions are met. If this is not the case in your area, it is highly recommended that you take it upon yourself to provide these basic features in new homes:

  • A dry basement, with no mold or mildew problems;
  • No elevated radon levels;
  • No backdrafting of the furnace, domestic water heater, or fireplace;
  • No lead-containing paint or solder in the water system;
  • No asbestos;
  • No unvented gas or kerosene appliances;
  • Humidity (relative) maintained between 35 to 55 percent;
  • Pesticides applied carefully if required; and
  • Kitchen, bathroom, and sometimes laundry room exhaust fan vented to the outside.

Beyond basic code and standard building practices, there are additional features a builder may choose to offer as an upgrade package to enhance home marketability by appealing to potential buyers with heightened indoor air quality concerns. The upgrade package may include:

  • A ventilation system, with or without a heat recovery system;
  • High-efficiency filtration systems for air and water;
  • Central vacuum system that exhausts to the outdoors (dust remains in the canister);
  • Avoid the excessive use of building materials known to emit formaldehyde and other gases, including hardwood plywood, wall paneling, particleboard cabinets, and carpet underlayment, paints, and finishes; and
  • Non-toxic alternatives to pesticides.

Please contact Renewable Energy for more detailed technical support on improving the indoor environmental quality of your projects. We can help you avoid issues with mold, chemical releases from building materials, and other design and specification problems associated with “sick building syndrome.”