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Reduce Off-Gassing for Better IAQ

Dec. 8, 2006
Start with these three steps to minimize off-gassing in your buildings

Providing clean air for your building's occupants is yet another way to strike an environmentally friendly, sustainable balance. Common building materials may actually be contaminating your building's air. Fortunately, there are cost-effective steps you can take to prevent these harmful chemicals from infiltrating the building environment and making occupants sick.

As defined by the Washington, D.C.-based U.S. Environmental Protection Agency (EPA), volatile organic compounds (VOCs) are "compounds that vaporize (become a gas) at room temperature." This process is referred to as "off-gassing," and building owners are now taking precautions in new-construction and modernization projects to minimize its effect. The EPA's definition warns of potential harmful effects from VOCs, including, "eye, nose, and throat irritations; headaches; dizziness; visual disorders; [and] memory impairment." Although the long-term effects of VOCs in commercial buildings are unknown, some VOCs (such as formaldehyde) are known to cause cancer in humans. The problem is widespread. Owners' quest for energy efficiency, dating back to the 1970s, has often closed buildings off to fresh air, forcing reliance on building-ventilation systems for clean air. According to Air Quality Sciences, an IAQ testing and consulting company based in Marietta, GA, indoor VOC levels are 2- to 5-times higher than outdoor levels. The EPA estimates that indoor VOC levels can grow up to 10-times higher than outdoor levels, especially during construction and modernization projects.

Start with these best practices to reduce off-gassing in your buildings:

1. Research building materials and specify those with low-VOC levels.
The biggest VOC offenders are adhesives and sealants, paints and coatings, carpet systems, composite wood and laminate adhesives, and systems furniture and seating. These materials may not only emit odors (pleasant or unpleasant) during installation, but they may continue to off-gas throughout the life of the material. Pay particular attention to materials selection in the building's sensitive areas (places occupants spend most of their time) and in sensitive buildings (such as healthcare and educational facilities).

Unlike the first generation of low-VOC paints and adhesives, according to the EPA, many of today's VOC-minded products perform as well as those with VOCs. Fortunately, product-certification programs are available to help you specify low-emitting products. For example, the Atlanta-based GREENGUARD Environmental InstituteTM (GEI) certifies a variety of building materials and products that meet the EPA's guidelines for low emissions. The GEI also has a separate certification with more rigid product standards for children and schools. LEED for Commercial Interiors (LEED-CI) also awards 1 point for using qualifying materials in each of the groups listed above.

2. Follow the proper order of materials installation.
To reduce the absorption of VOCs during construction or modernization, you should create guidelines for the installation of interior building materials. These products can be classified into two different groups. Type One materials off-gas for a short amount of time and include composite wood products, adhesives, sealants, glazing compounds, paint, hard finishes requiring adhesive installation, and gypsum board. These components should be installed and allowed to dry before Type Two materials are brought into the building. Called "fuzzy" for their woven, fibrous, or porous construction, Type Two materials often act as "sinks," absorbing VOCs from Type One materials for later release. Materials in this category include carpet and padding, fabric wallcoverings, and upholstered furnishings. If this installation order is not possible (especially in modernization projects), ensure that all Type Two materials are covered with plastic sheeting to prevent VOC absorption.

3. Conduct a building flush-out.
A flush-out is defined by the EPA as a process where "large amounts of outdoor air are forced through a recently completed building for a period of 3 to 90 days so that the majority of pollutant emissions from building materials, finishes, and furnishings can be removed before occupancy." The GEI recommends flushing 100-percent fresh air into the building for 2 to 4 weeks. Although opinions differ on the amount of time needed for a flush-out, the goal is the same - to get chemical levels in the building to acceptable levels (levels needed for LEED-CI certification can be found under Credit 3.2). Owners must find a balance between the costs of leaving a completed building unoccupied and immediately stuffing it full of people with the risk of lingering contaminates. In the 2001 construction of its campus in North Carolina, the EPA found that total VOCs dropped to an acceptable range between 12 and 14 days after the beginning of the 90-day flush-out - evidence that proper planning and steps to prevent off-gassing save time and money in the long run.

Anne K. Goedken ([email protected]) is new products editor at Buildings magazine.

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