Design and Detailing for
Toxic Chemical Reduction in Buildings

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6.1 Steel Frame and Concrete Block Cavity Wall
6.2 Timber Kit Construction
6.3 Steel Frame Construction
6.4 Rehabilitation
6.5 Precast Concrete

 

 
Key Principles

1. Different materials off-gas VOCs at different rates and therefore each can have a different impact on the indoor climate.

2. Benign design has been catagorised here into priorities depending on the type of construction and subsequent use of materials and their impact on indoor air quality.

3. The use of surface finishes/chemical treatments and particle board/MDF can be significant sources of toxicity in all design types.
 

 
General

When it comes to internal air quality, it is wrong to believe that “natural” products are necessarily better for internal air quality than synthetic products. Many toxic substances occur quite naturally, including arsenic, asbestos, formaldehyde, radon and moulds. Also quite a number of “natural” materials may have been treated in the manufacturing process (such as wool, cellulose, wood).

VOC contents can be quite low in some materials such as particleboard, but emission of VOCs can last several years. Whilst some paint finishes can have high VOC emissions but may only emit VOCs for a short period. (1) (Note: The reference numbers in (brackets) for this section refer to Appendix F - Specific Notes found on pages 65-72)

Such a wide range of VOCs can be emitted from building materials that it can be difficult for any specifier to find adequate information about a product or to assess the health risk on the internal air quality. VOC exposure from building products is likely to be highest over the first two years of a building’s life. Indoor VOC levels in older buildings and homes are typically about 7 times as high as outdoor levels (sources include dry cleaned clothes, air fresheners, cleaning materials). A new building will often have VOCs 100 times higher than those outdoors, falling to 10 times the outdoor level in about 2 to 3 months. Different materials will absorb and give off VOCs at different rates. In one German study complaints of the internal air quality started two years after occupancy. Studies found a number of new VOCs which rather than being released at an early stage, were emitting for a smaller but steadier rate over the years (37). Materials with large surface areas such as wall and floor surfaces, potentially have a strong impact on internal air quality, so paints, wall and floor finishes (38) are important when making choices to reduce VOCs and formaldehydes.

6.1 Steel Frame and Concrete Block Cavity Wall
6.2 Timber Kit Construction
6.3 Steel Frame Construction
6.4 Rehabilitation
6.5 Precast Concrete

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