How do we cope with a crawlspace with a concrete floor?

The modelling concept for vapour intrusion to indoor air assumes that the crawl space has no floor, i.e., the crawl space is in direct contact with the soil. If you have a crawl space with a concrete floor, then the model concept will overestimate concentrations and be too conservative.

For simulating a crawl space with a concrete floor, you can take a stepwise approach.

  1. Select the "basement" option in the "Indoor" tab, enter dimensions for the basement equal to the effective crawl space dimensions, and set the volume of the indoor space to 0 m³ and the basic air exchange rate for indoor space to 19.2 d-1 (default value for a crawl space);
  2. Perform a simulation run and note the resulting indoor air concentration (i.e., “indoor air concentration from volatilization (mg/m³)” within the section “Building: General” of the detailed report);
  3. In a second run, select "crawl space" in the "Indoor" tab and enter the real dimension for crawl space and indoor building volume (groundfloor) as appropriate for the site;
  4. The indoor air concentration from the first run can now be filled in as a measured "Crawl space" concentration in the "Concentrations" tab.

last modified on 25/11/2016 - 11:37

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