Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
Years
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 2 (1992), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Where indoor concentrations are high, radon entry into houses with basements is usually due primarily to the convective transport of soil gas through openings in the subsurface part of the building shell. The factors determining the rate of entry may conveniently be divided into those associated with the undisturbed soil and those associated with the structure and its surroundings. This paper uses a numerical model to determine the influence of the latter factors on the soil gas and radon entry rates. The most important of these is the presence or absence of a gravel layer below the slab; the presence of the gravel can increase the radon entry rate through the perimeter gap betureen the foundation footer, slab, and wall (slab-footer gap) by as much as a factor of 5 over that for homogazeous soil. The permeability of the gravel becomes important when the soil permeability is unusually high, i.e., greater than 10−10 m2. Of lesser importance are the thickness of the gravel layer and the radium content of the gravel. The sizes and numbers of openings in the slab are relatively unimportant so long as the total opening area is vey small compared to the slab area. If cracks in the basement walls are major radon entry paths, as in concrete-block construction, the permeability of the soil restored to the region adjacent to the walls after completion of construction (backfill) is the determining factor in convective radon entry through these openings; if the soil is packed loosely, so that there is a gap between wall and soil, radon entry through a wall crack may be further increased by as much as a factor of 7.5. Radon entry rates through the slab-footer gap and through openings in the slab are only weakly influenced by the permeability of the backfill. The resistance of the perimeter gap to soil gas entry becomes significant when the gap width falls below 0.001 m, assuming a soil permeability of 10−11 m2.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: We model radon entry into basements using a previously developed three-dimensional steady-state finite difference model that has been modified in the following ways: first, cylindrical coordinates are used to take advantage of the symmetry of the problem in the horizontal plane, thereby increasing resolution and computing eficiency without signifiant loss of generality; second, the configuration of the basement has been made m e realistic by incorporating the concrete fmtm which sup ports the basement walls and floor; third, a quadratic relationship between the pressure and flow in the L-shaped gap between slab, footer, and wall has been employed; and fourth, the natural convection of the soil gas which follows from the heating of the basement in winter has been taken into account. The temperature field in the soil is determined fiom the equation of energy consmation, using the basement, surface, and deep-soil temperatures as boundary conditions. The pressure field is determined from Darcy's law and the equation of mass conservation (continuity), assuming that there is nofIow across any boundary except the soil surface (atmospheric pressure) and the opening in the basement shell (fixed pressure), Since the energy conservation equation includes both heat advection and conduction, the temperature and pressure equations must be coupled. After the pressure and temperature fields have been obtained, the velocity field is found fiom Darcy's h. Finally, the radon concentration field is found from the equation of mass-transport, assuming that diffusive entry through openings may be neglected. The convective radon entry rate through the opening or openings is then calculated. In this paper we describe the modified model, compare the predicted radon entry rates with and without the consideration of thermal convection, and compare the predicted rates with rates determined from data from seven houses in the Spokane River valley of Washington and Idaho. Although the predicted rate is much lower than the mean of the rates determined from measurements, er-TOTS in the measurement of soil permeability and variations in the permeability of the area immediately under the basement slab, which has a signifiant influence on the pressure field, can account for the range of entry rates inferredfiom the data.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...