Investigation of a Model for the Ventilation of Suspended Floors

  • YEAR
    Williamson, Terry
    Delsante, Angelo
    2006 Conference Papers
    Building and Energy


ABSTRACT: International Standard ISO 13370 “Thermal performance of buildings — Heat transfer via
the ground — Calculation methods” provides a method to calculate the R-value of a suspended floor.
The method is a modification of a methodology first published in the CIBSE Environmental Design
Guide A -1998. The thermal network that forms the basis of the CIBSE calculation includes radiative
transfer between the suspended platform and the ground, conductive components and a sub-floor
ventilation component. In the ISO 13370 methodology the surface resistance (the inverse of the
combined convective and radiative co-efficient) is used as a proxy for the more explicit calculation (as
is done in most building heat transfer calculations). This paper deals with the ventilation component of
the ISO 13370 calculations. This component would seem to have its origins in an infiltration model
developed during the late 1970s and early 1980s by Max Sherman and others at LBL. It is a singlezone
model that incorporates both stack and wind induced effects. This paper investigates whether this
model can in fact be applied to sub-floors and shows how an “exact” formulation may be derived from
first principles.


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