Sol-air temperature

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Sol-air temperature (Tsol-air) is a variable used to calculate cooling load of a building and determine the total heat gain through exterior surfaces. It is an improvement over

\frac{q}{A} = h_o(T_o - T_s)

where

ho = heat transfer coefficient for radiation (long wave) and convection
To = outdoor surroundings' temperature
Ts = outside surface temperature

This equation only takes into account the temperature differences thus, ignoring solar radiative flux and infrared exchanges from the sky. The Tsol-air was then introduced to accommodate these two parameters.

T_\mathrm{sol-air} = \frac{T_o + (a \cdot I - \Delta Q_{ir})}{h_o}

where

a = solar radiation absortivity of a surface
I = global solar irradiance
ΔQir = infrared radiation transfer of sky temperature to surface

and is to be used in

\frac{q}{A} = h_o(T_\mathrm{sol-air} - T_s)

[edit] References

  1. Fundamentals volume of the ASHRAE Handbook, ASHRAE, Inc., Atlanta, GA, USA, 2005
  2. Heating and Cooling of Buildings, 2nd ed., Kreider, Curtiss, Rabl, McGraw-Hill, New York, USA, 2002

[edit] See also