The 3-D conduction equation of the glazing considers constant thermophysical properties and is given by:

SHAPE * MERGEFORMAT

where F(x) = 0<Є Sg(x x, Sg is the extinction coefficient of the glazing and Hx is the length of the edge sides of the cubic cavity. The interior surface boundary condition is calculated by applying the following energy balance:

qabs (Hx, y,z) = qcd-g (Hx, y,z) + qcd-a(Hx, y,z) +qr4 (Hx, y,z) (14)

where qabs(Hx, y,z) is the thermal energy that is absorbed by the solar control coating of the glazing and is given by the heat flux that is transported by conduction in the glass, qcd. g(Hx, y,z), the heat flux that is transported to the interior air by the solar control coating, qCd — a(Hx, y,z) and the net radiative exchange from the glazing to the interior air, qr4(Hx, y,z).

The exterior boundary conditions used are the ones measured and reported in [Flores and Alvarez, 2002]. Figure 2 shows the temperature distribution on the exterior of the glazing that was taken as boundary condition for the mathematical model.

Tg (Hx2,y, z)= Texo(Hx2,y, z)

The boundary conditions for the edge sides of the glazing were adiabatic:

dT, . dT dTg . . dTg. .

-(xAz) = 0 , -x, Hy, z)= 0 , -(x, y,°)= 0 y -((y, Hz )= 0

dy dy dz dz

for Hx < x < Hx+Hx2.