SHGC formula for frame

[Ale]

Hi all,

have you ever calculated the SHGC of a whole product using spreadsheet and not Window7?

Using the following formula

of the NFRC Simulation manual (pag.8-246), the U-factor of frame to consider is the one obtained (with Therm) with boundary conditions for SHGC:

Tout = 89.6°F and hc=2.64 (wind speed 6.15mph)

Tin = 75.2°F

or do I have to consider the boundary conditions:

Tout = -0.4°F and hc=4.579 (wind speed 12.8mph)

Tin = 69.8°F

and then apply hc = 3.63Btu/h.ft2.K (20.6W/m2-K) in the formula?

I hope someone can clarify it to me.

Thank you in advance.

Regards,

A.

[Steve Zhou]

Hi A.

As per NFRC-200,

(i) the U_frame in the SHGC formula is calculated using winter nighttime condition.

(ii) the h_out contains convection and conduction, and 30 W/(m2K) is used by WINDOW .

You may want to use both spreadsheet and WINDOW to calculate the same window for verifying.

Regards,

Steve