[Equest-users] Glass center-of-glass to assembly U-Value?

[Daniel Grammier]

According to the California Energy code (Title 24) Non-Residental ACM manual
Section NI.1:

NI.1 Solar Heat Gain Coefficient
This section describes the alternative calculation method for determining
compliance for eligible site-built
products. The following equation may be used to calculate the fenestration
product's SHGC used to
determine compliance. Convert the center of glass SHGC, SHGCc, from the
manufacturer's documentation
to a value for the fenestration product with framing, SHGCfen,
SHGCfen = 0.08 + 0.86 X SHGCc
Where:
SHGCfen is the SHGC for the fenestration including glass and frame.
SHGCc is the SHGC for the center of glass alone

This is how California defines the overall SHGC for code compliance.  I'm
not sure where they got the equation from, but I have used it successfully
in the past.

Daniel Grammier, LEED AP
Mechanical Engineer IV
Syska Hennessy Group
9665 Granite Ridge Dr #110
San Diego, CA 92123


On Mon, Sep 22, 2008 at 9:06 AM, Josh Greenfield <
JGreenfield at primerachicago.com> wrote:

>  Does anyone have any rules of thumb on a quick/easy approximation for
> taking a Center-of-Glass U-value and converting it to an Assembly U-value
> based on industry standard assembly constructions?  I know this depends on a
> lot of variables, like frame material and conductance, and the size of the
> overall glass assembly, etc., but I'm just looking for a quick estimate on
> performance reduction for comparisons to other window types for a particular
> building.
>
>
>
> Also, is there an ASHRAE 90.1-2004 Baseline glass Visible Light
> Transmittance (VLT)?
>
>
>
> Josh Greenfield, PE, LEED AP
> Senior Associate
> Primera Engineers, Ltd.
> 100 S. Wacker Drive, Suite 700
> Chicago, IL 60606
> 312.606.0910 Main
> 312.242.6392 Direct
> 312.606.0415 Fax
> jgreenfield at primerachicago.com
> http://www.primerachicago.com
>
> Be Green...please consider the environment before printing this email.
>
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