[Bldg-sim] "Opaque" windows

[Robin Mitchell]

If you do decide to use WINDOW 6 to generate the SHGC, you can export an
Energy Plus input "snippet" in IDF format from the Window Library, Reports
button. Make the glazing system, then create a window using that glazing
system, and then you can generate the E+ IDF file for that window / glazing
system / frame system.

 

Robin Mitchell

Windows & Daylighting Group

Lawrence Berkeley National Laboratory 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Liam O'Brien
Sent: Wednesday, February 29, 2012 4:58 PM
To: energy.wwind at cox.net; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] "Opaque" windows

 

Strictly speaking, every construction (window or wall) has a non-zero SHGC.
A portion of absorbed solar radiation will ultimately end up inside a space
(via conduction through the surface and later radiation/convection into the
space). A highly insulated wall will transmit a negligible amount of energy.
The ASHRAE Handbook of Fundamentals (Fenestration chapter) provides a method
for calculating the SHGC of window frames. 

 

For your opaque windows, the transmittance may be zero, but the SHGC > 0.
The magnitude will depend on the construction of the "window"; with higher
U-values leading to a higher SHGC. 

 

Why not use LBNL Window software to calculate it? I ran the following tests
with opaque glass and clear glass. Here are the results:

Plain opaque glass: SHGC = 0.31

Opaque outside, air, Clear inside: SHGC = 0.16

Clear outside, air, Opaque inside: SHGC = 0.5

 

 

Liam O'Brien

Assistant Professor

Carleton University

 

 

  _____  

Date: Wed, 29 Feb 2012 19:11:02 -0500
From: energy.wwind at cox.net
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] "Opaque" windows

It depends which surface is black........  S1 (outside) clear >>>  normal
reflected / transmitted fractions....etc.


On 2/29/2012 7:00 PM, Alex Krickx wrote: 

Hi Robert,

 

If it's an opaque window, can't it be described as a construction/wall
material? Why still define it as a window? 

 

Alex Krickx

 

Alex Krickx, LEED AP

Building Energy Specialist

Serious Energy, Inc.

1250 Elko Dr, Sunnyvale, CA 94089

(t) 408.541.8124

akrickx at seriousenergy.com

 

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-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of RobertWichert
Sent: Wednesday, February 29, 2012 3:59 PM
To: bldg-sim at lists.onebuilding.org; EnergyPro at yahoogroups.com; energysoftllc
Subject: [Bldg-sim] "Opaque" windows

 

Does anybody know a SHGC for "Opaque" windows?  I think they painted 

them black.

 

I don't think "0.00" is appropriate, but I'm willing to listen to reason...

 

 

 

 

-- 

Robert Wichert P.Eng. LEED AP

+1 916 966 9060

FAX +1 916 966 9068

 

 

 

 

 

 

 

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