<html><body><span style="font-family:Arial; color:#000000; font-size:10pt;">Bldg-Sim & eQuest users,<br><br>When creating a Proposed Baseline building based on ASHRAE 90.1-G and most energy codes, the windows are defined using an Assembly u-value which includes the frame effects. As a result, it is easiest to define the windows using the simplified method in eQuest and a window assembly u-value. In assition, the window dimensions measured to the outside of the frame. When the Proposed or EEM building is created from the Proposed Baseline and it is easiest to define the windows the same way.<br><br>The problem with this methodology arises when a glazing or frame improvement measure is applied followed by a daylighting measure. If high performance coated glazing is used as a measure, the simplified methodology may not correctly accounr for the benefit due to angular dependence and spectral properties.<br><br>From the eQuest documentation:<br><br><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="ProgId" content="Word.Document"><meta name="Generator" content="Microsoft Word 12"><meta name="Originator" content="Microsoft Word 12"><link href="file:///C:%5CDOCUME%7E1%5Cbrycem%5CLOCALS%7E1%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_filelist.xml" rel="File-List"><link href="file:///C:%5CDOCUME%7E1%5Cbrycem%5CLOCALS%7E1%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_themedata.thmx" rel="themeData"><link href="file:///C:%5CDOCUME%7E1%5Cbrycem%5CLOCALS%7E1%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml" rel="colorSchemeMapping"><!--[if gte mso 9]><xml>
Normal
0
false
false
false
EN-US
X-NONE
X-NONE
MicrosoftInternetExplorer4
</xml><![endif]--><!--[if gte mso 9]><xml>
</xml><![endif]--><style>
</style><!--[if gte mso 10]>
<style>
/* Style Definitions */
table.MsoNormalTable
{mso-style-name:"Table Normal";
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-qformat:yes;
mso-style-parent:"";
mso-padding-alt:0in 5.4pt 0in 5.4pt;
mso-para-margin:0in;
mso-para-margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:11.0pt;
font-family:"Calibri","sans-serif";
mso-ascii-font-family:Calibri;
mso-ascii-theme-font:minor-latin;
mso-fareast-font-family:"Times New Roman";
mso-fareast-theme-font:minor-fareast;
mso-hansi-font-family:Calibri;
mso-hansi-theme-font:minor-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;}
</style>
<![endif]-->"If you are doing a daylighting calculation you can also enter VIS-TRANS, the visible transmittance of the glazing at normal incidence.<br>In the shading coefficient method the solar heat gain through the window is first calculated for standard, 1/8-in thick clear glass, then multiplied by the shading coefficient. Because this method uses the angular dependence of solar transmission and absorption for standard glass rather than the actual angular dependence, it can lead to errors, which are generally small (less than 10%) for monthly integrated solar gains but can be large (up to 30% or so) for peak solar gains for multipane or coated glazing. Another limitation of the shading coefficient method is that the conductance does not depend on the temperature difference across the window."<br><br>As a result, it makes sense to define the windows using the glass layers methodology in the Baseline. The problem is finding the glazing layers that correspond to the Baseline glazing in the Glass Library or creating the correct definition using Windows 5.<br><br>I am interested in learning how others have dealt with this issue.<br><br>Thanks,<br><br>Bryce<br><br><br></span></body></html>