<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><DIV><BR class="khtml-block-placeholder"></DIV><DIV>A recent question about optical properties (outside and inside panes)</DIV><DIV><BR class="khtml-block-placeholder"></DIV><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Arial" size="3"><SPAN class="Apple-style-span" style="font-size: 11px;">The absorptions at the external and internal clear float glass layers are taken from DCF7671_06nb, which appear to be:</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Arial" size="3"><SPAN class="Apple-style-span" style="font-size: 11px;">0.157 0.172 0.185 0.201 0.202</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Arial" size="3"><SPAN class="Apple-style-span" style="font-size: 11px;">0.117 0.124 0.127 0.112 0.077</SPAN></FONT></DIV></BLOCKQUOTE><BR><DIV>The treatment of optical properties, as calculated by tools such as WIS and</DIV><DIV>Window 5.2 and used by simulation tools such as ESP-r are based on</DIV><DIV>absorption being calculated from the outside to the inside. </DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>The absorption of an inner layer, is, by tradition, calculated "relative" to that of </DIV><DIV>an outer layers. Another way of saying this is if 100 units reach the outer glass </DIV><DIV>and it absorbs 40 units any inside layers of glass can only know about the </DIV><DIV>remaining 60 units rather than the initial 100 units. The values seen in the</DIV><DIV>optical database take this into account.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>In ESP-r the thermophysical properties of glass are held separately from</DIV><DIV>the optial properties of the glass. A thermophysical material labeled as</DIV><DIV>clear float might have a range of possible optical properties. It is up to</DIV><DIV>authors that define databases and the links between databases to ensure</DIV><DIV>that the names of the entities are clear and the correct associations</DIV><DIV>are defined. It is certainly the case that some of the names that have</DIV><DIV>been given to database entities are a bit opaque. We are working towards</DIV><DIV>allowing longer (and hopefully more expressive names).</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>-ESRU</DIV></BODY></HTML>