<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"> <META content="MSHTML 6.00.2900.3020" name=GENERATOR></HEAD> <BODY> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>Gulsu,</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>the problem in ESP-r is that the g-value is not calculated (and used) explecitly.</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>A more sophisticated model is used: 1-D-finite differences together with heat sources</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>in the glaz panes; the heat source is the absorption of solar radiation within the</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>glaz panes. But nevertheless you could get a g-value from the results library</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>(varying with time) in the </SPAN></FONT><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>following way:</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>In common the g-value shows two parts: The transmission of solar radiation and</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>the so called secondary heat gain, which represents the heatflux from the inner</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>surface of the glazing into the room. The sum of solar radiation transmission and</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>secondary heat flux is the g-value.</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>In ESP-r the solar radiation transmission is calculated </SPAN></FONT><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>depending on the angle of </SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>incidence of the sun (based on the </SPAN></FONT><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>values given in the optics-lib). The problem is </SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>that ESP only calculates the entering </SPAN></FONT><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>solar radiation as the sum over all glazing </SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>(see toggle solar process in <FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>the res-modul). So you can use this value for </SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>solar radiation transmission for the first part of the g-value only if you have one</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>single window - otherwise you have to splitt this value in several parts and assign</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>them to the different glazings. And be aware that this value varies with time - as</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>the sun is changing it´s incidence angle during day .....</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007></SPAN></FONT></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>The second part of the g-value - the secondary heat gain - must also be extracted</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>a little bit elaborately: You have to look at the surface balance of the glazing</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>(inner surface towards the room) </SPAN></FONT></SPAN></FONT><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>and the sum of convective and longwave radiative </SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>heatflux is the secondary heat </SPAN></FONT></SPAN></FONT><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>flux of the g-value. </SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>But be aware that this heat fluxes also vary with time, as the</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>absorption of solar radiation within the glaz panes varies with time (again </SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>corresponding to the incident angle of the sun) and also the convective and</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>radiative heat fluxes into the </SPAN></FONT></SPAN></FONT><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>room vary with time, corresponding to cooling,</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>internal heat gains, etc.</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007></SPAN></FONT></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>Overall you can get a variable g-value for your glazing, which is a little bit elaborately</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>to calculate. Thus you might ask the ESP development team to include an additional</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>output - the g-value - for each glazing in future versions of ESP-r.</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007></SPAN></FONT></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007>-Gunter</SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007></SPAN></FONT></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007> <P><FONT size=2>--------------------------------------------<BR>Dr.-Ing. Gunter Pültz<BR>Müller-BBM GmbH<BR>Robert-Koch-Str. 11<BR>82152 Planegg bei München<BR>Telefon +49 (89) 85602-336<BR>Telefax +49 (89) 85602-111<BR><A href="http://www.mbbm.de/" target=_blank>http://www.mbbm.de</A><BR>email:plz@mbbm.de</FONT> </P>  </SPAN></FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007></SPAN></FONT></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007><FONT face=Arial color=#0000ff size=2><SPAN class=984255106-01022007> </SPAN></FONT></SPAN></FONT></DIV> <BLOCKQUOTE dir=ltr style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px"> <DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma size=2>-----Original Message-----<BR><B>From:</B> esp-r-bounces@lists.strath.ac.uk [mailto:esp-r-bounces@lists.strath.ac.uk]<B>On Behalf Of </B>Gulsu Ulukavak Harputlugil<BR><B>Sent:</B> Wednesday, January 31, 2007 8:52 PM<BR><B>To:</B> esp-r@lists.strath.ac.uk<BR><B>Subject:</B> [esp-r] g-value analysis<BR><BR></FONT></DIV> <DIV>hi,</DIV> <DIV>for a sensitivity analysis, one of my parameter is g-value of glazing. But I could not modify "only" g-value to check its effect on energy consumption in Esp-r v.11.2.I could be able to make visible transmittance modification and u-value modification of glazing separately. If I am not wrong there was a discussion held about g-value before here in this list. Will you remind me if this subject is explained before? </DIV> <DIV>Moreover will someone explain me calculation procedure of heat gain from glazings in Esp-r? (specific question is: how is g-value  calculated for a particular glazing in Esp-r and when/where is g-value used in calculations?) </DIV> <DIV> </DIV> <DIV>Thanks in advance.</DIV> <DIV> </DIV> <DIV>Gulsu</DIV></BLOCKQUOTE></BODY></HTML>