<!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 6.00.6000.16640" name=GENERATOR></HEAD> <BODY text=#000000 bgColor=#ffffff> <DIV dir=ltr align=left><SPAN class=151374609-23052008><FONT face=Arial color=#0000ff size=2>The mrt calculation assumes all surfaces are black (emissivity 1.0), as is the sensor cube.  It is a reasonable approximation for most common energy analysis problems.  Where significant differences in surface emissivities exist in a space, a first principles approach would correctly include emissivities in the calculation of mrt.  It seems we do not have this capability, so far.</FONT></SPAN></DIV> <DIV dir=ltr align=left><SPAN class=151374609-23052008><FONT face=Arial color=#0000ff size=2>Jeremy Cockroft, ESRU</FONT></SPAN></DIV><BR> <DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left> <HR tabIndex=-1> <FONT face=Tahoma size=2><B>From:</B> esp-r-bounces@lists.strath.ac.uk [mailto:esp-r-bounces@lists.strath.ac.uk] <B>On Behalf Of </B>Paul Strachan<BR><B>Sent:</B> 22 May 2008 23:04<BR><B>To:</B> Francesco Frontini<BR><B>Cc:</B> esp-r@lists.strath.ac.uk<BR><B>Subject:</B> [esp-r] Re: R: Mean Radiant Temperature; esp-r Digest, Vol 22, Issue 15<BR></FONT><BR></DIV> <DIV></DIV>Dear Francesco,<BR><BR>As far as I can ascertain from the ESP-r code, the MRT calculation does not take account of emissivity. The default MRT is simply the area weighted surface temperatures (subroutine MOMNRD in temps.F in esrures). <BR><BR>It is possible to specify MRT calculations at specific points in the zone (using sensor "cubes"), in which case the calculation includes viewfactors and 4th power radiant exchange (subroutine SENMRT in temps.F in esrures) - but again emissivity is not included. Although rather out-of-date in terms of the user interface, the following publication on the ESRU website gives the basis of the method for user-defined positions for MRT sensors: <A class=moz-txt-link-freetext href="http://www.esru.strath.ac.uk/Documents/ESPmrt.pdf">http://www.esru.strath.ac.uk/Documents/ESPmrt.pdf</A><BR><BR>Regards<BR>Paul<BR><BR>Francesco Frontini wrote: <BLOCKQUOTE cite=mid:!~!UENERkVCMDkAAQACAAAAAAAAAAAAAAAAABgAAAAAAAAAru7KqoPmvUiwJBhxMD9pLMKAAAAQAAAAUa6zXH6QPEm9TJ19xKXRDgEAAAAA@polimi.it type="cite"><PRE wrap="">Dear Jon, Ok, but where I can found the fomula used by ESP-r for the MRT calculation? Best regards Francesco -----Messaggio originale----- Da: <A class=moz-txt-link-abbreviated href="mailto:esp-r-bounces@lists.strath.ac.uk">esp-r-bounces@lists.strath.ac.uk</A> [<A class=moz-txt-link-freetext href="mailto:esp-r-bounces@lists.strath.ac.uk">mailto:esp-r-bounces@lists.strath.ac.uk</A>] Per conto di <A class=moz-txt-link-abbreviated href="mailto:esp-r-request@lists.strath.ac.uk">esp-r-request@lists.strath.ac.uk</A> Inviato: martedė 20 maggio 2008 13.00 A: <A class=moz-txt-link-abbreviated href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</A> Oggetto: esp-r Digest, Vol 22, Issue 15 Send esp-r mailing list submissions to <A class=moz-txt-link-abbreviated href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</A> To subscribe or unsubscribe via the World Wide Web, visit <A class=moz-txt-link-freetext href="http://lists.strath.ac.uk/mailman/listinfo/esp-r">http://lists.strath.ac.uk/mailman/listinfo/esp-r</A> or, via email, send a message with subject or body 'help' to <A class=moz-txt-link-abbreviated href="mailto:esp-r-request@lists.strath.ac.uk">esp-r-request@lists.strath.ac.uk</A> You can reach the person managing the list at <A class=moz-txt-link-abbreviated href="mailto:esp-r-owner@lists.strath.ac.uk">esp-r-owner@lists.strath.ac.uk</A> When replying, please edit your Subject line so it is more specific than "Re: Contents of esp-r digest..." Today's Topics: 1. Mean Radiant Temperature (<A class=moz-txt-link-abbreviated href="mailto:francesco.frontini@polimi.it">francesco.frontini@polimi.it</A>) 2. Re: Mean Radiant Temperature (Geissler Achim) 3. R: Mean Radiant Temperature (Francesco Frontini) 4. Re: R: Mean Radiant Temperature (Geissler Achim) 5. Re: R: Mean Radiant Temperature (Jon Hand) ---------------------------------------------------------------------- Message: 1 Date: Tue, 20 May 2008 08:45:52 +0200 From: <A class=moz-txt-link-abbreviated href="mailto:francesco.frontini@polimi.it">francesco.frontini@polimi.it</A> Subject: [esp-r] Mean Radiant Temperature To: <A class=moz-txt-link-abbreviated href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</A> Message-ID: <A class=moz-txt-link-rfc2396E href="mailto:20080520084552.y2yaryo9kcs880ks@webmail.polimi.it"><20080520084552.y2yaryo9kcs880ks@webmail.polimi.it></A> Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes"; format="flowed" Dear All, I have a question about MRT. We want to assess the impact on the operative temperature in an office if we use an internal blind with a low-emissivity coating (0,5 emissivity for indoor-facing surface) instead of 0.9 emissivity. We made two different simulation: static (with WIS program) and Dynamic (ESP-r). The results from WIS and from ESP-R for the blind surface temperature are consistent (blind temperature about 5K higher for the low-emissivity blind). However, the mean radiant temperature at a position close to the blind (0.5 m in ESP-R) is lower for the high-emissivity blind than the low-emissivity blind with the ESP-R calculation. Could you please send me the formula that ESP-r uses for the MRT calculation? Is there any approximation that would not be appropriate for low-emissivity surfaces? I model the double glazing fa?ade with the internal blind like a single construction (no air-ventilation between the glass and the blind). I set the U-value for each fa?ade construction (it is similar but not identical for the two different solutions, U=0,985+-0,005, obtained from the WIS calculation), and the g-value. What changes in the model is the emissivity of the indoor-facing surface of the blind (e=0,9 for the first case and e=0,5 for the second one!), whereas the solar-optical properties remain the same for the two blinds. In the WIS model, the emissivity of the two blind surfaces is specified separately. For both blinds, the emissivity of the outdoor-facing surface in the WIS model is 0.9. Looking forward to your answer and thanking you for your help. Any advice and help on this will be much appreciated. Francesco Frontini ------------------------------ Message: 2 Date: Tue, 20 May 2008 09:22:39 +0200 From: "Geissler Achim" <A class=moz-txt-link-rfc2396E href="mailto:Achim.Geissler@josef-gartner.ch"><Achim.Geissler@josef-gartner.ch></A> Subject: [esp-r] Re: Mean Radiant Temperature To: <A class=moz-txt-link-rfc2396E href="mailto:francesco.frontini@polimi.it"><francesco.frontini@polimi.it></A>, <A class=moz-txt-link-rfc2396E href="mailto:esp-r@lists.strath.ac.uk"><esp-r@lists.strath.ac.uk></A> Message-ID: <A class=moz-txt-link-rfc2396E href="mailto:5410907208A9F149ADB6E44744892B3C45EBE8@sgartgum1.gart.intra"><5410907208A9F149ADB6E44744892B3C45EBE8@sgartgum1.gart.intra></A> Content-Type: text/plain; charset="iso-8859-1" Dear Francesco, </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">We want to assess the impact on the operative temperature in an office if we use an internal blind with a low-emissivity coating (0,5 emissivity for indoor-facing surface) instead of 0.9 emissivity. We made two different simulation: static (with WIS program) and Dynamic (ESP-r). </PRE></BLOCKQUOTE><PRE wrap=""> </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">The results from WIS and from ESP-R for the blind surface temperature are consistent (blind temperature about 5K higher for the low-emissivity blind). </PRE></BLOCKQUOTE><PRE wrap="">That is good news. </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">However, the mean radiant temperature at a position close to the blind (0.5 m in ESP-R) is lower for the high-emissivity blind than the low-emissivity blind with the ESP-R calculation. </PRE></BLOCKQUOTE><PRE wrap=""> As the mean radiant temperature is defined by view factors and surface temperature, only, all is well, no? The low-e blind has a higher temperature, thus I would expect the mean radiant temperature close to the blind to be higher. That is what you seem to have obtained as result? Best regards, Achim ------------------------------ Message: 3 Date: Tue, 20 May 2008 10:35:15 +0200 From: "Francesco Frontini" <A class=moz-txt-link-rfc2396E href="mailto:francesco.frontini@polimi.it"><francesco.frontini@polimi.it></A> Subject: [esp-r] R: Mean Radiant Temperature To: "'Geissler Achim'" <A class=moz-txt-link-rfc2396E href="mailto:Achim.Geissler@josef-gartner.ch"><Achim.Geissler@josef-gartner.ch></A>, <A class=moz-txt-link-rfc2396E href="mailto:esp-r@lists.strath.ac.uk"><esp-r@lists.strath.ac.uk></A> Message-ID: <!~!UENERkVCMDkAAQACAAAAAAAAAAAAAAAAABgAAAAAAAAAru7KqoPmvUiwJBhxMD9pLMKAAAAQ <A class=moz-txt-link-abbreviated href="mailto:AAAAq+fYsqTr4E+5QjbiDeTAbQEAAAAA@polimi.it">AAAAq+fYsqTr4E+5QjbiDeTAbQEAAAAA@polimi.it</A>> Content-Type: text/plain; charset="iso-8859-1" Dear Achim Yes I have obtained a MRT, close to the blind, higher for the solution with low-e blind (that has a higer surface temperature). But for my opinion the MRT has to take into account not only the view factor and the temperature of the surface but also the emissivity. For that reason I'm also supposing that with a low emmissivity also the MRT should be low (for exemple if the view factor is the same: 43,88?x0,9>48.21?x0,5! Where the formula is (T1(?C)blind)*(emissivity(1))>(T2(?C)blind)*(emissivity(2))!!!). It's not correct? Best regards, Francesco -----Messaggio originale----- Da: Geissler Achim [<A class=moz-txt-link-freetext href="mailto:Achim.Geissler@josef-gartner.ch">mailto:Achim.Geissler@josef-gartner.ch</A>] Inviato: marted? 20 maggio 2008 9.23 A: <A class=moz-txt-link-abbreviated href="mailto:francesco.frontini@polimi.it">francesco.frontini@polimi.it</A>; <A class=moz-txt-link-abbreviated href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</A> Oggetto: RE: [esp-r] Mean Radiant Temperature Dear Francesco, </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">We want to assess the impact on the operative temperature in an office if we use an internal blind with a low-emissivity coating (0,5 emissivity for indoor-facing surface) instead of 0.9 emissivity. We made two different simulation: static (with WIS program) and Dynamic (ESP-r). </PRE></BLOCKQUOTE><PRE wrap=""> </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">The results from WIS and from ESP-R for the blind surface temperature are consistent (blind temperature about 5K higher for the low-emissivity blind). </PRE></BLOCKQUOTE><PRE wrap="">That is good news. </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">However, the mean radiant temperature at a position close to the blind (0.5 m in ESP-R) is lower for the high-emissivity blind than the low-emissivity blind with the ESP-R calculation. </PRE></BLOCKQUOTE><PRE wrap=""> As the mean radiant temperature is defined by view factors and surface temperature, only, all is well, no? The low-e blind has a higher temperature, thus I would expect the mean radiant temperature close to the blind to be higher. That is what you seem to have obtained as result? Best regards, Achim ------------------------------ Message: 4 Date: Tue, 20 May 2008 11:33:33 +0200 From: "Geissler Achim" <A class=moz-txt-link-rfc2396E href="mailto:Achim.Geissler@josef-gartner.ch"><Achim.Geissler@josef-gartner.ch></A> Subject: [esp-r] Re: R: Mean Radiant Temperature To: "Francesco Frontini" <A class=moz-txt-link-rfc2396E href="mailto:francesco.frontini@polimi.it"><francesco.frontini@polimi.it></A>, <A class=moz-txt-link-rfc2396E href="mailto:esp-r@lists.strath.ac.uk"><esp-r@lists.strath.ac.uk></A> Message-ID: <A class=moz-txt-link-rfc2396E href="mailto:5410907208A9F149ADB6E44744892B3C45EC09@sgartgum1.gart.intra"><5410907208A9F149ADB6E44744892B3C45EC09@sgartgum1.gart.intra></A> Content-Type: text/plain; charset="iso-8859-1" Dear Francesco, the definitions I know of for mean radiant temperature do not take emissivity into account. The interesting question probably is, is the measure "MRT" useful for environments with large differences in emissivity? Of course, for radiation heat transfer, the emissivity is important (that is what I think you want to describe?). I would assume that the definition of MRT is based on the "normal" case, that all surfaces of an indoor space have an emissivity of approx. 0.9. Thus, the description of the radiative surroundings by temperature alone is sufficient. For your case, you may need to define a "new" MRT - maybe more a "mean radiant heat exchange" type of coefficient (or try PPD / PMV calculations, however, these also use standard mean radiant temperature for their calculation). Regards, Achim </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">-----Original Message----- From: <A class=moz-txt-link-abbreviated href="mailto:esp-r-bounces@lists.strath.ac.uk">esp-r-bounces@lists.strath.ac.uk</A> [<A class=moz-txt-link-freetext href="mailto:esp-r">mailto:esp-r</A>- <A class=moz-txt-link-abbreviated href="mailto:bounces@lists.strath.ac.uk">bounces@lists.strath.ac.uk</A>] On Behalf Of Francesco Frontini Sent: Tuesday, May 20, 2008 10:35 AM To: Geissler Achim; <A class=moz-txt-link-abbreviated href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</A> Subject: [esp-r] R: Mean Radiant Temperature Dear Achim Yes I have obtained a MRT, close to the blind, higher for the solution with low-e blind (that has a higer surface temperature). But for my opinion the MRT has to take into account not only the view factor and the temperature of the surface but also the emissivity. For that reason I'm also supposing that with a low emmissivity also the MRT should be low (for exemple if the view factor is the same: 43,88?x0,9>48.21?x0,5! Where the formula is (T1(?C)blind)*(emissivity(1))>(T2(?C)blind)*(emissivity(2))!!!). It's not correct? Best regards, Francesco -----Messaggio originale----- Da: Geissler Achim [<A class=moz-txt-link-freetext href="mailto:Achim.Geissler@josef-gartner.ch">mailto:Achim.Geissler@josef-gartner.ch</A>] Inviato: marted? 20 maggio 2008 9.23 A: <A class=moz-txt-link-abbreviated href="mailto:francesco.frontini@polimi.it">francesco.frontini@polimi.it</A>; <A class=moz-txt-link-abbreviated href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</A> Oggetto: RE: [esp-r] Mean Radiant Temperature Dear Francesco, </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">We want to assess the impact on the operative temperature in an office if we use an internal blind with a low-emissivity coating (0,5 emissivity for indoor-facing surface) instead of 0.9 emissivity. We made two different simulation: static (with WIS program) and Dynamic (ESP-r). </PRE></BLOCKQUOTE> <BLOCKQUOTE type="cite"><PRE wrap="">The results from WIS and from ESP-R for the blind surface temperature are consistent (blind temperature about 5K higher for the low-emissivity blind). </PRE></BLOCKQUOTE><PRE wrap="">That is good news. </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">However, the mean radiant temperature at a position close to the blind (0.5 m in ESP-R) is lower for the high-emissivity blind than the low-emissivity blind with the ESP-R calculation. </PRE></BLOCKQUOTE><PRE wrap="">As the mean radiant temperature is defined by view factors and surface temperature, only, all is well, no? The low-e blind has a higher temperature, thus I would expect the mean radiant temperature close to the blind to be higher. That is what you seem to have obtained as result? Best regards, Achim _______________________________________________ esp-r mailing list <A class=moz-txt-link-abbreviated href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</A> <A class=moz-txt-link-freetext href="http://lists.strath.ac.uk/mailman/listinfo/esp-r">http://lists.strath.ac.uk/mailman/listinfo/esp-r</A> </PRE></BLOCKQUOTE><PRE wrap=""> ------------------------------ Message: 5 Date: Tue, 20 May 2008 11:36:21 +0100 From: Jon Hand <A class=moz-txt-link-rfc2396E href="mailto:jon@esru.strath.ac.uk"><jon@esru.strath.ac.uk></A> Subject: [esp-r] Re: R: Mean Radiant Temperature To: "Geissler Achim" <A class=moz-txt-link-rfc2396E href="mailto:Achim.Geissler@josef-gartner.ch"><Achim.Geissler@josef-gartner.ch></A>, "Francesco Frontini" <A class=moz-txt-link-rfc2396E href="mailto:francesco.frontini@polimi.it"><francesco.frontini@polimi.it></A>, <A class=moz-txt-link-rfc2396E href="mailto:esp-r@lists.strath.ac.uk"><esp-r@lists.strath.ac.uk></A> Message-ID: <A class=moz-txt-link-rfc2396E href="mailto:B94620A0857DFE4DB194C4A2DBDC088F8B5FD6@BE-SCAM2.ds.strath.ac.uk"><B94620A0857DFE4DB194C4A2DBDC088F8B5FD6@BE-SCAM2.ds.strath.ac.uk></A> Content-Type: text/plain; charset="iso-8859-1" There is a radiant asymmetry report as part of the comfort report and I think that will be taking account of the emissivity. There is an esp-r model which deals with a heated ceiling panel and location specific comfort for a patient in a bed which needs to be added as an exemplar model. -Jon Hand -----Original Message----- From: <A class=moz-txt-link-abbreviated href="mailto:esp-r-bounces@lists.strath.ac.uk">esp-r-bounces@lists.strath.ac.uk</A> on behalf of Geissler Achim Sent: Tue 5/20/2008 10:33 AM To: Francesco Frontini; <A class=moz-txt-link-abbreviated href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</A> Subject: [esp-r] Re: R: Mean Radiant Temperature Dear Francesco, the definitions I know of for mean radiant temperature do not take emissivity into account. The interesting question probably is, is the measure "MRT" useful for environments with large differences in emissivity? Of course, for radiation heat transfer, the emissivity is important (that is what I think you want to describe?). I would assume that the definition of MRT is based on the "normal" case, that all surfaces of an indoor space have an emissivity of approx. 0.9. Thus, the description of the radiative surroundings by temperature alone is sufficient. For your case, you may need to define a "new" MRT - maybe more a "mean radiant heat exchange" type of coefficient (or try PPD / PMV calculations, however, these also use standard mean radiant temperature for their calculation). Regards, Achim </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">-----Original Message----- From: <A class=moz-txt-link-abbreviated href="mailto:esp-r-bounces@lists.strath.ac.uk">esp-r-bounces@lists.strath.ac.uk</A> [<A class=moz-txt-link-freetext href="mailto:esp-r">mailto:esp-r</A>- <A class=moz-txt-link-abbreviated href="mailto:bounces@lists.strath.ac.uk">bounces@lists.strath.ac.uk</A>] On Behalf Of Francesco Frontini Sent: Tuesday, May 20, 2008 10:35 AM To: Geissler Achim; <A class=moz-txt-link-abbreviated href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</A> Subject: [esp-r] R: Mean Radiant Temperature Dear Achim Yes I have obtained a MRT, close to the blind, higher for the solution with low-e blind (that has a higer surface temperature). But for my opinion the MRT has to take into account not only the view factor and the temperature of the surface but also the emissivity. For that reason I'm also supposing that with a low emmissivity also the MRT should be low (for exemple if the view factor is the same: 43,88?x0,9>48.21?x0,5! Where the formula is (T1(?C)blind)*(emissivity(1))>(T2(?C)blind)*(emissivity(2))!!!). It's not correct? Best regards, Francesco -----Messaggio originale----- Da: Geissler Achim [<A class=moz-txt-link-freetext href="mailto:Achim.Geissler@josef-gartner.ch">mailto:Achim.Geissler@josef-gartner.ch</A>] Inviato: marted? 20 maggio 2008 9.23 A: <A class=moz-txt-link-abbreviated href="mailto:francesco.frontini@polimi.it">francesco.frontini@polimi.it</A>; <A class=moz-txt-link-abbreviated href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</A> Oggetto: RE: [esp-r] Mean Radiant Temperature Dear Francesco, </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">We want to assess the impact on the operative temperature in an office if we use an internal blind with a low-emissivity coating (0,5 emissivity for indoor-facing surface) instead of 0.9 emissivity. We made two different simulation: static (with WIS program) and Dynamic (ESP-r). </PRE></BLOCKQUOTE> <BLOCKQUOTE type="cite"><PRE wrap="">The results from WIS and from ESP-R for the blind surface temperature are consistent (blind temperature about 5K higher for the low-emissivity blind). </PRE></BLOCKQUOTE><PRE wrap="">That is good news. </PRE> <BLOCKQUOTE type="cite"><PRE wrap="">However, the mean radiant temperature at a position close to the blind (0.5 m in ESP-R) is lower for the high-emissivity blind than the low-emissivity blind with the ESP-R calculation. </PRE></BLOCKQUOTE><PRE wrap="">As the mean radiant temperature is defined by view factors and surface temperature, only, all is well, no? The low-e blind has a higher temperature, thus I would expect the mean radiant temperature close to the blind to be higher. That is what you seem to have obtained as result? Best regards, Achim _______________________________________________ esp-r mailing list <A class=moz-txt-link-abbreviated href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</A> <A class=moz-txt-link-freetext href="http://lists.strath.ac.uk/mailman/listinfo/esp-r">http://lists.strath.ac.uk/mailman/listinfo/esp-r</A> </PRE></BLOCKQUOTE><PRE wrap=""></PRE></BLOCKQUOTE><BR></BODY></HTML>