<div style="font-family: Arial, sans-serif; font-size: 14px;">I think Dru Crawley coined the phrase, "All models are wrong. Some are useful."</div><div style="font-family: Arial, sans-serif; font-size: 14px;"><br></div><div style="font-family: Arial, sans-serif; font-size: 14px;">Chris, you highlighted an assortment of variables which are omnipresent, inconsistent and uncontrollable - so what, exactly, does your client expect? Is it a realistic expectation? For example, are they going to nail you to the wall when, inevitably, you are "wrong" next year?</div><div style="font-family: Arial, sans-serif; font-size: 14px;"><br></div><div style="font-family: Arial, sans-serif; font-size: 14px;">I have not calibrated many models, but have been made more appreciative of all the uncontrollables by the ones I calibrated :(. All the statisticians know that there is always more than one solution which will result in a high R2 value or low CVRSME, so which is correct?</div><div style="font-family: Arial, sans-serif; font-size: 14px;"><br></div><div style="font-family: Arial, sans-serif; font-size: 14px;">Rather than a calibrated model, lately I've been encouraging clients to consider one of the FDD platforms on top of their Building Automation System. Spending time and money to evaluate whether things are working properly makes more sense to me - it's "real life" vs a prediction. (Can't forget to mention thoughtful and thorough commissioning here; that's essential.)</div><div style="font-family: Arial, sans-serif; font-size: 14px;"><br></div><div style="font-family: Arial, sans-serif; font-size: 14px;">ps, I love your thoughtful approach. You're setting a great example! One aspect of that is to reach out to the wider modeling community to gather input and feedback.</div><div style="font-family: Arial, sans-serif; font-size: 14px;"><br></div>
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<p style="margin-bottom:6pt;" class="MsoNormal"><span style="background-color:rgb(255,255,255);" class="highlight"><span style="color:rgb(34,34,34);" class="colour"><span style="font-family:Arial, Helvetica, sans-serif;" class="font">Jim Dirkes 1631 Acacia Drive NW Grand Rapids, MI 49504 - 616 450 8653</span></span></span><br></p><div><span style="background-color:rgb(255,255,255);" class="highlight"><span style="color:rgb(34,34,34);" class="colour"><span style="font-family:Arial, Helvetica, sans-serif;" class="font"><b>Coffee Conversation:</b></span></span></span></div><div><span style="background-color:rgb(255,255,255);" class="highlight"><span style="color:rgb(34,34,34);" class="colour"><span style="font-family:Arial, Helvetica, sans-serif;" class="font"><b><span style="color:rgb(0,0,0);font-family:Calibri, sans-serif;font-size:14.6667px;font-weight:400;background-color:rgb(255,255,255);display:inline;">The "individual" is an impossible concept, conceived by the Enlightenment philosophers. It makes no sense to the Christian. In marriages, and families, in associations and friendships and religious orders, we are not individuals, but a communion of persons.</span><br></b></span></span></span></div>
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On Tuesday, March 14th, 2023 at 2:10 PM, chris.malcolm.yates@gmail.com <chris.malcolm.yates@gmail.com> wrote:<br><br>
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<div class="WordSection1"><p class="MsoNormal"><span style="mso-fareast-language:EN-US">I think I need to qualify this: informed by G14, but definitely not compliant with it! There is some allowance for repairing or “healing” data, but when the data has a lot of holes or modes/ category variables then forget it. This is my case, but the client still wants some kind of representative simulation.</span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US">Monthly models can be garbage. School holidays cut across months at different times, combined heat and power is popular which complicates gas usage especially when metering is limited… did the heat by-product of electricity generation go to the building, or was it rejected? They can work for heating in our temperate climate, but not for cooling.</span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US">Nevertheless, we need some kind of representative simulation model. We can’t make any ECM qualifying claims but we can do something useful. This is where these methods can give you a lot of insight before you start modelling.</span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US">I hadn’t tried the IMT previously. We tend to have limited our regression analysis to monthly “degree day” methods (your 2p model, I think). I plugged some project specific daily electricity data into the MVR example (multi variate regression) and it seemed to give decent CVRMSE (~2-3%) but low R2 (~0.7). However, it appeared to provide some insight on cooling usage (monthly 2p models are meaningless for this in the UK’s temperate climate).</span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US">I also made some 2p monthly models of gas. I thought these were good until I compared successive years. <b>I guess this is were understanding a range of statistical indices is helpful.</b></span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US">Here’s the final rub, because the underlying data has so many inconsistencies that can only be made sense of with some regression models, it’s easier to “calibrate” the simulation model to the regression models than the original data. But I may use 2p monthly for gas, daily MVR for electric…</span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US">So I need to ask if I have wondered completely off-piste with this!</span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US">Chris</span></p><p class="MsoNormal"><span style="mso-fareast-language:EN-US"> </span></p><div><div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm"><p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> David Eldridge <dancingdavide@hotmail.com> <br><b>Sent:</b> Tuesday, March 14, 2023 12:53 PM<br><b>To:</b> Jim Dirkes <jvdirkes2@protonmail.com><br><b>Cc:</b> chris.malcolm.yates@gmail.com; bldg-sim@onebuilding.org<br><b>Subject:</b> Re: [Bldg-sim] Lies, darn lies, and statistics</span></p></div></div><p class="MsoNormal"> </p><p class="MsoNormal">Indirectly there probably isn’t a daily set of metrics in the Guideline since the simulation programs aren’t usually outputting daily results, but there’s no reason there couldn’t be one statistically. </p><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">You could make one if you had only daily utility data and had to aggregate the simulation results to daily totals, there isn’t a published target metric but you could still show that you calculated one and why you think it was a good or bad result.</p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">DSE Mobile</p></div><div><div><p class="MsoNormal"><br><br></p><blockquote style="margin-top:5.0pt;margin-bottom:5.0pt"><p style="margin-bottom:12.0pt" class="MsoNormal">On Mar 14, 2023, at 6:10 AM, Jim Dirkes via Bldg-sim <<a href="mailto:bldg-sim@lists.onebuilding.org" rel="noreferrer nofollow noopener" target="_blank">bldg-sim@lists.onebuilding.org</a>> wrote:</p></blockquote></div><blockquote style="margin-top:5.0pt;margin-bottom:5.0pt"><div><p class="MsoNormal"> </p><div><p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Dear Chris,</span></p></div><div><p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Kudos for appreciating a gap in your understanding. (I'm in your camp)</span></p></div><div><p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> </span></p></div><div><p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">On the other hand, there are SO many variables in building operation that, short of a highly instrumented (and carefully calibrated) building for everything from lights to people to plug loads to HVAC - calibration is a fiction (and I'm confident that no such building exists). Daily calibration is a complete fiction, perhaps even a deception. On top of that, a "calibrated" model is just a moment in time; everything going forward is guaranteed to be different than during the calibration time period.</span></p></div><div><p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> </span></p></div><div><p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">I think of "calibration" as more like a sensitivity analysis - determine which variables matter more and which matter less. GenOpt works nicely for that purpose <a target="_blank" href="https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Flbl-srg%2FGenOpt&data=05%7C01%7C%7C0d63c1ff284443bc766608db247cc033%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C638143890442545264%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=hMX7ISkjm6aByq3ZaUXf5p2QKTf3nlOBYbgP7ALodWQ%3D&reserved=0" rel="noreferrer nofollow noopener">https://github.com/lbl-srg/GenOpt</a></span></p></div><div><p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> </span></p></div><div><div><p style="mso-margin-top-alt:auto;margin-bottom:6.0pt" class="MsoNormal"><span class="font"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:#222222;background:white">Jim Dirkes 1631 Acacia Drive NW Grand Rapids, MI 49504 - 616 450 8653</span></span><span style="font-size:10.5pt;font-family:"Arial",sans-serif"></span></p><div><p class="MsoNormal"><span class="font"><b><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:#222222;background:white">Coffee Conversation:</span></b></span><span style="font-size:10.5pt;font-family:"Arial",sans-serif"></span></p></div><div><p class="MsoNormal"><span class="font"><span style="color:black;background:white">The "individual" is an impossible concept, conceived by the Enlightenment philosophers. It makes no sense to the Christian. In marriages, and families, in associations and friendships and religious orders, we are not individuals, but a communion of persons.</span></span><span style="font-size:10.5pt;font-family:"Arial",sans-serif"></span></p></div></div></div><div><p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"> </span></p></div><div><p class="MsoNormal">------- Original Message -------<br>On Tuesday, March 14th, 2023 at 6:52 AM, Chris Yates via Bldg-sim <<a href="mailto:bldg-sim@lists.onebuilding.org" rel="noreferrer nofollow noopener" target="_blank">bldg-sim@lists.onebuilding.org</a>> wrote:<br><br><br></p><blockquote style="margin-top:5.0pt;margin-bottom:5.0pt"><div><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal">Hi All</p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal"> </p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal">I do find ASHRAE Guideline 14 a little too hardcore for my basic understanding of statistics. I can plug any of the equations into Excel, but I’ve realised my statistics understanding is very limited! (I’m outed!)</p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal"> </p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal">We don’t actually have to work to G14 in the UK (probably good because my copy is a bit old). I finally realised I didn’t know enough after I’d been (lazily) using R2 in Excel on some monthly data. I thought that R2 > 0.9 was generally ok… yeah, it wasn’t.</p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal"> </p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal">So, are there any easy to understand resources available?</p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal"> </p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal">I’ve been messing around with the IMT as well. It’s been fun going back to DOS <span style="font-family:"Segoe UI Emoji",sans-serif">😊</span>. This got me into daily methods, which leads to my next question. Is there any reason why there isn’t a daily calibration option specified in G14?</p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal"> </p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal">Many thanks!</p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal"> </p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal">Chris Yates</p><p style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto" class="MsoNormal"> </p></div></blockquote><p class="MsoNormal"> </p></div><p class="MsoNormal">_______________________________________________<br>Bldg-sim mailing list<br><a href="http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org" rel="noreferrer nofollow noopener" target="_blank">http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org</a><br>To unsubscribe from this mailing list send a blank message to <a href="mailto:BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG" rel="noreferrer nofollow noopener" target="_blank">BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG</a></p></div></blockquote></div></div>
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