I agree that Nick's interpretation is correct, but this is my biggest frustration with 90.1. For multi-zone buildings, the limit should be on the sum of "non-concident" unmet load hours for each zone. For standard energy modeling output reports, you can determine the total annual unmet hours for each zone, but you don't know which hours of the year they occur. <br>
<br>In Jim's example, what if each of the 300 zones had 1 unmet load hour that all occurred during the same hour of the year? Or better yet, what if you had 300 zones with 30 hours of unmet loads (all at the same hours)? By the 90.1 reasoning, you would have 9000 unmet load hours (greater than the number of hours in a year!).<br>
<br>I have thought about requesting a change to 90.1, but if the standard were to require people to determine the sum of non-coincident unmet load hours for each zone, it would put a large burden on the energy modeler to develop hourly output reports for each zone and hand calculate this. It seems like we're stuck with what we have until the energy modeling programs can produce an output report that describes the sum of non-coincident unmet load hours.<br>
<br clear="all">Kendra Tupper, PE, LEED AP<br>Senior Consultant<br>Built Environment Team<br><br>Rocky Mountain Institute | T 303-567-8641 | F 303-245-7213 | <a href="http://www.rmi.org">www.rmi.org</a><br>
<br><br><div class="gmail_quote">On Mon, Oct 26, 2009 at 6:38 PM, Rosenberg, Michael I <span dir="ltr"><<a href="mailto:michael.rosenberg@pnl.gov">michael.rosenberg@pnl.gov</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<p class="MsoNormal"><span style="font-size: 10pt;">Nick,</span></p>
<p class="MsoNormal"><span style="font-size: 10pt;"> </span></p>
<p class="MsoNormal"><span style="font-size: 10pt;">Your
interpretation is the correct one. According to the definitions in Standard
90.1.</span></p>
<p><b><i><span>unmet
load hour:</span></i></b><span> an
hour in which one or more zones is outside of the thermostat setpoint range.</span></p>
<p class="MsoNormal"><span style="font-size: 10pt;"> </span></p>
<p class="MsoNormal"><span style="font-size: 10pt;"> </span></p>
<p class="MsoNormal"><span style="font-size: 10pt;">Mike</span></p>
<div>
<p class="MsoNormal"><b><span style="color: rgb(212, 117, 0);">__________________________</span></b>
</p>
<p class="MsoNormal"><b><span>Michael Rosenberg</span></b> <br>
<span style="font-size: 10pt;">Senior
Commercial Buildings Energy Analyst</span> <br>
<span style="font-size: 10pt;">ENERGY &
ENVIRONMENT DIRECTORATE </span></p>
</div>
<p class="MsoNormal"><span style="font-size: 10pt;">Pacific
Northwest National Laboratory </span><br>
<span style="font-size: 10pt;">2032 Todd
Street </span><br>
<span style="font-size: 10pt;">Eugene, OR
97405 </span><br>
<span style="font-size: 10pt;">(541)
844-1960 </span><br>
<span style="font-size: 10pt;"><a href="mailto:michael.rosenberg@pnl.gov" target="_blank">michael.rosenberg@pnl.gov</a>
</span><br>
<span style="font-size: 10pt; color: rgb(212, 117, 0);"><a href="http://www.pnl.gov" target="_blank">www.pnl.gov</a></span>
<span style="font-size: 10pt;"></span></p>
<div>
<div style="border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; border-width: 1pt medium medium; padding: 3pt 0in 0in;">
<p class="MsoNormal"><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;">
<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>
[mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Nick Caton<br>
<b>Sent:</b> Monday, October 26, 2009 5:33 PM<br>
<b>To:</b> Crockett, Jim; <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br>
<b>Subject:</b> Re: [Bldg-sim] Ashrae 90.1 - Unmet hours</span></p>
</div>
</div><div><div></div><div class="h5">
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Jim,</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">That’s actually a really good question that I was afraid
to ask when I first encountered it – kudos to you! I’ve
currently resolved to follow what others seemed to be doing within and outside
of my office: Sum up all unmet hours for cooling and heating between the
zones just as you describe. In your example, I’d agree that
the unmet hours of your 301 zone building total 301.</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">I do agree that this doesn’t seem intuitively to be the
intent of the standard, however between what is suggested within 90.1, the LEED
handbook, and the LEED credit templates – I honestly can’t see any
clear indication either way on which is the appropriate interpretation. </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">I think the appropriate metric for ensuring appropriately sized
systems should be something like: “hours of the modeled year in which at
least one zone has an unmet cooling/heating load,” but I think that
was avoided by all concerned parties because it’s too wordy!</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">My acting interpretation, again referencing your example, is
that all systems of your 301 zone example affecting the zones with unmet
cooling/heating hours should have their heating/cooling/overall sizing capacity
ratios increased incrementally until the design hours fall below 300 (and/or
within 50 of the sum from the other model, depending on your situation).</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Afraid I’m only really adding to the discussion here
without providing a solid answer. Would like to echo the desire to see
anyone’s experiences that would help us know the “right” way
to interpret this (in my case, specifically in the context of a LEED
submittal).</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<div>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"><img src="" alt="cid:489575314@22072009-0ABB" height="37" width="119"></span><b><span style="font-size: 11pt; color: rgb(45, 77, 94);"></span></b></p>
<p class="MsoNormal"><b><span style="font-size: 11pt; color: rgb(45, 77, 94);"> </span></b></p>
<p class="MsoNormal"><b><span style="font-size: 11pt; color: rgb(45, 77, 94);">NICK CATON, E.I.T.</span></b><b><span style="color: rgb(45, 77, 94);"></span></b></p>
<p class="MsoNormal"><span style="font-size: 7.5pt; color: rgb(204, 153, 0);">PROJECT ENGINEER</span><span style="font-size: 7.5pt; color: rgb(204, 153, 0);"></span></p>
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<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
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<p class="MsoNormal"><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;">
<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>
[mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Crockett,
Jim<br>
<b>Sent:</b> Monday, October 26, 2009 4:27 PM<br>
<b>To:</b> <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br>
<b>Subject:</b> [Bldg-sim] Ashrae 90.1 - Unmet hours</span></p>
</div>
</div>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Courier New";">Ashrae
90.1 (2004) Appendix G3.1.2.2 requires a baseline building to have less than
300 unmet hours. What exactly does this mean?</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Courier New";"> </span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Courier New";">To
illustrate my question: assume you have a building with 301 zones, and each
zone has 1 unmet hour per year. This gives you a total of 301 unmet
hours, and requires you to increase your baseline equipment capacity. But
you could argue that, on average, the building has only 1 unmet hour per year.</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Courier New";"> </span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Courier New";">Have
any of you run into this? Is it addressed in an addendum somewhere, etc?</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Courier New";"> </span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Courier New";">Any
help is appreciated. Thanks,</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Courier New";"> </span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Courier New";"> </span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Courier New";"> </span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Courier New";">Jim
Crockett, P.E.</span><span style="font-family: "Courier New";"></span></p>
<p class="MsoNormal"><span style="font-family: "Courier New";"> </span></p>
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