Hi Laura,<div><br></div><div>This sounds a lot like what we typically do for garage ventilation CO control. What you're describing would fall under an Exceptional Calculation Method per ASHRAE 90.1-2007 G2.5. </div><div>
<br></div><div>I would agree that this is a valid energy savings strategy, but it should not be presented as part of your base savings. You should model it as an ECM under the appropriate section of the submittal template. Show the savings of this ECM and provide supporting documentation that shows that you have modeled the system appropriately to how it will actually be operated (i.e. justify your hourly DCV schedule). In this manner, if the reviewer chooses not to accept your modeling methodology, they will award you only the base level of savings and you will not have further review comments holding up your project.</div>
<div><br></div><div><p class="MsoNormal"><a name="_MailAutoSig"><span style="font-family:"Franklin Gothic Demi","sans-serif";color:#632423">Robby Oylear, </span></a><span style="font-size:10.0pt;font-family:"Franklin Gothic Demi","sans-serif";color:#632423">P.E., LEED
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<br><div class="gmail_quote">On Fri, Jun 15, 2012 at 11:30 AM, Laura Howe, RCE <span dir="ltr"><<a href="mailto:laurahowe.rce@qwestoffice.net" target="_blank">laurahowe.rce@qwestoffice.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div lang="EN-US" link="blue" vlink="purple"><div><p class="MsoNormal">HI Again all-<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">Thanks for everyone for their assistance earlier this week, it really helped me progress with this model adjustment. I am currently at another dilemma. This is DCV not for typical occupancy, but for ventilating infrequent diesel fumes.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal"> I have two systems modeled as one, a constant volume packaged unit along with an exhaust system (no heating/cooling). The exhaust system will operate separate from the packaged unit and the proposed case includes a fraction in the operation schedule to reflect DCV operation. That schedule doesn’t affect the package unit except it will have less heating/cooling load due to the DCV. I don’t see the DCV affecting the fan sizing or operation of the baseline packaged unit. The packaged unit is constant volume. So, the LEED comments refer to identically modeling the base and proposed systems, for fan volume and fan power, on this exhaust system. I’ve worked out matching the exhaust system well enough, but now I’m wondering if I need to match the supply also. The simplistic answer would be “yes”, even if the comments refer only to the exhaust system I am concerned a cursory review may still not be happy with the supply fan volume/power not matching. I think not matching is valid and it is definitely more favorable, so that’s what I’d rather do.<span style="font-family:"Times New Roman","serif""><u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">The baseline system has a larger supply fan, and will have a greater heating/cooling load (no DCV). The proposed system will have a smaller supply fan and a smaller heating/cooling load. I think the base case fan sizing is more accurate since it is based on the actual loads of the baseline building. If I use the fan sizing/power from proposed, the project will take a big hit. Basically I think this means in theory that not matching the supply fans, even though they are tied to the exhaust DCV, is an accurate estimation of savings from baseline to proposed.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">Right now I’m inclined to leave the supply not matching, and provide an explanation. However since there has already been one review, I don’t like the potential that they will just come back with a response of eliminating a certain number of points. If they don’t think my response is adequate, I don’t think they will give me another chance, correct?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">For those that requested their actual response, I finally got my hands on a document I could copy text:<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p>
<p><u></u><span style="font-size:11.0pt;font-family:"Times New Roman","serif""><span>1.<span style="font:7.0pt "Times New Roman""> </span></span></span><u></u>“<span style="font-size:11.0pt;font-family:"Times New Roman","serif"">The Baseline fan power calculations and the SV-A reports for the Baseline model indicate that the exhaust fan systems (SF-1 and SF-2, as indicated in the mechanical schedules provided for PI Form 4: Schedule and Overview Documents) have not been modeled identically in the Proposed and Baseline cases. All independent fan systems of the HVAC systems in the actual design must be modeled identically between the Proposed and Baseline models at actual equipment capacities (fan volume and fan power) as required by Table G3.1.10 in the Proposed building column, since the fan design air flow rates and fan power per Sections G3.1.2.8 and G3.1.2.9, respectively, only applies to system types 1 through 8 in Table G3.1.1A. Revise the Proposed and Baseline model so all independent fan systems of the HVAC systems are modeled identically between the Proposed and Baseline model. In addition, provide revised SV-A reports for the Proposed and Baseline model reflecting the changes. <u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">Thoughts? Must I go simplistic and make supply match? Am I offbase thinking not matching is a valid energy consumption model comparison?<u></u><u></u></p><p class="MsoNormal">
<u></u> <u></u></p><p class="MsoNormal">Thanks<span class="HOEnZb"><font color="#888888"><u></u><u></u></font></span></p><span class="HOEnZb"><font color="#888888"><p class="MsoNormal">Laura<u></u><u></u></p></font></span></div>
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