Yes, sometimes there will be one guy, who takes the calcs to ask you prove your model result, like a challenge. It's not a happy thing and you must know a lot of details in your model and the energy distribution in annual energy consumption, to answer such questions. <div>
<br></div><div>At the beginning I am angry with these kind of actions, but soon I realize that these actions can push me to become a better energy modeler. When you can answer these questions, and point out the mistake in their hand calcs, you prove yourself and grow up to a better modeler~<br>
<br><div class="gmail_quote">On Thu, Aug 26, 2010 at 9:00 PM, Chris Jones <span dir="ltr"><<a href="mailto:cj@enersave.ca">cj@enersave.ca</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div>
Re equest and hand calcs. I know a few people that actually use
hand calcs to demonstrate where equest, ecotect and other simulation
programs are coming up with incorrect answers. Graham, care to
illustrate?<br><br>
<br><br>
At 08:38 AM 26/08/2010, Carol Gardner wrote:<br>
<blockquote type="cite">Let me take a crack at this.
What John is saying is that eQUEST takes into consideration all building
components and their interactions. You can't just pull out one and ask
hey why doesn't this match my hand calc? In fact, if you want eQUEST to
match a hand calc, you shouldn't be using it: use the hand calc.<br><br>
Carol<br><br>
On Wed, Aug 25, 2010 at 2:04 PM, Paul Riemer
<<a href="mailto:Paul.Riemer@dunhameng.com" target="_blank">
Paul.Riemer@dunhameng.com</a>> wrote:<br>
<dl><br>
<dd>John,<br><br>
</dd><dd>Internal gains figure into Ben 's approach by choosing a HDD number
based on a balance point temperature that is below the actual space set
point.<br><br>
</dd><dd>The balance point temperature is a theoretical temperature at which
the building does not require heating because the internal gains offset
the envelope loads.<br><br>
</dd><dd>To say it accounts for solar gain is a stretch but hey it is just a
hand calc. <br><br>
</dd><dd>Ben does not state which HDD base he chose, but there are published
values for temps like 55F, 60F, 65F etc. <br><br>
</dd><dd> <br><br>
</dd><dd>Ben,<br><br>
</dd><dd>It is good you are checking your results but I would ask do you
believe your baseline model? Try your HDD calc on the your building
U rather than the differential. How does that gas consumption
compare to your baseline model heating gas consumption?<br><br>
</dd><dd>Does a different HDD base fit your model better?<br><br>
</dd><dd> <br><br>
</dd><dd>If you think your baseline model is okay, when you changed the U did
you also change your shading coefficient? A lower SC would
eliminate some passive solar heating.<br><br>
</dd><dd>A daylighting interaction could be another possibility.<br><br>
</dd><dd> <br><br>
</dd><dd>You'll figure it out.<br><br>
</dd><dd>Paul Riemer<br><br>
</dd><dd>Dunham<br><br>
</dd><dd> <br><br>
</dd><dd> <br><br>
</dd><dd> <br><br>
</dd><dd>From:
<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">
equest-users-bounces@lists.onebuilding.org</a>
[<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">
mailto:equest-users-bounces@lists.onebuilding.org</a>] On Behalf Of
John Aulbach<br>
</dd><dd>Sent: Wednesday, August 25, 2010 3:38 PM<br>
</dd><dd>To: Ben Pressman;
<a href="mailto:equest-users@lists.onebuilding.org" target="_blank">
equest-users@lists.onebuilding.org</a><br>
</dd><dd>Subject: Re: [Equest-users] BEPU space heating
calculation<br><br>
</dd><dd> <br><br>
</dd><dd>Ben - dumb question.<br><br>
</dd><dd> <br><br>
</dd><dd>How is internal load figuring into this equation? And solar gain from
the sun?<br><br>
</dd><dd> <br><br>
</dd><dd>I NEVER get an exact U x A x dT savings, as eQuest takes ALL factors
into consideration.<br><br>
</dd><dd> <br><br>
</dd><dd>John R. Aulbach, PE, CEM<br><br>
</dd><dd>Senior Energy Engineer<br>
<br>
</dd><dd>Partner Energy<br>
<br>
</dd><dd>1990 E. Grand Avenue, El Segundo, CA 90245<br>
</dd><dd>W: 888-826-1216, X254| D: 310-765-7295 | F: 310-817-2745<br><br>
</dd><dd><a href="http://www.ptrenergy.com/" target="_blank">www.ptrenergy.com</a>
<a href="mailto:%7C%20jaulbach@ptrenergy.com" target="_blank">|
jaulbach@ptrenergy.com</a><br><br>
</dd><dd> <br><br>
</dd><dd> <br>
<div align="center"><br>
</div>
</dd><dd>From: Ben Pressman
<<a href="mailto:bpressman@practicalenergy.net" target="_blank">
bpressman@practicalenergy.net</a>><br>
</dd><dd>To:
<a href="mailto:equest-users@lists.onebuilding.org" target="_blank">
equest-users@lists.onebuilding.org</a><br>
</dd><dd>Sent: Wed, August 25, 2010 1:32:04 PM<br>
</dd><dd>Subject: [Equest-users] BEPU space heating calculation<br><br>
</dd><dd>I have a Window Glass EEM run that upgrades the windows in a 1970s
school building from single-paned to double-paned, tinted, and
argon-filled; a decrease in U-factor from 1.04 to 0.35. The LV-D report
shows a decrease in building U-factor from 0.176 to 0.142 which, based on
an HDD calculation:<br><br>
</dd><dd>(0.176-0.142)*24hrs*(estimated HDD for my area)*A/eff = 1217
therms<br><br>
</dd><dd>of savings, or 24.7% of the overall energy usage of my baseline
model. The BEPU report, however, shows almost no energy savings. How can
this be? Is there some way to see what schedule, or number of degree days
the calculation in the BEPU is using? Has anyone had this sort of
problem?<br><br>
</dd><dd>Thanks,<br>
</dd><dd>Ben<br><br>
</dd><dd>-- Ben Pressman<br>
</dd><dd>Project Engineer<br>
</dd><dd>Practical Energy Solutions<br>
</dd><dd>770 E. Market Street, Suite 250<br>
</dd><dd>West Chester, PA 19382<br>
</dd><dd>ph 610.430.1382<br>
</dd><dd>cell 610.733.9518<br>
</dd><dd>web
<a href="http://www.practicalenergy.net/" target="_blank">www.practicalenergy.net</a><br>
<br>
<br>
</dd><dd>_______________________________________________<br>
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</dd><dd> <br><br>
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</dd></dl><br><br>
<br>
-- <br>
Carol Gardner PE<br>
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<p>
<br>
Chris Jones<br>
14 Oneida Avenue<br>
Toronto, ON M5J 2E3.<br>
Tel. 416-203-7465<br>
Fax. 416-946-1005<br><br>
</p></div>
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