[Equest-users] BEPU space heating calculation

[Grammy]

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.

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~

On Thu, Aug 26, 2010 at 9:00 PM, Chris Jones <cj at enersave.ca> wrote:

>  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?
>
>
>
> At 08:38 AM 26/08/2010, Carol Gardner wrote:
>
> 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.
>
> Carol
>
> On Wed, Aug 25, 2010 at 2:04 PM, Paul Riemer < Paul.Riemer at dunhameng.com>
> wrote:
>
> John,
>
> 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.
>
> The balance point temperature is a theoretical temperature at which the
> building does not require heating because the internal gains offset the
> envelope loads.
>
> To say it accounts for solar gain is a stretch but hey it is just a hand
> calc.
>
> Ben does not state which HDD base he chose, but there are published values
> for temps like 55F, 60F, 65F etc.
>
>
>
> Ben,
>
> 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?
>
> Does a different HDD base fit your model better?
>
>
>
> 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.
>
> A daylighting interaction could be another possibility.
>
>
>
> You'll figure it out.
>
> Paul Riemer
>
> Dunham
>
>
>
>
>
>
>
> From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org<equest-users-bounces at lists.onebuilding.org>]
> On Behalf Of John Aulbach
> Sent: Wednesday, August 25, 2010 3:38 PM
> To: Ben Pressman; equest-users at lists.onebuilding.org
> Subject: Re: [Equest-users] BEPU space heating calculation
>
>
>
> Ben - dumb question.
>
>
>
> How is internal load figuring into this equation? And solar gain from the
> sun?
>
>
>
> I NEVER get an exact U x A x dT savings, as eQuest takes ALL factors into
> consideration.
>
>
>
> John R. Aulbach, PE, CEM
>
> Senior Energy Engineer
>
> Partner Energy
>
> 1990 E. Grand Avenue, El Segundo, CA 90245
> W: 888-826-1216, X254| D: 310-765-7295 | F: 310-817-2745
>
> www.ptrenergy.com | jaulbach at ptrenergy.com <%7C%20jaulbach at ptrenergy.com>
>
>
>
>
>
>  From: Ben Pressman < bpressman at practicalenergy.net>
> To: equest-users at lists.onebuilding.org
> Sent: Wed, August 25, 2010 1:32:04 PM
> Subject: [Equest-users] BEPU space heating calculation
>
> 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:
>
> (0.176-0.142)*24hrs*(estimated HDD for my area)*A/eff = 1217 therms
>
> 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?
>
> Thanks,
> Ben
>
> -- Ben Pressman
> Project Engineer
> Practical Energy Solutions
> 770 E. Market Street, Suite 250
> West Chester, PA 19382
> ph  610.430.1382
> cell  610.733.9518
> web  www.practicalenergy.net
>
>
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>
>
> --
> Carol Gardner PE
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>
> Chris Jones
> 14 Oneida Avenue
> Toronto, ON M5J 2E3.
> Tel.  416-203-7465
> Fax. 416-946-1005
>
>
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