[Bldg-rate] Bldg-rate Digest, Vol 18, Issue 3
Nick Caton
ncaton at smithboucher.com
Tue May 4 07:22:42 PDT 2010
Christina et al,
First, wishing you the best of luck with your training experience - I'm
sure others along with myself would be very interested to hear your
thoughts after the fact! I am in a similar boat of being "self-taught"
without any formal instruction, which has led me down a unique path of
having intimate knowledge with some more obscure DOE2/eQuest
capabilities, but also being dumbfounded at some of the more "basic"
capacities (It's taken me more than a year to discover parametric runs -
doh!)... I often wonder whether I might gain a lot or a little from
jumping into such "intermediate" courses...
I have modeled many existing and "on-paper" buildings using eQuest. My
impression is DOE2/eQuest is not quite intended for either case, but
with a broader goal to generally to be a powerful engine to model the
energy behavior of any building situation. I personally find eQuest to
be my tool-of-choice for existing building modeling as it does have so
much flexibility to account for nearly anything you wish to. It's a
task that is hard, but gets easier as you learn where to find things and
how the beast operates!
Trying to use eQuest for purposes other than strictly energy modeling
for design work, such as coming up with design heating/cooling loads, is
for most users analogous to being given a powerful chainsaw when all you
need is a butter knife for your morning bagel. Sure, it can (?) be done
by those who've been chainsaw users for years and years, but individuals
or teams relatively new to energy modeling will probably be better off
and spend less time using simpler tools/software for MEP design
purposes, and then using eQuest to verify results and possibly tweak the
design after the fact. Personally, I look forward to being someone that
can use the eQuest-chainsaw for all kinds of things.
Modeling "on-paper" buildings is difficult because of all the variables
we cannot know. Modeling existing buildings accurately is kinda a
degree harder because of all of the things you CAN know, but don't.
You're right that on the design side we often overestimate the building
loads, but I'm sure across the industry it's more often to have a saftey
factor to account for the plug loads of the future we cannot know,
rather than to deceive the owner by suprising them with low utility
bills.
If you haven't already, I'd strongly encourage you to check out the
other onebuilding.org mailing lists - particularly [bldg-sim] and
[equest-users]. They are much more active groups with vast archives of
useful discussions, tips and other information that I'm sure you'll find
useful. If you should have specific questions about modeling existing
building with eQuest or more generally with any software, I'm sure
you'll find plenty of help if you ask for it in those forums =).
Best of luck!
~Nick
NICK CATON, E.I.T.
PROJECT ENGINEER
25501 west valley parkway
olathe ks 66061
direct 913 344.0036
fax 913 345.0617
Check out our new web-site @ www.smithboucher.com
-----Original Message-----
From: bldg-rate-bounces at lists.onebuilding.org
[mailto:bldg-rate-bounces at lists.onebuilding.org] On Behalf Of Chris
Baker
Sent: Tuesday, May 04, 2010 8:41 AM
To: Christina A. Snyder; bldg-rate Energy
Subject: Re: [Bldg-rate] Bldg-rate Digest, Vol 18, Issue 3
Being able to adjust the proportion of heat to space allows you to model
situations such as fume hoods or kitchen hoods where heat gain is
extracted by exhaust without adding to the space load. It also allows
you to have heat gain to a space be either latent or sensible.
Chris Baker, AIA, EIT, LEED(r) AP,
THE WEIDT GROUP(r)
5800 Baker Road
Minnetonka, MN 55345
T 952.938.1588
F 952.938.1480
twgi.com
-----Original Message-----
From: bldg-rate-bounces at lists.onebuilding.org
[mailto:bldg-rate-bounces at lists.onebuilding.org] On Behalf Of Christina
A. Snyder
Sent: Tuesday, May 04, 2010 2:26 AM
To: bldg-rate Energy
Subject: Re: [Bldg-rate] Bldg-rate Digest, Vol 18, Issue 3
Wow, Nick, you're ahead of me on this one.
I didn't know that the multiplier on the lighting loads added to the
power density without adding to the heat loads. Not sure how that is
possible, except that one can opt to make a theoretical model not follow
the laws of physics if one wants to. I've used that multiplier as a way
to try to make the energy model we do as a part of a commercial energy
rating match the reality of the energy bills of the existing building.
My experience has been that Equest is consistantly way overestimating
the power consumption of a building (nearly a factor of 2 on the last
building I did), so I have to use that multiplier to try to rein it in,
and I wish there were multipliers on all the other electric input
fields, not just lighting.
I'm about to go tomorrow to my 1st Equest training (in Milwaukee) - I'm
jumping right in at the intermediate level of training after going about
as far as I can w/ beating my head against the brick wall of trying to
work with this energy DESIGN software to model existing buildings I have
to rate. I find the help files /documentation to be pathetic - tends to
tell me no more than I can read off the screens of the wizards. I'm
looking for info as to what Equest is assuming when you give it the
various inputs and why, as well as better descriptors of what the inputs
on the drop-down menus in the wizards are. This info you gave me on the
magical properties of the multiplier to vary power density without
varying internal heat gains is a good example of the kind of info I need
about Equest, and I'm going to check it out at the training. I may not
get many good answers though, as the trainers state that they are
focused on the use of the software for design, and that they aren't
going to get into HVAC equipment much - basically all of my problems are
areas they are planning to dodge.
Since you posted to the Bldg-rate list, I'm curious to know if you (and
others on this list) are also predominately doing simulations of
existing buildings, and if so, what your evaluation of the available
energy modeling software is for this purpose. I can see why one would
want to overestimate consumption in DESIGN software - then your
customers think you are wonderful when the buildings actually use less
energy then predicted. But its not very helpful when using the software
to RATE existing buildings - I have to struggle to tweak the model to
even come close to approximating the reality of the energy bills, else
the Energy Efficiency Measures I plan to recommend look laughable. I'd
love to find some easily used affordable energy modeling software that
actually does a good job of simulating existing buildings.
I can't answer as to the intent of USGBC or ASHRAE as to requirements
for LEED. It wouldn't surprise me if they were choosing to ad arbitrary
loads to buildings that would result in oversized equipment - that's the
old-school engineering mindset that is getting in our way now as we want
to move towards ultra-efficient building. I've also been trained by the
Passivhaus Institute to model with their PHPP software, and you can't
get to the Passivhaus Standard with oversized equipment. Sometimes it
seems change is glacially slow, but at least LEED is moving in the right
direction now with their latest release.
Thanks for a thought provoking query,
Christina
architect, Certified Passive House Consultant, and commercial energy
rater Clean Energy Coalition Ypsilanti, Michigan
On Fri, 30 Apr 2010 12:01:00 -0700,
bldg-rate-request at lists.onebuilding.org said:
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> Today's Topics:
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> 1. LEED+90.1 Process/Plug Loads Conundrum (Nick Caton)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 30 Apr 2010 12:54:39 -0500
> From: "Nick Caton" <ncaton at smithboucher.com>
> To: <bldg-rate at lists.onebuilding.org>
> Subject: [Bldg-rate] LEED+90.1 Process/Plug Loads Conundrum
> Message-ID:
>
> <FCEBC0C28321F7479789B25A13030F6901208708 at sandbinc2.sbi.smithboucher.c
> om>
>
> Content-Type: text/plain; charset="us-ascii"
>
> Something new occurred to me this week and I'd love to hear others'
> thoughts!
>
>
>
> LEED prescribes baseline/proposed energy models to follow ASHRAE 90.1
> with a caveat: the "process energy costs" must total 25% of the
> baseline energy costs. By extension, 90.1 requires the same
> loads/schedules be applied to the proposed model as they have to
match.
> As an aside, the LEED EAc1 templates appear to calculate/check this
> using process energy consumption (not cost), but that's not what I'm
> getting at...
>
>
>
> I just had a typical case where I had to inflate the baseline internal
> miscellaneous equipment loads to get to 25%. These additional loads
> were substantial enough that when applied to the proposed
> model/design, I ran into many unmet cooling hours for the equipment
> capacities entered.
>
>
>
> Then I realized: We can define additional equipment electricity loads
> but simultaneously apply a multiplier (in eQuest anyway - I expect
> this is feasible other programs also) to reduce/negate the
> corresponding heat load contributions. This results in the energy
> consumption/costs showing up correctly in the final results/reports,
> but does not artificially inflate the internal loads that the
> baseline/proposed systems must handle.
>
>
>
> Would this practice (which incidentally can be a time saver) of
> accounting for extra process/miscellaneous loads without extra thermal
> contributions be in line with the intent of ASHRAE/USGBC? It would
> still normalize the otherwise unstandardized process consumption/costs
> of the baseline/proposed models between different building types...
>
>
>
> On the other hand, if it really is the intent of USGBC to add
> arbitrary additional internal heat loads to our models that our actual
> designs were not designed and sized for, does it follow that we should
> allow the proposed models to autosize cooling equipment/fan capacities
> and not specify them (this would seem incongruous with 90.1 to me)?
>
>
>
>
>
> ~Nick
>
>
>
>
>
>
>
> NICK CATON, E.I.T.
>
> PROJECT ENGINEER
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> Check out our new web-site @ www.smithboucher.com
>
>
>
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> End of Bldg-rate Digest, Vol 18, Issue 3
> ****************************************
--
Christina A. Snyder
casnyder at ic.org
voice: 734-428-9249
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