[Bldg-sim] Training (UNCLASSIFIED)

Nick Caton ncaton at smithboucher.com
Thu May 26 16:51:44 PDT 2011


Hi John!

 

Here's some thoughts generally following your queries for everyone's
benefit.  

 

Keep in mind that for some of these questions - there are no black and
white answers, all you'll ever get is "what works for me."  I expect
others will concur & courteously differ with me on at least a few points
=).

 

1.       If sticks are analogous to the bare minimum required by 90.1,
then make a Mona Lisa with sticks =).  LEED models are at once both
difficult and simple - there are many rules and procedures to follow,
but the degree of accuracy expected of the final product is not nearly
so rigorous as historically calibrated models and similar.  It's a whole
different ball game.  I've written much on how LEED models are not
"predictive models" (nor should they be).  Be very clear with yourself
and your colleagues/clientele on that point, or else be prepared to
spend an extra few magnitudes of time on the project.

2.       As a general rule:  scheduling can be as simple or complex as
you like, provided baseline & proposed models are treated identically.
Some exceptions exist where the scheduling can/should differ (common
example in my models: exterior lighting controls).  Start "simple,"
(work with the default libraries/curves), then add detail to the models
as is necessary.  For example: one weighted plug load schedule for the
entire building is in many cases absolutely fine, but you may find it
necessary to break things out further to demonstrate actual equipment
performance in your proposed model (such as in an IT room with a
mini-split) - refine schedules as you need to along the way, and just
make sure the baseline receives the same refinements as you go.

3.       Define custom equipment performance curves as is necessary to
get credit where it's due, or where it's known/expected your software's
library curves do not cut it for that system type.  Library curves are
themselves totally acceptable provided they're a reasonable
approximation.  Be prepared to document and create custom curves however
should your reviewer ask for it, particularly if you are using equipment
known to require custom curves to be modeled correctly.

4.       Restroom exhaust:  depends on the software you're using, where
the air is coming from, and the answers can vary for both proposed and
baseline models... G.3.1.2.8. speaks to relief systems if that's what
you're getting at.

5.       Baseline infiltration: don't believe it's defined through
appendix G... but a very good question!  I know 90.1 addresses envelope
sealing to some extent but I don't think there's anything quantified for
the overall construction's leakage rate... I match proposed model levels
as practice, and haven't had the issue come up yet.  Would love to hear
if others have successfully documented something different for
baseline/proposed!

6.       Humidity control should be considered if it is in the actual
design.  90.1 requires humidity setpoints be kept the same between the
models, alongside thermostat setpoints somewhere in that big 2-column
table.

7.       Picking a "close" construction is something I used to do, until
I learned that actual constructions aren't really so hard to define
after all.  Either approach can be acceptable for LEED's rigor in my
experience, but as with anything it depends on the reviewer lottery
(some may not accept an approximation).  As a practice these days, I do
carefully define each layer for the envelope constructions, and make a
point to keep a photocopy of the referenced envelope construction
details in my project design file.  Makes for easy documentation later.

8.       Generally:  All baseline capacities
(airflows/gpms/heating/cooling) are auto-sized in the model in a "sizing
run"  - corresponding efficiencies for each are worked from those
quantities.  Refer to Appendix G (and the archives here) for specifics
;-).

 

General advice:

-          Trace-specific questions I can't help much with, but for any
modeler I'd advise reading Appendix G, then reading Appendix G again.
Appendix G pretty much sets the bar regarding what you must do
irrespective of the energy modeling software of choice.  It's pretty
prescriptive, and should be read that way.  Don't hesitate to refer to
earlier sections (incl. Appendix A) and give them a cursory review from
time to time as you try to better define baseline behavior for various
systems.

-          Anyone unfamiliar with submitting EAc1 for LEED v3 really
really really must log in, and download the EAp2 excel spreadsheet that
will be uploaded for documentation.  It would be a good idea to grab the
EAc1 template (pdf) while you're there.  Review the spreadsheet/template
carefully for your project before starting and periodically as you
develop your models... the excel spreadsheet is pretty much a one-stop
shop for what your reviewer will be looking at down the road, and can
help remind you of what needs attention along the way.  I consider
myself very familiar with 90.1, and still do this with every LEED
project.

-          The 2007 90.1 user's manual is a worthwhile text for those
intermediate to modeling under 90.1.  Get a few projects under your belt
first then you'll get  more out of it.

-          If you meet a fellow energy modeler in person it's totally
appropriate to buy him/her a beer.  Fist bumps are fine for some of the
population, but watch for a confused expression and be prepared to
gracefully transition into a handshake.

-          Don't wax your car in direct sunlight.

-          Water your lawn in the early AM.

-          Call your mother sometimes.

-          Real bikers wear spandex.

 

~Nick

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

Smith & Boucher Engineers

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

www.smithboucher.com 

 

 

-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Eurek, John
S NWO
Sent: Thursday, May 26, 2011 4:57 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Training (UNCLASSIFIED)

 

Classification: UNCLASSIFIED

Caveats: NONE

 

I am looking for training.

 

What I'd like to learn.

How detailed to models need to be for LEED?  Do I make a stick figure or
the

Mona Lisa

      Do I make one schedule for the building or one per room.

      Do I make unloading curves for the equipment or use the defaults.

      How is exhaust air from restrooms supposed to be handled.

      What is the baseline infiltration rate supposed to be.

      Does humidity need to be considered.

      Do I need to model the wall construction or can I pick something

close and type in the u-value

      What is the ft of heat for the baseline design if I use a boiler.

      

Not counting the rooms geometry there still seems to be over 500 (maybe
1000)

different values in Trace that can be adjusted.  Some large like the
type of

system to small like is it draw thru or blow thru (or the Outside long
wave

emissivity of the window which the architect still hasn't found for me).

 

I understand that when comparing different options (such as R value A or
B)

the detail doesn't need to be on the gnat's ass.  So energy modeling at
the

onset of a project isn't too hard to figure out. What is required for a
LEED

reviewer to get a warm fuzzy from my model is the big question I'd like
to

get training on.

 

The simple answer is to do it all, consider everything, but then reality
sets

in and I have a budget to consider.

 

Classification: UNCLASSIFIED

Caveats: NONE

 

 

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