[Bldg-sim] Fwd: Re: RE: Voodoo Engineering

Thu May 20 15:57:48 PDT 2010

John,

I would call the files 1 & 2  Coincidental and Non-coincidental loads -
Coincidental for primary plant and non-coincidental for zone equipment. As
well as your "file 3" energy modeling we use (in the UK) a frequency
analysis based on an extreme summer year (Design Summer Year). Most of the
time it is used for informing natural ventilation design but it can equally
be used where plant is undersized or the room system is restricted (e.g.
chilled ceilings delivering say 75w/m2 @ 25degC Room Air temp). It works
well for our temperate climate and goes along the lines of an "allowance" of
occupied hours when temperatures can be above certain limits.

Virtually all simulation engines can have their weather files "frigged" to
represent steady state winter conditions or a summer design day. The only
issue - as far as CIBSE is concerned - is that it can be tricky to implement
the strictest form of steady state heat loss where coincidental fabric gains
from adjacent spaces are ignored (synonymous with your file 2).

The other nice thing about simulation is capability to undertake "what if"
scenarios. For example, my heating has been on low during a holiday, how
long will it take to heat it back up with 20% plant oversize?

Chris

on 20/5/10 8:09 PM, "Eurek, John S NWO" <John.S.Eurek at usace.army.mil> wrote:

> Matt,
>
> I use trace for Sizing and energy modeling.  But I have 3 different files.
>
> 1.  Equipment sizing - This has the max number of people ever expected in
> the
> building. So if it was a school I don't count a child in the classroom and
> the lunch room (he is either in one place or the other).  I set the lights
> and people to be cooling only.  This is used to size chillers, boilers,
the
> other plants.
>
> 2.  System sizing -  I call this a butt in every seat. This has the max
> number of people in each zone. I use this to size VAV boxes and other zone
> equipment.  The number of people is larger than reality.
>
> 3.  Energy Model - This has schedule, the office equipment schedules (heat
> rejection counts), I input data about equipment performance, drift
> points....
> Well you know about energy modeling.
>
> What you can't do is print out your enegy model and try to use the results
> to
> size equipment. (from what I understand)
>
> I use the same program, same construction, same temperature setting but
each
> file has a different intent.  I change the weather from 99.5% to the 8760,
I
> change the number of people from worst case, to actual.
>
> There many be other methods, but this is how I do it.
>
> -----Original Message-----
> From: MAWK (Matthew Kimball) [mailto:MAWK at nnepharmaplan.com]
> Sent: Thursday, May 20, 2010 1:45 PM
> To: Eurek, John S NWO; bldg-sim at lists.onebuilding.org
> Subject: RE: [Bldg-sim] Fwd: Re: RE: Voodoo Engineering
>
> So let me ask you John,
>
> How do you find peak heating and cooling loads without using a modeling
> program such as HAP or Trane Trace to take into account equipment loads
and
> solar heating loads?  Of course you can't use equipment loads to find peak
> heating load, but you can use them to find peak cooling loads.  Do you
only
> size heating equipment?  And don't you realize that modeling software can
be
> changed for different occupation conditions?  If you are using effective
> modeling software, there are a multitude of factors and situations that
are
> taken into account.  Its not the software itself that is effective, it is
> the
> person who is using it intelligently ; )
>
> Matthew Kimball
> AutoCAD Developer, Process & Mechanical
>
> NNE Pharmaplan
>
> mawk at nnepharmaplan.com    www.nnepharmaplan.com
>
>
>
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> -----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 20, 2010 1:59 PM
> To: bldg-sim at lists.onebuilding.org
> Subject: Re: [Bldg-sim] Fwd: Re: RE: Voodoo Engineering
>
> Brad,
>
> Using energy modeling for system sizing would be a misuse of a tool.
>
> The energy model uses average temperatures, design uses extreme
> temperatures.
>
> Another example would be a classroom which can hold up to 40 people.
> Actual use is estimated at 25 people, but owner would like to be able to
> have
> 40 people.  The model would use 25 people (actual use) but the designer
> would
> size equipment for 40 people (worst case).
>
> Also, energy models get to count rejected heat from office equipment
> and people.  When sizing equipment you can not count the lighting, office
> equipment and people heat to assist in heating.
>
> There is more CYA in equipment sizing.  There is more liability.
>
>
> -----Original Message-----
> From: bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Acker, Brad
> Sent: Thursday, May 20, 2010 12:45 PM
> To: Paul Carey; Chris Yates; Varkie C Thomas
> Cc: bldg-sim at lists.onebuilding.org
> Subject: Re: [Bldg-sim] Fwd: Re: RE: Voodoo Engineering
>
> I do not do modeling on a daily basis so I'm not as experience as many
other
> here. I do agree modeling just for LEED is silly. I have seen modeling
> inform
> designs, reduce loads, and SIZE SYSTEMS. This last part is what most bugs
> me.
> Why do people put so much effort into models and then not use them to size
> the systems? Preventing over sizing is a great benefit of modeling. What
is
> your experience with using models to size systems? Why do engineers fall
> back
> on the vendor based programs and 9 out of 10 times end up over sizing
> systems?
>
> Brad Acker, P.E.
>
> -----Original Message-----
> From: bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Paul Carey
> Sent: Thursday, May 20, 2010 3:42 AM
> To: 'Chris Yates'; 'Varkie C Thomas'
> Cc: bldg-sim at lists.onebuilding.org
> Subject: Re: [Bldg-sim] Fwd: Re: RE: Voodoo Engineering
>
> Just to add a couple of points to this interesting debate.
>
> I see the problem being that, as we increasingly set more defined limits
> regarding energy modelling and its role in building regulation, we are
> seeing
> buildings that are being built and designed to purely meet compliance.
This
> is in some part is useful as it brings all buildings up to a minimum
> standard, the flip side of that problem is that it also means, that to
many
> developers this means there is no incentive to strive for alternatives or
> innovative solutions.  It can also allow therefore lead to the use of
> simpler
> tools that meet those prescribed limits, but really don't push the
> boundaries
> of engineering design enhancement of buildings.
>
> The correct implementation and use of energy modelling need not be a
> hindrance to projects nor be seen as a necessary "extra" or evil if you
> consider the design process as a whole.  If you use the tools at the
concept
> or schematic design phases, this can quantitatively confirm an engineer's
> instinct or gained experience in way that will enable them to show
> compliance
> later on. It will then allow the team to come to a decision on the most
> energy efficient but also compliant route of design earlier on in the
design
> stage and should stop the repeat iteration of designs as the building
design
> progresses and therefore reduce design costs and with luck increase
> productivity and profit accordingly.  Fanciful dream perhaps, but it does
> work.
>
> I visited an architect a while back and he said to me "Why do I need to do
> modelling, I know the principles of good low energy design, I can read
books
> and learn more if I need to".   To which I replied, "Well every time you
> send me a job to check for building regulation compliance 3 weeks before
it
> goes before a planning team, I normally have to tell you what you need to
do
> in terms of meeting compliance as your buildings are consistently failing
> and
> you then have to rush to make those changes.  I am effectively designing
> your
> buildings for you, so if you want to continue without using energy
modelling
> then please carry on, and I'll continue to design your buildings."
> As you can imagine this was one of those Eureka moments for this
Architect,
> as I waved my red rag in front of his face.
>
> My tuppence worth.
>
> Paul
>
> -----Original Message-----
> From: bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Chris Yates
> Sent: 20 May 2010 07:55
> To: Varkie C Thomas
> Cc: bldg-sim at lists.onebuilding.org
> Subject: Re: [Bldg-sim] Fwd: Re: RE: Voodoo Engineering
>
> Varkie
>
> Vast subject. Kudos for condensing it whilst conveying all the necessary
> meaning.
>
> We are now at a point where Energy Modellers are at the very least
> specialist
> engineers. In fact, you could say the best are indeed "wizards"!
>
> Chris
>
> Sent from my iPhone
>
> On 19 May 2010, at 21:35, Varkie C Thomas <thomasv at iit.edu> wrote:
>
>> Since my response has ended up on Bldg-Sim, I might as well include
>> the attachment with the response which gave my views
>> <Building-Energy-Programs-VCT.doc>
>> I am including the attachment that I included with my earlier response
>> to John Eurek. Using energy programs is like voodoo engineering if you
>> don't understand its engineering basis.  It analyzes the various
>> options quantitatively.  It cannot be used as a magic black box.
>> Experience and judgement have to applied to the results.
>>
>> ----- Original Message -----
>> From: Eric O'Neill <elo at MichaelsEngineering.com>
>> Date: Wednesday, May 19, 2010 12:03 pm
>> Subject: RE: Voodoo Engineering
>>
>>> John,
>>>
>>> The purpose of energy modeling is to identify differences between two
>>> energy related setups. The idea is to tell you how much you could
>>> conceivably save by switching from one design to another. This is
>>> usefulfor a payback analysis or life cycle cost analysis.
>>>
>>> Hope this helps, (I'm really not trying to be inflammatory :) )
>>>
>>> Eric
>>>
>>> -----Original Message-----
>>> From: Eurek, John S NWO [mailto:John.S.Eurek at usace.army.mil]
>>> Sent: Wednesday, May 19, 2010 11:19 AM
>>> To: Varkie C Thomas
>>> Cc: Eric O'Neill; cmg750 at gmail.com
>>> Subject: RE: Voodoo Engineering
>>>
>>> Varkie, I read your attached paper.
>>>
>>> "Energy programs are external to the design process. The results are
>>> not used to generate construction drawings."  This may be my #1 beef
>>> with energymodeling.  What is the purpose?
>>>
>>> If you say, to save energy...  It does not.
>>>
>>>
>>> John Eurek
>>> LEEP AP
>>>
>>>
>>> -----Original Message-----
>>> From: Varkie C Thomas [mailto:thomasv at iit.edu]
>>> Sent: Wednesday, May 19, 2010 10:08 AM
>>> To: Eurek, John S NWO
>>> Subject: Voodoo Engineering
>>>
>>> Academia institutions and research centers tend to attach
>>> disproportionate amount of importance to energy modeling.  Most them
>>> have not dealt withreal buildings.  Attached are my views on energy
>>> modeling.
>>>
>>> ----- Original Message -----
>>> From: "Eurek, John S NWO" <John.S.Eurek at usace.army.mil>
>>> Date: Wednesday, May 19, 2010 8:14 am
>>> Subject: Re: [Equest-users] Compliance rule set for Oregon
>>>
>>>>
>>>> I would prefer Lynn work to ban/destroy/do-away-with energy
>>> modeling.>
>>>> Any chance this voo-doo engineering will go away any time soon?
>>>> It is only
>>>> statistical analysis with no meaningful/useful results for anyone.
>>>>
>>>> As a community I think we are going in the wrong direction for
>>> the
>>>> rightgoals.
>>>>
>>>> -----Original Message-----
>>>> From: equest-users-bounces at lists.onebuilding.org
>>>> [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of
>>> Carol
>>>> Gardner
>>>> Sent: Wednesday, May 19, 2010 12:30 AM
>>>> To: Scott Criswell
>>>> Cc: equest-users at lists.onebuilding.org; curt.strobehn at eesinet.com
>>>> Subject: Re: [Equest-users] Compliance rule set for Oregon
>>>>
>>>> All,
>>>>
>>>> Lynn Bellenger will soon be the first female president of ASHRAE..
>> _______________________________________________
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