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

[Haynes, Glenn]

The difference between using equipment sizing software and hourly
building energy simulation software is interpretation of the peak loads.
The equipment sizing software utilizes a worst case scenario of load
contributing conditions to size the equipment and yields an appropriate
peak system load up front - no need to beef it up except to cover errors
or extenuating circumstances.

A building energy simulation code yields the peak loads under the most
probable conjunction of extreme conditions, so you should beef those up
by some reasonable factor if you need to guarantee enough capacity under
the most extreme combination of factors.

Either way, you should end up with approximately the same system size
without unnecessary over sizing.  But if you beef up the equipment
sizing software results without proper justification, and then select
the next higher modular equipment size, you will probably end up with an
unnecessarily oversized system; a low personal risk approach, but not
the best design choice for the client who has to pay for it and live
with it.

Glenn

-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Steven
Savich
Sent: Thursday, May 20, 2010 2:12 PM
To: 'Eurek, John S NWO'; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Fwd: Re: RE: Voodoo Engineering

John,

Using energy modeling programs for sizing is another topic that we'll
find a lot of people on the list disagreeing about.

Really, Trane Trace and Carrier HAP are equipment sizing programs that
also do energy modeling.

eQuest/DOE 2.2 (the program I am most familiar with) also has the option
of setting design day schedules, and will give you reports that show
peak Heating and Cooling loads.  With sound engineering judgment, a
thorough understanding of the modeling program you're using, and careful
checking of your results, I believe that you can use many hourly
modeling programs to size your equipment, or at least to provide a
"second opinion" about the results from your primary sizing program.


Steven



-----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 10:59 AM
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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