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

Fri May 21 14:54:48 PDT 2010

can we see jason's email please?

On Sat, May 22, 2010 at 12:31 AM, Haynes, Glenn <Glenn.Haynes at kema.com>wrote:

>  Jason,
>
> Thanks for your insightful response.  To a large degree I concur.  You
> encounter various situations out there as a design consultant, and you need
> to understand the plans and needs of your client.  But surely you recognize
> that there are some cases where over sizing is not required, and the client
> may actually prefer to pay less up front and get a better operating system
> than always be able to maintain set point under the most extreme combination
> of conditions.  When maintaining perfect environmental control is critical,
> then you must oversize accordingly, but when it isn't, you may assign more
> priority to proper sizing, or, in rare cases, under sizing.
>
> I personally would prefer a slightly undersized AC system in my home to an
> oversized one if I had to choose between the two.  I understand the
> advantages, and prefer to risk having to tolerate a little discomfort for a
> few hours a year than to pay for and operate an excessively oversized system
> for the next 15 to 20 years.
>
> But to offer this to a client may be risky business unless you get him to
> sign a waiver, and then it is still risky.  On the other hand, if you can
> determine the maximum probable system load and add a reasonable 10-25% to
> that, you will have satisfied the client's needs with a reasonable margin of
> safety.  The only angry clients I have ever encountered were angry because
> their system was failing to deliver a significant amount of the time when
> circumstances were only normal, in which cases the engineer had made a
> serious error and specified a system that was grossly undersized.  I don't
> recommend over sizing to make certain this doesn't happen.  Instead I
> recommend checking and double checking your sizing calculations so you don't
> make such a mistake.
>
> This is a hot issue because nearly every HVAC engineer is going to sooner
> or later make that proverbial mistake, lose self-confidence, and from then
> on join those that oversize their systems more than necessary just
> to cover potential mistakes.  Most clients are none the wiser anyhow, and,
> after it has all been paid for, some actually enjoy the feeling of knowing
> they have a "honker of an air conditioner" that is capable of cooling the
> place down in 60 seconds or less.  So what do we have to lose?  I think
> it might be some of our own professional and personal integrity!  Not much
> else comes to mind.
>
> Now I have said too much, so I will bow out of this, knowing that last
> paragraph may ruffle some feathers.
>
> Glenn
>
>  ------------------------------
> *From:* Jason Humbert [mailto:jhumbert at sesnet.com]
> *Sent:* Friday, May 21, 2010 3:57 PM
> *To:* Haynes, Glenn
> *Subject:* RE: [Bldg-sim] Fwd: Re: RE: Voodoo Engineering
>
>  Glenn,
>
> For load sizing, over sizing equipment can be bad with them short cycling
> and energy hogs.  But on the other hand under sizing a system can be just as
> bad.  When you size equipment you normally can't select equipment that will
> meet your building load exact so most engineers normally go to the next size
> up in equipment. Very rare do I see or hear any one pick the size down in
> equipment.  Its the nature of the beast.  Everyone has the fear of being
> sued from an owner it is easier to oversize the equipment that way you have
> the extra capacity if you need it, than having to deal with an angry owner.
>
>
> My view on energy simulation is like trying to kill a fly with a bullet.
> Everyone is trying to predict exactly what a building will do and how it
> will perform, and you just can't.  There are so may variables in an energy
> simulation, some variables you can predict and even control and
> other variables you just can't predict or possibly even know.  That is why I
> believe it is important to relay the bases of your energy simulation to
> whomever you are presenting it to.  That the simulation is based on these
> parameters and based on these parameters this is how the building should
> perform.  And then when the building is build and its performance is better
> or worse than what you predicted then you can compare the variables and see
> which ones are off and how bad.  And the most common variables that is
> normally off is infiltration and weather.  But no one goes back to a
> building after it has been build to adjust there model to see what was off.
> And that is also the nature of the beast as well.
>
> Jason Humbert
>  4000 W. Eleven Mile Rd.
> Berkley, MI  48072
> p: 248.399.1900 ex. 215
> f: 248.399.1901
> jhumbert at sesnet.com
>
> **
>
>
>  ------------------------------
> *From:* Haynes, Glenn [mailto:Glenn.Haynes at kema.com]
> *Sent:* Friday, May 21, 2010 11:49 AM
> *To:* John Aulbach; Chris; backer at uidaho.edu; paul at zed-uk.com;
> thomasv at iit.edu
>
> *Cc:* bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] Fwd: Re: RE: Voodoo Engineering
>
>  John,
>
> Looks like I might have awakened a sleeping giant...been around awhile,
> huh?  Are you going to tell us how it worked out?
>
> Glenn
>
>  ------------------------------
> *From:* John Aulbach [mailto:jra_sac at yahoo.com]
> *Sent:* Friday, May 21, 2010 11:34 AM
> *To:* Haynes, Glenn; Chris; backer at uidaho.edu; paul at zed-uk.com;
> thomasv at iit.edu
> *Cc:* bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] Fwd: Re: RE: Voodoo Engineering
>
>  I did all that 30 years ago using the Meriwether ESAS program for Hilton
> Hotels. Before DOE-2. Before DOE-1 !!
>
>  ------------------------------
> *From:* "Haynes, Glenn" <Glenn.Haynes at kema.com>
> *To:* Chris <chris at zed-uk.com>; backer at uidaho.edu; paul at zed-uk.com;
> thomasv at iit.edu
> *Cc:* bldg-sim at lists.onebuilding.org
> *Sent:* Fri, May 21, 2010 8:22:53 AM
> *Subject:* Re: [Bldg-sim] Fwd: Re: RE: Voodoo Engineering
>
> Chris,
>
> You make a good point, and it also can apply to centrifugal chillers,
> which are sometimes most efficient at 60-80% loaded.  But you still have
> to remember that the client has to pay for the larger equipment, which
> costs more, plus larger system components (which cost more) and more
> space (which costs more).
>
> You also maake a good point about the system loads 90% of the time,
> which raises an interesting question regarding sizing for optimum
> operating efficiency.  What if we sized certain types of equipment to
> meet the most predominant loads within their most efficient capacity
> ranges?  That is not difficult when using hourly simulation software.
> Of course, you have to keep an eye on peak loads and capacities.  I
> haven't thought this through yet, but I'll bet someone else has.
>
> Thanks,
> Glenn
>
> -----Original Message-----
> From: "Chris" [mailto:chris at zed-uk.com]
> Sent: Thursday, May 20, 2010 7:13 PM
> To: Haynes, Glenn; backer at uidaho.edu; paul at zed-uk.com; thomasv at iit.edu
> Cc: bldg-sim at lists.onebuilding.org
> Subject: Re: [Bldg-sim] Fwd: Re: RE: Voodoo Engineering
>
> Glenn,
>
> Oversize isn't always bad! A condensing boiler is generally at its most
> efficient at < 20% of its capacity.
>
> All the same, the mid-season is largely ignored when it comes to sizing.
> Ridiculous really, when you think this is where the plant will be 90% of
> the time.
>
> Perhaps this is more of an issue when you are shifting large amounts of
> chilled water to various pieces of zone equipment but has anybody
> considered Valve Authority? Unfortunately my experience is limited when
> it comes to the nitty gritty of piping networks. But, I do know one
> thing: valve response is not linear, especially if there is a
> substantial head in the system. My hunch is mid season control could get
> really messed up if plant has spare capacity but designers haven't been
> quite as generous with pipe sizes.
>
> Such questions should be in the domain of simulation in the next few
> years.
>
> Chris
>
> on 20/5/10 8:15 PM, "Haynes, Glenn" <Glenn.Haynes at kema.com> wrote:
>
> > Brad,
> >
> > I did HVAC design consulting for 14 years, and I used to oversize
> > systems just like everyone else.  Now I am an energy conservation
> > programs evaluator, and have discovered the extent and negative
> > impacts of over sizing.  Not speaking for all designers who oversize,
> > I did it mainly out of willful ignorance.  It was easier for me to
> > loosely calculate the peak loads and then beef those estimates up
> > enough to safely cover and mistakes or false assumptions than it was
> > to calculate the loads with enough confidence to properly size the
> > systems.  I believed in the old adage that too much is just right from
>
> > my perspective, because it minimized risk.
> >
> > But now I have to measure the effects of excessive over sizing and see
>
> > the results, some of which are poor humidity control, short cycling,
> > reduced system operating efficiency and higher first cost to the
> owner.
> > My DOE2 models usually indicate peak (I mean absolute hourly peak
> > loads) at about 20% less than Manual J loads, on average, for
> > residential applications.  But even Manual J allows up to 20% above
> > their calculated loads, which have already been calculated using
> > conservative estimates for most inputs that are not explicitly
> > defined.  The observed
> > (measured) field results have proven the average residential AC system
>
> > to be about 70% to 75% oversized, with some as high as 200% (that's 3
> > times the peak load).  20% to 25% over ASHRAE's 2.5% design standard
> > is acceptable to me now, but anything above 25% without some
> > overriding owner requirement (plans to add on to the current building,
>
> > etc.) begins to waste the owner's resources (from first cost to energy
>
> > and maintenance costs) and reduce the lifetime of the equipment while
> > at the same time decreasing his overall level of comfort through
> > limited latent performance.
> >
> > There!  You obviously rubbed a sore spot in my emotional make-up, but
> > I appreciate the opportunity to make a point.  And the point is this:
> > no matter how good your modeling software is, the outcome is still in
> > the hands of the user.
> >
> > Glenn
> >
> > -----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 1:45 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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-- 
Carol Gardner PE
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