[Equest-users] LEED Review Comment on U-Value Input Method
Pasha Korber-Gonzalez
pasha.pkconsulting at gmail.com
Tue Jun 21 23:12:57 PDT 2011
Hi Bruce,
I enjoyed your response and support all your comments. I myself as a
modeler will always choose to use the U-value input method whenever I can
use this legitimately (i.e. something else isn't pushing me or mandating I
use layers method.)
Why- you ask? Pasha chooses this method for a couple of reasons:
- most of my models are already set with thier construction choices (with
or without massing), and therefore when I am building a compliance model (no
opportuntity for design analysis) then why take the extra time to input
layers-by-layers-by-layers when I know what the final construction choices
are. NOTE, none of these construction choices are ever mine....the
baseline is set by the minimum assembly U-value listed in the
B-tables...based on this given value, why should I waste my time building up
a layer-by-layer input....ASHRAE Standard 90.1 gives me the overall assembly
U-value that they want to see and therefore I am going to choose to use
thier data that they offered to me.
- The next reason I choose the U-value method is because in terms of
input time I like the one value input method. Now you might think this is
funny of me.....but it is also a part of my QC procedures...
- when I take-off my proposed design constructions (wall, roof,
etc.) I always open up my second laptop and open a new file in eQuest
where I take about 5-10 minutes and build-up the construction
layers in the
wizard so that I can double check what the output U-value is for the
assembly based on the DOE-2 calculations for the
layers-by-layers.... most
of the time I come soooooo very close to the layer-by-layer
U-value that was
calculated and so then I can choose to use a U-value method of input, and
not waste anymore time in my model with
layers-and-layers-and-layers....too
much extra information for me to visually manage; therefore I choose the
least tedious method of one input value = U-value method.
Just because I choose to use the U-value input method, doesn't automatically
imply that I took the lazy route, or didn't even consider or calculate the
layers-by-layers....THAT would be presupmtuous of the reviewer. That is
my "style" of modeling...I can't explain it nor should I have to justify it
to any reviewer why I choose that style of modeling...as long as I am
verifying that my output simulation results are indeed in the correct order
of magnitude and telling the "correct story" to my clients based on
engineering theory & calcs, then who is anyone else out there to tell me
that my style of modeling is wrong or inaccurate?
Now this brings me to the point of arguing the massing and sans
massing....IT DEPENDS!!!! If you have a project with massing that plays a
significant role in load shedding and such, then the simulator would be
ignorant to not use layers-by-layers...because as a trained engineer this
simulator should know if this does or doesn't make a difference in thier
analysis. ---The reviewer shouldnt have to worry their
pretty-little-heads about any of this because it is the responsibility of
the simulator to make sure that the simulation output is as close to
accurate as is possible with the nature of these programs we use.
However; if I choose (as an experience simulator and trained HVAC engineer)
that I don't want to include massing effects in my envelope constructions
because there is no opportunity or potential savings to be demonstrated from
the lack of such performance then who is the LEED reviewer to make that
engineering decision for me??? Again I would feel that this is very
PRESUMPTUOUS of them to blanket that (or any statement to me) especially if
they intend to "reform Pasha's style of modeling."
I've been able to gain the experience I have and submit successful LEED
models based on my professional education, training, testing, and
professional ethics in my work and projects. Based on this, it becomes my
sole right and my sole responsibility to the industry to make sure that
'Pasha's style of modelling' is in conformance with any standard or program
that wants to outline specific rules of engagement.
Until the point in time that any one authority states: *"you must use the
Layer-by-layer method for inputs in your simulation tool."* Then I am
allowed to reserve the right to use whatever input method that I deem is
best representation for my client's project and the modeling intent that
I've been asked to perform. *And as long as I have a sound engineering
foundation to stand on*, then my decision and approach will have a 99%
chance of being the most accurate for my client. The 1% outlier risk of
not falling into conformance rests on the "risk" of which LEED reviewer is
assigned to reviewing my model...
Hopefully it will be a reviewer that can discern the truth of a good
energy modeler in the work that I produced for them to reiview. If they do
pick on something that is allowed to be open for interpretation (as is this
case of massing vs no massing), then AS THE REVIEWERS THEY ARE WRONG for
trying to mandate something that thier organization has stated to be "open
for interrpretation."
IMHO---(take it with a grain of salt if you wish).....IF GBCI wants us to do
something as EAc1 energy modelers then they need to state it in Black &
White AND it has to be offered to all of us simulators at NO ADDITIONAL
COST----you can't make me comply with something but only provide me with the
compliance data if I pay for the information....that is being an Industry
Bully.
DEAR USGBC/GBCI--if you want me to do something specific for my energy
models then please publish it clearly and *at no cost *for all of us EAc1
energy modelers to follow. Only a true monopoly organization
*expects us*to follow thier rules and pay the cost to follow thier
rules at our own
expense. This type of "mandate" from any one organization makes them out
to be BULLIES to the little people like us.
Pasha
On Tue, Jun 21, 2011 at 10:15 PM, Bruce Easterbrook <bruce5 at bellnet.ca>wrote:
> **
> We have to remember eQuest is used on all kinds of buildings.
> "Lightweight assemblies" means different things to different types of
> commercial buildings. You could have a 2 story steel interior frame,
> fibre-glass blanket, Z bars, and a steel cladding. What I call a
> pre-engineered. You could also have a 60 story high rise. It can have a
> steel structure or a concrete structure or a combination of both. Either
> type can be pretty crappy construction if you don't deal with thermal breaks
> or sealing. Any steel which is not insulated on the exterior will severely
> derate the average performance of your exterior wall. We have the same
> problem with glass. useless insulator, prone to air leakage, lets the solar
> radiation in and kills birds by the thousands. But who wants to live or
> work in a building where you can't look outside. As I mentioned in a post
> to Bill earlier, I don't do LEED. I have more than enough work that I don't
> have to involve myself with what I consider is a bit of a slight of hand. I
> do 90.1, energy efficient buildings, 62.1, IAQ, and my goal is to make the
> best building possible with what I am given and how much I can convince my
> client to spend up front to save them money for the next 30 years on running
> their building. No politics, no marketing, no environmentalists, nothing
> but cold cash and economics. I have no choice in building orientation, it
> faces the street. I have no choice in landscaping, the building footprint
> is maximum allowable and everything else is concrete, maybe a few planters.
> The standards which matter are 90.1, 62.1, occupant comfort and money. The
> first 2 are ASHRAE standards, backed by sound engineering, decades of work
> and revision, the third is in the ASHRAE fine print and the fourth, the root
> of all evil and corruption. They are not the flavour of the month. eQuest
> is a tool for us to use to investigate different techniques to make better
> buildings. Hasn't anyone noticed the testing of older LEED buildings and
> the fact that within a few years they don't meet the LEED standard they were
> designed to? We are not talking 20%, we are talking 60%+. Some don't even
> meet the standard on the day they are opened. WHY? ASHRAE has a few ideas,
> poor commissioning, poor maintenance. New standards are in the works to
> deal with these issues, Standard 189.1,Commissioning Guideline 1.1, Proposed
> Operation and Maintenance Guideline. I will add poor design. A part of
> poor design is poor modelling, poor reviewing and the big one, first cost.
> ie money. And lets not forget the plaque on the wall, full page spread in
> the paper and bragging rights.
> Part of the problem is flavour of the month. Everyone is on the band
> wagon. There are not enough good modellers. There are not enough good
> reviewers. There is too much demand for both too fast. This is creating
> conflict as we have noticed by posts on this site. But we have to deal with
> this, patience and dialogue are required. The other thing is, this site is
> the gold standard for cutting edge idea's and I would expect/hope the
> reviewers are reading too. Everything is a work in progress and to stay
> current you have to read, experiment and learn from others. We all do a lot
> of hum drum projects, we don't always get to do the real neat stuff. So
> this site adds to everyone's knowledge when we get to put our 2 cents worth
> in on something tricky. Whether it is a cool project, a new way to
> manipulate eQuest or suggestions on what more we need eQuest to do.
> Don't get the idea I'm down on LEED, I just figure it is similar to
> R-2000. But this is how we go forward, we set something up, we run with it,
> critique it, modify it. It may bite the dust but there will still be good
> things which come from the attempt. I have been doing energy efficient
> design for 25 years and battling first cost. I am a member of ASHRAE, which
> for ones not in the know, takes a minimum of 12 years as an associate member
> to be allowed to apply to be a member. I am not an expert, the field is
> huge and I learn more every day. As a grey haired engineer I find these
> times exciting, we are starting to make a lot of headway. It isn't perfect
> but we are moving forward briskly and addressing important issues.
> On the topic, I use the layer method. It includes mass and time
> delay. The inputs are easy to understand, the layers are obvious and
> defined. It is easy for the reviewer to check. It is easy to adjust and
> try new constructions. It is simple to defend. That is the most important
> part. A modellers job is not done when eQuest runs. It is done when the
> powers that be say yes and cut the cheque. Saving a day or 2 on 2 or 3
> weeks of work means nothing if you spend 6 weeks fighting with a reviewer.
> It is like a thesis.
> All I can say in my defence to this viewpoint is look out when an
> engineer gets philosophical.
> Bruce Easterbrook P.Eng.
> Abode Engineering
>
> On 21/06/2011 05:39 PM, Carol Gardner wrote:
>
> Actually if I was a LEED reviewer I would accept it either way because I
> don't think it will make that much difference.
>
> It's all in the reading, though, so when you read it all in one piece it's:
> Opaque assemblies used for new buildings or additions shall conform with
> the following common, lightweight assembly types and shall match the
> appropriate assembly maximum U-factors in Tables 5.5-1 through 5.5-8:
> • Roofs—Insulation entirely above deck
> • Above-grade walls—Steel-framed
> • Floors—Steel-joist
> The roof/wall/floor types specified here *are *the lightweight assemblies
> that are also on the tables with their corresponding *assembly* u-values.
> (Please note I purposefully left out doors and slab on grade floors).
>
> Thanks for the historical document, Paul. I'll take it with some fine gray
> sea salt, thanks. I was looking for it earlier but didn't find it. It's
> worth while to know what the common definitions of these terms are even
> though they are less in use now. If you are using eQUEST this is especially
> true since this is what they mean by them.
>
> Carol
>
> On Tue, Jun 21, 2011 at 2:03 PM, Paul Riemer <Paul.Riemer at dunhameng.com>wrote:
>
>> I take the following info with a grain of salt but others may find them
>> more meaningful.
>>
>>
>>
>> From the eQUEST help files:
>>
>> Volume 2: Dictionary <http://volume2dictionary.htm/> > Envelope
>> Components <http://envelopecomponents1.htm/> > CONSTRUCTION<http://construction5.htm/>
>>
>> TYPE
>>
>> Specifies the type of construction.
>>
>> LAYERS Indicates that the LAYERS keyword will be used to specify a layered
>> construction. The program will calculate response factors for this
>> construction. The response factors will be used in the hourly simulation to
>> calculate the dynamic, time-delayed heat flow through the construction.
>> Recommended for all but lightweight (low heat capacity) constructions.
>>
>>
>>
>> U-VALUE Indicates that the U-VALUE keyword will be used to specify the
>> conductance of the construction. In this case, the heat flow through the
>> construction will be considered to be instantaneous, i.e., without time
>> delay. Recommended only for lightweight (low heat capacity) constructions.
>>
>>
>>
>>
>>
>> And from a recent LEED review comment:
>>
>> EDUCATIONAL NOTES FOR FUTURE PROJECTS (Optional):
>>
>>
>>
>> Section 1.4.1A of the table does not provide descriptions for any of the
>> Baseline and Proposed Case envelope components. Please revise the table to
>> include the descriptions (i.e. Roof as Insulation Entirely Above Deck, Walls
>> as Steel-Framed, etc.) for all envelope components.
>>
>>
>>
>> *Paul Riemer, PE, LEED AP*
>>
>> *DUNHAM*
>>
>>
>>
>> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
>> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Eric O'Neill
>> *Sent:* Tuesday, June 21, 2011 3:52 PM
>> *To:* Carol Gardner
>>
>> *Cc:* eQUEST Users List
>> *Subject:* Re: [Equest-users] LEED Review Comment on U-Value Input Method
>>
>>
>>
>> Well, perhaps I’m nitpicking, but I see two distinct statements here.
>>
>>
>>
>> 1. “shall conform with the following common, lightweight assembly
>> type”
>> AND
>>
>> 2. “shall match the appropriate assembly maximum U-factors in Tables
>> 5.5-1 through 5.5-8”
>>
>>
>>
>> If a baseline model does not meet both requirements, it doesn’t pass,
>> right?
>>
>>
>>
>> A mass construction, to me, meets both requirements. Just because it has
>> mass does not mean that it doesn’t match the assembly U-factors.
>>
>>
>>
>> However, I feel that a U-value only wall meets #2, but doesn’t meet #1. My
>> original point was that U-value only constructions *don’t conform* with
>> lightweight assembly types because lightweight constructions, by definition,
>> have some mass (or else they’d be no-weight, right?). ASHRAE has provided
>> examples of “light constructions” in the Fundamentals book as steel
>> constructions without brick or concrete, so that tells me that lightweight
>> doesn’t imply no mass.
>>
>>
>>
>> But I’ll confess that I’m only going on instinct and what I feel is the
>> spirit of the code as Bruce described. It is not terribly explicit, so I
>> understand your position and it could probably be argued both ways until the
>> cows come home. I’d just hate to be on the wrong end of it when the final
>> review came through…
>>
>>
>>
>> Eric
>>
>>
>>
>> *From:* Carol Gardner [mailto:cmg750 at gmail.com]
>> *Sent:* Tuesday, June 21, 2011 2:46 PM
>> *To:* Eric O'Neill
>> *Cc:* Robby Oylear; Bishop, Bill; Bruce Easterbrook; eQUEST Users List
>> *Subject:* Re: [Equest-users] LEED Review Comment on U-Value Input Method
>>
>>
>>
>> First of all, as a former energy code reviewer, 2 years for Oregon and
>> about 5 for the City of Portland, it was my responsibility to interpret the
>> intent of the code when the language or application was unclear. That
>> explains why I respond to the word "shall" so strongly.
>>
>> When I read "shall conform with the following common, lightweight assembly
>> type" which for walls is stated to be steel framed walls, and "shall match
>> the appropriate assembly maximum U-factors in Tables 5.5-1 through 5.5-8", I
>> assume I am being directed to use the Prescriptive assembly U-factor
>> provided on the Building Energy Requirements table for my climate zone in
>> Chapter 5.
>>
>> I did a bit of research to see if there was information in the past
>> versions of the standard and in the User's Manuals. What I found was that
>> prior to the adoption of Appendix G, the requirement was to model with the
>> Prescriptive assembly U-factors as well as to match the heat capacity in
>> each case: proposed and design. This meant that if the proposed wall was
>> steel framed then the baseline must be too and credit could not be taken for
>> added mass or changes in framing.
>>
>> After the adoption of Appendix G and the Energy Cost Budget Method in 2004
>> things changed a bit. At that point the direction in the User's Manual
>> states that the baseline building is assumed to be steel framed no matter
>> what the construction of the proposed building. If the proposed building
>> uses added mass, or wood framing or beneficial constructions it is credited
>> to the building. The baseline building *shall* comply with the applicable
>> prescriptive requirements for steel-framed walls, i.e the Prescriptive
>> assembly U-factor for steel framed walls on Table 5 for your climate zone..
>>
>> So, I do not see a mandate, or an implication even, to specify the
>> baseline building walls using layers. Rather I see a clear instruction to
>> use the Prescriptive Path U-value for the baseline and to take credit for
>> any improvements in the proposed building walls. I don't think this is
>> "gaming the system" at all. It is sad but true that many buildings being
>> built today just meet the minimum prescriptive requirement. I have even seen
>> some that didn't. If a building owner is willing to lay out the extra money
>> for a better wall, why shouldn't he/she get credit for it?
>>
>> Stepping off my soap box,
>>
>> Carol
>>
>> On Tue, Jun 21, 2011 at 8:55 AM, Eric O'Neill <ELO at michaelsenergy.com>
>> wrote:
>>
>> Robby,
>>
>>
>>
>> I see your point. However, I’m curious how many wall assembly types you
>> can think of that meet the criteria they discuss in that section (and
>> whether their different themal delay properties would impact the project):
>>
>>
>>
>> · Lightweight (I assume this means no brick exteriors)
>>
>> · Common
>>
>> · Steel Framed
>>
>> · R-13 + R-7.5ci (for instance, depending on climate zone)
>>
>>
>>
>> Now, I’m not saying they couldn’t be more explicit. You’re absolutely
>> right that they could be. However, I could fairly easily justify steel
>> siding, 1.5 inches of polystyrene, steel framed wall with batt insulation
>> and a gyp board finish. Maybe small changes like vinyl siding or an
>> equivalent level of spray foam insulation would have marginally different
>> time delay properties, but I’m guessing they would be negligible based on
>> the information found in the chapter I previously cited.
>>
>>
>>
>> Eric
>>
>>
>>
>> *From:* Robby Oylear [mailto:robbyoylear at gmail.com]
>>
>> *Sent:* Tuesday, June 21, 2011 10:12 AM
>>
>> *To:* Eric O'Neill; Bishop, Bill; Carol Gardner; Bruce Easterbrook;
>> eQUEST Users List
>>
>>
>> *Subject:* Re: [Equest-users] LEED Review Comment on U-Value Input Method
>>
>>
>>
>> While I agree that modeling the baseline with some level of light mass
>> should be done to get more accurate results, it's difficult to understand
>> why 90.1 would not specify a mass value to model. The definition of a
>> baseline is a minimum value for comparison. How can LEED reviewers judge
>> whether or not you're taking the appropriate credit for thermal mass when
>> the baseline building done by one modeler will have a different mass value
>> than one done by another modeler?
>>
>>
>>
>> Values that are vague and undefined (process loads or lighting plug loads
>> in residential for example) are typically left the same between both models.
>> This allows for the factor to be accounted for, but provides no credit to
>> the proposed model. The same could be done for thermal mass, to account for
>> it in both models, but not provide credit. Without a defined baseline, I
>> don't see how one can justify whether or not they've modeled the correct
>> "lightweight" assembly mass value.
>>
>>
>>
>> -Robby
>>
>> On Mon, Jun 20, 2011 at 9:47 AM, Eric O'Neill <ELO at michaelsenergy.com>
>> wrote:
>>
>> I think some confusion stems from the definition of “lightweight”. The
>> fundamentals book discusses light and heavy constructions in the radiant
>> time series, and defines a few examples in table 22, ch 30 (2005 handbook –
>> NonRes Cooling and Heating Load Calcs, Radiant Time Series Method). Light
>> constructions are steel sidings, 2 inches of insulation, an airspace, and
>> gyp board. It also defines medium and heavy, with brick and heavyweight
>> concrete, respectively.
>>
>>
>>
>> So when they say lightweight, I believe they’re referring to something
>> similar. I don’t believe “lightweight” is intended to mean “no-weight” for
>> the reasons Bruce described. It seems to me they’re giving design teams the
>> opportunity to take advantage of a heavy exterior construction if it reduces
>> the peaks. They do ask that they conform with the lightweight assemblies,
>> which, in my opinion, just a U-value does not.
>>
>>
>>
>> Eric
>>
>>
>>
>> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
>> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Bishop, Bill
>> *Sent:* Monday, June 20, 2011 11:01 AM
>> *To:* Carol Gardner; Bruce Easterbrook
>> *Cc:* eQUEST Users List
>>
>>
>> *Subject:* Re: [Equest-users] LEED Review Comment on U-Value Input Method
>>
>>
>>
>> Carol,
>>
>> As we noted earlier in this thread, we can’t find an explicit requirement
>> that layer-by-layer be used. It is strongly implied for at least the
>> proposed in Appendix G, and it is good practice for several reasons as Bruce
>> describes below. From the 90.1 User’s Manual – “The general rule for the
>> baseline building run is that all inputs must be identical to the proposed
>> design run, except for those features that are allowed to differ.” It seems
>> logical to extend this general rule to *input methods* as well as inputs.
>> Would you accept the modeling results if the proposed building was done in
>> TRACE while the baseline was done in eQUEST?
>>
>> Bilbo
>>
>>
>>
>>
>>
>> *From:* Carol Gardner [mailto:cmg750 at gmail.com]
>> *Sent:* Monday, June 20, 2011 11:30 AM
>> *To:* Bruce Easterbrook
>> *Cc:* Bishop, Bill; Pasha Korber-Gonzalez; eQUEST Users List
>> *Subject:* Re: [Equest-users] LEED Review Comment on U-Value Input Method
>>
>>
>>
>> I guess we'll have to agree to disagree.
>>
>>
>>
>> Bilizebub: could you point out the section in LEED or Std 90 that says
>> that walls must both be layer by layer. Thanks.
>>
>>
>>
>>
>>
>> On Mon, Jun 20, 2011 at 7:01 AM, Bruce Easterbrook <bruce5 at bellnet.ca>
>> wrote:
>>
>> I think what is being forgotten is "intent", and the accuracy of your
>> model. So for intent the desire of the powers that be is that smart design
>> be used to reduce the energy consumption of buildings. You should not be
>> manipulating the "system" to take credit for something which is not really a
>> credit. Your model should be as accurate as you can possibly make it with
>> reasonable effort. U-value construction is not accurate, all buildings have
>> mass. Mass serves to shave peaks. When you have a building modelled with
>> no mass as soon as the sun hits it you will have a cooling load. With
>> U-value construction the heat hitting the building is immediately loaded on
>> to the cooling system at 100%. This doesn't happen in reality and you will
>> oversize your cooling system. Therefore you have designed an inefficient
>> system, you are costing your client money because they have to buy and
>> operate a bigger cooling system than required. Logic and good modelling
>> dictate you account for mass. The baseline is a "standard" building
>> construction in use at this time and that is defined, "lightweight steel
>> construction". You don't get credit for the mass of this building. However
>> if you start adding mass strategically to further load shift your peaks you
>> should be able to take credit for that. Besides U-value construction is the
>> old school, brute force technique when energy was cheap and we used spread
>> sheets and calculators. eQuest allows us to accurately predict the mass
>> effect of a building and we have the computing power to run this program
>> sitting on our desk. A good modeller is required to use all the tools at
>> their disposal to create the best base model they can so that the project
>> people can assess different techniques to reduce the energy usage of the
>> building and the economic costs of doing this. I think it is pretty obvious
>> the evaluator will reject a model not done layer by layer. They can't
>> easily check the base construction, the U-value method is not accurate and
>> they are overloaded. So it's file 13 and on to the next project.
>> Bruce Easterbrook P.Eng.
>> Abode Engineering
>>
>>
>> On 20/06/2011 09:03 AM, Bishop, Bill wrote:
>>
>> Like Pasha mentioned, if you use layer-by-layer method in the proposed,
>> you should use the same method in the baseline, unless you want to argue
>> that “lightweight” *requires *the use of the U-value construction method.
>> I don’t see what advantage that serves, other than helping you avoid the
>> time of creating baseline envelope constructions. While “lightweight” is not
>> defined in 90.1, the baseline layer materials and thicknesses are described
>> in A3, so if you use the layer-by-layer method for both baseline and
>> proposed, and if there is a difference in the overall mass of each wall
>> construction, the modeling output will reflect that difference. Both
>> baseline and proposed constructions will have “mass”, and if the proposed
>> construction is optimized, there will be energy savings.
>>
>>
>>
>> The eQUEST help menu item for “EXTERIOR-WALL and ROOF” states that using
>> LAYERS rather than U-VALUE can result in greater computational time, but
>> gives more accurate results. Computational time is at the bottom of my
>> eQUEST concerns. I have not compared modeling results of LAYERS vs. U-VALUE.
>> Delayed construction appears to be required by Appendix G, is supposedly
>> more accurate, and I don’t see a good reason *not* to use it.
>>
>>
>>
>> Billzebub
>>
>>
>>
>> *Error! Filename not specified.*
>>
>>
>>
>> *From:* equest-users-bounces at lists.onebuilding.org [
>> mailto:equest-users-bounces at lists.onebuilding.org<equest-users-bounces at lists.onebuilding.org>]
>> *On Behalf Of *Pasha Korber-Gonzalez
>> *Sent:* Saturday, June 18, 2011 4:39 PM
>> *To:* eQUEST Users List
>> *Subject:* Re: [Equest-users] LEED Review Comment on U-Value Input Method
>>
>>
>>
>> Following the other comments on this, I am confused and worried too that
>> if they are requiring to simulate mass in the baseline, then how could we
>> use Mass constructions as "passive" design strategies and take credit for
>> this type of ECM?
>>
>>
>>
>> Directly from what I was reading in the 2007 code: Table G3.1.5-Baseline
>> Building Enevelope
>>
>> *Opaque Assemblies. Opaque assemblies used for new building or additions
>> shall conform with the following common, lightweight assembly types and
>> shall match the appropriate assembly maximum U-factors in Tables 5.5-1
>> through 5.5-8:*
>>
>>
>>
>> Doesn't the reference to "lightweight" assemblies mean that you don't have
>> to account for thermal lags (massing)? This has always been my
>> interpretation. Therefore, when it comes to modeling the U-values for the
>> assemblies with the U-value method versus the layer method would be
>> acceptable for your baseline simulations. Where there is no requirement to
>> show any type of massing effects it shouldn't matter if you choose to use
>> the U-value input method or the layer-by-layer method.
>>
>>
>>
>> But--it is important for the simulator to understand that when using
>> eQuest (I can't speak for other simulation tools); the input method has to
>> be matched in both the baseline and proposed. You can't choose U-value
>> input for the baseline and layer-by-layer for the proposed, you have to use
>> the "apples-to-apples" approach for both models.
>>
>>
>>
>> It will be a big issue if GBCI mandates that we have to use only
>> layer-by-layer inputs for compliance where Appendix G is clearly stating
>> that there is no need to account for thermal lag in the baseline building as
>> it states "lightweight" construction. Any type of thermal lag
>> characteristics in lightweight construction are negligible to the
>> performance of such constructions as required by Appendix G baseline inputs.
>>
>>
>>
>> pkg
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> On Fri, Jun 17, 2011 at 3:23 PM, Carol Gardner <cmg750 at gmail.com> wrote:
>>
>> I'll bite. What extends it to the baseline? I still see that it just says
>> to credit it to the proposed building. Wasn't this language created to guide
>> people to the fact that even if mass was added to a steel framed building it
>> still fell under the "steel framed" category and not the mass?
>>
>>
>>
>> On Fri, Jun 17, 2011 at 2:07 PM, Bishop, Bill <wbishop at pathfinder-ea.com>
>> wrote:
>>
>> Another piece of the puzzle. >From the 90.1 User’s Manual, section on
>> Baseline Building Opaque Assemblies (p.G14 in 2004 ed.):
>>
>> “The baseline building is assumed to be steel framed no matter what the
>> construction of the proposed building. If the proposed building has thermal
>> mass in the exterior construction and this is a benefit in a particular
>> climate, then the mass is credited in the building performance rating
>> method.”
>>
>>
>>
>> So delayed construction is the de facto method for modeling the proposed
>> envelope, and by extension, the baseline.
>>
>>
>>
>> Bill
>>
>>
>>
>> *Error! Filename not specified.*
>>
>>
>>
>> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
>> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Carol Gardner
>> *Sent:* Friday, June 17, 2011 4:40 PM
>> *To:* Daniel Knapp
>> *Cc:* equest-users at lists.onebuilding.org
>>
>>
>> *Subject:* Re: [Equest-users] LEED Review Comment on U-Value Input Method
>>
>>
>>
>> But the Simulation General Requirements are for the simulation model
>> itself and it's capabilities, they do not address the simulation inputs.
>>
>> I think this section of the code is what governs this issue:
>>
>> Opaque Assemblies. Opaque assemblies used for new buildings or additions
>> shall conform with the following common, lightweight assembly types and
>> shall match the appropriate assembly maximum U-factors in Tables 5.5-1
>> through 5.5-8:
>>
>> But I disagree with Guarav's interpretation for these reasons. The use of
>> the word assemblies might "suggest" the need to model the whole structure
>> but the use of "lightweight" in the sentence, and it's location after the
>> word *shall*, is the key. Those U-values in Tables 5.5-1 through 5.5-8
>> are for lightweight construction. Lightweight construction is not delayed
>> construction. The Standard 90 committee even gave us a variety of wall types
>> to select from on those tables so that we would have an *appropriate
>> assembly maximum U-factor* to use.
>>
>> Anyway, that's my interpretation.
>>
>> Carol
>>
>> On Fri, Jun 17, 2011 at 9:24 AM, Daniel Knapp <danielk at arborus.ca> wrote:
>>
>>
>> FYI, Simulation General Requirements as laid out in 11.2 of the 90.1
>> User's Manual specifically call for the treatment of Thermal Mass Effects in
>> the Minimum Modeling Capabilities. (see 11.1.2.3 and as already mentioned
>> G2.2.1.c) and notes that "A building's ability to absorb and hold heat
>> varies with its *type of construction* and with its system and ventilation
>> characteristics. This affects the timing and magnitude of loads handled by
>> the HVAC system. Simulation programs must be able to model these effects".
>>
>>
>>
>> On 2011-06-16, at 7:15 PM, Mehta, Gaurav wrote:
>>
>> > Michael,
>> >
>> > Agreed, appendix G does not specifically states that one needs to model
>> delayed construction. However, going by the semantics used in Appendix G,
>> one can conclude that delayed construction should be used. Consider the
>> following:
>> >
>> > Table G3.1-5 Building Envelope, under Baseline Building Performance,
>> part (b) Opaque Assemblies: states that Opaque assemblies......shall confirm
>> with the following common, lightweight assembly types and shall match the
>> appropriate assembly U-factors.....
>> >
>> > **The use of the term 'assemblies' suggests the need to model the whole
>> assembly rather than only the U-factor**
>> >
>> > To answer your other question, how do you know what comprises of the
>> baseline opaque assembly, I'll suggest use Appendix A. For example, for
>> steel framed walls, see section A3.3.1 General, you'll find the assembly
>> layers that you can use to model the baseline above grade walls. Similarly,
>> you can use respective sections for roof, floor, etc. to determine the
>> baseline assembly layers.
>> >
>> > If I remember correctly, somebody in the past has been kind enough to
>> post the baseline assemblies that can be copied to the inp file (or imported
>> into the inp file). Search the archives.
>> >
>> > Furthermore, eQUEST has an extensive library of materials that one can
>> use, which includes the thickens, specific heat and density of the material.
>> You can create your own materials by using the ASHRAE Handbook of
>> fundamentals, chapter 26 (2009).
>> >
>> >
>> > Thanks.
>> >
>> > Best regards,
>> >
>> > Gaurav
>> >
>> > Gaurav Mehta, LEED® AP BD+C
>> > Sustainable Building Analyst
>> > Stantec
>> > 1932 First Avenue Suite 307
>> > Seattle WA 98101
>> > Ph: (206) 770-7779
>> > Fx: (206) 770-5941
>> > Gaurav.Mehta at stantec.com
>> > www.stantec.com
>> >
>> > The content of this email is the confidential property of Stantec and
>> should not be copied, modified, retransmitted, or used for any purpose
>> except with Stantec's written authorization. If you are not the intended
>> recipient, please delete all copies and notify us immediately.
>> >
>> > Please consider the environment before printing this email.
>> > -----Original Message-----
>> > From: equest-users-bounces at lists.onebuilding.org [mailto:
>> equest-users-bounces at lists.onebuilding.org] On Behalf Of James Hansen
>> > Sent: Thursday, June 16, 2011 3:09 PM
>> > To: Bishop, Bill; Michael Mantai; equest-users at lists.onebuilding.org
>> > Subject: Re: [Equest-users] LEED Review Comment on U-Value Input Method
>> >
>> > Michael, I'd advise that you email the project coordinator (or whatever
>> GBCI calls the "head" of a project review team). Usually they will answer
>> relatively quick and easy questions so that you don't have to risk
>> improperly addressing a comment.
>> >
>> > Ask them where in Appendix G it specifically requires the time delayed
>> method be used.
>> >
>> > GHT Limited
>> > James Hansen, PE, LEED AP
>> > Senior Associate
>> > 1010 N. Glebe Rd, Suite 200
>> > Arlington, VA 22201-4749
>> > 703-338-5754 (Cell)
>> > 703-243-1200 (Office)
>> > 703-276-1376 (Fax)
>> > www.ghtltd.com
>> >
>> >
>> > -----Original Message-----
>> > From: equest-users-bounces at lists.onebuilding.org [mailto:
>> equest-users-bounces at lists.onebuilding.org] On Behalf Of Bishop, Bill
>> > Sent: Thursday, June 16, 2011 4:22 PM
>> > To: Michael Mantai; equest-users at lists.onebuilding.org
>> > Subject: Re: [Equest-users] LEED Review Comment on U-Value Input Method
>> >
>> > Michael,
>> >
>> > My understanding has always been that delayed construction should be
>> > used, though I can't find exact wording in Appendix G that requires it
>> > other than G2.2.1(c). For other components/layers of steel-framed walls,
>> > look to A3.3.1, and to Table A3.3 for assembly U-Factors for different
>> > stud spacing. You should be pretty close to the required U-Factor if you
>> > use the correct materials and thicknesses from A3.3. Yes, you may need
>> > to tweak a layer or two to get the construction to match the U-Factor
>> > exactly. As described in other posts, once you create these
>> > constructions for the baseline, copy them for future models.
>> >
>> > Regards,
>> > Bill
>> >
>> > -----Original Message-----
>> > From: equest-users-bounces at lists.onebuilding.org
>> > [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of
>> Michael
>> > Mantai
>> > Sent: Thursday, June 16, 2011 4:00 PM
>> > To: equest-users at lists.onebuilding.org
>> > Subject: [Equest-users] LEED Review Comment on U-Value Input Method
>> >
>> > We received the following comment on recent LEED review:
>> >
>> > "The simulation input screenshots, provided in the EAc1 modeling
>> > narrative
>> > report, indicate that the exterior wall and roof constructions were
>> > modeled
>> > as QUICK surface type (U Value Input specification method), which does
>> > not
>> > account for the time delayed heat flow through the constructions as
>> > required
>> > by Section G2.2.1(c). Revise the Proposed and Baseline models so the
>> > exterior walls and roof surface types are modeled as DELAYED (Layer
>> > Input
>> > specification method) with the thermal mass effects of the constructions
>> > taken into consideration. In addition, provide a revised LV I report for
>> > each model reflecting the changes."
>> >
>> > Section G2.2.1(c) describes modeling software requirements, but I don't
>> > see
>> > anywhere else in Appendix G that specifies that thermal mass effects
>> > have to
>> > be included in the baseline model.
>> >
>> > Previous review comments on other projects have led me to believe that
>> > U-value input was the correct method to set up the baseline model.
>> >
>> > If I revise the model to input each layer, what layers do I input?
>> > 90.1-2007 Appendix G states to use steel-framed walls, and the Tables
>> > provide minimum R-value for insulation and overall assembly U-value.
>> > But it
>> > does not appear to provide such other items as stud spacing, sheathing,
>> > or
>> > even what material is on the outside of the building (for exterior
>> > walls).
>> > Has anyone else had this type of comment before or are you using the
>> > layer
>> > input method for baseline models? It seems that if I need to specify
>> > layers, the resultant U-value should equal exactly the minimum U-value
>> > per
>> > the 90.1 tables. That would lead me to believe that there might be
>> > different combinations of layers that result in the same U-values but
>> > result
>> > in different energy use in the baseline, and obviously I would want to
>> > have
>> > the highest energy use for LEED purposes.
>> >
>> >
>> > _______________________________________________
>> > Equest-users mailing list
>> > http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
>> > To unsubscribe from this mailing list send a blank message to
>> > EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
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>>
>> —
>> Daniel Knapp, PhD, LEED® AP O+M
>> danielk at arborus.ca
>>
>> Arborus Consulting
>> Energy Strategies for the Built Environment
>> www.arborus.ca
>> 76 Chamberlain Avenue
>> Ottawa, ON, K1S 1V9
>> Phone: (613) 234-7178 ext. 113
>> Fax: (613) 234-0740
>>
>>
>>
>>
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>>
>>
>> --
>> Carol Gardner PE
>>
>>
>>
>> --
>> Carol Gardner PE
>>
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>> --
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>>
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> Carol Gardner PE
>
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