[Equest-users] Basic stuff - Infiltration

[Robby Oylear]

Gaurav's screenshot didn't come through for me, so to summarize, in order to
take wind-speed correction factors into account you need to take the value
of INF-FLOW/AREA that the wizard inputs into the detailed file and convert
it to an AIR-CHANGE/HR value.  eQUEST does not apply wind-speed correction
to INF-FLOW/AREA (see below).

>From DOE-2 help file on INF-METHOD:

AIR-CHANGE

The infiltration rate is calculated using the air-change method.
AIR-CHANGES/HR or INF-FLOW/AREA should be specified if INF-METHOD =
AIR-CHANGE. In this case the value AIR-CHANGES/HR will be corrected for wind
speed each hour, but the value of INF-FLOW/AREA will not be corrected. If
both AIR-CHANGES/HR and INF-FLOW/AREA are specified, the resulting
infiltration rates are added.

On Wed, Aug 10, 2011 at 9:50 AM, Mehta, Gaurav <Gaurav.Mehta at stantec.com>wrote:

> Here is a recent response that I posted on Bldg-Sim.****
>
> ** **
>
> *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****
>
> *stantec*.com <http://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.****
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> ** **
>
> ü Please consider the environment before printing this email. ****
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Nick Caton
> *Sent:* Wednesday, August 10, 2011 9:40 AM
> *To:* Robby Oylear; John Bixler
> *Cc:* equest-users at lists.onebuilding.org
>
> *Subject:* Re: [Equest-users] Basic stuff - Infiltration****
>
> ** **
>
> Robby – awesome post, thanks for linking that paper!****
>
> ** **
>
> As an extra heads up/thought:  depending on which infiltration method is
> selected, I do believe eQuest will also calculate hourly infiltration rates
> working from windspeed in the weather file.  Details would be in the help
> files...  I can’t recall if this happens with the default method, or if
> there is a single “default” method (it might vary based on how you define
> infiltration at the wizard level?)…****
>
> ** **
>
> ~Nick****
>
> ** **
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, P.E.*
>
> SENIOR ENGINEER****
>
> ** **
>
> Smith & Boucher Engineers****
>
> 25501 west valley parkway, suite 200****
>
> olathe, ks 66061****
>
> direct 913.344.0036****
>
> fax 913.345.0617****
>
> www.smithboucher.com* *****
>
> ** **
>
> *From:* Robby Oylear [mailto:robbyoylear at gmail.com]
> *Sent:* Wednesday, August 10, 2011 11:28 AM
> *To:* John Bixler
> *Cc:* Nick Caton; equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Basic stuff - Infiltration****
>
> ** **
>
> John,****
>
> ** **
>
> The infiltration as a function of exterior gross wall area is only
> available in the wizard.  I don't believe DOE2.2 is capable of having inputs
> that relate to the sum of a parameter of it's child components.  The DOE2.2
> BDL Functions do not have any references to child components (i.e. a Wall
> can reference a parameter of its parent Space, but a Space cannot reference
> a parameter of its child Wall).****
>
> ** **
>
> Regarding Lawrence's initial question about converting a known tested value
> to a value usable within eQUEST, the PNNL Report 18898, Infiltration
> Modeling Guidelines for Commercial Building Energy Analysis (
> http://www.pnl.gov/main/publications/external/technical_reports/PNNL-18898.pdf) contains
> formula for converting infiltration from a test case to an actual design
> case. Based on the example presented in the document, a conversion factor of
> 0.112 can be derived.****
>
> ** **
>
> So a tested air leakage of 0.40 CFM/SF at 0.30 in. w.g. would be modeled at
> 0.045 CFM/SF.  This value is modeled at 100% when building fan system is off
> and 25% when the building fan system is on.****
>
> ** **
>
> Granted, this may be an oversimplification for eQUEST, as the document was
> written for EnergyPlus which contains a wind-driven infiltration model, but
> it seems to be a good starting point at least if you have test information
> available.****
>
> ** **
>
> *Robby Oylear, LEED® AP BD+C*****
>
> *Mechanical Project Engineer*****
>
> *Energy Analyst*****
>
> * *****
>
> *D* 206-788-4571 | *C* 206-354-2721****
>
> *www.rushingco.com* <http://www.rushingco.com/>****
>
> ** **
>
> ** **
>
> On Wed, Aug 10, 2011 at 8:17 AM, John Bixler <JBixler at sebesta.com> wrote:*
> ***
>
> Thanks for the response Nick.****
>
>  ****
>
> As I recall from a recent foray into this subject in eQuest (in detailed
> mode), the cfm/sq ft entry is based on floor area.****
>
>
> It would be logical that if cfm/sq ft of exterior wall is an option in
> wizard mode, it would also be an option in detailed mode – I just haven’t
> dug that far yet.****
>
>  ****
>
> *From:* Nick Caton [mailto:ncaton at smithboucher.com]
> *Sent:* Wednesday, August 10, 2011 10:08 AM
> *To:* John Bixler; equest-users at lists.onebuilding.org
> *Subject:* RE: [Equest-users] Basic stuff - Infiltration****
>
>  ****
>
> Hi John – thanks for your thoughts!****
>
>  ****
>
> I was relating some of the same concerns with others off-list … I’m am no
> infiltration-auditing expert (though some lurk among us here on the lists
> ^_~), but one thing I can say based on my past attempts to build a better
> mousetrap regarding infiltration is that where ASHRAE may be generally vague
> on the topic – they are actually doing a lot to say (if not always directly)
> that whole building infiltration is a very difficult thing to quantify at
> best (sorry for excessive use of parentheticals (I mean it!)…).****
>
>  ****
>
> The best guidance imaginable that would still be practical in day-to-day
> use would have to rely in some part on subjective observations (guesses)
> regarding envelope constructions.  Two brick walls of certain grout/masonry
> ratios weathered for the same period in the same climate may still have
> different leakiness because the two masons used slightly different grout
> mixes…  What I’m getting at is you couldn’t realistically construct a table
> that covered every variable, and many variables are not “knowable.” ****
>
>  ****
>
> That’s not to say the residential ACH table isn’t useful for subjective
> estimations, nor that research couldn’t be undertaken to raise the bar a
> notch.  As John is alluding, a table providing representative commercial
> envelope constructions (with accompanying illustrations!) and/or layer
> combinations could be undertaken that would provide infiltration performance
> as a function of time.  Values could be given for new construction, and
> after weathering for 1/5/10 years.  While new constructions/layers could be
> assessed in a controlled environment, initial research on aged constructions
> would need to be done sampling within a single climate zone.
> Separate/concurrent research could explore determining multipliers on the
> weathering effects based on varying climate and geography…  All things being
> equal, a beachside wall built in Miami, FL with lots of sun/salt/torrential
> rain seasons and the occasional hurricane will weather differently over a
> decade than the same wall in a milder climate.  The net result of such
> research could ultimately produce some really helpful tools in better
> assessing existing and new constructions for a variety of industries and
> purposes (energy modeling included).****
>
>  ****
>
> Considering the growing presence and pressing need for better tools in the
> world of energy modeling, I would put forward prime candidates for whole
> construction assemblies would be ASHRAE 90.1 baseline constructions as
> defined in Appendix A.  ****
>
>  ****
>
> For all I know, such research may be underway or completed years ago – my
> ear is not quite so close to the ground with the academic world… can anyone
> comment?****
>
>  ****
>
>  ****
>
> To another point you brought up – eQuest is quite capable of using your
> personally developed CFM/ft2 values – in the wizards even!  In detailed mode
> you’ll find there are inputs for more involved estimations as well if you
> wish to pursue other methods:****
>
> *Error! Filename not specified.*****
>
> *Error! Filename not specified.*****
>
>  ****
>
> *Error! Filename not specified.*****
>
> * *****
>
> *NICK CATON, P.E.*****
>
> SENIOR ENGINEER****
>
>  ****
>
> Smith & Boucher Engineers****
>
> 25501 west valley parkway, suite 200****
>
> olathe, ks 66061****
>
> direct 913.344.0036****
>
> fax 913.345.0617****
>
> www.smithboucher.com* *****
>
>  ****
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *John Bixler
> *Sent:* Wednesday, August 10, 2011 9:23 AM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Basic stuff - Infiltration****
>
>  ****
>
> My own personal opinion is that ASHRAE Fundamentals has not rescued us
> here.****
>
>  ****
>
> As Nick mentioned, the data presented there is for residential houses and
> relies on incredibly vague and subjective judgment calls by the modeler. *
> ***
>
>  ****
>
> Furthermore, the values presented are in the unit’s of air changes per
> hour.  To me, this is a terrible way to use the data.  Your entries for
> infiltration then rely on the volume of the room to determine the amount of
> infiltration.  The volume of the room (zone is probably a better term) has
> NOTHING to do with the infiltration.  What if I have a gym that’s
> 150’x100’x50’ tall, but it only has 10’ wide by 50’ tall of exterior
> wall???  If I use the ASHRAE method and rely on air changes per hour, the
> zone will be modeled with a HUGE GIGANTIC REALLY REALLY LARGE amount of
> infiltration.  ****
>
>  ****
>
> Yet this seems to be the only recourse we have that is grounded in any sort
> of defendable data.****
>
>  ****
>
> I have looked and looked for a reliable report or other source for real
> world commercial/institutional construction infiltration values to no
> avail.  It would be so incredibly useful.****
>
>  ****
>
> I have, over the course of my energy modeling career, developed a set of
> seemingly practical infiltration values to use, using the units of “CFM per
> sq ft of gross external wall area” available in Trane Trace (I don’t believe
> these units are an option in eQuest).  These values were developed by taking
> a number of buildings with no infiltration and arbitrarily adding
> infiltration in, until I get a reasonable utility consumption value.  Hardly
> scientific and no way could I defend these values if they came under
> scrutiny, other than to say “well, you got a better idea????”****
>
>  ****
>
> Some may say “Eh, who cares about infiltration anyway?”.  Well, it makes a
> bigger difference then you’d think.  ****
>
>  ****
>
> A novice user who relies on the ASHRAE air changes per hour is likely
> significantly oversizing their cooling equipment in large rooms (ie
> conference, assembly, gyms, etc) which is exactly where you don’t want to be
> oversizing cooling equipment.  ****
>
>  ****
>
> Think about the components of a heating load – envelope conduction losses,
> taking in cold OA…and infiltration.  Envelope losses are generally small,
> the design community likes to temper their OA (rightfully so), so where is a
> major component of the heating (consumption) load coming from?  Infiltration
> really adds up.  ****
>
>  ****
>
> How do you justify replacing leaky, wood sash windows?  How bout making a
> switch to spray foam insulation?  How about modeling door seals?  ****
>
>  ****
>
> I’ve rambled enough.  Point being, we all are forced to use arbitrary
> numbers for something that is a significant component of both equipment
> sizing and energy modeling and it just makes me mad and embarrassed when I
> have to explain to a client or colleague “well those are really important,
> but completely imaginary, numbers…”****
>
>  ****
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Bruce
> Easterbrook
> *Sent:* Tuesday, August 09, 2011 5:41 PM
> *To:* John Bixler
> *Subject:* Re: [Equest-users] Basic stuff - Infiltration****
>
>  ****
>
> Since 1922!
> Bruce Easterbrook P.Eng.
> Abode Engineering
> ASHRAE Member
>
> On 09/08/2011 06:11 PM, lawrence Lile wrote: ****
>
> Good ol ASHRAE Fundamentals!  Why didn't I think of looking there?  Thanks!
>   ****
>
>  ****
>
>  ****
>
> On Mon, Aug 8, 2011 at 11:36 AM, Nick Caton <ncaton at smithboucher.com>
> wrote:****
>
> Hi Lawrence,****
>
>  ****
>
> My copy of ASHRAE Principles of HVAC includes a table (5-1) excerpted from
> ASHRAE Fundamentals, 2001 (Table 7, Ch 28).  This table provides air change
> rates as a function of subjective envelope airtightness (“tight” / “medium”
> / “loose”) and as a function of the outdoor design temperature.  Upon
> reviewing the referenced Fundamentals chapter, I learned this table is built
> from research surveying residential homes of various vintages, so it helps
> to know that these are “tight” to “loose” residential constructions.  ****
>
>  ****
>
> In any case, I’ve used and cited this resource before when modeling
> infiltration and calculating sizing loads for non-residential projects as
> well.  I’ve searched, but have yet to come up with an equivalent table based
> on surveying and measuring commercial constructions from a
> subjective/objective standpoint… That might be handier, but in the meantime
> this is a good tool for “converting” your subjective observations into the
> right ballpark.  ****
>
>  ****
>
> ~Nick****
>
>  ****
>
> *Error! Filename not specified.*****
>
> * *****
>
> *NICK CATON, P.E.*****
>
> SENIOR ENGINEER****
>
>  ****
>
> Smith & Boucher Engineers****
>
> 25501 west valley parkway, suite 200****
>
> olathe, ks 66061****
>
> direct 913.344.0036****
>
> fax 913.345.0617****
>
> www.smithboucher.com* *****
>
>  ****
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *lawrence Lile
> *Sent:* Sunday, August 07, 2011 12:50 PM****
>
>
> *To:* equest-users at lists.onebuilding.org****
>
> *Subject:* [Equest-users] Basic stuff - Infiltration****
>
>  ****
>
> In building modeling programs one always has to provide precise values for
> infiltration.  In the real world, I will know one of two things:  almost
> nothing (The building appears to be kinda leaky with old windows), or I will
> have a blower door test done at a specific pressure.  How do I convert
> subjective ("kinda leaky") or objective (Blower door test) leakage into
> numbers that make sense in the program?  Is there a guide one can use?  **
> **
>
>  ****
>
>  ****
>
> --Lawrence****
>
>  ****
>
>  ****
>
> _______________________________________________****
>
> 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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> ** **
>
>
> ---------- Forwarded message ----------
> From: "Mehta, Gaurav" <Gaurav.Mehta at stantec.com>
> To: "bldg-sim at lists.onebuilding.org" <bldg-sim at lists.onebuilding.org>
> Date: Tue, 2 Aug 2011 11:12:31 -0600
> Subject: Re: [Bldg-sim] RE : Infiltration effect in Climate 1
>
> Richard,****
>
> ** **
>
> Are you using the default infiltration rate (0.038 cfm/ft2 of external wall
> area) for the perimeter spaces? ****
>
> ** **
>
> eQUEST calculates the cfm based on the external wall area and then converts
> this to an infiltration flow (cfm/ft2 of floor area of the space). ****
>
> ** **
>
> As Fredrick has pointed out this infiltration flow assigned by eQUEST to
> each perimeter space is not depended on the climate. ****
>
> ** **
>
> See the help section screenshot below:****
>
> ** **
>
> ** **
>
> ****
>
> ** **
>
> It is a flat rate assigned to each space and does not include any wind
> speed correction and inside-outside temperature difference. The 0.038
> cfm/ft2 (of external wall area) infiltration rate was included in the ASHRAE
> Standard 90.1-1989 as a beginning assumption and that’s what shows up in
> eQUEST as default.****
>
> ** **
>
> It is good that you are questioning the effect of infiltration on the
> energy use of building that you are modeling. In the absence of blower door
> test results it is difficult to imagine the real infiltration rate in a
> building as it depends on many factors such as the workmanship of the actual
> construction, stack effect, inside-outside temperature difference,
> wind-speed and how well the building is pressurized by the HVAC system. **
> **
>
> ** **
>
> I’ll suggest go through the following study by PNNL: Infiltration Modeling
> Guidelines for Commercial Building Energy Analysis<http://www.pnl.gov/main/publications/external/technical_reports/PNNL-18898.pdf>
> ****
>
> ** **
>
> Although the report is Energy Plus specific but it can be applied to eQUEST
> as well. In a recent project I used the PNNL guidelines and further
> converted the infiltration flow for each space to air-changes per hour to
> take the wind-speed correction into account. This method still has
> limitation of not taking into account the inside-outside temperature
> difference (see above screen-shot). I found the rest of the methods that
> include both wind-speed correction and inside-outside temperature difference
> to be specific to residential buildings.****
>
> ** **
>
> Hope it helps.****
>
> ** **
>
> 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****
>
> *stantec*.com <http://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.****
>
> ** **
>
> ü Please consider the environment before printing this email. ****
>
>  ****
>
> *From:* bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Genest,
> Frederic
> *Sent:* Monday, August 01, 2011 6:03 PM
> *To:* ROBERT GOMEZ; bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] RE : Infiltration effect in Climate 1****
>
> ** **
>
> ** **
>
> Hello Richard.
>
> I'm not used to eQuest, but since it is using DOE in the background, same
> as EE4 I'm using more frequently, I'll try to answer correctly.
>
> Climate Zone has nothing to do with infiltration rates, except when in
> comes to wind speed and such. However, I don't think DOE is considering wind
> speed when calculating infiltration rates; it is usually defined as a
> constant, based on a value such as ACH or cfm/ft.sq. of wall area.
>
> As such, I would start to check your infiltration inputs to see what is
> defined, first in eQuest and then in the DOE input file. I'm pretty sure
> you'll find your answer somewhere there.
>
> Also note that design infiltration rate and "actual, under operating
> conditions" infiltration rate, are two different things. The average
> constant infiltration rate is adequate enough for the later one.
>
> Also, if you ever need to model a real infiltration from blower door test
> results, I personnaly use the 50 Pa value divided by 20 for actual, normal
> operation conditions, while the 75 Pa value would be divided by 35 (in
> whatever units those values are provided).
>
> Regards.
>
>
>
> Frederic Genest, ing., M.Sc.A.
> LEED AP, ASHRAE HBDP
> fgenest at pageaumorel.com
>
> Pageau Morel et associés
> 210 Cremazie Ouest, suite 110
> Montréal, Qc H2P 1C6
> T) 514-382-5150 begin_of_the_skype_highlighting              514-382-5150      end_of_the_skype_highlighting
> begin_of_the_skype_highlighting              514-382-5150      end_of_the_skype_highlighting
> F)514-384-9872
> www.pageaumorel.com
>
>
> -------- Message d'origine--------
> De: ROBERT GOMEZ [mailto:rsg4999 at yahoo.com <rsg4999 at yahoo.com>]
> Date: dim. 31/07/2011 23:05
> À: bldg-sim at lists.onebuilding.org
> Objet : [Bldg-sim] Infiltration effect  in Climate 1
>
> Hello all,
>
> I'm currently involved in a project that is located in International
> Climate Zone 1 (Very Hot - Humid). The building has no heating system, HVAC
> systems are only for cooling. Infiltration effect is smaller than I expected
> from the eQuest energy model result. I know it has something to do with the
> climate. Can anyone tell me the reason why?
>
> Thanks in advance!
>
>
> Richard Gulli
> Project Engineer****
>
> _______________________________________________
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>
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