[Equest-users] Basic stuff - Infiltration (UNCLASSIFIED)
Bobby Sy
rsg4999 at gmail.com
Tue Aug 16 04:04:15 PDT 2011
Hi all,
In the UK when modeling houses, for example, the reduction in infiltration
provides a much bigger return on the overall energy saving – albeit with a
much simpler model engine. Let me explain.
British Building Regulations demand a maximum infiltration rate of 10m³
/h.m² of wall area (at 50pa) – equivalent to a little over a hole the size
of a 5 peso coin per m². Reducing the infiltration rate to 3m³ gets an
instant improvement in overall energy consumption of around 3%. Further,
Germany’s Passivhaus criteria has a maximum heating demand of 15kWh/m².yr –
ditto cooling demand. To achieve that they regularly build to infiltration
not exceeding 1m³. That’s difficult to achieve but the point is I don’t see
anywhere near the percentage improvements from similar ‘tests’ with
infiltration with the DOE models. Why is that?
Thanks in advance!
-Robert
On Thu, Aug 11, 2011 at 2:04 AM, Eurek, John S NWO <
John.S.Eurek at usace.army.mil> wrote:
> Classification: UNCLASSIFIED
> Caveats: NONE
>
>
> Another infiltration issue to consider is the infiltration schedule. Most
> of
> my designs include building pressurization during occupied hours. I make
> an
> infiltration schedule and set the infiltration to 10% during occupied
> hours.
>
> The biggest advantage is that all the outside air goes through an energy
> recovery unit and therefore is tempered.
>
>
>
> "Is Freedom a small price to pay to stop Global Warming?"
>
> John Eurek PE, LEED AP
>
>
> -----Original Message-----
> From: equest-users-bounces at lists.onebuilding.org
> [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Robby
> Oylear
> Sent: Wednesday, August 10, 2011 11:55 AM
> To: Mehta, Gaurav
> Cc: equest-users at lists.onebuilding.org
> Subject: Re: [Equest-users] Basic stuff - Infiltration
>
> 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 <tel:%28206%29%20770-7779>
> Fx: (206) 770-5941 <tel:%28206%29%20770-5941>
> 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: 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
>
>
>
> 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 <http://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.p
> df<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 <http://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 <http://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
>
>
>
>
>
> _______________________________________________
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>
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>
>
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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.p
> df<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 <tel:%28206%29%20770-7779>
> Fx: (206) 770-5941 <tel:%28206%29%20770-5941>
> 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]
> 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
>
>
> _______________________________________________
> 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
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>
>
>
>
>
> Classification: UNCLASSIFIED
> Caveats: NONE
>
>
> _______________________________________________
> Equest-users mailing list
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