[Bldg-sim] modelling stratification in houses
mark dewsbury
Mark.Dewsbury at utas.edu.au
Mon Nov 21 19:30:45 PST 2011
Dear Hayes,
First question – Unconditioned & Un-occupied or Conditioned & Occupied
This is very important as conditioning mixes the air.
In unconditioned & un-occupied we have measured stratification. This has
resulted in the measurement of temperature at different heights which is
then averaged to obtain a room air temperature.
Dr Mark Dewsbury
Residential Thermal Performance Research
School of Architecture
University of Tasmania
Locked Bag 1324
Launceston 7250
Ph: 03 6324 4471
mob: 0417 290 807
fax: 03 6324 4088
e: mark.dewsbury at utas.edu.au
_____
From: Hayes Zirnhelt [mailto:hzirnhelt at hotmail.com]
Sent: Thursday, 17 November 2011 11:35 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] modelling stratification in houses
Hi,
I'm modelling single family dwellings in EnergyPlus, and I am wondering
about the accuracy of the typical assumption that the zones are fully mixed
.
The results of my modelling are showing that the high ratio of ceiling
insulation to wall insulation required by the codes (BC and Canada) seems to
higher than practical (i.e. no point having an R50 roof if your walls are
only R16). However, this is making me wonder if I should be trying to
account for the stratification that occurs in reality (which would increase
losses through the roof).
Anyone have any experience with modelling stratification in a scenario like
this? Or know of some empirical studies where the stratification has been
measured? I'm pretty sure I can set up a temperature gradient in the zone if
I know what it should be...
Thanks!
Hayes
Hayes Zirnhelt
M.A.Sc Candidate, RU Building Science
B.A.Sc Integrated Engineering
hayes.zirnhelt at ryerson.ca
On 2011-11-16, at 1:30 PM, bldg-sim-request at lists.onebuilding.org wrote:
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Today's Topics:
1. eQuest - Heating/Cooling Loads (Katherine Louman-Gardiner)
2. Re: eQuest - Heating/Cooling Loads (Katherine Louman-Gardiner)
3. Re: usgbc response to outdoor air question (Reba Schaber)
4. Re: usgbc response to outdoor air question
(Martin Roy ing. LEED AP)
5. EnergyPlus: Outlet Nodes not matching error (Sachin Sharma)
6. Re: usgbc response to outdoor air question
(Patrick J. O'Leary, Jr.)
7. Re: usgbc response to outdoor air question (Jim Dirkes)
8. Re: EnergyPlus: Outlet Nodes not matching error (Linda Lawrie)
9. Re: usgbc response to outdoor air question (Jeremy Poling)
10. HELP WANTED: Energy Modeler SWA (NY-CT) (Sandor Rosta)
From: "Katherine Louman-Gardiner" <klgardiner at flowgroup.ca>
Date: November 15, 2011 2:57:02 PM PST
To: <bldg-sim at lists.onebuilding.org>
Subject: [Bldg-sim] eQuest - Heating/Cooling Loads
Hi all,
I’m not sure I understand how eQuest calculates the heating/cooling
equipment loads.
I’ve built two models with identical envelopes and internal loads etc, and
OA supply. In model A, we have a boiler and chiller on hot and chilled
water loops and a four-pipe fan coil air-side system. In model B, we’re
using an air cooled Heat Pump and two-pipe fan coils.
In report PS-C for model A, the sum heat load is -29.6 MBTU, whereas for
model B, the sum heat load is -130.2 MBTU. I understand that the fuel use
should be very different, but I don’t know why the load is so different
between the models. Shouldn’t the heating energy delivered to the spaces be
the same in both cases? Why does the Heat Pump system have a load that is
so much higher than its counterpart?
Similarly, in report SS-E, January has 110 Heating load hours for Model A,
and 385 Heating load hours for Model B. Again, shouldn’t the loads be the
same between the two models?
Thanks in advance for the help,
Katherine
From: "Katherine Louman-Gardiner" <klgardiner at flowgroup.ca>
Date: November 15, 2011 4:06:48 PM PST
To: <bldg-sim at lists.onebuilding.org>
Subject: Re: [Bldg-sim] eQuest - Heating/Cooling Loads
Thanks Brian,
But I’d already examined LS-C, LS-D, SS-C and SS-D. As one would expect,
LS-C and LS-D are the same for both models. SS-D, however, is not. I guess
what I don’t understand is what eQuest considers a “load” to be. I consider
“load” to be the requirements of the space (including envelope, occupants,
and OA), and none of those things have changed between my models. The only
thing that changes is what system is used to meet the load.
SS-D only has a monthly breakdown – but doesn’t explain why the loads are
different.
Thanks,
Katherine
From: Brian Fountain [mailto:greensimbf at gmail.com] On Behalf Of Brian
Fountain
Sent: November-15-11 3:15 PM
To: Katherine Louman-Gardiner
Subject: Re: [Bldg-sim] eQuest - Heating/Cooling Loads
Look at the SS-D and LS-C reports. SS-D shows the peak heating & cooling
loads with outdoor air, LS-C shows the same without outdoor air ... but will
show components so you can determine where the difference is.
On 11/15/2011 5:57 PM, Katherine Louman-Gardiner wrote:
Hi all,
I’m not sure I understand how eQuest calculates the heating/cooling
equipment loads.
I’ve built two models with identical envelopes and internal loads etc, and
OA supply. In model A, we have a boiler and chiller on hot and chilled
water loops and a four-pipe fan coil air-side system. In model B, we’re
using an air cooled Heat Pump and two-pipe fan coils.
In report PS-C for model A, the sum heat load is -29.6 MBTU, whereas for
model B, the sum heat load is -130.2 MBTU. I understand that the fuel use
should be very different, but I don’t know why the load is so different
between the models. Shouldn’t the heating energy delivered to the spaces be
the same in both cases? Why does the Heat Pump system have a load that is
so much higher than its counterpart?
Similarly, in report SS-E, January has 110 Heating load hours for Model A,
and 385 Heating load hours for Model B. Again, shouldn’t the loads be the
same between the two models?
Thanks in advance for the help,
Katherine
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From: Reba Schaber <Rschaber at PHMECH.com>
Date: November 15, 2011 6:41:36 PM PST
To: Jim Dirkes <jim at buildingperformanceteam.com>,
"equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>,
"'bldg-sim at lists.onebuilding.org'" <Bldg-sim at lists.onebuilding.org>
Subject: Re: [Bldg-sim] usgbc response to outdoor air question
RE: “. . . can’t find) anything in 621.1 which says that unoccupied
ventilation should be zero.”
I think this requirement comes from the mandatory provisions of 90.1.
6.4.3.4.3 Shutoff Damper Controls. Both outdoor
air supply and exhaust systems shall be equipped with motorized
dampers that will automatically shut when the systems or
spaces served are not in use. Ventilation outdoor air dampers
shall be capable of automatically shutting off during preoccupancy
building warm-up, cool down, and setback, except
when ventilation reduces energy costs (e.g., night purge) or
when ventilation must be supplied to meet code requirements.
Thoughts??
Reba
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Jim Dirkes
Sent: Monday, October 17, 2011 9:32 AM
To: equest-users at lists.onebuilding.org; 'bldg-sim at lists.onebuilding.org'
Subject: Re: [Bldg-sim] usgbc response to outdoor air question
Dear Patrick,
Thank you for sharing this GBCI response! It is very informative and, while
I won’t admit that I’ve been modeling anything incorrectly, I am going to
change a couple of things :-).
In particular, I have heard on several occasions that the Increased
Ventilation credit was a clear case of “IEQ vs. energy”; you make a decision
to trade one against the other. After reading the GBCI response below and
then double-checking with ASHRAE 90.1, I find that they are consistent with
each other and effectively allow no penalty for the increased energy caused
by increased ventilation. Very curious, considering there is no science
which demonstrates a health benefit for outdoor airflows greater than that
required by ASHRAE 62.1!
The other item is that I failed to notice (and still can’t find) anything in
621.1 which says that unoccupied ventilation should be zero. I guess that
is OK, but is also curious, since a portion of the ventilation calcs in 62.1
include consideration for off-gassing materials (which are always present.)
All in all, I’m smarter than I was as a result of your post, so it’s a good
day! Thanks again.
The Building Performance Team
James V. Dirkes II, P.E., BEMP , LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Patrick J.
O'Leary, Jr.
Sent: Monday, October 17, 2011 11:46 AM
To: equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] usgbc response to outdoor air question
back in september there was a thread about what the outdoor air rate in a
baseline simulation should be compared to a proposed simulation,
specifically when one is adding 30% more outdoor air to meet the ieqc2
requirement and earn 1 leed point. there were differences of opinions about
the flow rates between baseline and proposed being either the same (as
required in 90.1 app g) or the baseline being the calculated per 62.1 and
the proposed being as designed.
so i submitted a support request to the usgbc and the reply i received is
below, but in short the response is that unless you're using dcv optionally
the outdoor air rates in the baseline and proposed energy simulations for
eac1 should be the same. the response below gives the standard responses to
differing outdoor air rate scenarios.
regards,
patrick
[Fwd: Case 00531150: General LEED Questions
-------- Original Message --------
Subject:
Case 00531150: General LEED Questions [ ref:00D49UeD.5004GN692:ref ]
Date:
Mon, 17 Oct 2011 06:54:51 +0000 (GMT)
From:
"No reply GBCI" <mailto:no-reply at gbci.org> <no-reply at gbci.org>
<mailto:no-reply at gbci.org> <no-reply at gbci.org>
To:
patrick@
Dear Patrick,
Thank you for contacting the Green Building Certification Institute.
You ask very good questions related to the relationship between ASHRAE
Standards 62.1 and 90.1, and how these standards are applied across multiple
LEED Rating System prerequisites and credits.
The simple answer to your question is that, for systems without demand
controlled ventilation, the outdoor air included in EA Credit 1 energy
simulations must be the same in the Baseline and Proposed cases. If the
project is attempting IEQ Credit 2 Increased Ventilation, then the values
calculated in IEQc2 must be used in the EAc1 Basline and Proposed case
energy models. Note that IEQc2 does not limit the project to providing only
30% more outdoor air than AHRAE 62.1 Ventilation Rate Procedure minimums, so
higher amounts are acceptable, as long as they are modeled identically in
both the Baseline and Proposed case energy models.
The following generic LEED Review Comment applies to ventilation systems
that do not have demand controlled ventilation:
It is unclear whether the minimum outside air rates (in CFM) were modeled
identically in the Baseline and Proposed case for all zones not having
Demand Control Ventilation in the Proposed case. Please confirm that minimum
outside airflow (in units of cfm) was modeled identically in the Baseline
and Proposed cases using the proposed case rates. Additionally, please
verify that all systems in both the baseline and proposed case are modeled
with zero outside air flow when fans are cycled on to meet unoccupied
setback temperatures unless health or safety regulations mandate an
alternate minimum flow during unoccupied periods (in which case, the
unoccupied outside air rates should be modeled identically in the Baseline
and Proposed case).
The situation becomes a bit more complicated in you have systems that have
demand controlled ventilation (often implemented as Carbon Dioxide control
of outdoor air or as programmed control of outdoor air based on occupancy
sensors.) In this case the Baseline case energy model must include the
minimum outdoor air as determined by the ASHRAE 62.1 Ventilation Rate
Procedure calculations for all systems having demand controlled ventilation.
The following generic LEED Review Comment applies to ventilation systems
that do have demand controlled ventilation:
Demand control ventilation was modeled for credit in the proposed case.
Appendix G allows schedule changes for demand control ventilation as
approved by the rating authority (Table G3.1#4(Baseline)). As the LEED
Certification rating authority, GBCI requires that the outside air
ventilation rates for the Baseline case be modeled using minimum ASHRAE
62.1-2004 (or 2007 for LEED-NC 2009 projects) rates wherever credit is taken
for demand control ventilation in the Proposed case. The proposed case
minimum rates at design conditions should be modeled as designed. Please
verify that the Baseline Case model reflects ASHRAE 62.1-2004 (or 2007)
minimum rates for any spaces where credit is taken for demand control
ventilation, or revise the model accordingly. For all other spaces, please
confirm that minimum outside airflow (in units of cfm) was modeled
identically in the Baseline and Proposed cases. Additionally, please verify
that all systems in both the baseline and proposed cases are modeled with
zero outside air flow when fans are cycled on to meet unoccupied setback
temperatures unless health or safety regulations mandate an alternate
minimum flow during unoccupied periods (in which case, the unoccupied
outside air rates should be modeled identically in the Baseline and Proposed
case).
Finally, even though you don't address energy recovery in your question,
whether or not you have energy recovery in your ventilation systems may
affect how much better (or worse) your Proposed case energy models perform
in relation to your Baseline case energy models.
The following generic LEED Review Comment addresses energy recovery in EAc1
energy models as it relates to ventilation systems.
Energy recovery is modeled for credit in the Proposed case. Please provide
further information regarding the energy recovery efficiency, verify that
outside air is modeled with zero flow in both the Baseline and Proposed
cases during unoccupied periods when fans are cycled on to meet unoccupied
setback temperatures unless health or safety regulations mandate an
alternate minimum flow during unoccupied periods (in which case, the
unoccupied outside air rates should be modeled identically in the Baseline
and Proposed Case), and indicate the bypass mechanism used to bypass the
energy recovery during mild conditions.
I hope that helps, but if you have any further questions or concerns, please
feel free to use the contact form at http://www.gbci.org/contactus and
select "Follow up to GBCI Response," inputting your case number from this
email's subject line.
Best Regards,
Dan Katzenberger, P.E., CEM, BEMP, LEED-AP BD+C
Green Building Certification Institute
2101 L Street NW, Suite 500
Washington, DC 20037
800-795-1746 (phone)
202 828-5110 (fax)
www.gbci.org/contactus
The text above represents a staff opinion of a particular issue, and does
NOT set any precedent to be upheld during a LEED Certification Review. For
official rulings in advance of a LEED Certification Review, customers should
utilize the Formal Inquiries process available in LEED Online that results
in a Project Credit Interpretation Ruling (Project CIR) and possibly a LEED
Interpretation (formerly CIRs or Public Rulings). Applications for LEED
Certification will be thoroughly reviewed based on USGBC Member balloted and
approved LEED Rating Systems, with addenda, and USGBC approved LEED
Interpretations, or Project CIRs administered by GBCI, as applicable. Please
note that certain inquiries submitted to USGBC are forwarded to GBCI for
reply as appropriate.
_______________________________
CUSTOMER EMAIL ADDRESS:
patirck@
CUSTOMER INQUIRY:
I am trying to verify what the minimum outdoor airflow rate required for
EAc1 is and am not sure if this requires a CIR.
If the Proposed outdoor air ventilation is a minimum of 30% higher than the
minimum required by ASHRAE 62 in order to achieve 1 LEED point for credit
IEQC2 is the Baseline outdoor air rate also 30% higher than the minimum
required by ASHRAE 62? or would the Baseline outdoor air ventilation rate be
the minimum outdoor air rate per ASHRAE 62 calculations.
In other words, if ASHRAE 62 requires a minimum of 1,000 CFM of outdoor air,
and 1,300 CFM is provided to attain 1 LEED point via IEQC1, is the Baseline
outdoor air flow rate 1,000 CFM or 1,300 CFM in the energy simulation?
90.1-2007/2004 both say the minimu m outdoor airflow rates shall be the
same for both the proposed and baseline building designs, as does the user
manual.
But this logic seems to reward the Proposed simulation by conditioning the
additional outdoor air supplied (300 cfm in the example above) to achieve
IEQC1 in the Baseline system as well as the proposed.
The logic of using the minimum required in the Baseline case is reflected in
EAC1 in the equipment efficiency requirements. Baseline efficiencies are the
minimum required, e.g. SEER 13 for packaged units.
It is the intent of the requirement that I am not sure is clear. Increasing
the outdoor air ventilation rate increases the energy used to condition the
outdoor air, so if the intent is to put the onus on Proposed design to show
energy reduction/LEED compliance over the 90.1/62 requirements shouldn't the
Baseline outdoor air be the minimum air flow rate per the ASHRAE 62
calculations? This puts the onus on the design team to provide a design that
compensates for the increase in energy to meet IEQC2 by providing some
method of processing the increase in outdoor air while still reducing energy
consumption.
From: "Martin Roy ing. LEED AP" <martin.roy at mra.qc.ca>
Date: November 15, 2011 7:15:12 PM PST
To: Reba Schaber <Rschaber at PHMECH.com>
Cc: "equest-users at lists.onebuilding.org"
<equest-users at lists.onebuilding.org>, "'bldg-sim at lists.onebuilding.org'"
<Bldg-sim at lists.onebuilding.org>
Subject: Re: [Bldg-sim] usgbc response to outdoor air question
Ouch!
In the Model energy code in Canada only up to 20% more than ASHRAE 62 is
allowed in the base case. Imagine a building with 100% more OA and a ERV of
70% on the proposed case it can easily reach 10 EAcr1 point especially in
cold climate.
Martin
At 21:41 15/11/2011, Reba Schaber wrote:
Content-Language: en-US
Content-Type: multipart/alternative;
boundary="_000_FAA9B7F58E5E4A46BDDF900F4CCAC3FE03ABA763DD3DPHSERVERphm_"
RE: “. . . can’t find) anything in 621.1 which says that unoccupied
ventilation should be zero.”
I think this requirement comes from the mandatory provisions of 90.1.
6.4.3.4.3 Shutoff Damper Controls. Both outdoor
air supply and exhaust systems shall be equipped with motorized
dampers that will automatically shut when the systems or
spaces served are not in use. Ventilation outdoor air dampers
shall be capable of automatically shutting off during preoccupancy
building warm-up, cool down, and setback, except
when ventilation reduces energy costs (e.g., night purge) or
when ventilation must be supplied to meet code requirements.
Thoughts??
Reba
From: bldg-sim-bounces at lists.onebuilding.org [
<mailto:bldg-sim-bounces at lists.onebuilding.org>
mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Jim Dirkes
Sent: Monday, October 17, 2011 9:32 AM
To: equest-users at lists.onebuilding.org; 'bldg-sim at lists.onebuilding.org'
Subject: Re: [Bldg-sim] usgbc response to outdoor air question
Dear Patrick,
Thank you for sharing this GBCI response! It is very informative and, while
I won’t admit that I’ve been modeling anything incorrectly, I am going to
change a couple of things J.
In particular, I have heard on several occasions that the Increased
Ventilation credit was a clear case of “IEQ vs. energy”; you make a decision
to trade one against the other. After reading the GBCI response below and
then double-checking with ASHRAE 90.1, I find that they are consistent with
each other and effectively allow no penalty for the increased energy caused
by increased ventilation. Very curious, considering there is no science
which demonstrates a health benefit for outdoor airflows greater than that
required by ASHRAE 62.1!
The other item is that I failed to notice (and still can’t find) anything in
621.1 which says that unoccupied ventilation should be zero. I guess that
is OK, but is also curious, since a portion of the ventilation calcs in 62.1
include consideration for off-gassing materials (which are always present.)
All in all, I’m smarter than I was as a result of your post, so it’s a good
day! Thanks again.
The Building Performance Team
James V. Dirkes II, P.E., BEMP , LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653
From: bldg-sim-bounces at lists.onebuilding.org [
<mailto:bldg-sim-bounces at lists.onebuilding.org>
mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Patrick J.
O'Leary, Jr.
Sent: Monday, October 17, 2011 11:46 AM
To: equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] usgbc response to outdoor air question
back in september there was a thread about what the outdoor air rate in a
baseline simulation should be compared to a proposed simulation,
specifically when one is adding 30% more outdoor air to meet the ieqc2
requirement and earn 1 leed point. there were differences of opinions about
the flow rates between baseline and proposed being either the same (as
required in 90.1 app g) or the baseline being the calculated per 62.1 and
the proposed being as designed.
so i submitted a support request to the usgbc and the reply i received is
below, but in short the response is that unless you're using dcv optionally
the outdoor air rates in the baseline and proposed energy simulations for
eac1 should be the same. the response below gives the standard responses to
differing outdoor air rate scenarios.
regards,
patrick
[Fwd: Case 00531150: General LEED Questions
-------- Original Message --------
Subject:
Case 00531150: General LEED Questions [ ref:00D49UeD.5004GN692:ref ]
Date:
Mon, 17 Oct 2011 06:54:51 +0000 (GMT)
From:
"No reply GBCI" <mailto:no-reply at gbci.org> <no-reply at gbci.org>
<mailto:no-reply at gbci.org> <no-reply at gbci.org>
To:
patrick@
Dear Patrick,
Thank you for contacting the Green Building Certification Institute.
You ask very good questions related to the relationship between ASHRAE
Standards 62.1 and 90.1, and how these standards are applied across multiple
LEED Rating System prerequisites and credits.
The simple answer to your question is that, for systems without demand
controlled ventilation, the outdoor air included in EA Credit 1 energy
simulations must be the same in the Baseline and Proposed cases. If the
project is attempting IEQ Credit 2 Increased Ventilation, then the values
calculated in IEQc2 must be used in the EAc1 Basline and Proposed case
energy models. Note that IEQc2 does not limit the project to providing only
30% more outdoor air than AHRAE 62.1 Ventilation Rate Procedure minimums, so
higher amounts are acceptable, as long as they are modeled identically in
both the Baseline and Proposed case energy models.
The following generic LEED Review Comment applies to ventilation systems
that do not have demand controlled ventilation:
It is unclear whether the minimum outside air rates (in CFM) were modeled
identically in the Baseline and Proposed case for all zones not having
Demand Control Ventilation in the Proposed case. Please confirm that minimum
outside airflow (in units of cfm) was modeled identically in the Baseline
and Proposed cases using the proposed case rates. Additionally, please
verify that all systems in both the baseline and proposed case are modeled
with zero outside air flow when fans are cycled on to meet unoccupied
setback temperatures unless health or safety regulations mandate an
alternate minimum flow during unoccupied periods (in which case, the
unoccupied outside air rates should be modeled identically in the Baseline
and Proposed case).
The situation becomes a bit more complicated in you have systems that have
demand controlled ventilation (often implemented as Carbon Dioxide control
of outdoor air or as programmed control of outdoor air based on occupancy
sensors.) In this case the Baseline case energy model must include the
minimum outdoor air as determined by the ASHRAE 62.1 Ventilation Rate
Procedure calculations for all systems having demand controlled ventilation.
The following generic LEED Review Comment applies to ventilation systems
that do have demand controlled ventilation:
Demand control ventilation was modeled for credit in the proposed case.
Appendix G allows schedule changes for demand control ventilation as
approved by the rating authority (Table G3.1#4(Baseline)). As the LEED
Certification rating authority, GBCI requires that the outside air
ventilation rates for the Baseline case be modeled using minimum ASHRAE
62.1-2004 (or 2007 for LEED-NC 2009 projects) rates wherever credit is taken
for demand control ventilation in the Proposed case. The proposed case
minimum rates at design conditions should be modeled as designed. Please
verify that the Baseline Case model reflects ASHRAE 62.1-2004 (or 2007)
minimum rates for any spaces where credit is taken for demand control
ventilation, or revise the model accordingly. For all other spaces, please
confirm that minimum outside airflow (in units of cfm) was modeled
identically in the Baseline and Proposed cases. Additionally, please verify
that all systems in both the baseline and proposed cases are modeled with
zero outside air flow when fans are cycled on to meet unoccupied setback
temperatures unless health or safety regulations mandate an alternate
minimum flow during unoccupied periods (in which case, the unoccupied
outside air rates should be modeled identically in the Baseline and Proposed
case).
Finally, even though you don't address energy recovery in your question,
whether or not you have energy recovery in your ventilation systems may
affect how much better (or worse) your Proposed case energy models perform
in relation to your Baseline case energy models.
The following generic LEED Review Comment addresses energy recovery in EAc1
energy models as it relates to ventilation systems.
Energy recovery is modeled for credit in the Proposed case. Please provide
further information regarding the energy recovery efficiency, verify that
outside air is modeled with zero flow in both the Baseline and Proposed
cases during unoccupied periods when fans are cycled on to meet unoccupied
setback temperatures unless health or safety regulations mandate an
alternate minimum flow during unoccupied periods (in which case, the
unoccupied outside air rates should be modeled identically in the Baseline
and Proposed Case), and indicate the bypass mechanism used to bypass the
energy recovery during mild conditions.
I hope that helps, but if you have any further questions or concerns, please
feel free to use the contact form at http://www.gbci.org/contactus and
select "Follow up to GBCI Response," inputting your case number from this
email's subject line.
Best Regards,
Dan Katzenberger, P.E., CEM, BEMP, LEED-AP BD+C
Green Building Certification Institute
2101 L Street NW, Suite 500
Washington, DC 20037
800-795-1746 (phone)
202 828-5110 (fax)
www.gbci.org/contactus
The text above represents a staff opinion of a particular issue, and does
NOT set any precedent to be upheld during a LEED Certification Review. For
official rulings in advance of a LEED Certification Review, customers should
utilize the Formal Inquiries process available in LEED Online that results
in a Project Credit Interpretation Ruling (Project CIR) and possibly a LEED
Interpretation (formerly CIRs or Public Rulings). Applications for LEED
Certification will be thoroughly reviewed based on USGBC Member balloted and
approved LEED Rating Systems, with addenda, and USGBC approved LEED
Interpretations, or Project CIRs administered by GBCI, as applicable. Please
note that certain inquiries submitted to USGBC are forwarded to GBCI for
reply as appropriate.
_______________________________
CUSTOMER EMAIL ADDRESS:
patirck@
CUSTOMER INQUIRY:
I am trying to verify what the minimum outdoor airflow rate required for
EAc1 is and am not sure if this requires a CIR.
If the Proposed outdoor air ventilation is a minimum of 30% higher than the
minimum required by ASHRAE 62 in order to achieve 1 LEED point for credit
IEQC2 is the Baseline outdoor air rate also 30% higher than the minimum
required by ASHRAE 62? or would the Baseline outdoor air ventilation rate be
the minimum outdoor air rate per ASHRAE 62 calculations.
In other words, if ASHRAE 62 requires a minimum of 1,000 CFM of outdoor air,
and 1,300 CFM is provided to attain 1 LEED point via IEQC1, is the Baseline
outdoor air flow rate 1,000 CFM or 1,300 CFM in the energy simulation?
90.1-2007/2004 both say the minimu m outdoor airflow rates shall be the
same for both the proposed and baseline building designs, as does the user
manual.
But this logic seems to reward the Proposed simulation by conditioning the
additional outdoor air supplied (300 cfm in the example above) to achieve
IEQC1 in the Baseline system as well as the proposed.
The logic of using the minimum required in the Baseline case is reflected in
EAC1 in the equipment efficiency requirements. Baseline efficiencies are the
minimum required, e.g. SEER 13 for packaged units.
It is the intent of the requirement that I am not sure is clear. Increasing
the outdoor air ventilation rate increases the energy used to condition the
outdoor air, so if the intent is to put the onus on Proposed design to show
energy reduction/LEED compliance over the 90.1/62 requirements shouldn't the
Baseline outdoor air be the minimum air flow rate per the ASHRAE 62
calculations? This puts the onus on the design team to provide a design that
compensates for the increase in energy to meet IEQC2 by providing some
method of processing the increase in outdoor air while still reducing energy
consumption.
_______________________________________________
Bldg-sim mailing list
http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
To unsubscribe from this mailing list send a blank message to
BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG
_____
Martin Roy, ing. PA LEED®, président
Martin Roy et associés
1805 chemin Oka,
Deux-Montagnes, Qc
J7R 1N3
Tel: 450-623-0340
Cell. 514-594-6352
www.mra.qc.ca <http://www.mra.qc.ca/>
Message de confidentialité
Ce courriel (de même que les fichiers joints) est strictement réservé à
l'usage de la personne ou de l'entité à qui il est adressé et peut contenir
de l'information privilégiée et confidentielle. Toute divulgation,
distribution ou copie de ce courriel est strictement prohibée et peut être
l’objet de poursuites judiciaires. Si vous avez reçu ce courriel par erreur,
veuillez nous en aviser et le supprimer de votre système informatique sans
l'imprimer, le copier ou le faire suivre a quiconque.
Devez-vous vraiment imprimer ce courriel ? Pensons environnement...
From: "Sachin Sharma" <sachin5787 at gmail.com>
Date: November 16, 2011 2:55:12 AM PST
To: "'bldg-sim at lists.onebuilding.org'" <Bldg-sim at lists.onebuilding.org>
Subject: [Bldg-sim] EnergyPlus: Outlet Nodes not matching error
Hi,
I am getting the below error, I have checked the inlet and outlet nodes of
all the branches and components, all node names are matching but still I am
getting this error.
Is it that I am making a fundamental error? Please suggest how to rectify
it.
<image001.png>
Thanks,
With regards,
Sachin Sharma
M.Tech Energy Engg.
Department of Mechanical Engineering
NIT Jaipur
+91 9983912512
From: "Patrick J. O'Leary, Jr." <poleary1969 at gmail.com>
Date: November 16, 2011 4:13:53 AM PST
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] usgbc response to outdoor air question
imagine a building with 100% oa and evaporatively cooled ... 10 eac1 points
... unless you're gbci reviewer who doesn't understand evap cooling
On 11/15/11 8:15 PM, Martin Roy ing. LEED AP wrote:
Ouch!
In the Model energy code in Canada only up to 20% more than ASHRAE 62 is
allowed in the base case. Imagine a building with 100% more OA and a ERV of
70% on the proposed case it can easily reach 10 EAcr1 point especially in
cold climate.
Martin
From: "Jim Dirkes" <jim at buildingperformanceteam.com>
Date: November 16, 2011 5:53:12 AM PST
To: "'Martin Roy ing. LEED AP'" <martin.roy at mra.qc.ca>, "'Reba Schaber'"
<Rschaber at PHMECH.com>
Cc: equest-users at lists.onebuilding.org, "'bldg-sim at lists.onebuilding.org'"
<Bldg-sim at lists.onebuilding.org>
Subject: Re: [Bldg-sim] usgbc response to outdoor air question
While ASHRAE 90.1 does a pretty good job of defining higher efficiency
practices, it’s not perfect. On the other hand, that’s why Appendix G is
there; you can show why your idea is better, at least on the energy part of
things.
There are still issues with the general level of knowledge among both the
reviewer community as well as the energy modeling community, and that may
never cease. As is commonly the case, a designer often is facing either
(energy efficiency) / or (greater IAQ & productivity). The challenge is how
to get the best combination of both.
One benefit of LEED certification seems to have been that many engineer
designers have responded to the challenge of greater efficiency and
performance and changed their standard designs in favor of something with
better performance. That’s probably very good, largely because stagnation
is never good.
There certainly is experimentation going on, not all of which is producing
great results, but I still prefer a real attitude of “continuous
improvement” over stagnation!
The Building Performance Team
James V. Dirkes II, P.E., BEMP , LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653
From: Martin Roy ing. LEED AP [mailto:martin.roy at mra.qc.ca]
Sent: Tuesday, November 15, 2011 10:15 PM
To: Reba Schaber
Cc: Jim Dirkes; equest-users at lists.onebuilding.org;
'bldg-sim at lists.onebuilding.org'
Subject: Re: [Bldg-sim] usgbc response to outdoor air question
Ouch!
In the Model energy code in Canada only up to 20% more than ASHRAE 62 is
allowed in the base case. Imagine a building with 100% more OA and a ERV of
70% on the proposed case it can easily reach 10 EAcr1 point especially in
cold climate.
Martin
At 21:41 15/11/2011, Reba Schaber wrote:
Content-Language: en-US
Content-Type: multipart/alternative;
boundary="_000_FAA9B7F58E5E4A46BDDF900F4CCAC3FE03ABA763DD3DPHSERVERphm_"
RE: “. . . can’t find) anything in 621.1 which says that unoccupied
ventilation should be zero.”
I think this requirement comes from the mandatory provisions of 90.1.
6.4.3.4.3 Shutoff Damper Controls. Both outdoor
air supply and exhaust systems shall be equipped with motorized
dampers that will automatically shut when the systems or
spaces served are not in use. Ventilation outdoor air dampers
shall be capable of automatically shutting off during preoccupancy
building warm-up, cool down, and setback, except
when ventilation reduces energy costs (e.g., night purge) or
when ventilation must be supplied to meet code requirements.
Thoughts??
Reba
From: bldg-sim-bounces at lists.onebuilding.org [
<mailto:bldg-sim-bounces at lists.onebuilding.org>
mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Jim Dirkes
Sent: Monday, October 17, 2011 9:32 AM
To: equest-users at lists.onebuilding.org; 'bldg-sim at lists.onebuilding.org'
Subject: Re: [Bldg-sim] usgbc response to outdoor air question
Dear Patrick,
Thank you for sharing this GBCI response! It is very informative and, while
I won’t admit that I’ve been modeling anything incorrectly, I am going to
change a couple of things J.
In particular, I have heard on several occasions that the Increased
Ventilation credit was a clear case of “IEQ vs. energy”; you make a decision
to trade one against the other. After reading the GBCI response below and
then double-checking with ASHRAE 90.1, I find that they are consistent with
each other and effectively allow no penalty for the increased energy caused
by increased ventilation. Very curious, considering there is no science
which demonstrates a health benefit for outdoor airflows greater than that
required by ASHRAE 62.1!
The other item is that I failed to notice (and still can’t find) anything in
621.1 which says that unoccupied ventilation should be zero. I guess that
is OK, but is also curious, since a portion of the ventilation calcs in 62.1
include consideration for off-gassing materials (which are always present.)
All in all, I’m smarter than I was as a result of your post, so it’s a good
day! Thanks again.
The Building Performance Team
James V. Dirkes II, P.E., BEMP , LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653
From: bldg-sim-bounces at lists.onebuilding.org [
<mailto:bldg-sim-bounces at lists.onebuilding.org>
mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Patrick J.
O'Leary, Jr.
Sent: Monday, October 17, 2011 11:46 AM
To: equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] usgbc response to outdoor air question
back in september there was a thread about what the outdoor air rate in a
baseline simulation should be compared to a proposed simulation,
specifically when one is adding 30% more outdoor air to meet the ieqc2
requirement and earn 1 leed point. there were differences of opinions about
the flow rates between baseline and proposed being either the same (as
required in 90.1 app g) or the baseline being the calculated per 62.1 and
the proposed being as designed.
so i submitted a support request to the usgbc and the reply i received is
below, but in short the response is that unless you're using dcv optionally
the outdoor air rates in the baseline and proposed energy simulations for
eac1 should be the same. the response below gives the standard responses to
differing outdoor air rate scenarios.
regards,
patrick
[Fwd: Case 00531150: General LEED Questions
-------- Original Message --------
Subject:
Case 00531150: General LEED Questions [ ref:00D49UeD.5004GN692:ref ]
Date:
Mon, 17 Oct 2011 06:54:51 +0000 (GMT)
From:
"No reply GBCI" <mailto:no-reply at gbci.org> <no-reply at gbci.org>
<mailto:no-reply at gbci.org> <no-reply at gbci.org>
To:
patrick@
Dear Patrick,
Thank you for contacting the Green Building Certification Institute.
You ask very good questions related to the relationship between ASHRAE
Standards 62.1 and 90.1, and how these standards are applied across multiple
LEED Rating System prerequisites and credits.
The simple answer to your question is that, for systems without demand
controlled ventilation, the outdoor air included in EA Credit 1 energy
simulations must be the same in the Baseline and Proposed cases. If the
project is attempting IEQ Credit 2 Increased Ventilation, then the values
calculated in IEQc2 must be used in the EAc1 Basline and Proposed case
energy models. Note that IEQc2 does not limit the project to providing only
30% more outdoor air than AHRAE 62.1 Ventilation Rate Procedure minimums, so
higher amounts are acceptable, as long as they are modeled identically in
both the Baseline and Proposed case energy models.
The following generic LEED Review Comment applies to ventilation systems
that do not have demand controlled ventilation:
It is unclear whether the minimum outside air rates (in CFM) were modeled
identically in the Baseline and Proposed case for all zones not having
Demand Control Ventilation in the Proposed case. Please confirm that minimum
outside airflow (in units of cfm) was modeled identically in the Baseline
and Proposed cases using the proposed case rates. Additionally, please
verify that all systems in both the baseline and proposed case are modeled
with zero outside air flow when fans are cycled on to meet unoccupied
setback temperatures unless health or safety regulations mandate an
alternate minimum flow during unoccupied periods (in which case, the
unoccupied outside air rates should be modeled identically in the Baseline
and Proposed case).
The situation becomes a bit more complicated in you have systems that have
demand controlled ventilation (often implemented as Carbon Dioxide control
of outdoor air or as programmed control of outdoor air based on occupancy
sensors.) In this case the Baseline case energy model must include the
minimum outdoor air as determined by the ASHRAE 62.1 Ventilation Rate
Procedure calculations for all systems having demand controlled ventilation.
The following generic LEED Review Comment applies to ventilation systems
that do have demand controlled ventilation:
Demand control ventilation was modeled for credit in the proposed case.
Appendix G allows schedule changes for demand control ventilation as
approved by the rating authority (Table G3.1#4(Baseline)). As the LEED
Certification rating authority, GBCI requires that the outside air
ventilation rates for the Baseline case be modeled using minimum ASHRAE
62.1-2004 (or 2007 for LEED-NC 2009 projects) rates wherever credit is taken
for demand control ventilation in the Proposed case. The proposed case
minimum rates at design conditions should be modeled as designed. Please
verify that the Baseline Case model reflects ASHRAE 62.1-2004 (or 2007)
minimum rates for any spaces where credit is taken for demand control
ventilation, or revise the model accordingly. For all other spaces, please
confirm that minimum outside airflow (in units of cfm) was modeled
identically in the Baseline and Proposed cases. Additionally, please verify
that all systems in both the baseline and proposed cases are modeled with
zero outside air flow when fans are cycled on to meet unoccupied setback
temperatures unless health or safety regulations mandate an alternate
minimum flow during unoccupied periods (in which case, the unoccupied
outside air rates should be modeled identically in the Baseline and Proposed
case).
Finally, even though you don't address energy recovery in your question,
whether or not you have energy recovery in your ventilation systems may
affect how much better (or worse) your Proposed case energy models perform
in relation to your Baseline case energy models.
The following generic LEED Review Comment addresses energy recovery in EAc1
energy models as it relates to ventilation systems.
Energy recovery is modeled for credit in the Proposed case. Please provide
further information regarding the energy recovery efficiency, verify that
outside air is modeled with zero flow in both the Baseline and Proposed
cases during unoccupied periods when fans are cycled on to meet unoccupied
setback temperatures unless health or safety regulations mandate an
alternate minimum flow during unoccupied periods (in which case, the
unoccupied outside air rates should be modeled identically in the Baseline
and Proposed Case), and indicate the bypass mechanism used to bypass the
energy recovery during mild conditions.
I hope that helps, but if you have any further questions or concerns, please
feel free to use the contact form at http://www.gbci.org/contactus and
select "Follow up to GBCI Response," inputting your case number from this
email's subject line.
Best Regards,
Dan Katzenberger, P.E., CEM, BEMP, LEED-AP BD+C
Green Building Certification Institute
2101 L Street NW, Suite 500
Washington, DC 20037
800-795-1746 (phone)
202 828-5110 (fax)
www.gbci.org/contactus
The text above represents a staff opinion of a particular issue, and does
NOT set any precedent to be upheld during a LEED Certification Review. For
official rulings in advance of a LEED Certification Review, customers should
utilize the Formal Inquiries process available in LEED Online that results
in a Project Credit Interpretation Ruling (Project CIR) and possibly a LEED
Interpretation (formerly CIRs or Public Rulings). Applications for LEED
Certification will be thoroughly reviewed based on USGBC Member balloted and
approved LEED Rating Systems, with addenda, and USGBC approved LEED
Interpretations, or Project CIRs administered by GBCI, as applicable. Please
note that certain inquiries submitted to USGBC are forwarded to GBCI for
reply as appropriate.
_______________________________
CUSTOMER EMAIL ADDRESS:
patirck@
CUSTOMER INQUIRY:
I am trying to verify what the minimum outdoor airflow rate required for
EAc1 is and am not sure if this requires a CIR.
If the Proposed outdoor air ventilation is a minimum of 30% higher than the
minimum required by ASHRAE 62 in order to achieve 1 LEED point for credit
IEQC2 is the Baseline outdoor air rate also 30% higher than the minimum
required by ASHRAE 62? or would the Baseline outdoor air ventilation rate be
the minimum outdoor air rate per ASHRAE 62 calculations.
In other words, if ASHRAE 62 requires a minimum of 1,000 CFM of outdoor air,
and 1,300 CFM is provided to attain 1 LEED point via IEQC1, is the Baseline
outdoor air flow rate 1,000 CFM or 1,300 CFM in the energy simulation?
90.1-2007/2004 both say the minimu m outdoor airflow rates shall be the
same for both the proposed and baseline building designs, as does the user
manual.
But this logic seems to reward the Proposed simulation by conditioning the
additional outdoor air supplied (300 cfm in the example above) to achieve
IEQC1 in the Baseline system as well as the proposed.
The logic of using the minimum required in the Baseline case is reflected in
EAC1 in the equipment efficiency requirements. Baseline efficiencies are the
minimum required, e.g. SEER 13 for packaged units.
It is the intent of the requirement that I am not sure is clear. Increasing
the outdoor air ventilation rate increases the energy used to condition the
outdoor air, so if the intent is to put the onus on Proposed design to show
energy reduction/LEED compliance over the 90.1/62 requirements shouldn't the
Baseline outdoor air be the minimum air flow rate per the ASHRAE 62
calculations? This puts the onus on the design team to provide a design that
compensates for the increase in energy to meet IEQC2 by providing some
method of processing the increase in outdoor air while still reducing energy
consumption.
_______________________________________________
Bldg-sim mailing list
http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
To unsubscribe from this mailing list send a blank message to
BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG
_____
Martin Roy, ing. PA LEED®, président
Martin Roy et associés
1805 chemin Oka,
Deux-Montagnes, Qc
J7R 1N3
Tel: 450-623-0340
Cell. 514-594-6352
www.mra.qc.ca <http://www.mra.qc.ca/>
Message de confidentialité
Ce courriel (de même que les fichiers joints) est strictement réservé à
l'usage de la personne ou de l'entité à qui il est adressé et peut contenir
de l'information privilégiée et confidentielle. Toute divulgation,
distribution ou copie de ce courriel est strictement prohibée et peut être
l’objet de poursuites judiciaires. Si vous avez reçu ce courriel par erreur,
veuillez nous en aviser et le supprimer de votre système informatique sans
l'imprimer, le copier ou le faire suivre a quiconque.
Devez-vous vraiment imprimer ce courriel ? Pensons environnement...
From: Linda Lawrie <linda at fortlawrie.com>
Date: November 16, 2011 5:56:23 AM PST
To: "Sachin Sharma" <sachin5787 at gmail.com>
Cc: Bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] EnergyPlus: Outlet Nodes not matching error
Send your input file to the helpdesk: http://energyplus.helpdesk.com
<http://energyplus.helpdesk.com/>
The BldgSim list is not a list to supply EnergyPlus support.
Linda
EnergyPlus Development Team
At 03:55 AM 11/16/2011, Sachin Sharma wrote:
Hi,
I am getting the below error, I have checked the inlet and outlet nodes of
all the branches and components, all node names are matching but still I am
getting this error.
Is it that I am making a fundamental error? Please suggest how to rectify
it.
From: Jeremy Poling <Jeremy.Poling at transwestern.net>
Date: November 16, 2011 7:28:10 AM PST
To: Reba Schaber <Rschaber at PHMECH.com>, Jim Dirkes
<jim at buildingperformanceteam.com>, <equest-users at lists.onebuilding.org>,
"bldg-sim at lists.onebuilding.org" <Bldg-sim at lists.onebuilding.org>
Subject: Re: [Bldg-sim] usgbc response to outdoor air question
There was an earlier discussion on the list about this:
62.1-2007, Section 5.4 states “Mechanical ventilation systems shall include
controls, manual or automatic, that enable the fan system to operate
whenever the spaces served are occupied. The system shall be designed to
maintain the minimum outdoor airflow as required by Section 6 under any load
condition.”
62.1-2007, Section 6.2.6.1 states “Ventilation systems shall be designed to
be capable of providing the required ventilation rates in the breathing zone
whenever the zones served by the system are occupied, including all full-
and part-load conditions.”
These are generally applied to mean that the system is not required to
operate when spaces are unoccupied. Yes, the standard does not explicitly
state that unoccupied ventilation should be zero but the standard does not
explicitly state that unoccupied ventilation can’t be zero. Section 5.4 and
6.2.6.1 only require controls and ventilation rates “whenever the
spaces/zones served by the system are occupied” so it can be implied that
the requirement doesn’t apply when the spaces/zones are unoccupied. There’s
a fine interpretive line there, but many of the official interpretations on
62.1 also lean this direction. If in doubt, put in an official
interpretation request specifically on this with ASHRAE on the topic to
clarify.
Jeremy R. Poling, PE, LEED AP+BDC
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Reba Schaber
Sent: Tuesday, November 15, 2011 8:42 PM
To: Jim Dirkes; equest-users at lists.onebuilding.org;
'bldg-sim at lists.onebuilding.org'
Subject: Re: [Bldg-sim] usgbc response to outdoor air question
RE: “. . . can’t find) anything in 621.1 which says that unoccupied
ventilation should be zero.”
I think this requirement comes from the mandatory provisions of 90.1.
6.4.3.4.3 Shutoff Damper Controls. Both outdoor
air supply and exhaust systems shall be equipped with motorized
dampers that will automatically shut when the systems or
spaces served are not in use. Ventilation outdoor air dampers
shall be capable of automatically shutting off during preoccupancy
building warm-up, cool down, and setback, except
when ventilation reduces energy costs (e.g., night purge) or
when ventilation must be supplied to meet code requirements.
Thoughts??
Reba
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Jim Dirkes
Sent: Monday, October 17, 2011 9:32 AM
To: equest-users at lists.onebuilding.org; 'bldg-sim at lists.onebuilding.org'
Subject: Re: [Bldg-sim] usgbc response to outdoor air question
Dear Patrick,
Thank you for sharing this GBCI response! It is very informative and, while
I won’t admit that I’ve been modeling anything incorrectly, I am going to
change a couple of things :-).
In particular, I have heard on several occasions that the Increased
Ventilation credit was a clear case of “IEQ vs. energy”; you make a decision
to trade one against the other. After reading the GBCI response below and
then double-checking with ASHRAE 90.1, I find that they are consistent with
each other and effectively allow no penalty for the increased energy caused
by increased ventilation. Very curious, considering there is no science
which demonstrates a health benefit for outdoor airflows greater than that
required by ASHRAE 62.1!
The other item is that I failed to notice (and still can’t find) anything in
621.1 which says that unoccupied ventilation should be zero. I guess that
is OK, but is also curious, since a portion of the ventilation calcs in 62.1
include consideration for off-gassing materials (which are always present.)
All in all, I’m smarter than I was as a result of your post, so it’s a good
day! Thanks again.
The Building Performance Team
James V. Dirkes II, P.E., BEMP , LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Patrick J.
O'Leary, Jr.
Sent: Monday, October 17, 2011 11:46 AM
To: equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] usgbc response to outdoor air question
back in september there was a thread about what the outdoor air rate in a
baseline simulation should be compared to a proposed simulation,
specifically when one is adding 30% more outdoor air to meet the ieqc2
requirement and earn 1 leed point. there were differences of opinions about
the flow rates between baseline and proposed being either the same (as
required in 90.1 app g) or the baseline being the calculated per 62.1 and
the proposed being as designed.
so i submitted a support request to the usgbc and the reply i received is
below, but in short the response is that unless you're using dcv optionally
the outdoor air rates in the baseline and proposed energy simulations for
eac1 should be the same. the response below gives the standard responses to
differing outdoor air rate scenarios.
regards,
patrick
[Fwd: Case 00531150: General LEED Questions
-------- Original Message --------
Subject:
Case 00531150: General LEED Questions [ ref:00D49UeD.5004GN692:ref ]
Date:
Mon, 17 Oct 2011 06:54:51 +0000 (GMT)
From:
"No reply GBCI" <mailto:no-reply at gbci.org> <no-reply at gbci.org>
<mailto:no-reply at gbci.org> <no-reply at gbci.org>
To:
patrick@
Dear Patrick,
Thank you for contacting the Green Building Certification Institute.
You ask very good questions related to the relationship between ASHRAE
Standards 62.1 and 90.1, and how these standards are applied across multiple
LEED Rating System prerequisites and credits.
The simple answer to your question is that, for systems without demand
controlled ventilation, the outdoor air included in EA Credit 1 energy
simulations must be the same in the Baseline and Proposed cases. If the
project is attempting IEQ Credit 2 Increased Ventilation, then the values
calculated in IEQc2 must be used in the EAc1 Basline and Proposed case
energy models. Note that IEQc2 does not limit the project to providing only
30% more outdoor air than AHRAE 62.1 Ventilation Rate Procedure minimums, so
higher amounts are acceptable, as long as they are modeled identically in
both the Baseline and Proposed case energy models.
The following generic LEED Review Comment applies to ventilation systems
that do not have demand controlled ventilation:
It is unclear whether the minimum outside air rates (in CFM) were modeled
identically in the Baseline and Proposed case for all zones not having
Demand Control Ventilation in the Proposed case. Please confirm that minimum
outside airflow (in units of cfm) was modeled identically in the Baseline
and Proposed cases using the proposed case rates. Additionally, please
verify that all systems in both the baseline and proposed case are modeled
with zero outside air flow when fans are cycled on to meet unoccupied
setback temperatures unless health or safety regulations mandate an
alternate minimum flow during unoccupied periods (in which case, the
unoccupied outside air rates should be modeled identically in the Baseline
and Proposed case).
The situation becomes a bit more complicated in you have systems that have
demand controlled ventilation (often implemented as Carbon Dioxide control
of outdoor air or as programmed control of outdoor air based on occupancy
sensors.) In this case the Baseline case energy model must include the
minimum outdoor air as determined by the ASHRAE 62.1 Ventilation Rate
Procedure calculations for all systems having demand controlled ventilation.
The following generic LEED Review Comment applies to ventilation systems
that do have demand controlled ventilation:
Demand control ventilation was modeled for credit in the proposed case.
Appendix G allows schedule changes for demand control ventilation as
approved by the rating authority (Table G3.1#4(Baseline)). As the LEED
Certification rating authority, GBCI requires that the outside air
ventilation rates for the Baseline case be modeled using minimum ASHRAE
62.1-2004 (or 2007 for LEED-NC 2009 projects) rates wherever credit is taken
for demand control ventilation in the Proposed case. The proposed case
minimum rates at design conditions should be modeled as designed. Please
verify that the Baseline Case model reflects ASHRAE 62.1-2004 (or 2007)
minimum rates for any spaces where credit is taken for demand control
ventilation, or revise the model accordingly. For all other spaces, please
confirm that minimum outside airflow (in units of cfm) was modeled
identically in the Baseline and Proposed cases. Additionally, please verify
that all systems in both the baseline and proposed cases are modeled with
zero outside air flow when fans are cycled on to meet unoccupied setback
temperatures unless health or safety regulations mandate an alternate
minimum flow during unoccupied periods (in which case, the unoccupied
outside air rates should be modeled identically in the Baseline and Proposed
case).
Finally, even though you don't address energy recovery in your question,
whether or not you have energy recovery in your ventilation systems may
affect how much better (or worse) your Proposed case energy models perform
in relation to your Baseline case energy models.
The following generic LEED Review Comment addresses energy recovery in EAc1
energy models as it relates to ventilation systems.
Energy recovery is modeled for credit in the Proposed case. Please provide
further information regarding the energy recovery efficiency, verify that
outside air is modeled with zero flow in both the Baseline and Proposed
cases during unoccupied periods when fans are cycled on to meet unoccupied
setback temperatures unless health or safety regulations mandate an
alternate minimum flow during unoccupied periods (in which case, the
unoccupied outside air rates should be modeled identically in the Baseline
and Proposed Case), and indicate the bypass mechanism used to bypass the
energy recovery during mild conditions.
I hope that helps, but if you have any further questions or concerns, please
feel free to use the contact form at http://www.gbci.org/contactus and
select "Follow up to GBCI Response," inputting your case number from this
email's subject line.
Best Regards,
Dan Katzenberger, P.E., CEM, BEMP, LEED-AP BD+C
Green Building Certification Institute
2101 L Street NW, Suite 500
Washington, DC 20037
800-795-1746 (phone)
202 828-5110 (fax)
www.gbci.org/contactus
The text above represents a staff opinion of a particular issue, and does
NOT set any precedent to be upheld during a LEED Certification Review. For
official rulings in advance of a LEED Certification Review, customers should
utilize the Formal Inquiries process available in LEED Online that results
in a Project Credit Interpretation Ruling (Project CIR) and possibly a LEED
Interpretation (formerly CIRs or Public Rulings). Applications for LEED
Certification will be thoroughly reviewed based on USGBC Member balloted and
approved LEED Rating Systems, with addenda, and USGBC approved LEED
Interpretations, or Project CIRs administered by GBCI, as applicable. Please
note that certain inquiries submitted to USGBC are forwarded to GBCI for
reply as appropriate.
_______________________________
CUSTOMER EMAIL ADDRESS:
patirck@
CUSTOMER INQUIRY:
I am trying to verify what the minimum outdoor airflow rate required for
EAc1 is and am not sure if this requires a CIR.
If the Proposed outdoor air ventilation is a minimum of 30% higher than the
minimum required by ASHRAE 62 in order to achieve 1 LEED point for credit
IEQC2 is the Baseline outdoor air rate also 30% higher than the minimum
required by ASHRAE 62? or would the Baseline outdoor air ventilation rate be
the minimum outdoor air rate per ASHRAE 62 calculations.
In other words, if ASHRAE 62 requires a minimum of 1,000 CFM of outdoor air,
and 1,300 CFM is provided to attain 1 LEED point via IEQC1, is the Baseline
outdoor air flow rate 1,000 CFM or 1,300 CFM in the energy simulation?
90.1-2007/2004 both say the minimu m outdoor airflow rates shall be the
same for both the proposed and baseline building designs, as does the user
manual.
But this logic seems to reward the Proposed simulation by conditioning the
additional outdoor air supplied (300 cfm in the example above) to achieve
IEQC1 in the Baseline system as well as the proposed.
The logic of using the minimum required in the Baseline case is reflected in
EAC1 in the equipment efficiency requirements. Baseline efficiencies are the
minimum required, e.g. SEER 13 for packaged units.
It is the intent of the requirement that I am not sure is clear. Increasing
the outdoor air ventilation rate increases the energy used to condition the
outdoor air, so if the intent is to put the onus on Proposed design to show
energy reduction/LEED compliance over the 90.1/62 requirements shouldn't the
Baseline outdoor air be the minimum air flow rate per the ASHRAE 62
calculations? This puts the onus on the design team to provide a design that
compensates for the increase in energy to meet IEQC2 by providing some
method of processing the increase in outdoor air while still reducing energy
consumption.
From: Sandor Rosta <srosta at swinter.com>
Date: November 16, 2011 11:25:49 AM PST
To: "bldg-sim at lists.onebuilding.org" <bldg-sim at lists.onebuilding.org>
Subject: [Bldg-sim] HELP WANTED: Energy Modeler SWA (NY-CT)
Steven Winter Associates, Inc. (SWA) seeks a qualified professional to
provide energy analysis for high performance and green buildings, including
multifamily, commercial, and institutional buildings. Work will primarily
focus on energy modeling in eQUEST/Energy Plus. Energy modeling will support
LEED (Leadership in Energy and Environmental Design) projects nationally,
NYSERDA Multifamily Program or New Construction Program projects. Depending
on experience and interest, other opportunities may be available in energy
auditing services and building performance diagnostics. Opening may be
available in either SWA’s New York or Connecticut offices.
For more information, view the posting on our web site:
http://www.swinter.com/da44e168-725f-4ea5-9b89-9fd91e8ebb31/about-us-careers
-details-nyc.htm
Thanks
Sandor Rosta
Senior Mechanical Engineer, LEED AP
212.564.5800 x125 (direct)
212.741.8673 (fax)
srosta at swinter.com
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