Et = Ec + [flue & jacket losses, as a % of Qout] ? if only it were that
simple!
For the case of simulating large real-world hot water boilers, look here
first for AHRI certification testing:
https://www.ahridirectory.org/ahridirectory/pages/cblr/defaultSearch.aspx.
You can often find both combustion and thermal efficiencies tested for your
actual equipment. A secondary source would be to seek out
manufacturer-published data.
For the purposes of baseline boilers for 90.1/LEED, it unfortunately
remains a fuzzy topic.
I am not aware of a consistent position from 90.1/GBCI on the matter. I
have observed reviewers point out flue/thermal jacket losses are not
regulated by 90.1, and from there instructing
(A) to treat Et = Ec, or
(B) to ?not simulate flue/jacket losses? (which implies you should treat
HIR = 1/Ec for any/all proposed case HHW boilers as well)
I?ll readily admit there was a period of some years before I even noticed
the Ec/Et ?conundrum? for 90.1 and I just treated them as one and the same,
but today neither approach sits very well with me. In the face of such
commentary: Sometimes it?s a big deal to the end result, but other times I
don?t consider it worth the fight.
I personally support the idea of modeling *something* to account for
flue/jacket losses, but from here you have to decide what makes the most
sense to you (and what you?re comfortable defending). Options I?m aware of
include:
- Previous & separate discussions on the lists have repeatedly
suggested 1.5% and 2% losses as reasonable rules of thumb
- Take the auto-sized capacity of your baseline boilers, find some
examples of flue/jacket losses for real-world equivalents (see AHRI link
above), take a screenshot for documentation, and use an average
- The published 2013 Title 24 Nonresidential ACM
prescribes 2% for electric boiler heat loss, specifically. It seems to
presently dodge the topic for fuel-fired boilers b/c they only prescribe
baseline thermal efficiencies, with such losses considered worked into
those minimums.
- I have on occasion matched thermal losses between
Proposed/Baseline with the idea of ?leveling the playing field.? I?d
maintain at times this makes the most logical sense for specific DES
scenarios involving 90.1 baseline boilers? though it?s a position not
everyone agrees with!
~Nick
*NICK CATON, P.E.*
*Owner*
*Caton Energy Consulting*
1150 N. 192nd St., #4-202
Shoreline, WA 98133
office: 785.410.3317
www.catonenergy.com
*From:* Jones, Christopher [mailto:cjones at halsall.com]
*Sent:* Wednesday, May 27, 2015 11:40 AM
*To:* Nicholas Caton; Equest-users
*Subject:* Reply? The problem of minimum equipment efficiency requirement
of Ashrae 90.1-2007
Hello Nick,
Do you also have a handy conversion between Et and Ec?
*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org ] *On Behalf Of *Nicholas Caton
*Sent:* Friday, May 29, 2015 11:17 AM
*To:* ???; Equest-users
*Subject:* Re: [Equest-users] ???RE: ??? ???RE: Reply? The problem of
minimum equipment efficiency requirement of Ashrae 90.1-2007
Yeah same for my case (not AFUE), though that?s good thinking!
When I do have an AFUE boiler requirement, I have found it easier to stick
with the default library curves / standby inputs & to determine the full
load HIR with the following equations:
HIR = f(AFUE): * [Reference: California Energy Commission's 2005
"Nonresidential Alternative Calculation Method (ACM) Approval
Manual"]*
For single packaged central furnace (baseline system
#3): HIR =
(.005163*AFUE+0.4033)^-1
For Boilers where 75 ? AFUE < 80 (Baseline systems #1, #5
): HIR = (0.1*AFUE+72.5)^-1*100
For Boilers where 80 ? AFUE < 100 (Baseline systems #1, #5
): HIR =
(0.875*AFUE+10.5)^-1*100
For completeness, here are the other equations I keep handy for converting
other seasonal efficiencies to steady-state inputs:
EER=f(SEER): *[Reference: NREL Building America House Simulation
Protocol (Revised), citing Wassmer, M. (2003). A Component-Based Model for
Residential Air Conditioner and Heat Pump Energy Calculations.]*
COP=f(HSPF): *[Reference: Wassmer, M. (2003). A Component-Based Model
for Residential Air Conditioner and Heat Pump Energy Calculations. Masters
Thesis, University of Colorado at Boulder.]*
IIRC, each of the above cited references determines these equations based
on a survey of real-world equipment from various manufacturers in order to
plot a quadratic trendline. That trendline establishes the relationship
between steady state full load efficiency and the associated seasonal
efficiency rating. In time (or until such equations are added to Appendix
G to regulate how modelers approach seasonal efficiency requirements), it
may be appropriate to seek out similar research to update these equations
every so often, but for the present and past couple of years I have had
zero problems using this family of equations for my LEED reviews.
~Nick
*NICK CATON, P.E.*
*Owner*
*Caton Energy Consulting*
1150 N. 192nd St., #4-202
Shoreline, WA 98133
office: 785.410.3317
www.catonenergy.com
*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
Behalf Of *???
*Sent:* Monday, May 25, 2015 6:24 AM
*To:* Equest-users
*Subject:* [Equest-users] ???RE: ??? ???RE: Reply? The problem of minimum
equipment efficiency requirement of Ashrae 90.1-2007
I also find the definition of AFUE in manual , but the boiler
capacity of my project( a very big project) is larger than 88kW, So
the efficiency of boiler should be 80%(Ec),not 80%(AFUE).
------------------
*Yongqing Zhao*
*Changsha Green Building & Energy Saving Technology CO.,LTD*
NO.438,Shaoshan Road,Changsha,Hunan,China
Telephone:13574805636
Email:zhaoyongqing1987 at 126.com
503271081 at qq.com
------------------ ???? ------------------
*?**??**:* "Lapierre, Patrick"; ;
*?**?**??**:* 2015?5?25?(???) ??8:23
*???**:* "???"<503271081 at qq.com>; "Daniel Knapp"
*??**:* "equest-users at lists.onebuilding"
*?**?**:* RE: [Equest-users] ??? ???RE: Reply?
The problem of minimum equipment efficiency requirement of Ashrae 90.1-2007
I agree with Nick that removing the default start-up times in the
baseline seems inappropriate and that it should also be done in the
proposed design if done in the reference (when the baseline
performance is based on
*Et*)
I didn?t see any model attached so I couldn?t check but could it be
possible the boiler size falls into the smaller category of table
6.8.1F where it?s efficiency is defined as 80% AFUE? The comment of
the reviewer would make much more sense if it was the case, since
*80% AFUE* is different from *80% Et*
. In my understanding, 80% AFUE refers to a global annual efficiency
of 80% and 80% E
t
refers to 80% efficiency at peak load which would result in a global
annual efficiency lower than 80% when you consider part loads and
boiler cycling.
I would deem as correct the reviewer?s comment if the boiler size
falls into the 80% AFUE category.
?
The AFUE differs from the true 'thermal efficiency' in that it is not
a steady-state, peak measure of conversion efficiency, but instead
attempts to represent the actual, season-long, average efficiency of
that piece of equipment, including the operating transients.
[1] ?
1*^* Systems and Equipment volume of the *ASHRAE Handbook*
, ASHRAE, Inc., Atlanta, GA, USA, 2004
However, if your boiler size falls into the *Et* or *Ec *
category then, as everyone else here, I find the comment somewhat strange.
*Patrick* *Lapierre**_ing.*
plapierre at bpa.ca
*De :* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org ] *De la part de* ???
*Envoy? :* 24 mai 2015 20:42
*? :* Daniel Knapp; Nicholas Caton
*Cc :* equest-users at lists.onebuilding
*Objet :* [Equest-users] ??? ???RE: Reply?
The problem of minimum equipment efficiency requirement of Ashrae 90.1-2007
Hi,Dan
The comment is a full version,no context missing!I also feel very
strange with it.
------------------
*Yongqing Zhao*
*Changsha Green Building & Energy Saving Technology CO.,LTD*
NO.438,Shaoshan Road,Changsha,Hunan,China
Telephone:13574805636
Email:zhaoyongqing1987 at 126.com
503271081 at qq.com
------------------ ???? ------------------
*???**:* "Daniel Knapp";;
*????**:* 2015?5?25?(???) ??1:34
*???**:* "Nicholas Caton";
*??**:* "???"; "Julien Marrec"<
julien.marrec at gmail.com>; "equest-users at lists.onebuilding"<
equest-users at lists.onebuilding.org>;
*??**:* Re: [Equest-users] ???RE: Reply?
The problem of minimum equipment efficiency requirement of Ashrae 90.1-2007
I'm with Nick. I find the GBCI reviewer comment as reported to be a
bit strange and I wonder if there is some context missing. Is it
possible that the seasonal efficiency was much lower than 80% in the
baseline, suggesting either oversizing of the baseline boilers or a
curve that is different from the proposed curve?
Et = Ec + [flue & jacket losses, as a % of Qout] ? if only it were that
simple!
For the case of simulating large real-world hot water boilers, look here
first for AHRI certification testing:
https://www.ahridirectory.org/ahridirectory/pages/cblr/defaultSearch.aspx.
You can often find both combustion and thermal efficiencies tested for your
actual equipment. A secondary source would be to seek out
manufacturer-published data.
For the purposes of baseline boilers for 90.1/LEED, it unfortunately
remains a fuzzy topic.
I am not aware of a consistent position from 90.1/GBCI on the matter. I
have observed reviewers point out flue/thermal jacket losses are not
regulated by 90.1, and from there instructing
(A) to treat Et = Ec, or
(B) to ?not simulate flue/jacket losses? (which implies you should treat
HIR = 1/Ec for any/all proposed case HHW boilers as well)
I?ll readily admit there was a period of some years before I even noticed
the Ec/Et ?conundrum? for 90.1 and I just treated them as one and the same,
but today neither approach sits very well with me. In the face of such
commentary: Sometimes it?s a big deal to the end result, but other times I
don?t consider it worth the fight.
I personally support the idea of modeling *something* to account for
flue/jacket losses, but from here you have to decide what makes the most
sense to you (and what you?re comfortable defending). Options I?m aware of
include:
- Previous & separate discussions on the lists have repeatedly
suggested 1.5% and 2% losses as reasonable rules of thumb
- Take the auto-sized capacity of your baseline boilers, find some
examples of flue/jacket losses for real-world equivalents (see AHRI link
above), take a screenshot for documentation, and use an average
- The published 2013 Title 24 Nonresidential ACM
prescribes 2% for electric boiler heat loss, specifically. It seems to
presently dodge the topic for fuel-fired boilers b/c they only prescribe
baseline thermal efficiencies, with such losses considered worked into
those minimums.
- I have on occasion matched thermal losses between
Proposed/Baseline with the idea of ?leveling the playing field.? I?d
maintain at times this makes the most logical sense for specific DES
scenarios involving 90.1 baseline boilers? though it?s a position not
everyone agrees with!
~Nick
*NICK CATON, P.E.*
*Owner*
*Caton Energy Consulting*
1150 N. 192nd St., #4-202
Shoreline, WA 98133
office: 785.410.3317
www.catonenergy.com
*From:* Jones, Christopher [mailto:cjones at halsall.com]
*Sent:* Wednesday, May 27, 2015 11:40 AM
*To:* Nicholas Caton; Equest-users
*Subject:* Reply? The problem of minimum equipment efficiency requirement
of Ashrae 90.1-2007
Hello Nick,
Do you also have a handy conversion between Et and Ec?
Thanks for your assistance!
*Christopher Jones**,* P.Eng.
Tel: 416.644.4226 ? Toll Free: 1.888.425.7255 x 527
*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
] *On Behalf Of *Nicholas Caton
*Sent:* Friday, May 29, 2015 11:17 AM
*To:* ???; Equest-users
*Subject:* Re: [Equest-users] ???RE: ??? ???RE: Reply? The problem of
minimum equipment efficiency requirement of Ashrae 90.1-2007
Yeah same for my case (not AFUE), though that?s good thinking!
When I do have an AFUE boiler requirement, I have found it easier to stick
with the default library curves / standby inputs & to determine the full
load HIR with the following equations:
HIR = f(AFUE): * [Reference: California Energy Commission's 2005
"Nonresidential Alternative Calculation Method (ACM) Approval
Manual"]*
For single packaged central furnace (baseline system
#3): HIR =
(.005163*AFUE+0.4033)^-1
For Boilers where 75 ? AFUE < 80 (Baseline systems #1, #5
): HIR = (0.1*AFUE+72.5)^-1*100
For Boilers where 80 ? AFUE < 100 (Baseline systems #1, #5
): HIR =
(0.875*AFUE+10.5)^-1*100
For completeness, here are the other equations I keep handy for converting
other seasonal efficiencies to steady-state inputs:
EER=f(SEER): *[Reference: NREL Building America House Simulation
Protocol (Revised), citing Wassmer, M. (2003). A Component-Based Model for
Residential Air Conditioner and Heat Pump Energy Calculations.]*
(AC) (Baseline Systems #1, #3, #5 & #6): EERNET=
-0.0182*SEER^2 + 1.1088*SEER
(HP-cooling) (Baseline Systems #2 & #4): EERNET = -0.02*SEER^2
+ 1.1268*SEER
COP=f(HSPF): *[Reference: Wassmer, M. (2003). A Component-Based Model
for Residential Air Conditioner and Heat Pump Energy Calculations. Masters
Thesis, University of Colorado at Boulder.]*
(HP-heating) (Baseline Systems #2 & #4): COPNET =
-0.0255*HSPF^2 + 0.6239*HSPF
IIRC, each of the above cited references determines these equations based
on a survey of real-world equipment from various manufacturers in order to
plot a quadratic trendline. That trendline establishes the relationship
between steady state full load efficiency and the associated seasonal
efficiency rating. In time (or until such equations are added to Appendix
G to regulate how modelers approach seasonal efficiency requirements), it
may be appropriate to seek out similar research to update these equations
every so often, but for the present and past couple of years I have had
zero problems using this family of equations for my LEED reviews.
~Nick
*NICK CATON, P.E.*
*Owner*
*Caton Energy Consulting*
1150 N. 192nd St., #4-202
Shoreline, WA 98133
office: 785.410.3317
www.catonenergy.com
*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
Behalf Of *???
*Sent:* Monday, May 25, 2015 6:24 AM
*To:* Equest-users
*Subject:* [Equest-users] ???RE: ??? ???RE: Reply? The problem of minimum
equipment efficiency requirement of Ashrae 90.1-2007
I also find the definition of AFUE in manual , but the boiler
capacity of my project( a very big project) is larger than 88kW, So
the efficiency of boiler should be 80%(Ec),not 80%(AFUE).
------------------
*Yongqing Zhao*
*Changsha Green Building & Energy Saving Technology CO.,LTD*
NO.438,Shaoshan Road,Changsha,Hunan,China
Telephone:13574805636
Email:zhaoyongqing1987 at 126.com
503271081 at qq.com
------------------ ???? ------------------
;
*?**??**:* "Lapierre, Patrick";
*?**?**??**:* 2015?5?25?(???) ??8:23
*???**:* "???"<503271081 at qq.com>; "Daniel Knapp"
The problem of minimum equipment efficiency requirement of Ashrae 90.1-2007
I agree with Nick that removing the default start-up times in the
baseline seems inappropriate and that it should also be done in the
proposed design if done in the reference (when the baseline
performance is based on
*Et*)
I didn?t see any model attached so I couldn?t check but could it be
possible the boiler size falls into the smaller category of table
6.8.1F where it?s efficiency is defined as 80% AFUE? The comment of
the reviewer would make much more sense if it was the case, since
*80% AFUE* is different from *80% Et*
. In my understanding, 80% AFUE refers to a global annual efficiency
of 80% and 80% E
t
refers to 80% efficiency at peak load which would result in a global
annual efficiency lower than 80% when you consider part loads and
boiler cycling.
I would deem as correct the reviewer?s comment if the boiler size
falls into the 80% AFUE category.
?
The AFUE differs from the true 'thermal efficiency' in that it is not
a steady-state, peak measure of conversion efficiency, but instead
attempts to represent the actual, season-long, average efficiency of
that piece of equipment, including the operating transients.
[1] ?
1*^* Systems and Equipment volume of the *ASHRAE Handbook*
, ASHRAE, Inc., Atlanta, GA, USA, 2004
However, if your boiler size falls into the *Et* or *Ec *
category then, as everyone else here, I find the comment somewhat strange.
*Patrick* *Lapierre**_ing.*
plapierre at bpa.ca
*De :* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
] *De la part de* ???
*Envoy? :* 24 mai 2015 20:42
*? :* Daniel Knapp; Nicholas Caton
*Cc :* equest-users at lists.onebuilding
*Objet :* [Equest-users] ??? ???RE: Reply?
The problem of minimum equipment efficiency requirement of Ashrae 90.1-2007
Hi,Dan
The comment is a full version,no context missing!I also feel very
strange with it.
------------------
*Yongqing Zhao*
*Changsha Green Building & Energy Saving Technology CO.,LTD*
NO.438,Shaoshan Road,Changsha,Hunan,China
Telephone:13574805636
Email:zhaoyongqing1987 at 126.com
503271081 at qq.com
------------------ ???? ------------------;;; "Julien Marrec"<
*???**:* "Daniel Knapp";
*????**:* 2015?5?25?(???) ??1:34
*???**:* "Nicholas Caton"
*??**:* "???"
julien.marrec at gmail.com>; "equest-users at lists.onebuilding"<
equest-users at lists.onebuilding.org>;
*??**:* Re: [Equest-users] ???RE: Reply?
The problem of minimum equipment efficiency requirement of Ashrae 90.1-2007
I'm with Nick. I find the GBCI reviewer comment as reported to be a
bit strange and I wonder if there is some context missing. Is it
possible that the seasonal efficiency was much lower than 80% in the
baseline, suggesting either oversizing of the baseline boilers or a
curve that is different from the proposed curve?
Best,
Dan
?
Sent from my phone