# [Equest-users] 回复：RE: 回复： 回复：RE: Reply： The problem of minimum equipment efficiency requirement of Ashrae 90.1-2007

Nicholas Caton ncaton at catonenergy.com
Fri May 29 08:16:47 PDT 2015

```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
&#7):               HIR = (0.1*AFUE+72.5)^-1*100

For Boilers where 80 ≤ AFUE < 100 (Baseline systems #1, #5
&#7):            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
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] 回复：RE: 回复： 回复：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*
Telephone:13574805636
Email:zhaoyongqing1987 at 126.com
503271081 at qq.com

------------------ 原始邮件 ------------------
*发**件人**:* "Lapierre, Patrick";<plapierre at bpa.ca>;
*发**送**时间**:* 2015年5月25日(星期一) 晚上8:23
*收件人**:* "赵永青"<503271081 at qq.com>; "Daniel Knapp"<danielk at arborus.ca
>; "Nicholas Caton"<ncaton at catonenergy.com>;
*抄送**:* "equest-users at lists.onebuilding"<equest-users at lists.onebuilding.org
>;
*主**题**:* RE: [Equest-users] 回复： 回复：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
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
<equest-users-bounces at lists.onebuilding.org>] *De la part de* ???
*Envoyé :* 24 mai 2015 20:42
*À :* Daniel Knapp; Nicholas Caton
*Cc :* equest-users at lists.onebuilding
*Objet :* [Equest-users] 回复： 回复：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*
Telephone:13574805636
Email:zhaoyongqing1987 at 126.com
503271081 at qq.com

------------------ 原始邮件 ------------------
*发件人**:* "Daniel Knapp";<danielk at arborus.ca>;
*发送时间**:* 2015年5月25日(星期一) 凌晨1:34
*收件人**:* "Nicholas Caton"<ncaton at catonenergy.com>;
*抄送**:* "赵永青"<zhaoyongqing1987 at qq.com>; "Julien Marrec"<
julien.marrec at gmail.com>; "equest-users at lists.onebuilding"<
equest-users at lists.onebuilding.org>;
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

On May 24, 2015, at 11:38 AM, Nicholas Caton <ncaton at catonenergy.com> wrote:

I’m happy you are arriving at the same result, however to be clear I
do not think the reviewer is correct to assert the prescribed
efficiency is anything other than the full-load efficiency.

Follow the cited Test Procedure CFR 431 led me to:
https://www.law.cornell.edu/cfr/text/10/431.86

*“§ 431.86 (c) (3) (ii) Thermal Efficiency. Use the calculation
procedure for the thermal efficiency test specified in Section 11.1 of
the HI BTS-2000, Rev 06.07 (incorporated by reference, see§ 431.85).”*

I then found the referenced HI standard here (PDF link):

In that standard, section 5 reads:
*5.0  TYPES OF TESTS*
*5.1 *Thermal Efficiency Test
Shall consist of a test point conducted at 100% ± 2% of the nameplate
boiler input. The test shall
yield a complete accounting of the energy input in terms of output and losses.
*5.2 *Combustion Efficiency Test
Shall consist of a test point conducted at 100% ± 2% of the input to
the boiler and shall yield an
accounting of energy input in terms of products of combustion only.

>From this, it is clear Et and Ec as prescribed by 90.1 are only the
efficiencies as measured at full load.  The test procedures following
under section 9 deliberately exclude the effects of warmup/standby
(equipment is made to warm up and arrive at the mandated operating
conditions prior to measurements).

Section 11.1 of the standard prescribes all the calculations required,
including Et = 100*QOUT / QIN , however the preceding sections makes
clear we are in no way standardizing part load performance or
warmup/standby performance.

Rounding back to 90.1… section 6.4.1.1 further cements the notion
(“packaged boilers” fall under 1992 EPACT):

All this reinforces the point that 90.1 simply does not prescribe part
load performance for baseline boilers.  To perform a simulation in
compliance with Appendix G the onus is upon the energy modeler to make
reasonable, defensible assumptions on that front.  I don’t see how
removing standby/startup operation energies is more reasonable or
reflects reality better than the defaults.

If this is a new GBCI position they plan to hard-line on, then I would
speculate it would be equally fair (albeit far more unrealistic for
condensing cases) to give your proposed boilers the same treatment…
extra work for a step backwards from reality…?

Thoughts?

~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:* 冷面寒枪 [mailto:zhaoyongqing1987 at qq.com]
*Sent:* Sunday, May 24, 2015 7:13 AM
*To:* Nicholas Caton; Julien Marrec
*Cc:* equest-users at lists.onebuilding
The problem of minimum equipment efficiency requirement of Ashrae 90.1-2007

Hi,Nick

Except default curve and start up time, Min-Ratio also will result
in discrepancy between annual equivalent HIR and nominal HIR. After I
revised curve ,set start-time and Min-Ratio to 0,and hourly report and
PS-C report indicate that the annual equivalent HIR  is accord with
nominal HIR

------------------
*Yongqing Zhao*
*Changsha Green Building & Energy Saving Technology CO.,LTD*
Telephone:13574805636
Email:zhaoyongqing1987 at 126.com
503271081 at qq.com

------------------ 原始邮件 ------------------
*发件人**:* "Nicholas Caton";<ncaton at catonenergy.com>;
*发送时间**:* 2015年5月24日(星期天) 晚上9:53
*收件人**:* "赵永青"<503271081 at qq.com>; "Julien Marrec"<julien.marrec at gmail.com>;
*抄送**:* "equest-users at lists.onebuilding"<equest-users at lists.onebuilding.org
>;
The problem of minimum equipment efficiency requirement of Ashrae 90.1-2007

I received some similar review language very recently suggesting 80%
efficiency is expected at all/most part load conditions for the
baseline boiler….  Similar context in that case with the boiler rarely

My comment has other issues that would cloud the topic at-hand, but
here is  truncated version:

“…Furthermore, the average boiler efficiencies in the Baseline PS-C
output reports, calculated by dividing the boiler energy consumption
by the annual boiler heating energy generated was… [approximately 5%
lower than the nominal efficiency input & documented]. Revise the
baseline boiler efficiency to 80% and revise the boiler curve for the
Baseline case as necessary to have an average efficiency that is near
80%. Provide updated PS-C reports for the Baseline confirming that the
average baseline efficiency is near 80%.”

This is the first time I have run into commentary checking up on
PS-C’s output at all, and I’m using the same library curves as always
for typical baseline boilers.

I believe the PS-C discrepancy is explained both by the non-flat
library curve and by the boiler’s default start-up loads, in
combination.

Here is the default library curve – it is (roughly, but not quite) linear:
<image002.png>
<image003.png>

[For those unfamiliar, the Y-axis is a unitless multiplier]

If I’m not mistaken, this curve serves double-duty:  it simultaneously
applies the hourly PLR to the full capacity (as either input or
auto-sized) and also accounts for increased HIR (lower efficiency) as
the PLR drops.  My understanding in equation form:
Energy Consumed (for the hour) = (Boiler full capacity as
input/autosized) * (Boiler nominal HIR input @ full load) * HIRf(PLR)

If all of that is true, a perfectly “flat efficiency” curve, returning
your nominal input HIR at all efficiencies, would therefore be Z = X.
That’s plotted above for reference with a light/thin line.

Even with such a “flat efficiency” curve applied to a test-case,
PS-C’s outputs still suggest an annual equivalent HIR higher than the
nominal input.  Zeroing out the startup/standby inputs as well is
required to get PS-C to report your nominal HIR = annual fuel / annual

I think the correct response (which perhaps I’ve mostly composed
above) is to demonstrate the causes (library curve shape,
startup/standby defaults), and to assert these are all appropriately
applied to the baseline boiler, though
*none of this is regulated by 90.1*
to the best of my knowledge so it might be relatively shaky territory.

I would wager 90% of all eQuest baseline boilers submitted to GBCI to
date probably don’t mess with the library curves or standby/startup
inputs, but that’s pure speculation on my part.

Has anybody ever tried to explain/justify the default boiler curve and
default startup/standby inputs?  Do we know where those defaults come
from?

~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:* Sunday, May 24, 2015 5:34 AM
*To:* Julien Marrec
*Cc:* equest-users at lists.onebuilding
The problem of minimum equipment efficiency requirement of Ashrae 90.1-2007

Hi,Julien

I understand his meaning is keep a constant efficiency and I know the
flat efficiency in equest is a curve that is y=x, but I can't  confirm
if a constant efficiency is Ashrae 90.1-2007's original intent.

------------------
*Yongqing Zhao*
*Changsha Green Building & Energy Saving Technology CO.,LTD*
Telephone:13574805636
Email:zhaoyongqing1987 at 126.com
503271081 at qq.com

------------------ 原始邮件 ------------------
*发件人**:* "Julien Marrec";<julien.marrec at gmail.com>;
*发送时间**:* 2015年5月24日(星期天) 晚上8:19
*收件人**:* "赵永青"<503271081 at qq.com>;
*抄送**:* "equest-users at lists.onebuilding"<equest-users at lists.onebuilding.org
>;
*主题**:*
Re: [Equest-users] The problem of minimum equipment efficiency
requirement of Ashrae 90.1-2007

Hey,

He's saying that you need to make sure that the curve boiler-fPLR
gives you a constant efficiency. As far as I remember, the default
atmospheric curve from equest is like this.
Don't be confused by "flat". A flat efficiency curve is when you plot
efficiency=f(PLR). In equest, it should be a curve that is y=x

Look at the curve you used.

Best,
Julien

Envoyé de mon iPhone

Le 24 mai 2015 à 11:27, "赵永青" <503271081 at qq.com> a écrit :

I get the energy model comments from LEED reviewer as following:

The narrative response indicates that the Baseline boiler has been
modeled utilizing operating performance curves and a boiler HIR of
1.25. However, since the boiler operation HIR is based on the
performance curves, the HIR is less than 1.25 in the part-load
condition, which is inappropriate. Revise the Baseline boilers to
include a flat efficiency of 80% for all part-loads. Provide eQuest
input files or screen shots verifying the boiler efficiency has been
modeled as required.
However, I can not understand it very much. The minimum equipment
efficiency requirement(80 % Et) of Ashrae 90.1-2007 should be base on
full load condition.Why the LEED reviewer raise such a question?Any
insight is appreciate!!

Thanks
------------------
*Yongqing Zhao*
*Changsha Green Building & Energy Saving Technology CO.,LTD*
Telephone:13574805636
Email:zhaoyongqing1987 at 126.com
503271081 at qq.com

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