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

Nicholas Caton ncaton at catonenergy.com
Sun May 24 06:53:22 PDT 2015

```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 operating

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:

[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 load:

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
*Subject:* [Equest-users] Reply： 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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