[Bldg-sim] Spam:Re: LEED NC Submittal Template, Heating/Cooling Hours Loads Not Met

[Michael Tillou]

If you're using eQuest the Air Side Summary report in the eQuest interface
has all that info.  It is also reported in SS-R Zone Performance Summary in
the .SIM file.     

-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Jay Keazer
Sent: Thursday, August 21, 2008 5:16 PM
To: Dan Russell; Brandon Nichols; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Spam:Re: LEED NC Submittal Template,Heating/Cooling
Hours Loads Not Met

I am not certain, but I think the unmet load hours on the BEPS report is
consistent with the definition in Addendum a.  The BEPS report says "Percent
of hours any system zone outside of throttling range."  To me this is the
same as "one or more zones" being out of range for a particular hour.  

Adding up the unmet load hours of every zone would count a lot of coincident
unmet hours and could get large with a lot of systems (note this is what
SS-R does for multiple zone systems).  It could be greater than 8760, and I
don't think this is what appendix G is looking for.  If a lot of zones are
out of range during an hour (say an exceptionally cold night) that should
only count as 1 hour.

I don't think that the number on the BEPS is for the "worst case zone."  I
just checked a SIM file I had open and the BEPS report listed 3.3% unmet
load hours, so 289 hours (actually anywhere from 285-293).  Looking through
SS-R for each zone, the worst case had 177 hours under heated + 24 hours
under cooled, so 201 total unmet hours.

I have always gone by the BEPS (i.e. 3.4% or less is good), but have never
known how to find more detailed output regarding how many are cooling vs.
how many are heating.  Theoretically I think you could do this with an
hourly report for every zone and some postprocessing, but I don't really
want to go there.  Anybody have a more practical approach?


Jay Keazer,  EI
Energy Engineer
TME, Inc.
2039 N Green Acres Road
Fayetteville, AR  72703
 
ph   479.521.8634
fax  479.521.1014
jkeazer at tmecorp.com
www.tmecorp.com



-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Dan Russell
Sent: Thursday, August 21, 2008 1:12 PM
To: Brandon Nichols; bldg-sim at lists.onebuilding.org
Subject: Spam:Re: [Bldg-sim] LEED NC Submittal Template,Heating/Cooling
Hours Loads Not Met

Brandon, I have been on the same page regarding this issue, and have
submitted for successful LEED certifications using those assumptions ...
until I read Addendum a to 90.1-2004, which adds the definition of "unmet
load hour" to Section 3.2.  The definition is:

unmet load hour: an hour in which one or more zones is outside of the
thermostat setpoint range.

Unfortunately this seems to clearly indicate the unmet load hour value asked
for refers to all zones at once.  

My previous assumptions to only consider the worst-case zone were based on
the example set forth by the USGBC's document titled "Example LEED-NC
v2.1 Energy & Atmosphere Credit 1 Submittal", which I referenced back when I
did my first LEED submittal in 2005.  This document is still available from
their server at the following address:

http://www.usgbc.org/ShowFile.aspx?DocumentID=2423

This document uses the following paragraph to demonstrate compliance with
the unmet load hour requirement:

"The worst-case zone in the budget case is a North classroom. This zone is
under-heated 40 hours out of the year in the Energy Cost Budget case and 0
hours per year in the Design Energy Cost case. This is within the 50 hour
per year limit required by ASHRAE 90.1-1999."

Now, if Addendum a were not used in any part as basis for LEED submittal one
could possibly argue using the quoted precedent above.  Granted, the above
precedent applied to the 1999 version of 90.1 and the 2.1 version of LEED,
but it seems to reasonable that the implications made there should carry
over until otherwise directed (as in Addendum a).
Furthermore, it is my opinion that 90.1-2004 (not including addendums) does
not clearly resolve the issue.  The ASHRAE technical committee must have
agreed, hence the inclusion of the new definition for "unmet load hour" in
Addendum a.

So, if Addendum a is not used, there may be a possibility to consider unmet
load hour only on a worst-zone basis.  However, if Addendum a is used it
seems clear that the unmet load hour applies to all zones at once.

Certainly larger project simulations with multiple zones will suffer from
this added definition.

Thanks,

 Dan Russell, EIT 




-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Brandon Nichols
Sent: Thursday, August 21, 2008 11:22 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] LEED NC Submittal Template,Heating/Cooling Hours Loads
Not Met

 
All,

"Table 1.3 -- Advisory Messages" of the LEED NC Submittal Template requests
"number of hours heating loads not met" and "number of hours cooling loads
not met".  We've taken a vote here in the office, and its 2-0 in favor of
reporting the worst case zone as shown on the BEPS report.

But we have some lingering doubts... can anyone say definitively what
numbers are being asked to for here?  our runner-up in the voting was the
total of all zone hours out of throttling range -- however this could easily
exceed the limit of 300 hours on a large project with many zones.  

As 300 hours is less than 5% (3.4% actually) of 8760, we think that the 300
hours is "per zone", not a total limit for the entire project.  

Comments appreciated....
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