[Bldg-sim] Comparing ASHRAE 90.1 App G Models to Real Buildings
Jim Dirkes
jim at buildingperformanceteam.com
Thu May 21 07:36:26 PDT 2015
I agree fully with all of the above comments and would like to add these:
- Even buildings that are commissioned properly will see their
performance erode over time. There are hundreds of reason for this,
ranging from poor maintenance to well-intentioned maintenance people not
having time to monitor operations well. There is NO BUILDING that operates
well for long.
- Buildings often see changes in operation, occupancy and schedule.
These are oftimes gradual changes over a period of years, but can be
substantial
On Thu, May 21, 2015 at 10:22 AM, Nathan Kegel <nathan.kegel at iesve.com>
wrote:
> Climate files used in the simulations versus the actual weather.
>
>
>
> I’m in the midst of a project that shows a variance in EUI of up to 200%
> just by changing the climate file for the DOE primary school. Full results
> to be presented in September.
>
>
>
> Add in all the other factors already mentioned, and if your 90.1 model
> comes anywhere close the real buildings’ it’s far more likely that the 90.1
> model was extremely “lucky” than it is that the model used accurate
> assumptions.
>
>
>
> Regards,
>
>
>
> Nathan
>
>
>
> <http://www.iesve.com/>
>
> *Nathan Kegel*
> *Business Development Manager*
>
> O:
>
> 763.276.9981
>
> M:
>
> 415.420.9314
>
> http://www.iesve.com
>
> Integrated Environmental Solutions Limited. Registered in Scotland No.
> SC151456
> Registered Office - Helix Building, West Of Scotland Science Park, Glasgow
> G20 0SP
>
> Email Disclaimer <http://www.iesve.com/disclaimer.html>
>
>
>
>
>
> *From:* Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] *On
> Behalf Of *Maria-Lida Kou
> *Sent:* Thursday, May 21, 2015 9:17 AM
> *To:* Jacob Dunn
> *Cc:* bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] Comparing ASHRAE 90.1 App G Models to Real
> Buildings
>
>
>
> Jacob,
>
>
>
> Happy to hear that other people are thinking the same.
>
>
>
> I was into this subject on my own thoughts recently.
>
>
>
> I would like to add in your list: Occupants' behavior actually which is
> not in the stage to be included into the prediction.
>
> I would add commissioning as well along with controls simulation and
> controls operation.
>
>
>
> Apologies because I haven't worked with LEED projects but I think the
> above applied in general to "the performance gap".
>
>
>
> Really looking forward to hearing more about this subject as I am not that
> experienced engineer yet, but really interested in "the performance" side
> of buildings.
>
>
>
> Best,
>
> Maria-Lida Kounadi
>
>
>
>
>
> 2015-05-21 15:04 GMT+01:00 Jacob Dunn <jdunn at eskewdumezripple.com>:
>
> Bldg-Sim Community –
>
>
>
> I’m trying to compile a list of why it might be inappropriate to compare
> Appendix G models to actual consumption data. This comes about because I
> recently got into a debate with one of my co-workers when looking at the
> infamous NBI chart/study that shows little correlation to predicted and
> actual energy values of LEED buildings. I was trying to explain that the
> Appendix G model’s intent is NOT to be compared to actual consumption, as
> it is a modeling protocol aimed at creating consistent relative comparisons
> for LEED points.
>
>
>
> Here are the reasons thus far that support this notion (that App G models
> shouldn’t be compared to actual data). Does anyone know of any resources
> out there that expand upon this? Or can you think other reasons?
>
>
>
> - Appendix G does not take into account external shading, which
> can be critical in urban environments for accurate energy predictions
>
> - Schedules are typically not created with the intent of being
> predictive. Overall building hours are adhered to, but detailed schedule
> creation is not usually in the scope of a LEED model (or is it, in your
> experience?). For instance, typical plug load base values during
> unoccupied times are .3, this is a pretty big assumption.
>
> - The App G model uses a TMY weather file, which can vary from
> the current weather year (I wonder on average by how much?)
>
> - Infiltration values are assumed, unless blower door testing
> has been done (which is rare for commercial buildings).
>
> - Thermostat values are modeled as consistent across the
> building, which is rarely the case in an actual operating building
>
>
>
> Any additional insight is much appreciated!
>
>
>
>
>
> *Jacob Dunn LEED AP BD+C*
>
> *ESKEW+DUMEZ+RIPPLE, APC*
>
> 2014 AIA National Architecture Firm Award
>
>
>
> 365 Canal Street Suite 3150
>
> New Orleans LA 70130
>
> 504.561.8686
>
> *eskewdumezripple.com <http://www.eskewdumezripple.com/>*
>
>
>
>
> _______________________________________________
> 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
>
>
>
> _______________________________________________
> 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
>
>
--
James V Dirkes II, PE, BEMP, LEED AP
CEO/President
The Building Performance Team Inc.
1631 Acacia Dr, GR, Mi 49504
Direct: 616.450.8653
jim at buildingperformanceteam.com
Website <http://buildingperformanceteamcom>l LinkedIn
<https://www.linkedin.com/pub/jim-dirkes/7/444/413>
The truth is still the truth, even if nobody believes it. A lie is still
a lie, even if *everyone* believes it.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20150521/b30815f2/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 5346 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20150521/b30815f2/attachment-0003.png>
More information about the Bldg-sim
mailing list