[Bldg-sim] Energy Model from Green Star (LEED) to predictive model

[Jim Dirkes]

Nice graphs, Chris!  Even nicer calibration!
Random comment regarding % deviation for an individual month: Natural gas consumption often goes to near-zero in summer months.  This sometimes makes any deviation from the actual usage a very large number, which in reality may be a tiny fraction of total use.  There's no simple solution for this; it's not worth worrying about the deviation because it's so small a fraction of overall use, but it looks really bad to non-technical readers.  I've been reporting R-squared values calculated from the monthly deviation.  Not perfect, but it places the focus on the overall month-by-month match instead of a single month.

Morgan, you apparently work with excellent commissioning agents and very responsible owner / building managers!  10% sounds too good to be true.

James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com<http://www.buildingperformanceteam.com/>
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Chris Jones
Sent: Sunday, January 27, 2013 10:57 AM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Energy Model from Green Star (LEED) to predictive model

I don't believe there can be any hard rules about the percentage of error when calibrating a model.  The margin of error is proportional to the amount of information available.  The rest is engineering and experience.  Attached is a typical report we use to illustrate how close the calibration is.

This particular project is a community centre, pool, with an arena adjacent for heat exchange.  A tricky one.


At 05:16 PM 24/01/2013, Morgan Heater wrote:

Content-Type: multipart/alternative;
         boundary="----=_NextPart_000_004A_01CDFA3D.7921A6D0"
Content-Language: en-us

I've been getting within 10% without calibration on the last five or six buildings I've done where I've tracked the bills afterwards.  The key is to be thorough and careful.  If you're not getting reasonably close, how can you justify your recommendations for energy efficiency measures?


Morgan Heater, P.E.
BEMP, LEED AP
morgan at ecotope.com<mailto:morgan at ecotope.com>
206-322-3753
206-596-4709 Direct

From: bldg-sim-bounces at lists.onebuilding.org<mailto:bldg-sim-bounces at lists.onebuilding.org> [ mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Kapil Upadhyaya
Sent: Thursday, January 24, 2013 2:08 PM
To: Jason Quinn; bldg-sim at lists.onebuilding.org<mailto:bldg-sim at lists.onebuilding.org>
Subject: Re: [Bldg-sim] Energy Model from Green Star (LEED) to predictive model

Get utility bills (if you can), or Use Energy Star or CBECs for a reference building (CBECs median may be higher than a 1930 building !); based on these, you can present a range between 'simulated' savings and 'estimated' savings.

Kapil Upadhyaya, LEED AP
Associate
Kirksey | Architecture

From: Jason Quinn [ mailto:jason.e.quinn at gmail.com]
Sent: Wednesday, January 23, 2013 9:38 PM
To: bldg-sim at lists.onebuilding.org<mailto:bldg-sim at lists.onebuilding.org>
Subject: [Bldg-sim] Energy Model from Green Star (LEED) to predictive model

I've ALWAYS avoided predictive modeling (telling a client your energy usage will be below X) as I've been scared. Now I'm pretty deep into a project performing Green Star energy modeling and my client has popped the question.

We've discussed "why it is hard" and the big three un-knowns: Infiltration, Occupant behavior!!, and Actual Weather. They still want me to go forward and are willing to put a bunch of caviates and an agreed margin on the results.

This is an old 1930's building 200,000 sq ft with original metal window frames (single pane) that will not be replaced (heritage). We're insulating the roof and basement ceiling and a completely new HVAC system. Is there a standard process I can follow or specific suggestions the community could offer?

So far my idea is to try and guesstimate infiltration, box in comfort behavior with lease agreements and a survey, and put some margin on weather.

--
Jason
_______________________________________________
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<mailto:BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG>

>>
Christopher Jones, P.Eng.
Suite 1801, 1 Yonge Street
Toronto, ON M5E1W7
Tel. 416-203-7465
Fax. 416-946-1005
email cj at enersave.ca<mailto:cj at enersave.ca>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20130128/af87fc09/attachment-0002.htm>