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

[Andrew S. Hoover]

Hey Morgan:

 

Does your data include years 3 to 6 after construction?  It would be great
to see if usage is in line with predictions after real work use of the
building for a while.  What type and size of buildings were they in what
geography?

 

Thanks,

 

Andy

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sami, Vikram
Sent: Tuesday, January 29, 2013 3:30 PM
To: Morgan Heater; 'Kapil Upadhyaya'; 'Jason Quinn';
bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Energy Model from Green Star (LEED) to predictive
model

 

Morgan - 10% is pretty damn close - well done! 

 

That being said - I would like to respond to the second part of your email.
Personally I think it is possible to be slightly inaccurate, but still
correct.  

 

In my experience it is when you are in the early stages (when there is a
huge margin of error) that the modeling is actually at its most useful. Very
often it's the early on normative modeling that leads to good design
decisions. For example when modeling a VAV system versus a chilled beam
system, I might not have the exact BTU number, but if I can get the usage
patterns appropriately represented (cooling, heating, fans & reheat) then
the result might not be 'accurate', but correct. Your overall numbers might
go up and down with occupancy and weather, but the decision still remains a
good one. This is where having the experience and the backing of a good
database of comparable buildings is invaluable. CBECS is good for overall
usage, but it's even better to be able to look at how the BTUs are spent
over the year. Investing the time to collect utility bills for your building
type is worth a lot. 

 

Often we worry about the accuracy of our results to the nth degree before
making recommendations, but by the time we come up with the magic number its
too late - the design has morphed, or been finalized so your numbers are
either outdated or redundant (in some cases both). 

 

 

Vikram Sami, LEED AP BD+C

Sustainable Design Analyst

1315 Peachtree St. NE, Atlanta, GA 30309

t: 404-443-7462    f: 404.892.5823       e: vikram.sami at perkinswill.com
<http://www.perkinswill.com/> www.perkinswill.com

Perkins+Will.  Ideas + buildings that honor the broader goals of society

 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Morgan Heater
Sent: Thursday, January 24, 2013 5:17 PM
To: 'Kapil Upadhyaya'; 'Jason Quinn'; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Energy Model from Green Star (LEED) to predictive
model

 

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

206-322-3753

206-596-4709 Direct

 

From: 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
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
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 

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