[Bldg-sim] eQuest - Model verification

[Bishop, Bill]

Katherine,

 

The questions I would have for you (or your client) are:

*         Is this an existing building, or something in the design
phase?

*         What is the model going to be used for?

*         Is there something magical about the 1% number?

*         1% of what? Annual electrical consumption? Annual gas
consumption? Both? Monthly electric/gas consumption? Monthly/annual
electrical demand?

*         Why remove the plug loads? Even if everything else is modeled
perfectly, plug loads are typically 10% or more of annual electrical
consumption but can be all over the place.

*         "Easily adjusted" by whom? Does your client want you to hand
them a model and let them make all subsequent adjustments?

 

Even if you are an expert energy modeler, and there is monitored energy
data available for the building down to the individual electrical panels
or broken out by end use (lighting, plug loads, individual HVAC units
etc.) you will be hard-pressed to get to within 1% on a month-by-month
basis. Even 5% month-by-month is difficult. Sure, you can tweak to your
heart's content to get a model to match annual electric consumption
within 1% based on prior year's utility bills but to maintain a
calibrated model to that tolerance after that would require a lot of
work.

 

I suggest searching the bldg-sim and equest-users archives for
information about weather files.

 

Oh, one more question - how much money does your client have?

 

Regards,

Bill

 

William Bishop, PE, BEMP, LEED(r) AP | Pathfinder Engineers & Architects
LLP

Mechanical Engineer

 

 134 South Fitzhugh Street                 Rochester, NY 14608
T: (585) 325-6004 Ext. 114            F: (585) 325-6005

wbishop at pathfinder-ea.com           www.pathfinder-ea.com
<http://www.pathfinder-ea.com/> 

P   Sustainability - the forest AND the trees. P    

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Katherine
Louman-Gardiner
Sent: Thursday, April 28, 2011 1:49 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] eQuest - Model verification

 

Hi All,

Our client would like us to produce an eQuest model that

a)      Can be easily adjusted to include current and recently recorded
weather data

b)      Can be easily adjusted to reflect space occupancies and lighting
loads

c)       Will reflect the actual building energy usage to within 1%

Do any of you have experience trying to validate models like this?  

My concern is that models are approximations, and will not account for
small changes in occupancy, outdoor weather, etc.  

I guess my questions are these:

1)      Even if I manage to put in daily occupant and fan schedules
based on actual use, will the model be accurate enough to take me within
1%?

2)      We have been asked to remove plug loads (both for consumption
purposes and cooling loads).  Will this be too big of an assumption to
get any accuracy out of the model in the future?

3)      How do I modify the weather input file?

4)      Are there any other ideas I'm missing that will help us validate
a model as an absolute measure of actual building energy consumption?

Thank you for your help,
Katherine

 

Katherine Louman-Gardiner, EIT

Mechanical Engineer

 

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