[Bldg-sim] eQuest - Model verification

[Carol Gardner]

Bill summed it up really well, Katherine. Sometimes a client will think a
calibrated model must match the real building by an unrealistically high
number, like 1%. I really can't imagine an instance when that would be
desirable. It certainly would be costly to achieve.

Usually the plan is to use the calibrated model as a tool to examine various
energy saving measures/opportunities that the client may be interested in
implementing. It is important to remember, in this case that you are looking
at the usage between the calibrated model and the ECM model, so the 1%
deviation is consistent in both and not a worry.

Carol

On Thu, Apr 28, 2011 at 12:03 PM, Bishop, Bill <wbishop at pathfinder-ea.com>wrote:

> 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® AP **|** **Pathfinder Engineers &
> Architects LLP***
>
> Mechanical Engineer
>
>
>
> [image: Top 100 Rochester 2010]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
>
> 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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-- 
Carol Gardner PE
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