[Equest-users] Existing building simulation

[Nick Caton]

Some quick thoughts:

 

-          You'll want to simultaneously look at both your consumption
and demand results/curves.  Together you can use the resulting
differences to determine where you should make adjustments.

-          You should also be looking at both gas and electricity
consumption/demand "actual/modeled" curves if they apply - 4 total.

-          Take note that if you are using only a single-year's worth of
utility consumption data to develop your "actual" curve, you're bound to
have differences that come from your model using TMY weather conditions
(averaged over decades).  The likelihood of any one year being a "hot"
or "cold" year relative to the average is high.

-          The individual loads broken out are your first clue - some
loads when increased will raise the "modeled" curve uniformly, depending
on how they're scheduled.  Miscellaneous Loads, Lights and DHW for
example are generally a flat consumption every month, unless you're
incorporating daylighting controls or some other scheduling schemes.  As
a result, raising/lowering those loads (in a way that makes sense and
better syncs with the existing building) will raise/lower the "modeled"
curve, without changing its shape.

-          Loads that vary over time will affect the shape of the curve.
Space heating, fans and space cooling energy are generally the major
ones.  Increasing/Decreasing these is not as simple as entering a
different W/SF.   A few major things affect the overall quantity of
heating/cooling provided over the year - internal loads (particularly
solar/people), their associated schedules, equipment/fan efficiencies
(these act sorta like multipliers to whatever annual consumption shape
you arrive at),  building envelope - equally important is building
infiltration, and the true control behavior (actual thermostat
setpoints, setback behavior, economizer operation, etc...)

-          It's best to try to match curve shape (variable loads),
allowing your modeled consumption to ride uniformly above/below actual,
before "playing with" the constant-over-time components.

-          Ultimately, you will have a balance of work where you are
first matching the existing project to the best of your ability,
thereafter tweaking assumptions for which you cannot account for with
true accuracy.  If you commit yourself to this reality, you can define
when you are doing the former and carefully keep track of your
assumptions - this is good because you can sleep at night being able to
provide concrete answers regarding exactly which elements of your model
are true behavior.

 

I've been down this route (using eQuest to match an existing building).
It's quite do-able but as a forewarning may require you to become pretty
intimate with the existing building when all is said and done ;).

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

Check out our new web-site @ www.smithboucher.com 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Vaziri,
Mo (ON0F)
Sent: Tuesday, March 16, 2010 10:20 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Existing building simulation

 

If we are doing a simulation for an existing building and the actual
electricity consumption does not match with the simulation, how can we
adjust/calibrate it?

 

The snapshot shows the actual (blue graph) vs. simulation.

 

 

 

Regards,

Mo Vaziri 

 

                                             Honeywell 

Mo Vaziri, P. Eng. , LEED AP, CEM
Design Build / Energy Engineer 
Honeywell Building Solutions - Canada

85 Enterprise Boulevard, Suite 100

Markham, Ontario, L6G 0B5 
(       Phone: (289) 333-1340 
2                 Fax:      (289) 333-1333 
(       Cell:     (416) 527-4692 
*       mohammad.vaziri at honeywell.com
<mailto:pmohammad.vaziri at honeywell.com>  

 

 

 

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