[BLDG-SIM] Weather Normalization Question

[Michael Wilson]

Regarding the first comment from Dave Robison, I've
received the weather data in WYEC2 format from
Environment Canada, including solar, wind, etc.
However, the last time I had to do this was for a 1999
weather year, and I understand that recent automation
of the weather stations may make this data harder
(impossible?) to come by. But without this data, how
are you making the calibration?

And although I've only calibrated a few of these, not
hundreds, I'm not sure I'd agree that the model
doesn't need to be detailed and it's a low cost
simulation. If you don't put a fair bit of work into
making sure the simulation of systems is reasonably
similar to the operation of them, then you're not
calibrating, you're just matching the bills. And while
your model might line up nicely with the bills, if
your end-uses or hourly profiles are off its not going
to be so useful for running further simulations on.

--- Dave Robison <drobison at teleport.com> wrote:
> for the most part, I have been lurking on this group
> because, unlike you 
> designers, our specialty is calibrated models. We've
> done hundreds of them, 
> and there are very few doing such.
> 
> >I order up a years worth of weather
> >data for the most recent year and convert it to
> Doe2
> >format.
> 
> I don't see how one can do that. At best, you can
> set the actual 
> temperature data into a TMY file. But you still have
> the old solar, 
> humidity, wind speed etc. Now those data are
> completely incompatible with 
> the hourly set of temperatures. Or do you have
> source for those other 
> weather data? I don't believe they are being
> measured anymore.
> 
> >To calibrate models to reality, you must also watch
> out for what's
> >included in the utility bills.
> 
> Yes, you have to include things like parking lot
> lights, if applicable.
> 
> 
> >And, of course, there's the difference between how
> equipment is supposed
> >to operate and how it actually operates
> 
> As-built and as-operated. That's the whole point of
> a calibrated model. The 
> process of calibration often reveals operational
> opportunities for further 
> savings. As such, it is a low-cost commissioning
> tool.
> 
> >Calibrating models entails either incredibly
> detailed investigation of
> >the actual building,
> 
> nonsense. If you have only limited reference data
> (monthly bills), you 
> don't need a detailed hourly model. A monthly
> simulation works fine and is 
> a whole lot easier.
> 
> >or else application of the black art of making
> >informed guesses ("engineering judgment").
> 
> Any modeling involves informed guesses -- eg) how do
> you model passive 
> infiltration? At least with the calibrated model,
> you have a reality check.
> 
> >  In our experience, there's a
> >significant portion of models that just won't
> calibrate, because the
> >actual energy use is too strange and resources to
> investigate why are
> >not infinite.
> 
> Not so. The monthly bills are a cheap resource and
> the simulation cost is 
> minimal. The only ones we have had to reject were
> because the metering was 
> at a different level of aggregation.
> 
> 
> >The real objective of generating reasonable energy
> savings estimates,
> >however, can still be met if the model is overall
> reasonable.
> 
> How do you define reasonable? If fact, we have found
> that using actual 
> weather, rather than TMY, may be necessary to
> resolve the model sufficiently.
> 
> >  It's the
> >delta in energy use attributable to the efficiency
> measures of interests
> >that matter, not necessarily tracking down all the
> unusual quirks of
> >utility metering and billing systems.
> 
> Yeah, but if you don't have the building defined,
> can you be sure of the 
> calculated delta? At least if you start with a
> calibrated model, then move 
> off it incrementally, you have some confidence that
> the deltas are reasonable.
> 
> 
> >Using a whole building simulation can be a big
> >improvement on that practice.
> 
> Absolutely
> 
> 
> ====================
> David Robison
> Stellar Processes
> 1033 SW Yamhill Suite 405
> Portland, OR 97205
> (503) 827-8336
> www.ezsim.com
> 
>
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=====
Michael Wilson
455 Elphinstone Ave.
Gibsons, BC, V0N 1V1
604-886-9864 phone
604-676-2604 fax

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