[Bldg-sim] Cooling effeciency

[Karen Walkerman]

PTACs usually have the ability to run an economizer and WSHPs do not.  I am
not sure if you modeled it this way, you would need to check the inputs.
This would account for a drop in savings, but not sure it would account for
everything.  Also, I would expect an increase in pump energy use for the
WSHP system.  In regards to the part load efficiency curves, I have not
studied WSHP and PTACs next to each other.  You might want to make sure that
your curves are normalized to EERs you are inputting.

--
Karen


On Wed, Jul 9, 2008 at 4:55 PM, Tobias, Mike <mtobias at loringengineers.com>
wrote:

> Modeling a 30 story hotel with PTACs (9.54 EER) vs. WSHP (12 EER) I am
> expecting to see a large cooling energy reduction.  Since the envelopes
> are the same I'm expecting to see the full 26% improvement, however I
> only see an 11% improvement in cooling energy comparing the BEPS report.
> I would expect part load performance to maintain an almost constant
> efficiency spread of 25% through the whole part load curve.  But maybe
> for some unkown reason to me the efficiency spread decreases
> dramatically through part load?  Also is there any way to check overall
> building cooling efficiency like divide overall cooling loads into
> energy?  Cooling energy can be found on BEPS, but total building cooling
> load varies from LS-F and LS-D to SS-D.
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