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K Outdoor Air Unit
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L Energy Recovery Ventilator
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With respect to energy simulations,
normally process loads are included,
specifically for office, K- 12, and
multi-use applications (which are the
majority of these case studies).
Our scope was limited to the data
provided in the case study articles.
Although in theory it is possible to
check and track EUI over time for all
90 case studies, this is just not practical. From your practical experience,
you may be aware that it is sometimes
difficult to quantify/verify EUI for
even a single, well-metered building.
We limited the investigation to
the data available in the published
articles. Challenging the data in all
of these case study articles is again
more of a question for ASHRAE.
Other than actually gathering the
utility bills for all of these buildings,
I’m not sure what level of verification
we could perform that would be any
more robust than taking the data provided in the published articles.
We did not have enough information
to specifically determine cause of the
wide range of EUI for these building
types. But I am sure that you will agree
that in these buildings (hospitals and
labs) there is a high probability that the
high EUI is due to process loads, medical equipment, long hours of operation,
large quantities of OA and minimum
ventilation rates, excessive reheat, etc.
We hope that by showing EUI vs.
the various factors that making simple
conclusions from an individual EUI
value is very difficult. It is implied
therefore that professional expertise or
further analysis is need to determine
whether the “performance” of the
building is good or poor.
While I agree it would be helpful,
it seems impractical to include references for 90 articles in the magazine
article. The previous case study
reviews that we do reference took the
same approach and did not specifically reference all of the case studies
We agree that EUI values inherently
fail to capture the dynamic nature of
buildings. Our article shows that it is
difficult to make conclusions about a
building even with a static EUI value.
For the purposes of this paper the
only metric investigated was EUI.
However, other factors such as IAQ,
water use, thermal comfort, and
those that you mention could also be
metrics for “high performance”. In
addition, this type of information is
not readily available within the case
study articles for analysis.
As a result, the conclusion is that
EUI, as a metric of building performance, is impacted by too many
confounding factors. Therefore, one
must be careful in using it as lone
metric of building performance.
Overall, I think we agree with your
arguments and it is unfortunate if the
article wasn’t clear enough.
Itzhak Maor, Ph.D., P.E., Member ASHRAE, Cherry Hill, N.J.;
Steven C. Snyder, Associate Member ASHRAE, Philadelphia
Letters continued from Page 7