[Equest-users] Lighting Power Density

[David Eldridge]

Overestimated proposed design will result only if the proposed case also
used a lighting power density.  But if the proposed model is using design
values for fixtures, then the proposed airflows and lighting power (not
density) are based on the net occupied area.  Therefore the baseline power
(kW) should also be based on the “real” occupied area and not including the
chases, even if they are lumped in to simplify geometry.  So I’d say the
opposite – by including the chase area in the baseline the total kW is too
high compared to a proposed case that uses an actual kW.



If I’m understanding, the GBCI actually DOES want you to calculate lighting
power in terms of kW per occupied space and allocate it over the same
modeled area as your proposed lighting kW – in this way both cases will have
a modeled LPD that is lower than if only the occupied areas were used for
those spaces.



You do need a section in your narrative to explain the process of
determining LPD, equipment power density, occupancy per area, etc in the
context of the design documents  that don’t include the chases.  If I have
it backwards and the proposed design is not using actual values, then you
need to explain this to the reviewer in the narrative as to why the area
basis for power calculations does need to be the same as the zone area.



One possible course of action is to e-mail your reviewer for a clarification
on what they are looking for to make sure things are square, outlining your
understanding of the comments and proposed procedure.  (Don’t ask open ended
questions, provide the solution.)



Overall it sounds like the comment is clear, and as you mentioned originally
if the change to the results are negligible, then just do it according to
the comment and close the project out.



David



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David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP

*Grumman/Butkus Associates*

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*From:* equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] *On Behalf Of *M. Shields
*Sent:* Thursday, May 19, 2011 5:27 PM
*To:* 'equest-users'
*Subject:* Re: [Equest-users] Lighting Power Density



The issue is that if I don’t include the chase in the LPD calc then it will
over estimate the lighting because that area is included in the area for the
model.  Also I am concerned that they will say “well zone x is 100 sqft
where your LPD calculation says that area is only 98 sqft”.  I am fine with
overestimating it, I just wondered if anyone has experience about how strict
the reviewer might be for this.



Thanks for the feedback.
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