Interior LPD Baseline & Proposed

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Hi all,

In the baseline interior LPD I have gone with building area method, but for proposed the electrical floor plans as given space by space LPD ,if I go with space by method in proposed ASHRAE recommends ? or shall I have to go with both identical like if I follow building area method in baseline identical in proposed if yes, than can I take average LPD of the all spaces?

Any help will be greatly appreciated

Kind Regards
Soham babu

Soham Babu's picture
Joined: 2011-09-30
Reputation: 0

Hi Soham,

I am no USGBC reviewer, but I have submitted comparative models in the
past using the "actual" design, and working out an equivalent LPD for
the whole building applied uniformly to the spaces. I do not think
there is anything preventing you from entering the individual space
LPD's in the proposed model, excepting that could take a bit more time.
You may find it pushes your energy savings further however depending on
the rest of your model.


Nick-Caton's picture
Joined: 2011-09-30
Reputation: 805

Appendix G in 2004 says to use the same method of categorization that you use in the proposed building. This would be especially important if the areas of the project have varying schedules or methods of lighting control.


David S Eldridge's picture
Joined: 2011-09-30
Reputation: 2000

David & Nick are both correct-just remember either 'space-for-space' OR
'area-by-area'. I always use the area method--only for the reason that I
get bored and annoyed looking up individual space LPD's in the chapter 9
table. It is more interesting to me to do the space take-offs for my
proposed building and calculate the zone area-average LPD -it helps me get
more familiar with the characteristics of the spaces/zones I am modeling.
In some models where we don't have reflected ceiling plans or LPD-zone
take-off from the lighting desingers then I can still assume the area
method which keeps my inputs simplified.


Pasha Korber-Gonzalez's picture
Joined: 2011-09-30
Reputation: 600

My two cents:

Cent 1:
If you don't really have any controls out of the ordinary (occ sensors, daylight dimming), its probably not too far off using the whole building method. The dollar sign at the end of this cent is that if you have some spaces with a really high lighting power density (much higher than the average), you might want to use the space by space method to simulate the additional heat load to that space from the lights.

Cent 2:
If you have control strategies like occ sensors or daylight dimming, you probably want to use the space by space method. You don't want to penalize yourself (or credit yourself) for controls in a space that has a significantly different LPD from the average.

At the end of the day its a judgement call - I have done both on different projects.

Vikram Sami, LEED AP

Vikram Sami's picture
Joined: 2011-09-30
Reputation: 0