Lighting Control - Occupancy Sensor

8 posts / 0 new
Last post

Does anyone know if there is a spot for Occupancy Sensor lighting
controls ? In both of DD Wizard mode and Detailed Data Edit mode, I
didn't see any.

Thanks,

Derek Huang, LEED AP, CPD

Derek Huang's picture
Offline
Joined: 2011-09-30
Reputation: 0

fyi - even though i wasn't trying to model or claim savings from
occupancy sensors, i received the following comment on a recent leed review:

"Per ASHRAE 90.1-2004 Section 9.4.1.2, a lighting control device is
required in classrooms, conference rooms, and lunch and break rooms.

Credit for occupancy sensors cannot be taken in spaces where occupant
sensors are required by Section 9.4.1.2."

so be sure to check the occupancies before claiming credit for occupancy
sensors.

Patrick J. O'Leary, Jr.'s picture
Joined: 2011-09-30
Reputation: 200

For the spaces that don't require occupancy sensors you can show savings by
modifying the lighting schedule. I think a 15% reduction is allowed, but
verify that by looking in Appendix G where it tells you what you can do and
when. In fact it would be good for you to make a practice of researching the
answers to these types of questions yourself and save the more complicated
questions for the listserv. It is important to respect everyone's time and
do diligence by trying to find the answers yourself. I know it's a lot to
process at first but you will benefit from the study.

Regards,
Carol

cmg750's picture
Offline
Joined: 2010-10-05
Reputation: 0

A small correction - the reduction (0-15%) is modifying the installed
LPD (W/SF), not the schedules. The reduction amount does vary based on
the table Carol referenced in 90.1 Appendix G.

This is easiest to do in the wizards: there's an overall multiplier,
defaulted to 1.00, on the bottom of lighting load screen. In detailed
it would require you to modify the space LPD values in the spreadsheet
view, under the Internal Loads tab.

Agreeing with Carol's premise though - the way your question is worded
suggests you weren't clear on the contents Appendix G. For your own
sake, definitely avoid relying on others to tell you what's within 90.1
or you might find yourself in hot water down the road ;).

NICK CATON, E.I.T.

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

Nick,

For occupancy sensors, I have always reduced the % on in the lighting
schedules, never the installed LPD. Here's a thread from way back discussing
how to do this:http://www.gard.com/ml/bldg-sim-archive/msg02168.html.

If the methodology has changed to reducing the LPD by 15% I'd like to know.
It would be much easier and I'd love to be wrong!

How are others doing this?

Carol

cmg750's picture
Offline
Joined: 2010-10-05
Reputation: 0

Hi Carol,

Table G3.1 has the following wording in both 90.1-2004 and'07:

"For automatic lighting controls in addition to those required for
minimum compliance under Section 9.4.1, credit may be taken for
automatically controlled systems by reducing the connected lighting
power by the applicable percentages listed in Table G3.2."

I've interpreted this as a directive to simply reduce the installed
lighting power / LPD by the referenced percentages.

I've yet to receive any reviewer's commentary to the contrary, but
everyone's human... =)

NICK CATON, E.I.T.

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

"User's Manual for ANSI/ASHRAE/IESNA standard 90.1-2004" page G-18
says " Occupant sensors alone for a combination of occupancy sensors and
programmable timing controls have a 15% power adjustment factor for
daytime occupancies and building less than or equal to 4000 ft^2. The
power adjustment factor is 10% for all other buildings. " I think the
key is " Power adjustment factor". Please advise if my understanding is
right.

Thanks!

Lan Li, PE

Li, Lan's picture
Offline
Joined: 2011-09-30
Reputation: 0

Reducing the installed LPD or reducing the schedules by the same percentages yield the same results. However, it is far easier to just reduce the LPD.

______________
Demba NDIAYE

Demba Ndiaye's picture
Offline
Joined: 2011-09-30
Reputation: 200