Lighting controls in Leed certification

asked 2017-08-02 04:35:02 -0600

manfred
189 ●6

updated 2017-08-02 05:33:59 -0600

I would need some explanations regarding the proposed building lighting control for LEED certification, particularly in Table G3.1.6.g and Table G3.2 of Standard 90.1-2007.

If I have an occupancy sensor in a surface area greater than 460 m² with a installed power of 1000 W, should I have to insert a 900W (10% less) power in my proposed building model? Is this power reduction calculated to take into account the lower energy consumption that will occur due to the occupancy sensor?

If the occupancy is greater than zero, the lighting power must be nominal or must be proportional to occupancy? Remaining in the previous example, if I have 50% occupancy, should the lighting power be 900W or 450W?

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(Side note: we have a convention here to not include greetings (hello, thanks, etc))

Julien Marrec ( 2017-08-02 05:33:28 -0600 )edit

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answered 2017-08-02 05:39:06 -0600

Julien Marrec

29696 ●94 ●76 http://www.effibem.com/

updated 2017-08-02 05:43:35 -0600

Your proposed model has 1000 W of light power, but because you have an occupancy sensor you would install 900 W (10% less) if your area is greater than 5000 ft²/460m². You would then apply a lighting schedule, same in the proposed and baseline.

Let's say the zone is 6000 ft², an open office, and you're using the space by space area method.

Baseline: 6000 * 1.1 W/ft² = 6600 W
Proposed: 1000 W * (1-10%) = 900W
Both have the same schedule.

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It's all clear, thank you. Just another question: is the lighting program of the on-off type or modular? For example: whether there is a single person or 400 at a given time, the lighting will always be 900W or not?

manfred ( 2017-08-02 09:45:12 -0600 )edit

The lighting will always be 900W yes. Well, 900W times whatever value is in your schedule. (Note that there is a section about changing the schedule if you can submit something valid to the rating authority...).

Julien Marrec ( 2017-08-02 10:11:44 -0600 )edit

Just to avoid misunderstandings, if I have 50% occupancy at a given time, the lighting at that time must be 450W [(1000W-10%) * 0,5 occupation] or 900W [(1000W-10%) * 1 occupation]? In my opinion, it should be 900 W, because even if only one person is present, lighting should not be partial.

manfred ( 2017-08-02 11:25:21 -0600 )edit

@Julien Marrec can you confirm that I'm right?

manfred ( 2017-08-03 07:36:11 -0600 )edit

The light schedule is left at your discretion. 90.1 User's Manual has such schedules, that you can also find in more useful format in RMI's EMIT tool, and in OpenStudio too. These schedules tend to typically somewhat follow the general pattern of occupation, but they aren't the same exactly. For eg the light schedule for a typical open office would have 5% at night (to account for 24hr lighting + maybe some lights left on by mistake) while the occupancy schedule would be zero.

Julien Marrec ( 2017-08-07 03:51:43 -0600 )edit

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