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Adding Occupancy Sensing

asked 2016-08-05 10:24:17 -0500

joekers gravatar image

updated 2017-08-05 07:33:46 -0500

I'm currently writing a measure that allows the user to add an occupancy sensor to a space and was wondering the best way to implement this? Is it best to model it as a reduction in the lighting schedule? Or is there a better way to do this?

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answered 2016-08-05 11:08:24 -0500

Here is a measure that models occupancy sensors by reducing the lighting power density of certain space types by the percentage allowed by ASHRAE 90.1-2010 Table 9.6.2 and Addendum cg Table G3.1(g).

If you intend for your modeling method to comply with Appendix G you can modify the lighting schedule, as long as "credible technical documentation of the modifications" is provided to the rating authority.

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Table G3.2 also provides percentages for lighting power reductions for different controls including occupancy.

MatthewSteen gravatar imageMatthewSteen ( 2016-08-05 12:03:19 -0500 )edit

My preference for lighting and equipment controls is to change the schedule; for the following reasons.

  1. You have more control over how it impacts the model at different times of the day and days of the week.
  2. It makes applying downstream ECM's easier. If you lowered LPD or equipment wattage to model occupancy sensors, that information is lost if the lights are replaced.
  3. Minor but with schedule changes, sizing runs can be done with all lights and equipment on.

In OpenStudio a third option other than the load or schedule, is the load instance multiplier.

David Goldwasser gravatar imageDavid Goldwasser ( 2016-08-05 16:26:06 -0500 )edit

Hmmmm, the Scout occupancy sensor measure reduces LPD. Maybe we need to revisit.

__AmirRoth__ gravatar image__AmirRoth__ ( 2016-08-05 16:47:57 -0500 )edit

Is it possible to specify which thermal zone or spaces will be affected by this occupancy sensor ?

@Eric Ringold

Bo_Lin gravatar imageBo_Lin ( 2017-05-22 10:12:12 -0500 )edit

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Asked: 2016-08-05 10:24:17 -0500

Seen: 252 times

Last updated: May 22 '17