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Adding Occupancy Sensing

asked 8 years ago

joekers's avatar

updated 7 years ago

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 8 years ago

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's avatar MatthewSteen  ( 8 years ago )

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's avatar David Goldwasser  ( 8 years ago )

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

__AmirRoth__'s avatar __AmirRoth__  ( 8 years ago )

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

@Eric Ringold

BL's avatar BL  ( 7 years ago )

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Asked: 8 years ago

Seen: 533 times

Last updated: May 22 '17