Hi Fareed,

There are multiple approaches to modeling occupancy sensors in eQuest... I assume you're in the context of lights.

What's appropriate depends on how you have set up your model and to what degree their operation needs to be modeled explicitly.

A few approaches, from simple to involved:

* Established 90.1 Appendix G approach: Assign a flat % reduction to the installed LPD for the space(s) with occ sensors (only in those that don't already require them, if you're actually doing a proposed/baseline performance rating).

* Define alternate fractional schedules that represent hourly operation of lights with and without occ sensors. This can be approached with a few variations to achieve the same result. Some choose to apply a % reduction to the schedules instead of the installed watts per space, achieving an identical result.

* Redefine space occupancy schedules in a manner that makes them appropriate to assign to the lighting loads as well (i.e. setting 1.0 for occupied hours), and use the same schedules for both occupancy and lighting - if accuracy is critical, you'll want to consider moving away from a "whole building" fractional schedule as generated by the wizards and move towards "per space type" scheduling. In this scenario the hourly occupancy value is multiplied against the installed Watts for each space, so you could correctly account for an occ. sensor's time delay into an unoccupied hour with a fractional value.

More creative (and potentially convoluted) solutions are out there that might fit your model on a case-by-case basis, but the three above are approaches I've used more than once.

~Nick

[cid:489575314 at 22072009-0ABB]

NICK CATON, P.E.