The 10% decrease is an adjustment shown in ASHRAE 90.1 Table G3.2. For compliance modeling, it is what it is, but for a more accurate (albeit exceptional calc) model that can often show greater energy savings, you should use the occupancy schedule for the lighting in zones that contain multiple rooms. For example, if I have a large complex building where I need to do something like clump 6 offices and 2 document rooms into 1 zone, I may set the occupancy at 0.8 for most of the day if the document rooms are intermittently occupied by people leaving their offices to go into the document rooms. In such a case, the lighting should also be at 0.8 to account for the lights being off most of the time in the doc room and part time in the offices. This could change a little if the sensor controls are designed with a long delay.
For a zone that contains one large room, like an open office area, you should keep it at 1.0 unless everyone leaves at the same time for lunch or something.
This schedule-dependent technique is now allowed under LEED-NC 2.2.
Either modify the schedule by 10% or the input watts (or watts/sf) by 10%.
Before:
After:
Also, you were great in Caddyshack.
Timothy Howe, MS, LEED? AP
Tim,
Thanks, I figured it was something like that.
The groundhog bit me a couple times in Groundhog Day.....
Regards,
Bill
Bill,
The 10% decrease is an adjustment shown in ASHRAE 90.1 Table G3.2. For compliance modeling, it is what it is, but for a more accurate (albeit exceptional calc) model that can often show greater energy savings, you should use the occupancy schedule for the lighting in zones that contain multiple rooms. For example, if I have a large complex building where I need to do something like clump 6 offices and 2 document rooms into 1 zone, I may set the occupancy at 0.8 for most of the day if the document rooms are intermittently occupied by people leaving their offices to go into the document rooms. In such a case, the lighting should also be at 0.8 to account for the lights being off most of the time in the doc room and part time in the offices. This could change a little if the sensor controls are designed with a long delay.
For a zone that contains one large room, like an open office area, you should keep it at 1.0 unless everyone leaves at the same time for lunch or something.
This schedule-dependent technique is now allowed under LEED-NC 2.2.
Christopher Wark