[BLDG-SIM] LEED / ASHRAE 90.1 Modeling Question

[Fred Porter <fporter@xxxxxxxxxxxxxx>]

Wade McLaughlin wrote:

The LEED process requires modeling practices to follow those outlined in the ASHRAE 90.1 Standard User's Manual.  The standard does not allow for the augmentation of schedules to model efficiency measures.  This is a problem for us in that we often use schedules to simulate measures such as lighting occupancy sensors and demand controlled ventilation.

 

All;
My interpretatation has always been that the ECB/"performance" method in
ASHRAE 90.1-99/01 does not allow savings to be considered for occupancy sensors(above
and beyond those required) or DCV (above and beyond the required scheduling
of OA dampers closed during unoccupied periods). As far as I know, for these
types of ECMs, USGBC has not indicated that their Energy Modeling Protocol
should be different. 

It is legitimate to schedule OA, and LPD, to reflect these ECMs, as long
as the schedules are the same in the budget/baseline/benchmark and proposed/design/as-built
models used in the ECB method. These may be great ECMs for some spaces, but
they can't be used to generate savings in the process. (You can create another
model run of code-compliant buildings with and without these ECMs, to show
the effect of these ECMs, and hopelessly confuse your clients.) Daylight-responsive
lighting control can be used to generate savings, and the referenced wording
of standard seems to require that it be modeled explicitly, not with schedules,
thus requiring a true geometric model.

Typically:

-For lighting occupancy sensors, we adjust our known office schedules using a profile taken from the JIES (I'm afraid I don't have the specific source in front of me).

-For demand controlled ventilation, we develop an hourly outside air Fraction of Design schedule for each AHU using known occupancy schedules and an assumption of 20 CFM per occupant.

 

To us, both of these methods seem to be accepted modeling practice for determining measure performance.  However, as stated pretty explicitly in the archived credit interpretation requests (CIRs) on the LEED site, LEED won't allow for the adjustment of schedules to simulate these measures.  Does anyone have a method (or insight into developing a method) for either of these calculations in a manner that would be acceptable for the LEED process?

 

Many thanks in advance for your responses.

 

Wade

 

Wade McLaughlin
DMI
450 Lexington St.
Newton, MA  02466
p 617-527-1525 x103
f  617-527-6606

======================================================
You received this e-mail because you are subscribed 
to the BLDG-SIM@xxxxxxxx mailing list.  To unsubscribe 
from this mailing list send a blank message to 
BLDG-SIM-UNSUBSCRIBE@xxxxxxxx
  

-- 
Fred W. Porter
Senior Engineer
Architectural Energy Corp.
2540 Frontier Ave. Suite 201
Boulder CO 80301
email: fporter@xxxxxxxxxxxxxx
fax: 303-444-4304

office: 303-444-4149 x225
mobile: 303-748-4536





======================================================
You received this e-mail because you are subscribed 
to the BLDG-SIM@xxxxxxxx mailing list.  To unsubscribe 
from this mailing list send a blank message to 
BLDG-SIM-UNSUBSCRIBE@xxxxxxxx