[Bldg-sim] ASHRAE 90.1 Baseline LPD and occupancy sensor credit

[Nick Caton]

Reviewing Table G3.1.6.g., I see more than one right answer.  You can
revise either the installed lighting power (LPD) OR the associated
scheduling - I should think both approaches equally acceptable.  I
personally revise the LPD values.

 

This is inherently a "clear as mud" sort of topic since you need to
bounce between so many parts of 90.1 to get the full picture, so I'll
try to bullet the logic simply:

*         Prescribed LPD's from chapter 9 are representative of what
should be in the baseline.  

*         Prescribed baseline are representative of any applicable
required occ. sensors.  They should not be modified in any fashion in
the baseline model.

*         Proposed lighting LPD's as defined (using either the
space-by-space or whole building method), may apply the prescribed
reductions to the proposed installed LPD (10/15%) BUT ONLY against
fixtures in spaces containing such controls that are not otherwise
required to have them.

 

A simple example for illustration:

1.       Proposed office space and an employee lunch/break room each
have a designed LPD of 0.80

2.       Baseline model could use 1.0 W/SF for both spaces (whole
building / 90.1-2007)

3.       Since the break room is required to have an occ. sensor, the
proposed break room stays at 0.80 W/SF.

4.       Since an office space is not required to have an occ. sensor,
the proposed office space gets a reduction:  10% of 0.80 = 0.08, so the
revised LPD is 0.72 W/SF.

 

~Nick

 

 

NICK CATON, P.E.

SENIOR ENGINEER

 

Smith & Boucher Engineers

25501 west valley parkway, suite 200

olathe, ks 66061

direct 913.344.0036

fax 913.345.0617

www.smithboucher.com 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Steven
Savich
Sent: Thursday, December 01, 2011 11:35 AM
To: 'Ramana Koti'; 'Bldg-Sim'
Subject: Re: [Bldg-sim] ASHRAE 90.1 Baseline LPD and occupancy sensor
credit

 

Ramana,

 

90.1-2007 Table G3.1 section 6 under Baseline Building Performance
states: " . . . No automatic lighting controls (e.g. programmable
controls or automatic controls for daylight utilitzation) shall be
modeled in the baseline building design, as the lighting schedules used
are understood to reflect the mandatory control requirements in this
standard."

 

You should not be adjusting the power density number to simulate
lighting controls, but adjusting the schedules to reflect occupancy
sensor operation.  For example, say there are a number of offices and
conference rooms in the proposed building that will have occupancy
sensor controls.  This should be simulated by inputting the LPD or
actual connected load, and creating a schedule with a 10% - 15%
reduction for each hour of operation per Table G3.2.  In the LEED
baseline model, the schedule for the offices would be not have the
occupancy sensor reduction, but the conference room and other spaces
required by 90.1 to have occupancy sensor control would use the reduced
schedule.  Clear as mud?

 

Steven

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Ramana Koti
Sent: Thursday, December 01, 2011 8:21 AM
To: Bldg-Sim
Subject: [Bldg-sim] ASHRAE 90.1 Baseline LPD and occupancy sensor credit

 

All,

 

This question pertains to a LEED energy model per the ASHRAE 90.1
Appendix G. Occupancy sensors are required in spaces such as conference
rooms and employee lunch/break rooms per Section 9.4.1.2 and no lighting
power density credit can be taken for their use in the proposed design
model.

 

My question is, do the baseline maximum LPDs prescribed by ASHRAE, say
1.3 W/sf for conference rooms, already account for the power 10 or 15%
adjustment for occupancy sensor use or does the credit have to be
manually applied on top of the 1.3 W/sf in the Baseline model?

 

Thank you,

Ramana Koti.

 

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