[BLDG-SIM] Exterior Ltg & LEED EA Credit 1

[Tupper, Kendra]

I have taken credit for exterior lighting savings in the past, and it was never challenged.  I believe the non-tradable surfaces statement in Chapter 6 only applies when you are complying with 90.1-2004 via the prescriptive method.  Any time you move to the performance method, you can trade off your exterior lighting with other things such as mechanical and interior lighting.  For LEED energy modeling, your design must meet all mandatory requirements of 90.1-2004, but not all prescriptive requirements.

 

The way I have approached this in the past was to calculate allowed exterior power for each type of exterior lighting (based on the areas being lit in the Proposed design) and sum the total kW + 5% (Section 9.4.5 of 90.1-2004).  Then, I modeled the actual kW in the Proposed design.

 

Again, I have never been challenged on this, but I am not certain that this is the correct approach.

Kendra Tupper
LEED® AP
FLACK + KURTZ
405 Howard St. San Francisco, CA 94105
Direct          (415) 402-5840
Email   kendra.tupper at sf.fk.com <mailto:kendra.tupper at sf.fk.com%20> 

________________________________

From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Fred Porter
Sent: Friday, September 28, 2007 8:22 AM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Exterior Ltg & LEED EA Credit 1

 

I'm confused as to whether any exterior lighting power can differ between the proposed & baseline models. Any one have any experience from EA Cr1 submissions? 

 

The Users Manual for App G states at the end of the "Baseline Lighting" Section, ".... credit may be taken for improvements in exterior lighting efficacy or wattage... the proposed building can take credit for a more efficient system." So proposed parking lot lighting at 0.08 W/sf or whatever would be compared to a baseline of parking lot lighting at 0.15 W/sf. I believe façade lighting must be the same in both, as these are "non-tradable surfaces" in Chapter Six. 

 

But an apparently poorly-considered Credit Ruling from 4/25/07 simply states "No. Appendix G does not allow trade-offs for exterior lighting," directly contradicting the UM. 

 

Perhaps a post like this should be on the USGBC "engineers" "member-to-member" forum, but I don't see much traffic there. 

 

-- 

Fred W. Porter, B.S., LEED A.P.
Senior Engineer
Architectural Energy Corp., Boulder CO 

  

 

 
 
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