[Equest-users] LEED Energy Model Baseline vs Proposed Designs Interpretation Question

[David Eldridge]

One thought is that this might be considered in LEED lingo as an "exceptional calculation" - i.e. there would be three models:


*         Proposed building as-designed

*         Baseline building constructed with the same geometry as proposed using code minimum materials and equipment

*         Baseline building with conventional geometry using code minimum materials and equipment

By anlyzing the difference between the two baselines you'd have an idea what the impact was from changing the geometry with everything else the same.

I've reversed the order from what LEED asks for - usually the exceptional calculation is for adding a new energy-saving feature on top of the proposed case, but since your exceptional calculation is modifying the geometry I think it makes sense to go in reverse order from a calculation point of view. This will be easier to review step-by-step than making the middle case a proposed building with conventional geometry.

I'm curious...you don't have to respond, but some questions you might ask on behalf of your program:


1.       Does the new geometry cost more? If yes, can it be quantified? In most new construction programs an efficiency measure must add an incremental cost to be eligible for an incentive.

2.       Is the floor area the same in both models, or is there a reduction in real estate? If there was some innovation that resulted in a smaller building in the proposed case, the total energy use might be less while EUI could increase.

a.       For an incentive program it might be fine to look for absolute kWh or therms saved, rather than an EUI percentage improvement over a baseline.

3.       Was the change in geometry driven by energy savings, or were other factors dominant? This might push you one way or the other in determining if an energy efficiency incentive is warranted.

4.       How does the proposed energy use case compare to conventional benchmarks? How does the conventional baseline compare to benchmarking data?

I hope this helps!

David



David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
Grumman/Butkus Associates



From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Russo, Bryan
Sent: Wednesday, October 07, 2015 4:17 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] LEED Energy Model Baseline vs Proposed Designs Interpretation Question

Hello,

I work in an energy conservation program at a utility and have a question regarding baseline vs. proposed designs within energy models. A customer is considering a design approach that results in a fairly large departure from a standard design. In specific, the building foot print and geometry departs significantly from a typical baseline building, but the proposed design accomplishes all required parameters of the baseline design, i.e., the building produces the same function. My general experiences with approaching baseline vs. proposed energy models is that the footprint and general geometry of the building remains fixed. However, what's the recommended approach when the proposed design yields a certain building geometry that would not be encountered in a typical, baseline building, i.e., attempting to model a baseline building with the proposed geometry would not yield sensible results?

Thanks,

Bryan
_______________________________________________________________________
Bryan Russo, BESA
Senior Engineer
Conservation Resources Management
Tacoma Power

email: brusso at ci.tacoma.wa.us<mailto:brusso at ci.tacoma.wa.us>
office   253.502.8822
cell        253.306.0670
fax          253.502.8276

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