[BLDG-SIM] System Type in Appendix G

Hi, Bill,

My understanding agrees with Gail’s. I only need to mention one more thing in your statement. I do not think the Appendix G limits you to use only one single packaged rooftop VAV system to do the job. You may use a few units of the same type based on the building situation, and you are permitted to use a few constant flow roof tops if a certain exception met.

Shawn Lee

Beardsley Design Associates

Aurburn, NY

From: BLDG-SIM@xxxxxxxx [mailto:BLDG-SIM@xxxxxxxx] On Behalf Of gail
Sent: Tuesday, December 12, 2006 2:43 PM
To: BLDG-SIM@xxxxxxxx
Subject: [BLDG-SIM] System Type in Appendix G

Hi Bill,

Your interpretation is the correct interpretation. This is specific to Appendix G (the Performance Rating Method), and does not impact basic code compliance (the Energy Cost Budget Method from Chapter 11).

I expect the change was made in order to encourage the selection of more efficient system types for various buildings. With the energy cost budget method, buildings that select inherently efficient system types are not credited for this selection because the Baseline case moves with the Proposed case. Similarly, buildings that select inherently inefficient system types are not penalized for this selection. Appendix G attempts to correct this by

You are correct that the number of systems modeled in the baseline building may be high.

Gail Stranske

CTG Energetics, Inc.

On 12/12/06, Bill Talbert <btalbert@xxxxxxxxxx> wrote:

All,

I'm working on a LEED energy analysis for a small healthcare clinic project (~15K sqft). According to A90.1-2004 Appendix G, Table G3.1.1A, the baseline HVAC system for a nonresidential building with <=3 floors, <75K sqft, and fossil fuel heating should be a packaged single zone system with DX cooling and a gas-fired furnace for heating. This seems like a big departure from the baseline system types indicated in the ECB method. Is this a correct interpretation? If so, can anyone provide feedback as to why this change was made? It seems as though many buildings of this size would utilize a packaged rooftop VAV. Also, it potentially makes the number of systems necessary in the baseline building significantly high unless the thermal blocks are simplified in the proposed design model.

Thanks,

Bill Talbert, LEED AP
Mechanical Engineer
Phone: (608) 441-6677

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