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CS-2009 EAp2:Minimum Energy Performance

LEED CS - EAp2 Existing equipment to remain

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BAOQUY VU
Principal
R.W. Sullivan Engineering
LEEDuser Basic Member
3 thumbs up

I have an existing 90,000 SF, 3-story office building in Massachusetts consisting of VAV boxes with electric reheat and rooftop units that also have electric heat. The scope of this project consists of replacing these rooftop units with gas fired DX units. The VAV boxes will remain as is and are outside of the project scope. Since we now have gas as a heating source, ASHRAE 90.1 requires that the baseline system consists of DX cooling and a hot water fossil fuel boiler. I do not see any exemption that would allow me to model the VAV boxes as is. So with the baseline model using a fossil fuel boiler for reheat and the proposed model using the existing electric for reheat I am not able to meet this pre-requisite. Is there an exemption somewhere that I am missing?

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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Wed, 09/28/2011 - 01:58

You always model the Proposed (with a few minor exceptions) according to the design. If there is no design, match the Baseline. So while the VAVs are not changing they are still part fo the modeling scope for LEED. Whether the Baseline system is fossil fuel or electric is determined by the predominant heating system. So in your renovated building is the gas in the roof tops or the electric reheat the predominant heating source? If gas than it looks like system 5 unless you can claim any of the exceptions in G3.1.1 to enable the use of a different system type.

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