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NC-v4 EAp2:Minimum energy performance

Option 2 ASHRAE 50% AEDG - Equipment type not listed

I have a project in Climate Zone 6, which is trying to use Option 2 under the prescriptive path, using the 50% AEDG for Small to Medium Office Buildings.  They'd like to avoid the ASHRAE 90.1 modeling, as this is only a 7,000 sf facility.  The planned mechanical system is for a single air source heat pump VRF system feeding 3 fan coils for heating and cooling in the majority of the building, with radiant infloor heat driven by an electric boiler.  The project is planning to get to net-zero with on-site solar production, so have intentionally gone with electric-based systems.

Neither of these systems are listed under the CZ6 recommendations for mechanical system efficiencies - although the ASHP meets the requirements for efficiency under the packaged single-zone air-source heat pump category.  

If a system type is not listed, is there some alternative to show compliance with Option 2 or is this option unavailable without one of the specific mechanical types listed?

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

Mon, 03/12/2018 - 14:39

There is probably a way around your situation. What I would do is figure out the difference in efficiency represented in the AEDG for other heat pumps. What percentage higher than the 90.1 minimum in effect at the time of the writing of the AEDG are the heat pumps? Then apply this percentage to the minimum efficiency for VRF from 90.1-2010 and make sure I comply with that. I understand the desire to avoid the expense of an energy model, but you will be giving up a lot of points following this route. A net zero project would earn all the points under Optimize Energy Performance assuming the building itself meets the minimum energy use reduction without the PV system. The AEDG has a very limited number of points available and is often fraught with danger. All you have to do is not comply with just one small item it requires and you don't meet the requirements of this option.

Mon, 03/12/2018 - 17:40

Thanks for your response, Marcus.  The building will initially install enough PV to offset about 50% and hopes to fundraise and install the rest in the next year or so.  I had anticipated we'd do well under modeling due to offsetting half, but the energy modelers said that the on-site PV will not factor in to the Optimize Energy Performance - only under Renewable Energy Production.  If it doesn't count to improve our situation in Optimize Energy Performance, then we feel like we'd only get minimal points under that credit item.  Have you seen the PV able to count for the credits for Optimize Energy Performance?
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Tue, 03/13/2018 - 16:36

The PV production does count toward the Optimize Energy Performance credit, it always has and this continues in v4. 

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