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NC-v4 EAp2:Minimum energy performance

Double HVAC system per zone

Profile picture for user jorge.lopez
Jorge Lopez de Obeso
Architect / Environmental adviser
eosis Consulting
LEEDuser Basic Member
20 thumbs up

Hi everyone, I have this project where the HVAC engineer is designing some interesting HVAC system based on load profiles.

The intent of this strategy is to have one HVAC system running at somewhat 80% of its capacity almost all year around, but when peak load exceeds the main system capacity (this is anticipated to happen no more than 25% of the year), the second HVAC system enters as a backup system. Main system is air handling units connected to absorption chiller, backup is connected to air cooled chillers.

Another system designed for another zone is as follows: DOAS pre-cooling outside air and supplying it to Fan and Coil units. So the F&C could be downsized to just beating the room internal gains.

Has anyone have experienced systems as complicated as these ones and how could I ideally model them in any software? Since most softwares limit one system per thermal zone.

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

Wed, 02/13/2019 - 15:26

As you indicate most software can't model two systems in one zone. So this would likely be very software specific. I'd suggest this part of the question is better served on one of the software specific forums at onebuilding.org. If you are trying to find out which software can do this I would think that EnergyPlus is the most likely. The DOAS with FC is a common system type that most software has a methodology for modeling. It again varies by software as some can model it directly and some require a workaround.

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