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NC-v4 EAp2:Minimum energy performance

Designing Baseline with Natural Ventilation using IDA-ICE

Profile picture for user azra.semic
LEEDuser Basic Member
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Hi,
Does someone know how are we to design baseline when we have natural ventilation?  According to ASHRAE 90.1 - 2010 Table G3.1.1A, we have to use System 7 as baseline HVAC System Type, where we have to put in mechanical ventilation as way of conditioning the room. 

Reference Guide states:
"Natural ventilation: The ASHRAE User’s Manual indicates that an exceptional calculation method is not required for natural ventilation and gives some further examples. Perform sufficient analysis to document that loads can be met when credit is taken for passive cooling and natural ventilation using a simulation tool capable of ensuring thermal conditions are met with natural ventilation. A simple load calculation is not sufficient."

Is IDA-ICE simply not the right tool for this or are we missing something entirely?
Any other input or things to look out for?
 

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Wed, 02/07/2024 - 10:19

I can answer the IDA ICE related question. IDA ICE can handle natural ventilation via leaks, windows and doors (both external and internal).
Profile picture for user azra.semic
LEEDuser Basic Member
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Wed, 02/07/2024 - 11:29

Thanks for your answer, Samer! :) That is then cleared, we're on a good path.
Now we seem to be missing some point from ASHRAE on how to model baseline with natural ventilation when using HVAC system 7.. 

Fri, 04/05/2024 - 15:37

The Baseline is modeled as a traditional system with mechanical cooling and mechanical ventilation. Natural ventilation is only modeled in the Proposed when conditions allow for ventilation and comfort requirements to be met, as demonstrated by the analysis referenced. During all other times the Proposed would be modeled with mechanical cooling and mechanical ventilation. Refer to the ASHRAE 90.1-2010 User's Manual for the natural ventilation modeling example which is referenced by the LEED Reference Guide.

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