In exception C in section G3.1.2.6 Ventilation, it states that 'If the minimum outdoor air intake flow in the proposed design is provided in excess of the amount required by the rating authority or building official then the baseline building design shall be modeled to reflect the greater of that required by the rating authority or building official and will be less than the proposed design.'
If outdoor air rates exceed Minimum Outdoor air Prerequisite rates because the local standard requieres higher outdoor rates, do we need to set the baseline rates equal to the Minimum requiered for the Prerequisite IEQp1 or we can use the same outdoor rate of the proposed case (rates requiered by local standard)?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
April 25, 2016 - 9:45 am
In 90.1-2010 you pay a penalty for installing equipment that exceeds the calculated outdoor air. The baseline is as calculated and the proposed is as designed. So the baseline would be equal to the minimum.
Meike Borchers
BüroleiterinWSP Deutschland AG
5 thumbs up
January 4, 2018 - 8:31 am
I have the same query and am not sure that I understand the answer provided.
In our case the local building regulations (UK) prescribe a minimum fresh air rate that is much higher than what ASHRAE 90.1 would require. If I read the guidance correctly we are to use the minimum rate required as per the local building regulations for the baseline model. Is that correct?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
January 4, 2018 - 10:44 am
You are correct, mostly. ASHRAE 90.1 does not require a minimum fresh air rate. In the US ASHRAE 62.1 dictates the code required ventialtion air and LEED references this standard as well as EN15251-2007 and EN13779-2007 via an alternative compliance path for European projects. If the local requirements require more fresh air than either of these you can use the local requirements to establish the minimum fresh air. If the local code requires less fresh air then you must use one of the LEED referenced standards.
90.1 does dictate the energy modeling protocol and define the baseline in Appendix G. The baseline model must include the calculated minimum outside air as determined by whatever standard or code you are required to use. The proposed model must include the amount of outside air included in the project's design. So if the calculated outdoor air for a system is 10,435 cfm and the system design provides 11,000 cfm then it meets the ventialtion requirements and these divergent values should be used within the respective energy models.
Luis Andrade
3 thumbs up
June 15, 2018 - 11:43 am
Hi Marcus,
If we are persuing EQ credit "Enhanced IAQ Strategies" using the "Increased Ventilation" option (ASHRAE 62.1 + 30%), what should we consider to be the minimum outdoor airflow for the Baseline building? Should we add the 30%? or do we get a penalty in the energy simulation so that we can get that extra credit (via this option)?
Thank you in advance!
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
June 15, 2018 - 11:52 am
In 90.1-2010 the baseline outdoor airflow is always the calculated value from 62.1-2010. You do not get to ad 30%. So going over this value will always have a penalty associated with it.