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NC-2009 EAp2:Minimum Energy Performance

Documentation of Natural Ventilation in PDF Template

We have modelled our building which is equipped with hydronic heating and natural ventilation (no cooling) according to App D of the Advanced Energy Modelling Guide v2.0. So we modelled an additional default cooling system which turns on whenever room conditions can not be met by NV. So far, so good. However we received a review comment saying that "energy savings should be reported separately from the other efficiency measures in Section 1.7 - Table EAp2-7." I think this is also mentioned in App D of the Advanced Energy Modelling Guide under "Modeling Methodology". But seems that the guide refers to tables which are not printed!? Am I right that we have to model the Proposed Case two times: First with NV and then without NV? Do I have to enter the result of the simulation without NV in Table EAp2-5 and the energy savings dedicated to the NV in Section 1.7 Exceptional Calculation Measure Summary?

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

Wed, 05/08/2013 - 14:06

If you are claiming energy savings related to natural ventilation then yes you must do an exceptional calculation. Your Proposed building is modeling without natural ventilation and the results entered in the form. You then model the proposed again with natural ventilation. The difference between the first model and the second is the savings you enter in Section 1.7. You are also typically required to demonstrate equivalent comfort conditions to the baseline. With all that said is your natural ventilation just opening windows? This methodology is typically applied to an engineered natural ventilation system.

Wed, 05/08/2013 - 14:46

Thanks for the fast reply! Our natural ventilation is via opening windows which is quite common in our climate zone 5a and complies to local code. We modelled equivalent comfort conditions by using an additional (virtual) default cooling system to maintain the max. room temperature of 26 °C.
Profile picture for user sheffer
Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Wed, 05/08/2013 - 15:02

Is this how you are complying with ASHRAE 62? If so then you do not really have natural ventilation. Is the baseline modeled with the same ventilation as the proposed? If so you would not need to do an exceptional calculation as you are not claiming any savings for natural ventilation.

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