I have a question regarding section G3.1.2.8 of Appendix G. This section says that "design supply airflow rates for the baseline building design shall be based on a supply-air-to-room-air temperature difference of 11C". If I understand it well, for cooling mode if the room temperature is 24C then the supply air in the AHU should be 13C. The max supply air temperature, based on section G3.1.3.12 Supply Air Temperature Reset in this case should be 15.3C (13C+2.3C) - is that correct? And what about the heating mode? If the room temperature for system 5 and 7 is 21C then according to section G3.1.2.8 supply air temperature in the AHU should be 32C (21C +11C)? If this is correct then in our case the reference building will be using much more energy for heating than the design case.
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Agnieszka Rylska
GO4IT SP Z OO SP K30 thumbs up
May 15, 2015 - 9:26 am
We got a comment from GBCI that "the heating supply air delivered to each zone should be 11 degrees C higher than the setpoint" in the reference model (system 7). Could you confirm that?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
May 15, 2015 - 11:37 am
Sounds right according to G3.1.2.8.
Agnieszka Rylska
GO4IT SP Z OO SP K30 thumbs up
May 18, 2015 - 10:34 am
The baseline system is VAV (single duct) with reheat (system 7). The simulation program sizes the system based on cooling supply temperature - cooling mode is considered to be worse case than heating mode. That is why the temperature difference of 11C can be applied for cooling. Doesn't section G3.1.2.8 apply only to cooling mode in this case?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
June 8, 2015 - 3:29 pm
Yes. In all cases this is for cooling.
Agnieszka Rylska
GO4IT SP Z OO SP K30 thumbs up
June 11, 2015 - 4:57 am
I'm asking about that because we received a comment from GBCI asking us to show that "the heating supply air delivered to each zone is 11 degrees C higher than the setpoint" according to G3.1.2.8 requirements. Did they make a mistake then?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
June 11, 2015 - 9:37 am
I think so. I believe that the User's Manual has some information that clarifies this issue.