Hi all!
I can't figure it out how to model an excepted spaces and its baseline systems correctly. Here is my issue:
We are working on office building, C&S v2009, HVAC completely designed. According to G3.1.1 exception (b) I need to model separate HVAC system for server rooms (but not only for server rooms), the primary HVAC system is system 7. Since server rooms are unoccupied but conditioned by DX systems it should has its own baseline HVAC system if I am not wrong - it should be system 3. In case when server rooms are not directly supplied by OA but they are supplied by transfer air from office spaces, how should be system 3 set? The issue is that in such a configuration of HVAC systems we will have increased OA ventilation rates in baseline against the proposed which will occur in Table 1.4 in "Outdoor Airflow" totals. When we consider the other excepted spaces with transfer air and model the separate systems the OA vent rates might be twice as high as in proposed when I exaggerate it. And it's not only about OA rates but fan energy etc. So what to do? Or it's not such a problem and it would be OK just explain the discrepancies in OA vent rates between proposed and baseline in narration? Or myabe the best question is: Must be the Minimum Outdoor Airflow Totals the same in Table 1.4 for P and B?
Thanks in advance for any help and suggestions!
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
September 19, 2016 - 11:31 am
If the proposed system has no outside air then the corresponding baseline system should not either. Always remember that you are not "designing" the baseline system to function. The outside air must be identical. It must be identical in the Table 1.4 documents and the models.
Martin K
September 20, 2016 - 4:44 am
Thank you Marcus.