In the report â??HVAC Sizing Summaryâ?? the â??User Design Air Flow [m3/s]â?? is greater than the â??Calculated Design Air Flow [m3/s]â?? and the ratio between them is what I imposed in the field â??Zone heating sizing factorâ?? of the object Sizing:Zone (i.e. 1.25). That is clear.
My problem is understanding the â??System Design Air Flow Ratesâ??. Among the â??System Design Air Flow Ratesâ?? there are â??calculated heating [m3/s]â?? and â??user heating [m3/s]â??. For the AHU â??UTA 28centraleâ?? (System 3) I get the following table:
https://imageshack.com/i/npbyh7j
Is â??calculated heatingâ?? greater than â??user heating [m3/s]â?? because â??calculated heating [m3/s]â?? is what is neccessary to meet the heating gain while the â??user heatingâ?? is relative to the outdoor air need?
The calculated heating is equal to 0.49 m^3/s but in the graphs I don't see such a value. The following graph regards the winter design day and maximum value is equal to 0.12m^3/s, i.e. what I imposed as outdoor air flow rate in the object Controller:OutdoorAir (during the afternoon there is occupation and therefore there is outdoor air flow, while during the night and the morning there is â??night cycleâ??):
https://imageshack.com/i/neyr1qp
How can the value 0.49 m^3/s be explained, please?
In the calculation of the system fan power according to G3.1.2.9 shall I consider 0.49 m^3/s?
Regards
On 22.10.2013, at 18:24, <fpasserini.tn@...> wrote:
The equations of the paragraph G3.1.2.9 of ASHRAE 90.1-2007 need the "baseline system maximum design supply fan air flow rate". I consider the html report. Is the "baseline system maximum design supply fan air flow rate" the maximum between "System Design Air Flow Rates" in HVACSizingSummary and "Max Air Flow Rate" in "Fans" in Equipment Summary?
I think that the "System Design Air Flow Rates" is evaluated in the SizingPeriod:DesignDays conditions while the "Max Air Flow Rate" is evaluated in the RunPeriod, right?Regards