[Bldg-sim] Appendix C Building envelope performance factor

[Rathna Shree]

Dear All,
According to appendix C, section C5 lists methodology for modeling and an equation C1 is provided defining the envelope performance factor (EPF)EPF = (6600xMBTU+kwhx80)/total building area.
Further, there are envelope tradeoff calculations in C6 of appendix C which gives detailed calculations for EPF which can be performed in COMcheck software.
 The main EPF equation is EPF = FAF x (HVACsurface + LIGHTINGzone). This is the equation C2.
I have a basic doubt. What is the difference between EPF obtained from equations C1 and C2?
If we have a modeled a project in a simulation software, is it correct if we revise the parameters(Setpoint, LPD, EPD, HVAC etc.) to reflect the assumptions listed in section C5 of appendix C and then calculate EPF from Equation C1. We will anyway get the kwh, MBTU values from simulation software. Is it required to use equation C2 also?
Please respond. Thank you.
Regards,Rathnashree

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