The following content is copied from https://www.energizect.com/sites/default/files/WBP-EMG-V2.0-2017.pdf
126.96.36.199 Extracting Fan Power – Baseline Design
Per G188.8.131.52 , “where efficiency ratings, such as EER and COP, include fan energy, the descriptor shall be broken down into its components so that supply fan energy can be modeled separately.”
For baseline systems 1, 2, 3, 4, 5, and 6, calculate the minimum COPNFCOOLING and COPNFHEATING from the rated efficiencies from tables 6.8.1A, 6.8.1B, and 6.8.1D using equations 7-3 through 7-7 below. Where both part-load and full-load ratings are given in tables 6.8.1A, 6.8.1B, or 6.8.1D, use the full load rating.
- COPNFCOOLING = 7.84E-8 × EER × Q + 0.338 × EER (Equation 7-3)
- COPNFCOOLING = 0.0076 × SEER2 + 0.3796 × SEER (Equation 7-4)
- COPNFHEATING = 1.48E-7 × COP47 × Q + 1.062 × COP47 (Equation 7-5)
- COPNFHEATING = -0.026 × HSPF2 + 0.7134 × HSPF (Equation 7-6)
- COPNFCOOLING is the adjusted cooling COP with fan power removed, to be used for simulation purposes
- COPNFHEATING is the adjusted heating COP with fan power removed
- Q is the AHRI rated total cooling capacity of the unit (net capacity) in btu/h*
- *When using equations 7-3 and 7-5 to calculate COPNFCOOLING and COPNFHEATING in conjunction with tables 6.8.1A and 6.8.1B , Q shall be capped at the lower capacity of the highest capacity bracket for the applicable equipment type.
- When using equations 7-3 and 7-5 to calculate COPNFCOOLING and COPNFHEATING in conjunction with Table 6.8.1D  (PTAC and PTHP systems), Q shall be capped at 15,000 btu/h and shall be no less than 7,000 btu/h.
- For the purposes of calculating COPNFCOOLING and COPNFHEATING for the baseline model, Q need only be within the 20% of the modeled system capacity (it is not required that Q exactly match the modeled capacity). This is to prevent the need for recalculating COPNFCOOLING and COPNFHEATING numerous times during the modeling process.
My Questions are,
- Whether the above points 1, 2 & 3 is acceptable to calculate EIR in Baseline Energy Model?
- How the 20% limit can be arrived to calculate EIR as per the point 3?