Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
I'm not familiar with IECC, so I only mention ASHRAE90.1.
Appropriate fan curve coefficients: ASHRAE 90.1 Appendix G Table G3.1.3.15 Method 2 as you already mentioned. I personally have no doubt about this.
Fan Power Minimum Flow Fraction: That's what I also want to know the answer. We might be able to refer to Section 6.5.3.2.1, but I have another suggestion. ASHRAE90.1 does not specify all the parameters for the Baseline case. Some parameters are not found such as Fan Total Efficiency, Pump Total Efficiency, Chiller Minimum Part Load Ratio, Chiller Minimum Unloading Ratio, etc. When I come across such unspecified parameters, I often refer to ANSI/ASHRAE/IES Standard 90.1 Performance Rating Method Reference Manual. The Table below is extracted from the Reference Manual. (b) is the curve of G3.1.3.15 Method 2.
Please note the rightmost column. %PowerMin is 20%. %PowerMin = Fraction of Full Load Fan Power * 100.
The chart below is what I plotted the curve (b). The Minimum Fraction of Full Load Fan Power = 0.2. The Fraction of Full Load Airflow Rate corresponding to the Minimum Fraction of Full Load Fan Power of 0.2 is 0.393198 ≈ 0.4. So, I vote for Min Flow Fraction = 0.4, but I'm not that confident. Please take this as just one opinion.
| | 2 | No.2 Revision |
I'm not familiar with IECC, so I only mention ASHRAE90.1.
Appropriate fan curve coefficients: ASHRAE 90.1 Appendix G Table G3.1.3.15 Method 2 as you already mentioned. I personally have no doubt about this.
Fan Power Minimum Flow Fraction: That's what I also want to know the answer. We might be able to refer to Section 6.5.3.2.1, but I have another suggestion. ASHRAE90.1 does not specify all the parameters for the Baseline case. Some parameters are not found such as Fan Total Efficiency, Pump Total Efficiency, Chiller Minimum Part Load Ratio, Chiller Minimum Unloading Ratio, etc. When I come across such unspecified parameters, I often refer to ANSI/ASHRAE/IES Standard 90.1 Performance Rating Method Reference Manual. The Table below is extracted from the Reference Manual. (b) is the curve of G3.1.3.15 Method 2.
Please note the rightmost column. %PowerMin is 20%. %PowerMin = Fraction of Full Load Fan Power * 100.Minimum Fraction of Full Load Fan Power.
The chart below is what I plotted the curve (b). The Minimum Fraction of Full Load Fan Power = 0.2. The Fraction of Full Load Airflow Rate corresponding to the Minimum Fraction of Full Load Fan Power of 0.2 is 0.393198 ≈ 0.4. So, I vote for Min Flow Fraction = 0.4, but I'm not that confident. Please take this as just one opinion.
