[Bldg-sim] Modeling CHP Plants serving Campus DES

[Dónal O'Connor]

Hi all,

I'm looking for guidance on the interpretation of CHP modeling according to Appendix B in the LEED Canada Interpretation Guide for District Energy Systems or Appendix D in the USGBC Treatment of District or Campus Thermal Energy in LEED v2 and LEED 2009 using the Method 2/Option 2 route.

For the project that I'm working on, metered data is available. Annual metered electricity consumption shows that the campus uses 73%
 of the electricity generated by the CHP plant with the remaining 27% 
coming from grid supplied electricity. So, I intend to use this fraction
 and apply it to the total electricity consumption of the proposed 
building. Charge the 27% at the local grid supplied electricity rates 
and charge the remaining 73% CHP generated electricity based on Annual 
Fuel Input Cost to CHP ($)/Annual CHP Electricity Generation (kWh).


Again from metered data, 67% of the heating energy supplied to the 
DES is from the waste heat generated by the CHP plant. The remaining 33%
 is provided by backup boilers using grid supplied natural gas. So 67% 
of the proposed building's heating energy will be "free" with the 
remaining 33% charged based on local natural gas utility rates. I'm setting the proposed boiler efficiency equal to the back up boiler efficiency.


The baseline building heating and electricity consumption will be charged at the local utility rates.

Is this methodology acceptable for the proposed model? I'm not sure if I should be using the formulas provided in the Appendix to calculate CHP Electric Output and CHP Fuel Input? Are these formulas to be used when metered data is not available?


Thanks

Dónal
 		 	   		  
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