A building that is being certificate under LEED 2009 will be built in a campus with a dedicated District Energy System (DES) based on a combined heat and power plant (CHP). This DES is working for more than 5 years, serving several other buildings that started its activity along with the DES.

LEED Guidance for this case (Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction, August 2010 – APPENDIX D) states that CHP electricity shall be allocated to the Proposed Building in the proportion of heat used by it. The question is how to calculate the proportion of heat that the new building will use (please note that historic data from the DES only accounts for the existing buildings only). Our proposal is:

1) If the DES system has capacity to feed the 100% of the new building heating needs (calculated by energy simulation), then we will make the calculation assuming that 100% of the proposed building heating needs will be fed by the DES. Heating energy use of the other buildings will remain the same;
2) If the DES system has not capacity to feed 100% of the new building heating needs (calculated by energy simulation), then we will make the calculation assuming that the proposed building will use all the capacity of the DES that is now available. DES heating energy supply to the existing buildings will remain unchanged.

Do you agree with this option ?