We are certifying a project that is being developed in a site that comprises a District Energy System based on a Combined Heating and Power Plant (DES-CHP). DES-CHP thermal energy is directly supplied and sold to all the buildings in the site (including the building that is under certification) while electricity is exported to the grid.

According to the USGBC guidance document “Treatment of District or Campus Thermal Energy in LEED v2 and LEED 2009 – Design&Construction” (13th, August 2010) one of the criteria to determine if the DES-CHP upstream equipment shall be included in the scope of commissioning is the percentage of the project building’s annual energy cost supplied by DES-CHP.

My doubt relates with how to calculate the cost associated with the DES_CHP:

  1. Only the cost of the thermal energy sold by the DES-CHP to the building ? In this case, which energy rate shall be used ? The real one ?
  2. Costs of the thermal energy sold by the DES-CHP to the building PLUS the cost of the fraction of the electricity produced by the DES-CHP that can be allocated to the building ? In this case, can we calculate the fraction of the electricity produced by the DES-CHP that is allocated to the building using the methodology described in Appendix D of the guidance document above referred (based on the fraction of heat used by the building) ?
  3. Only the fuel cost of the DES-CHP, calculated using the methodology described in Appendix D of the guidance document above referred ?