This question relates to the thread below (“Absorption chiller in baseline model”) but is of more general nature. The district heating system uses waste and wood as fuel in addition to gas and oil. Our approach would be to replace waste and wood with oil and gas in the baseline model (DES model option 2). We already submitted a project using this approach and received certification. The GBCI stated in a CIR that ASHRAE 90.1 prohibits fuel switching. They refer to section G3.1.3.2 , “The boiler plant shall use the same fuel as the proposed design.”. This is pretty straight forward but…in table G3.1.1 B (system 7) a hot-water FOSSIL fuel boiler is required. These two requirements seem to be contradictive if the fuel in the proposed case is not fossil. Which is then the right one? In addition the GBCI refers the DES guide, section 2.4.2.2, which states: “For fuels used at the central plant that are not available at the building (e.g. diesel fuel), use the central plant rates for that fuel type in the Baseline and Proposed Case. ” To my understanding this applies only to pricing information if for example natural gas is not available at the certifying building. This section does not dictate fuel selection in the models, or do I get this wrong? In addition the GBCI states that that we may use alternative “code” efficiencies from European standards for wood and waste burning boilers as there are no minimum requirements in the ASHRAE 90.1 (which we argued) to obtain the fuel price. Alternatively we may calculate the prices based on primary energy factor and carbon emissions as a one-time exception for this project only. We understand that it is difficult to apply the ASHRAE 90.1 to European district heating but we don’t think project specific alternatives in CIRs are a good way. Any views or comments on that? As we already certified a building using the same approach we ask ourselves if the GBCI changed some internal guidelines or do reviewers take a different approach now?
LEEDuser Basic Member
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