Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
There is description in the EnergyPlus Input/Output Reference for the Nominal Thermal Efficiency field here:
This required numeric field contains the heating efficiency (as a fraction) of the boiler’s burner. This is the efficiency relative to the higher heating value (HHV) of fuel at a part load ratio of 1.0. Manufacturers typically specify the efficiency of a boiler using the higher heating value of the fuel. For the rare occurrences when a manufacturers (or particular data set) thermal efficiency is based on the lower heating value (LHV) of the fuel, multiply the thermal efficiency by the lower-to-higher heating value ratio. For example, assume a fuel’s lower and higher heating values are approximately 45,450 and 50,000 kJ/kg, respectively. For a manufacturers thermal efficiency rating of 0.90 (based on the LHV), the nominal thermal efficiency entered here is 0.82 (i.e. 0.9 multiplied by 45,450/50,000). Note that a nominal efficiency greater than 1.0 is allowed for special applications, but will generate a warning.
