Output from the calculations

Output from the calculations The model calculates the energy use and losses based upon constant fractions. The fraction of the energy use and the different losses is displayed by the model. A diagram shows the energy supply per temperature bin and how it is covered from different energy sources.  The seasonal energy efficiency, etas, is calculated.  
Etas = Lh/Qtot+cctrl where Qtot=Lh + Lsys + Qgen + Qel
etas is the net space heating demand of the house over the sum of the generated heat of the system. Qtot is the sum of the space heating demand (Lh), the losses from the heating system (Lsys), the primary energy losses of the energy input to the system (Qgen) and the energy needed by the auxiliary equipment such as control and heat sink pumps (Qel).  
All electricity used by the heat pump and the backup heater is multiplied by a primary energy factor of 2.5. The model is not transparent. It is tricky to follow the outputs of the model since it consists from several excel-sheets and the information turns up all over. It is also difficult to understand all steps of the calculations. To be able to compare the results with field measurements and prEN14825 a value of SPF, the so called “average COP” (see the system boundaries) is calculated without the system losses. Average COP corresponds to SCOPnet in prEN14825.