Wrong return temperature calculation if using virtual backup heater

[StGoebel]

• For test point E with virtual booster heater parametrization of 𝑈𝐴_HB not correct in building model v0.1 e6ac1aa
• Calculated heat transfer between transfer system and building does only consider measured supply temperature but not the virtual temperature behind the booster heater
• Following equations has to be changed:
• $\dot{Q}_\mathrm{HB} = UA_\mathrm{HB}\left( \frac{\vartheta_\mathrm{S} + \Delta \vartheta_\mathrm{BUH,calc}(t)+ \vartheta_\mathrm{H}}{2} - \vartheta_\mathrm{B} \right)$ with
• $\Delta \vartheta_\mathrm{BUH,calc}(t) = \frac{\dot{Q}_\mathrm{BUH,calc}(t)}{\dot{m} \cdot c_p}$