The requirements for KfW55 remain the same as before, to my knowledge, even after 01.04.16. The tightening of KfW is only spoken/written about because from 01.04. at least KfW 70 must be built and this is no longer eligible for funding. If one planned to build KfW 55 anyway, nothing becomes more stringent. With a heat pump, it even improves, as the primary energy factor of electricity improves. The alternative proof for KfW55 using reference values is a simplified procedure where the calculations are not as complex. Only the individual components (wall, roof, ceiling, windows, etc.) must meet a minimum U-value, without the entire house having to be calculated in detail. Please correct if this is not the case. Thank you