Heat pumps (HP) will dominate the heating of buildings in the future, at least in places where district heating is not available. However, the implementation of HPs into existing buildings in an urban environment is challenging and involves a wide range of decisions. In order to be able to offer targeted planning in an early but essential decision-making phase, engineers (buildings physics, HVAC, energy consultant) must be able to rely on planning tools and databases and cooperate in an integral design process right from the start. A workflow was developed with which different variants of thermal renovation (i.e. renovation deepness and degree of invasiveness) and different HP system solutions for multi-apartment residential buildings (i.e. central, semi-central, decentralized, mixed) as well as integration of onsite renewables (i.e. PV and storage) can be evaluated, compared and optimized. This includes the distribution and storage losses as well as the efficiency of the HP depending on the required flow temperature as a function of the heat emission systems and the heating load of the building. Based on the suggested workflow a holistic planning tool is being developed which represents a step towards a Digital Twin if integrated into the building energy management system.